universe essay in english

• The Universe

The Universe is everything we can touch, feel, sense, measure or detect. It includes living things, planets, stars, galaxies, dust clouds, light, and even time. Before the birth of the Universe, time, space and matter did not exist.

The Universe contains billions of galaxies, each containing millions or billions of stars. The space between the stars and galaxies is largely empty. However, even places far from stars and planets contain scattered particles of dust or a few hydrogen atoms per cubic centimeter. Space is also filled with radiation (e.g. light and heat), magnetic fields and high energy particles (e.g. cosmic rays).

The Universe is incredibly huge. It would take a modern jet fighter more than a million years to reach the nearest star to the Sun. Travelling at the speed of light (300,000 km per second), it would take 100,000 years to cross our Milky Way galaxy alone.

No one knows the exact size of the Universe, because we cannot see the edge – if there is one. All we do know is that the visible Universe is at least 93 billion light years across. (A light year is the distance light travels in one year – about 9 trillion km.)

The Universe has not always been the same size. Scientists believe it began in a Big Bang, which took place nearly 14 billion years ago. Since then, the Universe has been expanding outward at very high speed. So the area of space we now see is billions of times bigger than it was when the Universe was very young. The galaxies are also moving further apart as the space between them expands.

Story of the Universe

• Extreme life
• In the beginning
• The Big Bang
• The birth of galaxies
• What is space?
• Black Holes
• The mystery of the dark Universe
• Cosmic distances

Geography Notes

Universe: essay on our universe | geography.

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Essay on Our Universe

Our Universe contains 176 billion (one billion = 100 crores) constellations (group of stars) and each constellation includes hundreds of billion stars. Universe consists, constellation, in which Sun exists, is so big that from the core of constellation, light takes around 27 thousand years to reach up to sun. The solar system which is part of Milky Way galaxy is in disc-shaped spiral form.

Essay # 1. Sun:

Sun rotates round its axis from West to East. About 99.85% mass of solar system lies with sun only whereas planets constitute – 0.135%, comets – 0.01%, satellites – 0.00005%, dwarf planets – 0.000002%, shooting stars – 0.0000001% and inter planetary medium consists of 0.0000001% of the rest of mass.

Sun is not stationery and completes one rotation round its own axis in 25 days. One rotation of sun takes 25 days (of Earth) if observed from the equator while if we observe it from its poles, each rotation of sun takes 36 days. The rotation of sun was observed by Galileo first of all.

Sun is source of light, heat, energy and life on our Earth. Normally looking pale, this spherical ball of fire has 13 lakh multiples more volume than that of Earth and 3.25 lakh times more weight. Pressure of gaseous material on its centre is 200 billion multiples more than the pressure of air, Earth experiences while density of gases is 150 times more than that of water. Temperature of sun is 50 lakh degrees Kelvin (one Kelvin is equal to one degree on Celsius scale).

Hydrogen in form of Plasma turns into Helium at this temperature. This fusion gives birth to energy. The quantum of such produced energy may be imagined from the fact that fusion produced energy in one second is more than as much mankind has used on Earth till date. This fusion is continuous process on the surface of Sun.

Gravity of Sun is 28 times more than that of earth and black spots visible on sun are actually very powerful magnetic regions. Each magnetic regions of sun is more than 10 thousand times more powerful than magnetic power of Earth. Actual size of each black spot may be lakhs of square kilometers. Temperature at photosphere of sun is only 6000° Kelvin while ends of chromospheres experience it 10 thousand degree.

At corona this temperature varies from 10 lakh Kelvin to 50 lakh Kelvin. Continuous winds blow at the surface of sun at speed of 800 to 900 kilometer per second and these may prove dangerous for Earth at times. These winds have their fatal effect on Ionosphere. Solar storms disturb communication system on Earth. Many a times, power grids get destroyed or seized because of disturbance at the surface of Sun.

Optical telescope at Udaipur and Kodyekanal along with Radio telescope at Pune keep continuous watch over happenings related to Sun.

Essay # 2. Planets:

Planet is a Greek word which means, Wanderer. All the planets are spherical and are total eight in number.

We can group these planets in two, that is:­

a. Inner Planets:

Inner planets are those planets which are nearer to sun as compared to others. Secondly their relief constitution includes rocks and metals. These planets are known as terrestrial planets also. Namely these planets are; Mercury, Venus, Earth & Mars.

b. Outer Planets:

Outer planets are beyond asteroids and are constituted of gases, popularly known as Gas Giants. These are; Jupiter, Saturn, Uranus and Neptune.

The planets do not have any light of their own but these illuminate by reflecting sunlight and are visible at night. In the sequence of their distance from sun, these may be retented from initial alphabets of words in this sentence; My Very Efficient Mother Just Served Us Nuts.

i. Mercury:

This planet is not only smallest one but also lies closest to Sun. It does not have atmosphere of its own and is engulfed by blasts taking place because of Sun. Its core is made of iron and has this part larger than crust.

It is presumed that this crust reduced due to some comet accident. Mercury lies some 579 million (57crore 90 lakh) kilometer away from Sun and its average temperature varies between 420°C during day to -180°C at night.

It completes its revolution around Sun in 88 days while takes 58 days and 16 hours to complete its one rotation on its axis. Galileo founded Mercury in 1631 which has no satellite.

This is a rocky celestial body like Earth and second planet if counted serial vise from Sun. It completes its revolution round sun is 224.7 days while takes 243 long days to complete its rotation round its own axis from East to West.

All the other planets rotate around their axis from West to East. This hottest planet is second most glittering celestial body, first being the Moon. Also known as sister planet of Earth, Venus resembles to it in shape, size and gravity.

It has a number of volcanoes just like Earth and its surface has been formed because of volcanic eruptions. Its atmosphere consists of Carbon dioxide (96.5%) and Nitrogen. That is why it is called ‘Veiled planet’ also. Venus lies nearly 1082 million kilometers away from Sun.

iii. Earth:

Our mother planet’s name has not been derived from Greek or Roman language but from old English and Germanic. According to International Astronomical Union (IAU) biggest among Inner planets, Earth is only planet which has Geological activity taking place in its core.

Its atmosphere is also quite different to that of other planets as it consists of 77% Nitrogen and 21% Oxygen which gives it a name of ‘blue planet’. Earth is only planet where life exists. Situated nearly 14.96 crore kilometers away from sun.

The earth completes a rotation round its axis in 23 hours, 56 minutes and 4.09 seconds (approximately 24 hours) while to revolve around the sun, it takes 365 days 5 hours and 48 minutes. It has a satellite named Moon.

Known as the Red Planet, Mars is fourth planet of our solar system as counted from Sun. Its soil has very rich iron content and because of Ferrus content it looks red. As far its rotation on axis is concerned, it has similarity with Earth and it supports various seasons also.

Mars is a cold planet which has thin atmosphere. Its one rotation on its axis is completed in 24 hours, 37 minutes and 23 seconds while its revolution against sun takes 687 days. Having two satellites, Mars is placed around 2279 lakh kilometer away from sun.

The success of India to plant its Orbiter in orbit of Mars in its just first attempt has made it a pioneer and an exceptional one. Mars is only planet other than Earth which has ice-caps on its poles which have been named as Planum Boreum (North Pole) and Planum Australe (South Pole) or Southern Cap. The spacecraft that reached in the orbit of Mars is named 440 Newton Liquid Apogee Motor (LAM).

v. Jupiter:

First beyond the Asteroids, Jupiter is fifth planet of our solar system and is the biggest planet. This planet is one of the Gas Giants and has 1280 kilometer wide atmosphere composed of gases like Methane, Ammonia, Hydrogen and Helium.

It revolves around the sun in anti-clockwise direction and completes one revolution in 12 years. Its rotation on its axis is very fast and completes one in just 10 hours causing severely blowing winds.

These winds look like multi-coloured cloud belts. Jupiter is tilted on its axis at 3.1° and has more than 60 satellites. Most of the satellites are unknown for mankind as far information about them is concerned.

vi. Saturn:

The sixth from sun and second largest planet in solar system is Saturn. Situated some 1,431 million kilometers (More than 143 crore km) away from Sun, it is constituted of iron and nickel principally. Completing its rotation on its axis in 10 hours and 41 minutes, it makes one revolution around Sun in 29.5 years.

Its swift rotation gives rise to winds at the speed of 1800 kilometers per hour. Speed of winds on Saturn is higher than that on Jupiter but lesser than that on Neptune. There are nine rings around Saturn which from three arcs around it. These rings are made of frozen ice and rocks. It has around 62 satellites and biggest among them is Titan which is almost double the size of Moon. The atmosphere of Titan is thicker than that of Earth.

vii. Uranus:

This is seventh planet of our Solar System and third largest planet. Its size is 63 multiples bigger than earth but in weight it is only 14.5 multiples than that of Earth. Constituted of gases, Uranus has coldest atmosphere as compared to all the planets and has an average temperature of 223°C. Many layers of clouds are found on Uranus.

Higher cloud formation consists of Methane gas while lower formation consists of water. Speed of winds on this planet is 250 meters per second while it is tilted at 97.77° on its axis. Revolving round sun in anti-clockwise direction, it completes one revolution in 84 years while for completing one rotation around its axis, it takes 10 hours and 48 minutes.

viii. Neptune:

Neptune resembles to Uranus as seen in the Solar System. But it is smaller than Uranus and its surface is more condense. Presence of Methane gas makes it look green. Winds blow at speed of 2100 kilometers per hour in the atmosphere of this planet.

The planet consists of around 900 full circles and various incomplete arcs. Situated approximately 4,498 million kilometer away from Sun, it completes one rotation its axis in 16 hours and a revolution around sun in 164.8 years. Neptune has 13 satellites while Triton and Neried are two main satellites.

There are various dwarf planets in our solar system, out of which only five have been recognised.

1. Pluto (Earlier know as ninth planet, was declared dwarf in August, 2006)

4. Make make

Essay # 3. Satellites:

Satellites are of two types, manmade and natural. Satellites are actually celestial objects that revolve around some other celestial object. Natural satellites rotate on their axis also. They neither have atmosphere nor light of their own but due to reflection of sunlight, they look illuminated.

Manmade satellites are made of aluminium or plastic and are hardened with help of carbonic sheets. They travel at the speed which is 10 to 30 multiples more than that of an aircraft. Humankind has been benefitted extremely by manmade satellites in fields of telecommunications, weather forecasting, geological activities and atmospheric activities among other fields. India fired its first satellite named Arya Bhatt in 1975 and since then, we have sent more than 75 satellites into the orbit.

Moon is natural satellite of our Earth. It is around 3,84,403 kilometers away from Earth and takes 27.3 days to complete its revolution around Earth. As yet mankind has touched only this celestial body i.e. Moon on 21st July 1969. Atmosphere of Moon is so thin that it weighs only 104 kilograms and gravity is only one sixth part of the gravity of Earth.

Essay # 4. Asteroids or Planetoids:

These are too smaller than planets of Solar System but bigger than Asteroids. These celestial bodies revolve round the sun in anti-clockwise direction. These rocky bodies are numerous and most of these are concentrated between Mars and Jupiter. Five of them namely Ceres, Pallas, Vesta, Hypiea and Euphrosyne have been recognised. European Space Agency has found water vapour on Ceres on 22nd January, 2014.

Essay # 5. Comets:

The word comet is derived from Latin word ‘Stella Cometa’ which means ‘hairy star’. These celestial bodies were part of sun earlier and are made of frozen gases, ice and small rocky substances. Head of comet is 16 million kilometers in diameter and is followed by cloud of misty substance looking like a tail.

This tail is also lakhs of kilometer long. Tail is never towards sun facing side of comet and shines with rays from Sun. Comet which passed through Solar System was first seen in 1705 and it passes close to sun after every 75.5 years. English scientist Edmond Halley founded it and it was therefore named Halley’s Comet.

Comets are being traced regularly. Their total number was 5,186 in August, 2014. Halley’s Comet was seen in 1910, then in 1986 and next it shall be sighted in 2062. Nucleus of Halley’s Comet is 16 x 8 x 8 kilometers and it is the darkest object in solar system. This comet is periodical one and may be sighted at specific intervals but all the comets are not periodical.

Essay # 6. Meteors or Meteorites:

One can see a streak of star light in the sky sometimes, it gives an impression that any part of star has broken away. These are actually meteorites. Parts of meteorites that remain unburnt and reach our Earth in small parts are named as meteorites.

When these enter the atmosphere of Earth, burn out immediately and vanish in shape of ash most of times. A part of Arizona desert in U.S. is known to have come into form due to striking of some meteor. There are, however, various principles about formation of meteors. Some thinkers part them parts of planet which has vanished while others say these are parts of Sun, Earth and Moon only.

Indian Museum at Kolkata is known for preserving remains of meteors. Biggest such museum in Asia, it has 468 meteor parts. Their study has concluded that meteors are made of metals like iron, nickel, aluminium, oxygen and tin.

These get attracted towards Earth because of gravity of Earth. On April 21, 2013 a meteor shower was observed in many parts of the world in which more than 20 shooting stars were seen within an hour. This shower is known as Orionid Meteor Shower. Such wonderful sights are very common in our solar system.

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M y most vivid encounter with the vastness of nature occurred years ago on the Aegean Sea. My wife and I had chartered a sailboat for a two-week holiday in the Greek islands. After setting out from Piraeus, we headed south and hugged the coast, which we held three or four miles to our port. In the thick summer air, the distant shore appeared as a hazy beige ribbon—not entirely solid, but a reassuring line of reference. With binoculars, we could just make out the glinting of houses, fragments of buildings.

Then we passed the tip of Cape Sounion and turned west toward Hydra. Within a couple of hours, both the land and all other boats had disappeared. Looking around in a full circle, all we could see was water, extending out and out in all directions until it joined with the sky. I felt insignificant, misplaced, a tiny odd trinket in a cavern of ocean and air.

Naturalists, biologists, philosophers, painters, and poets have labored to express the qualities of this strange world that we find ourselves in. Some things are prickly, others are smooth. Some are round, some jagged. Luminescent or dim. Mauve colored. Pitter-patter in rhythm. Of all these aspects of things, none seems more immediate or vital than size. Large versus small. Consciously and unconsciously, we measure our physical size against the dimensions of other people, against animals, trees, oceans, mountains. As brainy as we think ourselves to be, our bodily size, our bigness, our simple volume and bulk are what we first present to the world. Somewhere in our fathoming of the cosmos, we must keep a mental inventory of plain size and scale, going from atoms to microbes to humans to oceans to planets to stars. And some of the most impressive additions to that inventory have occurred at the high end. Simply put, the cosmos has gotten larger and larger. At each new level of distance and scale, we have had to contend with a different conception of the world that we live in.

T he prize for exploring the greatest distance in space goes to a man named Garth Illingworth, who works in a ten-by-fifteen-foot office at the University of California, Santa Cruz. Illingworth studies galaxies so distant that their light has traveled through space for more than 13 billion years to get here. His office is packed with tables and chairs, bookshelves, computers, scattered papers, issues of Nature, and a small refrigerator and a microwave to fuel research that can extend into the wee hours of the morning.

Like most professional astronomers these days, Illingworth does not look directly through a telescope. He gets his images by remote control—in his case, quite remote. He uses the Hubble Space Telescope, which orbits Earth once every ninety-seven minutes, high above the distorting effects of Earth’s atmosphere. Hubble takes digital photographs of galaxies and sends the images to other orbiting satellites, which relay them to a network of earthbound antennae; these, in turn, pass the signals on to the Goddard Space Flight Center in Greenbelt, Maryland. From there the data is uploaded to a secure website that Illingworth can access from a computer in his office.

The most distant galaxy Illingworth has seen so far goes by the name UDFj-39546284 and was documented in early 2011. This galaxy is about 100,000,000,000,000,000,000,000 miles away from Earth, give or take. It appears as a faint red blob against the speckled night of the distant universe—red because the light has been stretched to longer and longer wavelengths as the galaxy has made its lonely journey through space for billions of years. The actual color of the galaxy is blue, the color of young, hot stars, and it is twenty times smaller than our galaxy, the Milky Way. UDFj-39546284 was one of the first galaxies to form in the universe.

“That little red dot is hellishly far away,” Illingworth told me recently. At sixty-five, he is a friendly bear of a man, with a ruddy complexion, thick strawberry-blond hair, wire-rimmed glasses, and a broad smile. “I sometimes think to myself: What would it be like to be out there, looking around?”

O ne measure of the progress of human civilization is the increasing scale of our maps. A clay tablet dating from about the twenty-fifth century b.c. found near what is now the Iraqi city of Kirkuk depicts a river valley with a plot of land labeled as being 354 iku (about thirty acres) in size. In the earliest recorded cosmologies, such as the Babylonian Enuma Elish, from around 1500 b.c. , the oceans, the continents, and the heavens were considered finite, but there were no scientific estimates of their dimensions. The early Greeks, including Homer, viewed Earth as a circular plane with the ocean enveloping it and Greece at the center, but there was no understanding of scale. In the early sixth century b.c. , the Greek philosopher Anaximander, whom historians consider the first mapmaker, and his student Anaximenes proposed that the stars were attached to a giant crystalline sphere. But again there was no estimate of its size.

The first large object ever accurately measured was Earth, accomplished in the third century b.c. by Eratosthenes, a geographer who ran the Library of Alexandria. From travelers, Eratosthenes had heard the intriguing report that at noon on the summer solstice, in the town of Syene, due south of Alexandria, the sun casts no shadow at the bottom of a deep well. Evidently the sun is directly overhead at that time and place. (Before the invention of the clock, noon could be defined at each place as the moment when the sun was highest in the sky, whether that was exactly vertical or not.) Eratosthenes knew that the sun was not overhead at noon in Alexandria. In fact, it was tipped 7.2 degrees from the vertical, or about one fiftieth of a circle—a fact he could determine by measuring the length of the shadow cast by a stick planted in the ground. That the sun could be directly overhead in one place and not another was due to the curvature of Earth. Eratosthenes reasoned that if he knew the distance from Alexandria to Syene, the full circumference of the planet must be about fifty times that distance. Traders passing through Alexandria told him that camels could make the trip to Syene in about fifty days, and it was known that a camel could cover one hundred stadia (almost eleven and a half miles) in a day. So the ancient geographer estimated that Syene and Alexandria were about 570 miles apart. Consequently, the complete circumference of Earth he figured to be about 50 × 570 miles, or 28,500 miles. This number was within 15 percent of the modern measurement, amazingly accurate considering the imprecision of using camels as odometers.

As ingenious as they were, the ancient Greeks were not able to calculate the size of our solar system. That discovery had to wait for the invention of the telescope, nearly two thousand years later. In 1672, the French astronomer Jean Richer determined the distance from Earth to Mars by measuring how much the position of the latter shifted against the background of stars from two different observation points on Earth. The two points were Paris (of course) and Cayenne, French Guiana. Using the distance to Mars, astronomers were also able to compute the distance from Earth to the sun, approximately 100 million miles.

A few years later, Isaac Newton managed to estimate the distance to the nearest stars. (Only someone as accomplished as Newton could have been the first to perform such a calculation and have it go almost unnoticed among his other achievements.) If one assumes that the stars are similar objects to our sun, equal in intrinsic luminosity, Newton asked, how far away would our sun have to be in order to appear as faint as nearby stars? Writing his computations in a spidery script, with a quill dipped in the ink of oak galls, Newton correctly concluded that the nearest stars are about 100,000 times the distance from Earth to the sun, about 10 trillion miles away. Newton’s calculation is contained in a short section of his Principia titled simply “On the distance of the stars.”

N ewton’s estimate of the distance to nearby stars was larger than any distance imagined before in human history. Even today, nothing in our experience allows us to relate to it. The fastest most of us have traveled is about 500 miles per hour, the cruising speed of a jet. If we set out for the nearest star beyond our solar system at that speed, it would take us about 5 million years to reach our destination. If we traveled in the fastest rocket ship ever manufactured on Earth, the trip would last 100,000 years, at least a thousand human life spans.

But even the distance to the nearest star is dwarfed by the measurements made in the early twentieth century by Henrietta Leavitt, an astronomer at the Harvard College Observatory. In 1912, she devised a new method for determining the distances to faraway stars. Certain stars, called Cepheid variables, were known to oscillate in brightness. Leavitt discovered that the cycle times of such stars are closely related to their intrinsic luminosities. More luminous stars have longer cycles. Measure the cycle time of such a star and you know its intrinsic luminosity. Then, by comparing its intrinsic luminosity with how bright it appears in the sky, you can infer its distance, just as you could gauge the distance to an approaching car at night if you knew the wattage of its headlights. Cepheid variables are scattered throughout the cosmos. They serve as cosmic distance signs in the highway of space.

Using Leavitt’s method, astronomers were able to determine the size of the Milky Way, a giant congregation of about 200 billion stars. To express such mind-boggling sizes and distances, twentieth-century astronomers adopted a new unit called the light-year, the distance that light travels in a year—about 6 trillion miles. The nearest stars are several light-years away. The diameter of the Milky Way has been measured at about 100,000 light-years. In other words, it takes a ray of light 100,000 years to travel from one side of the Milky Way to the other.

There are galaxies beyond our own. They have names like Andromeda (one of the nearest), Sculptor, Messier 87, Malin 1, IC 1101. The average distance between galaxies, again determined by Leavitt’s method, is about twenty galactic diameters, or 2 million light-years. To a giant cosmic being leisurely strolling through the universe and not limited by distance or time, galaxies would appear as illuminated mansions scattered about the dark countryside of space. As far as we know, galaxies are the largest objects in the cosmos. If we sorted the long inventory of material objects in nature by size, we would start with subatomic particles like electrons and end up with galaxies.

Over the past century, astronomers have been able to probe deeper and deeper into space, looking out to distances of hundreds of millions of light-years and farther. A question naturally arises: Could the physical universe be unending in size? That is, as we build bigger and bigger telescopes sensitive to fainter and fainter light, will we continue to see objects farther and farther away—like the third emperor of the Ming Dynasty, Yongle, who surveyed his new palace in the Forbidden City and walked from room to room to room, never reaching the end?

Here we must take into account a curious relationship between distance and time. Because light travels at a fast (186,000 miles per second) but not infinite speed, when we look at a distant object in space we must remember that a significant amount of time has passed between the emission of the light and the reception at our end. The image we see is what the object looked like when it emitted that light. If we look at an object 186,000 miles away, we see it as it appeared one second earlier; at 1,860,000 miles away, we see it as it appeared ten seconds earlier; and so on. For extremely distant objects, we see them as they were millions or billions of years in the past.

Now the second curiosity. Since the late 1920s we have known that the universe is expanding, and that as it does so it is thinning out and cooling. By measuring the current rate of expansion, we can make good estimates of the moment in the past when the expansion began—the Big Bang—which was about 13.7 billion years ago, a time when no planets or stars or galaxies existed and the entire universe consisted of a fantastically dense nugget of pure energy. No matter how big our telescopes, we cannot see beyond the distance light has traveled since the Big Bang. Farther than that, and there simply hasn’t been enough time since the birth of the universe for light to get from there to here. This giant sphere, the maximum distance we can see, is only the observable universe. But the universe could extend far beyond that.

In his office in Santa Cruz, Garth Illingworth and his colleagues have mapped out and measured the cosmos to the edge of the observable universe. They have reached out almost as far as the laws of physics allow. All that exists in the knowable universe—oceans and sky; planets and stars; pulsars, quasars, and dark matter; distant galaxies and clusters of galaxies; and great clouds of star-forming gas—has been gathered within the cosmic sensorium gauged and observed by human beings.

“Every once in a while,” says Illingworth, “I think: By God, we are studying things that we can never physically touch. We sit on this miserable little planet in a midsize galaxy and we can characterize most of the universe. It is astonishing to me, the immensity of the situation, and how to relate to it in terms we can understand.”

T he idea of Mother Nature has been represented in every culture on Earth. But to what extent is the new universe, vastly larger than anything conceived of in the past, part of nature ? One wonders how connected Illingworth feels to this astoundingly large cosmic terrain, to the galaxies and stars so distant that their images have taken billions of years to reach our eyes. Are the little red dots on his maps part of the same landscape that Wordsworth and Thoreau described, part of the same environment of mountains and trees, part of the same cycle of birth and death that orders our lives, part of our physical and emotional conception of the world we live in? Or are such things instead digitized abstractions, silent and untouchable, akin to us only in their (hypothesized) makeup of atoms and molecules? And to what extent are we human beings, living on a small planet orbiting one star among billions of stars, part of that same nature?

The heavenly bodies were once considered divine, made of entirely different stuff than objects on Earth. Aristotle argued that all matter was constituted from four elements: earth, fire, water, and air. A fifth element, ether, he reserved for the heavenly bodies, which he considered immortal, perfect, and indestructible. It wasn’t until the birth of modern science, in the seventeenth century, that we began to understand the similarity of heaven and Earth. In 1610, using his new telescope, Galileo noted that the sun had dark patches and blemishes, suggesting that the heavenly bodies are not perfect. In 1687, Newton proposed a universal law of gravity that would apply equally to the fall of an apple from a tree and to the orbits of planets around the sun. Newton then went further, suggesting that all the laws of nature apply to phenomena in the heavens as well as on Earth. In later centuries, scientists used our understanding of terrestrial chemistry and physics to estimate how long the sun could continue shining before depleting its resources of energy; to determine the chemical composition of stars; to map out the formation of galaxies.

Yet even after Galileo and Newton, there remained another question: Were living things somehow different from rocks and water and stars? Did animate and inanimate matter differ in some fundamental way? The “vitalists” claimed that animate matter had some special essence, an intangible spirit or soul, while the “mechanists” argued that living things were elaborate machines and obeyed precisely the same laws of physics and chemistry as did inanimate material. In the late nineteenth century, two German physiologists, Adolf Eugen Fick and Max Rubner, each began testing the mechanistic hypothesis by painstakingly tabulating the energies required for muscle contraction, body heat, and other physical activities and comparing these energies against the chemical energy stored in food. Each gram of fat, carbohydrate, and protein had its energy equivalent. Rubner concluded that the amount of energy used by a living creature was exactly equal to the energy it consumed in its food. Living things were to be viewed as complex arrangements of biological pulleys and levers, electric currents, and chemical impulses. Our bodies are made of the same atoms and molecules as stones, water, and air.

And yet many had a lingering feeling that human beings were somehow separate from the rest of nature. Such a view is nowhere better illustrated than in the painting Tallulah Falls (1841), by George Cooke, an artist associated with the Hudson River School. Although this group of painters celebrated nature, they also believed that human beings were set apart from the natural world. Cooke’s painting depicts tiny human figures standing on a small promontory above a deep canyon. The people are dwarfed by tree-covered mountains, massive rocky ledges, and a waterfall pouring down to the canyon below. Not only insignificant in size compared with their surroundings, the human beings are mere witnesses to a scene they are not part of and never could be. Just a few years earlier, Ralph Waldo Emerson had published his famous essay “Nature,” an appreciation of the natural world that nonetheless held humans separate from nature, at the very least in the moral and spiritual domain: “Man is fallen; nature is erect.”

Today, with various back-to-nature movements attempting to resist the dislocations brought about by modernity, and with our awareness of Earth’s precarious environmental state ever increasing, many people feel a new sympathy with the natural world on this planet. But the gargantuan cosmos beyond remains remote. We might understand at some level that those tiny points of light in the night sky are similar to our sun, made of atoms identical to those in our bodies, and that the cavern of outer space extends from our galaxy of stars to other galaxies of stars, to distances that would take light billions of years to traverse. We might understand these discoveries in intellectual terms, but they are baffling abstractions, even disturbing, like the notion that each of us once was the size of a dot, without mind or thought. Science has vastly expanded the scale of our cosmos, but our emotional reality is still limited by what we can touch with our bodies in the time span of our lives. George Berkeley, the eighteenth-century Irish philosopher, argued that the entire cosmos is a construct of our minds, that there is no material reality outside our thoughts. As a scientist, I cannot accept that belief. At the emotional and psychological level, however, I can have some sympathy with Berkeley’s views. Modern science has revealed a world as far removed from our bodies as colors are from the blind.

V ery recent scientific findings have added yet another dimension to the question of our place in the cosmos. For the first time in the history of science, we are able to make plausible estimates of the rate of occurrence of life in the universe. In March 2009, NASA launched a spacecraft called Kepler whose mission was to search for planets orbiting in the “habitable zone” of other stars. The habitable zone is the region in which a planet’s surface temperature is not so cold as to freeze water and not so hot as to boil it. For many reasons, biologists and chemists believe that liquid water is required for the emergence of life, even if that life may be very different from life on Earth. Dozens of candidates for such planets have been found, and we can make a rough preliminary calculation that something like 3 percent of all stars are accompanied by a potentially life-sustaining planet. The totality of living matter on Earth—humans and animals, plants, bacteria, and pond scum—makes up 0.00000001 percent of the mass of the planet. Combining this figure with the results from the Kepler mission, and assuming that all potentially life-sustaining planets do indeed have life, we can estimate that the fraction of stuff in the visible universe that exists in living form is something like 0.000000000000001 percent, or one millionth of one billionth of 1 percent. If some cosmic intelligence created the universe, life would seem to have been only an afterthought. And if life emerges by random processes, vast amounts of lifeless material are needed for each particle of life. Such numbers cannot help but bear upon the question of our significance in the universe.

Decades ago, when I was sailing with my wife in the Aegean Sea, in the midst of unending water and sky, I had a slight inkling of infinity. It was a sensation I had not experienced before, accompanied by feelings of awe, fear, sublimity, disorientation, alienation, and disbelief. I set a course for 255°, trusting in my compass—a tiny disk of painted numbers with a sliver of rotating metal—and hoped for the best. In a few hours, as if by magic, a pale ocher smidgen of land appeared dead ahead, a thing that drew closer and closer, a place with houses and beds and other human beings.

December 2012

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Cosmic History

The Universe’s History

The origin, evolution, and nature of the universe have fascinated and confounded humankind for centuries. New ideas and major discoveries made during the 20th century transformed cosmology – the term for the way we conceptualize and study the universe – although much remains unknown. Here is the history of the universe according to cosmologists’ current theories.

Cosmic Inflation

Around 13.8 billion years ago, the universe expanded faster than the speed of light for a fraction of a second, a period called cosmic inflation. Scientists aren’t sure what came before inflation or what powered it. It’s possible that energy during this period was just part of the fabric of space-time. Cosmologists think inflation explains many aspects of the universe we observe today, like its flatness, or lack of curvature, on the largest scales. Inflation may have also magnified density differences that naturally occur on space’s smallest, quantum-level scales, which eventually helped form the universe’s large-scale structures.

Big Bang and Nucleosynthesis

When cosmic inflation stopped, the energy driving it transferred to matter and light – the big bang. One second after the big bang, the universe consisted of an extremely hot (18 billion degrees Fahrenheit or 10 billion degrees Celsius) primordial soup of light and particles. In the following minutes, an era called nucleosynthesis, protons and neutrons collided and produced the earliest elements – hydrogen, helium, and traces of lithium and beryllium. After five minutes, most of today’s helium had formed, and the universe had expanded and cooled enough that further element formation stopped. At this point, though, the universe was still too hot for the atomic nuclei of these elements to catch electrons and form complete atoms. The cosmos was opaque because a vast number of electrons created a sort of fog that scattered light.

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Recombination

Around 380,000 years after the big bang, the universe had cooled enough that atomic nuclei could capture electrons, a period astronomers call the epoch of recombination. This had two major effects on the cosmos. First, with most electrons now bound into atoms, there were no longer enough free ones to completely scatter light, and the cosmic fog cleared. The universe became transparent, and for the first time, light could freely travel over great distances. Second, the formation of these first atoms produced its own light. This glow, still detectable today, is called the cosmic microwave background. It is the oldest light we can observe in the universe.

After the cosmic microwave background, the universe again became opaque at shorter wavelengths due to the absorbing effects of all those hydrogen atoms. For the next 200 million years the universe remained dark. There were no stars to shine. The cosmos at this point consisted of a sea of hydrogen atoms, helium, and trace amounts of heavier elements.

First Stars

Gas was not uniformly distributed throughout the universe. Cooler areas of space were lumpier, with denser clouds of gas. As these clumps grew more massive, their gravity attracted additional matter. As they became denser, and more compact, the centers of these clumps became hotter – hot enough eventually that nuclear fusion occurred in their centers. These were the first stars. They were 30 to 300 times more massive than our Sun and millions of times brighter. Over several hundred million years, the first stars collected into the first galaxies.

Reionization

At first, starlight couldn’t travel far because it was scattered by the relatively dense gas surrounding the first stars. Gradually, the ultraviolet light emitted by these stars broke down, or ionized, hydrogen atoms in the gas into their constituent electrons and protons. As this reionization progressed, starlight traveled farther, breaking up more and more hydrogen atoms. By the time the universe was 1 billion years old, stars and galaxies had transformed nearly all this gas, making the universe transparent to light as we see it today.

For many years, scientists thought the universe’s current expansion was slowing down. But in fact, cosmic expansion is speeding up. In 1998, astronomers found that certain supernovae, bright stellar explosions, were fainter than expected. They concluded this could only happen if the supernovae had moved farther away, at a faster rate than predicted.

Scientists suspect a mysterious substance they call dark energy is accelerating expansion. Future research may yield new surprises, but cosmologists suggest it’s likely the universe will continue to expand forever.

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Black Holes

Origins of the universe, explained

The most popular theory of our universe's origin centers on a cosmic cataclysm unmatched in all of history—the big bang.

The best-supported theory of our universe's origin centers on an event known as the big bang. This theory was born of the observation that other galaxies are moving away from our own at great speed in all directions, as if they had all been propelled by an ancient explosive force.

A Belgian priest named Georges Lemaître first suggested the big bang theory in the 1920s, when he theorized that the universe began from a single primordial atom. The idea received major boosts from Edwin Hubble's observations that galaxies are speeding away from us in all directions, as well as from the 1960s discovery of cosmic microwave radiation—interpreted as echoes of the big bang—by Arno Penzias and Robert Wilson.

Further work has helped clarify the big bang's tempo. Here’s the theory: In the first 10^-43 seconds of its existence, the universe was very compact, less than a million billion billionth the size of a single atom. It's thought that at such an incomprehensibly dense, energetic state, the four fundamental forces—gravity, electromagnetism, and the strong and weak nuclear forces—were forged into a single force, but our current theories haven't yet figured out how a single, unified force would work. To pull this off, we'd need to know how gravity works on the subatomic scale, but we currently don't.

It's also thought that the extremely close quarters allowed the universe's very first particles to mix, mingle, and settle into roughly the same temperature. Then, in an unimaginably small fraction of a second, all that matter and energy expanded outward more or less evenly, with tiny variations provided by fluctuations on the quantum scale. That model of breakneck expansion, called inflation, may explain why the universe has such an even temperature and distribution of matter.

After inflation, the universe continued to expand but at a much slower rate. It's still unclear what exactly powered inflation.

Aftermath of cosmic inflation

As time passed and matter cooled, more diverse kinds of particles began to form, and they eventually condensed into the stars and galaxies of our present universe.

By the time the universe was a billionth of a second old, the universe had cooled down enough for the four fundamental forces to separate from one another. The universe's fundamental particles also formed. It was still so hot, though, that these particles hadn't yet assembled into many of the subatomic particles we have today, such as the proton. As the universe kept expanding, this piping-hot primordial soup—called the quark-gluon plasma—continued to cool. Some particle colliders, such as CERN's Large Hadron Collider , are powerful enough to re-create the quark-gluon plasma.

Radiation in the early universe was so intense that colliding photons could form pairs of particles made of matter and antimatter, which is like regular matter in every way except with the opposite electrical charge. It's thought that the early universe contained equal amounts of matter and antimatter. But as the universe cooled, photons no longer packed enough punch to make matter-antimatter pairs. So like an extreme game of musical chairs, many particles of matter and antimatter paired off and annihilated one another.

Somehow, some excess matter survived—and it's now the stuff that people, planets, and galaxies are made of. Our existence is a clear sign that the laws of nature treat matter and antimatter slightly differently. Researchers have experimentally observed this rule imbalance, called CP violation , in action. Physicists are still trying to figure out exactly how matter won out in the early universe.

A tiny, ghostly particle called a neutrino and its antimatter counterpart, an antineutrino, could shed some light on the matter, and two big experiments, called DUNE and Hyper-Kamiokande , are using these chargeless, nearly massless particles to try to solve the mystery.

Building atoms

Within the universe's first second, it was cool enough for the remaining matter to coalesce into protons and neutrons, the familiar particles that make up atoms' nuclei. And after the first three minutes, the protons and neutrons had assembled into hydrogen and helium nuclei. By mass, hydrogen was 75 percent of the early universe's matter, and helium was 25 percent. The abundance of helium is a key prediction of big bang theory, and it's been confirmed by scientific observations.

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Despite having atomic nuclei, the young universe was still too hot for electrons to settle in around them to form stable atoms. The universe's matter remained an electrically charged fog that was so dense, light had a hard time bouncing its way through. It would take another 380,000 years or so for the universe to cool down enough for neutral atoms to form—a pivotal moment called recombination. The cooler universe made it transparent for the first time, which let the photons rattling around within it finally zip through unimpeded.

We still see this primordial afterglow today as cosmic microwave background radiation , which is found throughout the universe. The radiation is similar to that used to transmit TV signals via antennae. But it is the oldest radiation known and may hold many secrets about the universe's earliest moments.

From the first stars to today

There wasn't a single star in the universe until about 180 million years after the big bang. It took that long for gravity to gather clouds of hydrogen and forge them into stars. Many physicists think that vast clouds of dark matter , a still-unknown material that outweighs visible matter by more than five to one, provided a gravitational scaffold for the first galaxies and stars.

Once the universe's first stars ignited , the light they unleashed packed enough punch to once again strip electrons from neutral atoms, a key chapter of the universe called reionization. Scientists have tried to glimpse this “cosmic dawn,” but the results have been mixed. Back in 2018, an Australian team announced detected signs of the first stars forming around 180 million years after the big bang, though other groups haven't been able to recreate their results. By 300 million years after the big bang , the first galaxies were born. In the billions of years since, stars, galaxies, and clusters of galaxies have formed and re-formed—eventually yielding our home galaxy, the Milky Way, and our cosmic home, the solar system.

Even now the universe is expanding . To astronomers' surprise, the pace of expansion is accelerating . Estimates of the expansion rate vary, but data from the James Webb Space Telescope adds to a growing body of evidence that it's significantly faster than it should be.

It's thought that this acceleration is driven by a force that repels gravity called dark energy. We still don't know what dark energy is, but it’s thought that it makes up 68 percent of the universe's total matter and energy. Dark matter makes up another 27 percent. In essence, all the matter you've ever seen—from your first love to the stars overhead—makes up less than five percent of the universe.

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• Introduction

Earliest conceptions of the universe

Astronomical theories of the ancient greeks.

• The system of Aristotle and its impact on medieval thought
• The Copernican revolution
• Kapteyn’s statistical studies
• Shapley’s contributions
• Hubble’s research on extragalactic systems

• What are the planets in the solar system?
• How did the solar system form?
• Why do stars tend to form in groups?
• Why do stars evolve?

Our editors will review what you’ve submitted and determine whether to revise the article.

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• Table Of Contents

universe , the whole cosmic system of matter and energy of which Earth , and therefore the human race, is a part. Humanity has traveled a long road since societies imagined Earth, the Sun , and the Moon as the main objects of creation, with the rest of the universe being formed almost as an afterthought. Today it is known that Earth is only a small ball of rock in a space of unimaginable vastness and that the birth of the solar system was probably only one event among many that occurred against the backdrop of an already mature universe. This humbling lesson has unveiled a remarkable fact, one that endows the minutest particle in the universe with a rich and noble heritage: events that occurred in the first few minutes of the creation of the universe 13.7 billion years ago turn out to have had a profound influence on the birth, life, and death of galaxies , stars , and planets . Indeed, a line can be drawn from the forging of the matter of the universe in a primal “ big bang ” to the gathering on Earth of atoms versatile enough to serve as the basis of life . The intrinsic harmony of such a worldview has great philosophical and aesthetic appeal, and it may explain why public interest in the universe has always endured.

The “ observable universe ” is the region of space that humans can actually or theoretically observe with the aid of technology. It can be thought of as a bubble with Earth at its centre. It is differentiated from the entirety of the universe , which is the whole cosmic system of matter and energy, including the human race. Unlike the observable universe, the universe is possibly infinite and without spatial edges.

This article traces the development over time of humanity’s perception of the universe, from prehistoric observations of the night sky to modern calculations on the recessional velocity of galaxies. For articles on component parts of the universe, see solar system , star , galaxy , and nebula . For an explanation of the scientific study of the universe as a unified whole, see cosmology . For an article about the possible existence of other universes, see multiverse .

All scientific thinking on the nature of the universe can be traced to the distinctive geometric patterns formed by the stars in the night sky. Even prehistoric people must have noticed that, apart from a daily rotation (which is now understood to arise from the spin of Earth ), the stars did not seem to move with respect to one another: the stars appear “fixed.” Early nomads found that knowledge of the constellations could guide their travels, and they developed stories to help them remember the relative positions of the stars in the night sky. These stories became the mythical tales that are part of most cultures .

When nomads turned to farming, an intimate knowledge of the constellations served a new function—an aid in timekeeping, in particular for keeping track of the seasons . People had noticed very early that certain celestial objects did not remain stationary relative to the “fixed” stars; instead, during the course of a year, they moved forward and backward in a narrow strip of the sky that contained 12 constellations constituting the signs of the zodiac . Seven such wanderers were known to the ancients: the Sun , the Moon , Mercury , Venus , Mars , Jupiter , and Saturn . Foremost among the wanderers was the Sun: day and night came with its rising and setting, and its motion through the zodiac signaled the season to plant and the season to reap. Next in importance was the Moon: its position correlated with the tides , and its shape changed intriguingly over the course of a month. The Sun and Moon had the power of gods; why not then the other wanderers? Thus probably arose the astrological belief that the positions of the planets (from the Greek word planetes , “wanderers”) in the zodiac could influence worldly events and even cause the rise and fall of kings. In homage to this belief, Babylonian priests devised the week of seven days, whose names even in various modern languages (for example, English, French, or Norwegian) can still easily be traced to their origins in the seven planet-gods.

The apex in the description of planetary motions during classical antiquity was reached with the Greeks , who were of course superb geometers . Like their predecessors, Greek astronomers adopted the natural picture, from the point of view of an observer on Earth , that Earth lay motionless at the centre of a rigidly rotating celestial sphere (to which the stars were “fixed”), and that the complex to-and-fro wanderings of the planets in the zodiac were to be described against this unchanging backdrop. They developed an epicyclic model that would reproduce the observed planetary motions with quite astonishing accuracy. The model invoked small circles on top of large circles, all rotating at individual uniform speeds, and it culminated about 140 ce with the work of Ptolemy , who introduced the ingenious artifact of displaced centres for the circles to improve the empirical fit. Although the model was purely kinematic and did not attempt to address the dynamical reasons for why the motions were as they were, it laid the groundwork for the paradigm that nature is not capricious but possesses a regularity and precision that can be discovered from experience and used to predict future events.

The application of the methods of Euclidean geometry to planetary astronomy by the Greeks led to other schools of thought as well. Pythagoras ( c. 570– c. 490 bce ), for example, argued that the world could be understood on rational principles (“all things are numbers”); that it was made of four elements—earth, water , air , and fire; that Earth was a sphere; and that the Moon shone by reflected light . In the 4th century bce Heracleides Ponticus , a follower of Pythagoras, taught that the spherical Earth rotated freely in space and that Mercury and Venus revolved about the Sun . From the different lengths of shadows cast in Syene and Alexandria at noon on the first day of summer, Eratosthenes ( c. 276–194 bce ) computed the radius of Earth to an accuracy within 20 percent of the modern value . Starting with the size of Earth’s shadow cast on the Moon during a lunar eclipse , Aristarchus of Samos ( c. 310–230 bce ) calculated the linear size of the Moon relative to Earth. From its measured angular size, he then obtained the distance to the Moon. He also proposed a clever scheme to measure the size and distance of the Sun. Although flawed, the method did enable him to deduce that the Sun is much larger than Earth. This deduction led Aristarchus to speculate that Earth revolves about the Sun rather than the other way around.

Unfortunately, except for the conception that Earth is a sphere (inferred from Earth’s shadow on the Moon always being circular during a lunar eclipse), these ideas failed to gain general acceptance. The precise reasons remain unclear, but the growing separation between the empirical and aesthetic branches of learning must have played a major role. The unparalleled numerical accuracy achieved by the theory of epicyclic motions for planetary motions lent great empirical validity to the Ptolemaic system . Henceforth, such computational matters could be left to practical astronomers without the necessity of having to ascertain the physical reality of the model. Instead, absolute truth was to be sought through the Platonic ideal of pure thought. Even the Pythagoreans fell into this trap; the depths to which they eventually sank may be judged from the story that they discovered and then tried to conceal the fact that the square root of 2 is an irrational number (i.e., cannot be expressed as a ratio of two integers ).

Illustration by Claire Scully

In the beginning

Cosmology has been on a long, hot streak, racking up one imaginative and scientific triumph after another. is it over.

by Ross Andersen   + BIO

One crisp day last March, Harvard professor John Kovac walked out of his office and into a taxicab that whisked him across town, to a building on the edge of the MIT campus. People were paying attention to Kovac’s comings and goings that week. He was the subject of a fast-spreading rumour. Kovac is an experimental cosmologist midway through the prime of a charmed career. He did his doctoral work at the University of Chicago and a postdoc at Caltech before landing a professorship at Harvard. He is a blue chip. And since 2009, he has been principal investigator of BICEP2, an ingenious scientific experiment at the South Pole.

Kovac had come to MIT to visit Alan Guth, a world-renowned theoretical cosmologist, who made his name more than 30 years ago when he devised the theory of inflation. Guth told Kovac to take the back steps up to his office, to avoid being seen. If Guth’s colleagues caught a glimpse of the two men talking, the whispers swirling around Kovac would have swelled to a roar.

The science of cosmology has achieved wonders in recent centuries. It has enlarged the world we can see and think about by ontological orders of magnitude. Cosmology wrenched the Earth from the centre of the Universe, and heaved it, like a discus, into its whirling orbit around one unremarkable star among the billions that speed around the black-hole centre of our galaxy, a galaxy that floats in deep space with billions of others, all of them colliding and combining, before they fly apart from each other for all eternity. Art, literature, religion and philosophy ignore cosmology at their peril.

But cosmology’s hot streak has stalled. Cosmologists have looked deep into time, almost all the way back to the Big Bang itself, but they don’t know what came before it. They don’t know whether the Big Bang was the beginning, or merely one of many beginnings. Something entirely unimaginable might have preceded it. Cosmologists don’t know if the world we see around us is spatially infinite, or if there are other kinds of worlds beyond our horizon, or in other dimensions. And then the big mystery, the one that keeps the priests and the physicists up at night: no cosmologist has a clue why there is something rather than nothing.

T o solve these mysteries, cosmologists must make guesses about events that are absurdly remote from us. Guth’s theory of inflation is one such guess. It tells us that our Universe expanded, exponentially, a trillionth of a trillionth of a trillionth of a second after the Big Bang. In most models of this process, inflation’s expansive kick is eternal. It might cease in particular parts of the cosmos, as it did in our region, after only a fraction of a second, when inflation’s energy transformed into ordinary matter and radiation, which time would sculpt into galaxies. But somewhere outside our region, inflation continued, generating an infinite number of new regions, including those that are roaring into existence at this very moment.

Not all these regions are alike. Quantum mechanics puts a slot-machine spin on the cosmic conditions of every region, so that each has its own physical peculiarities. Some contain galaxies, stars, planets, and maybe even people. Others are entirely devoid of complex structures. Many are too alien to imagine. The slice of space and time we can see from Earth is 90 billion light years across. Today’s inflationary models tell us that this enormous expanse is only one small section of one tiny bubble that floats along in a frothy sea whose proportions defy comprehension. This vision of the world is wondrous, in its vastness and variety, in the sheer range of possibilities it suggests to the mind. But could it ever be proved?

John Kovac had come to MIT to deliver good news. In 2009, Kovac and colleagues installed a telescope at the bottom of the Earth, and with it caught some of the oldest light in the Universe. He’d come to tell Guth that this light bore scars from time’s violent beginning, scars that strongly suggested the theory of inflation is true.

If the BICEP2 discovery held up, it would mint Nobel Prizes, and his would be the first

That same week, Chao-Lin Kuo, one of Kovac’s collaborators, paid a similar visit to Andrei Linde, another pioneer of inflationary theory. Kuo surprised Linde at his home, not far from Stanford’s sunny Silicon Valley campus. He brought a cameraman to record the moment for posterity, and a bottle of Champagne. When he knocked on Linde’s door, Linde and his wife answered. ‘I have a surprise for you,’ Kuo said. Linde’s wife, Renata Kallosh, who is also a physicist, was the first to react. She closed her eyes and hugged Kuo. Linde was stunned. ‘What?!’ he said, before asking Kuo to repeat the data. Soon, they were drinking Champagne, and Linde was effusive. ‘If this is true,’ he said, ‘this is a moment of understanding of nature of such magnitude, it just overwhelms.’

Back at MIT, Guth grilled Kovac with question after question, feeling around for weaknesses in the data. Guth would want to be sure. If the BICEP2 discovery held up, it would mint Nobel Prizes, and his would be the first. It would mean that an extraordinary idea entered human culture by way of his imagination. After more than an hour of interrogation, Guth relented. He could find no fault with the data.

A week later, the BICEP2 team went public, sparking a rare media event for the cerebral science of cosmology. In a front-page story for The New York Times Magazine , Kovac was quoted saying there was a one-in-10-million chance that the result was a fluke. The MIT physicist Max Tegmark told the Times that Kovac’s work would be one of the greatest discoveries in the history of science, ‘if [it] stays true’. For a time, it seemed as though cosmology had once again delivered a new cosmos.

W hen you read that word cosmos , you might begin to imagine the most expansive physical world your mind can build. Deep fields of glittering, star-filled galaxies stretching out in every direction, and maybe into forever. But even that image represents only the barest sliver of what is meant by ‘cosmos’. To build a cosmos, you have to extend your imagination to all of space and all of time. Only one of Earth’s creatures can pull off that cognitive trick. All living things are attuned to their environment: bacteria can sense chemical shifts in their immediate surroundings; migrating birds know our planet well enough to wing annually across its whole face; dung beetles navigate by the light of the Milky Way. But only the human being lives inside a cosmos, and only recently.

By the end of the last Ice Age, humans had travelled to every continent on Earth except Antarctica. At some point during these prehistoric wanderings, we began to pay close attention to the celestial realm. There are hints of this in Paleolithic cave art, where we find the first etchings of the Moon and its phases, its cycling from silver sliver to illuminated whole, and back again. We see it in the stone pillars that humans hauled across landscapes, to form rings that tracked the Sun’s seasonal arcs through the sky.

But these clues are few and far between. They aren’t enough for us to sketch the wider cosmos that the prehistoric mind inhabited. The first cosmos we can confidently describe comes down to us from the Bronze Age, whose belief systems were caught and preserved, in a newly invented cultural amber called writing. Even these, we know only crudely. Just well enough to identify a few of their common elements.

The ancient cosmos was not a complex mathematical structure. It was a sensory world, stitched together from people’s everyday experiences, people who had never seen Earth’s curves from orbit, or the night sky as magnified by a telescope. The ancient cosmos had a beginning, a birth out of a formless state, usually an infinite liquid realm, or a chaotic void that would suddenly separate into opposites, like light and darkness, or fire and ice, or earth and sky. This separation concept is still with us today in scientific creation stories, which often invoke a primordial splitting of symmetries. But the ancient versions were much more vivid. In the sacred Sanskrit text the Rig Veda, the universe begins as a symmetrical orb of pure potential, an egg surrounded by an infinite amniotic sea, which splits into two bowls of earth and sky, with the yolk-like sun hovering somewhere in the middle.

The earth that emerged from this primordial separation was usually a flat, round disc, wrinkled by mountains, cut through with rivers, and surrounded by ocean on every side. Above this disc was the closed dome of the sky, and below it was an underground realm of equivalent size. Together, they formed a sphere. Every night, the sun would travel through the invisible underworld after teetering over the horizon’s edge. The ancients knew this because the sun reappeared at dawn on the earth’s opposite side.

The ancients imbued the cosmos with consciousness and agency. The sun became a person, and so did the ocean

Of course, the idea that there is a singular ‘ancient cosmos’ is a gross simplification. Not all were spheres. Each had its cultural quirks and oddities. But they did have one thing in common: they were all teeming with gods.

When ancient peoples sought to explain the more mystifying aspects of their environment, they projected their own nature onto the cosmos. They imbued the cosmos with consciousness and agency. The sun became a person, and so did the ocean. The ancient gods had human frailties, the sort you’d expect from a highly intelligent, highly social animal. They acted impulsively. They were jealous. Their mood swings determined events in the world. Earthquakes, droughts, storms, floods, and rainbows. Their conflicts would eventually bring about the world’s end, in a fiery battle between the twin human concepts of good and evil.

In some cases, a phoenix universe would arise from the ashes, taking its place in a series that had no beginning or end, an infinite multiverse in time. This cosmic cycle of destruction and rebirth would sometimes occur on human time scales, but in more imaginative traditions, it could span billions or even trillions of years. Among today’s physicists, there are some who still believe the cosmos cycles in and out of being in this way.

L ast November, I spent a week with Paul Steinhardt, the director of the Princeton Center for Theoretical Sciences. Steinhardt was one of the first high-profile physicists to question BICEP2’s findings in public. In a column for Nature last June, he said that the team’s analysis was seriously flawed. Few cosmologists were surprised. Steinhardt is inflationary theory’s most vocal critic, and has been for years. But perhaps critic is the wrong word. Apostate might be better, for Steinhardt was present at inflation’s birth. You might even say he midwifed it.

Steinhardt learned the art of theory at Caltech, at the feet of Richard Feynman, the charismatic Nobel Prize-winner and Manhattan Project veteran. As an evangelist for science, Feynman was second only to Carl Sagan and, even then, it’s a matter of taste. Feynman took Steinhardt under his wing, serving as his student thesis advisor, and his personal mentor. The two of them created a course together, a weekly meeting called Physics X where students would propose a question or some unexplained phenomenon, and then watch as Feynman riffed, hopping back and forth between disciplines with ease. The meetings were held in an old lecture hall with creaky wood benches, which is now named for Feynman. Steinhardt makes it sound like a grove outside Athens.

Steinhardt didn’t give much thought to cosmology until his postdoc days at Harvard, when he attended a talk by Guth. This was back in 1982, when Guth was a postdoc at Stanford, a ‘struggling postdoc’, according to Steinhardt.

‘Guth gave the most wonderful talk,’ Steinhardt told me. ‘He detailed his new theory of inflation from the ground up, including the basics of Big Bang cosmology, which I had never been exposed to.’

Guth explained that there were problems with Big Bang cosmology. For one, the Universe is mysteriously uniform in all directions. If you position telescopes at the North and South poles, and point each of them at a dark patch of sky, you can catch light from opposite ends of the Universe. If you measure the temperature of light from these regions, all the way out to eight digits, you’ll see the same number. This is mysterious because the two regions are separated by more than 20 billion light years, too far to have ever interacted in a way that would lead to such extraordinary equilibrium. It’s possible to generate a uniform universe such as ours within the standard Big Bang framework, but you have to carefully calibrate its initial conditions. You have to ‘fine-tune’ it.

Guth said the Big Bang’s problems could be avoided if the early universe had expanded, exponentially, so that its structure stretched and smoothed. He also said particle physics provided a mechanism for this expansion. But there was a catch: Guth couldn’t figure out how the expansion would end.

Within a few years, ‘eternal inflation’ was ascendant. A decade later, it was the sexiest idea in cosmology. Today, it is virtually a paradigm

‘It was the most exciting and most depressing talk I had ever been to,’ Steinhardt told me. ‘I couldn’t believe that such a sweet idea would have such a sour ending.’

Steinhardt decided to take a few weeks off, to brush up on astrophysics and cosmology, and to see if he could come up with a workaround for Guth’s problem. Weeks turned into months. In the meantime, Steinhardt landed a professorship at the University of Pennsylvania, where he picked up a talented grad student named Andreas Albrecht. Together, the two men developed an inflationary model that allowed inflation to continue forever, generating an infinite, bubbly multiverse as it went along. Linde hit upon a similar idea a few months before, but he was in Moscow at the time. His work was still hidden behind the Iron Curtain. When Guth debuted the theory of inflation, it was widely seen as stillborn, but Linde, Albrecht and Steinhardt breathed new life into it. Within a few years, ‘eternal inflation’ was ascendant. A decade later, it was the sexiest idea in cosmology. Today, it is virtually a paradigm.

Steinhardt had everything to gain by continuing to champion inflation, but before long, the theory’s flaws began to nag at him. ‘I made the first eternal inflation model, but I left the problems for someone else to solve,’ he told me. When decades passed with no solutions, Steinhardt’s doubts grew. He began to wonder whether there might be another way to fix Big Bang cosmology. He wondered if there were previous Big Bangs before our Big Bang. He began working on a new theory. So far, the work has been lonely.

‘The last 30 years is a very unusual period in the history of fundamental physics and cosmology,’ Steinhardt told me. ‘There’s confusion, and maybe even a certain amount of fear. People are wedded to these ideas, because they grew up with them. Scientists don’t like to change ideas unless they’re forced to. They get involved with a theory. They get emotionally attached to it. When an idea is looking shaky, they go into defensive mode. If you’re working on something besides inflation, you find yourself outside the social network, and you don’t get many citations. Only a few brave souls are willing to risk that.’

I teased Steinhardt, pointing out that he hadn’t exactly been hauled before the Inquisition. Steinhardt is fully tenured, a lion of Princeton’s storied physics department. He walks the same leafy streets that Albert Einstein walked. Indeed, his official title at Princeton is Albert Einstein Professor in Science. Still, he feels overmatched. He told me he has asked for help from outside the field.

‘The outside community isn’t recognising the problem,’ he said. ‘This whole BICEP2 thing has made some people more aware of it. It’s been nice to have that aired out. But most people give us too much respect. They think we know what we’re doing. They take too seriously these voices that say inflation is established theory.’

I asked him who might help. What cavalry was he calling for?

‘I wish the philosophers would get involved,’ he said.

I n his magisterial history Conceptions of Cosmos (2006), the Danish historian Helge Kragh anoints cosmology ‘the most philosophical of sciences’. To create a cosmos, a story that encompasses the origins and ultimate fate of all that is, you have to leave established science behind. You have to face down the cold void of the unknown. Philosophers are always in a dogfight to prove their utility to society, but this is something they do well.

It was the philosophers of ancient Greece who first began to drive gods out of the cosmos. By explaining phenomena with natural laws instead of human-like personalities, Greek philosophers kicked off a slow rolling process that would, over millennia, reduce the world’s gods from many to a few. A trinity, perhaps. Or a lone deity. Or something more impoverished still: a first cause sitting outside space and time, its nature forever unknowable. For atheists, even this chilly, alien god is too much.

Thales of Miletus is generally thought to be the first natural philosopher. According to Plato, Thales was so dazzled by the stars that he once fell into a well while walking. According to Herodotus, the Greek father of history, Thales predicted a solar eclipse two years in advance. No one knows if these legends about Thales are true, but we do know that his habits of mind inspired a group of Greek philosophers who would, over the course of several centuries, develop a number of radical ideas about the cosmos. These philosophers were the first upright primates to understand that they stood on the surface of a sphere. Some of them suggested it might be spinning. Some knew the Moon wasn’t luminous, but merely a mirror for sunlight. A few famously argued that all of these things – the Earth, Moon, Sun, stars, and every other material body in existence – were composed of atoms that were too small to see, all moving around in a void.

Unlike Thales and Aristotle, Plato had no affection for the stars. He regarded them as mere ephemera compared with his pristine realm of ideas

When it came time to craft his cosmos, Aristotle took on a number of these ideas, but not all. He preferred the five elements of earth, water, air, fire and ether to a void filled with atoms. Aristotle’s cosmos is best imagined as a series of concentric spheres. The Earth was fixed at the centre. Whirling around it were spheres containing the Moon, Sun and stars. Aristotle’s Earth was made of degraded, decaying materials, but these outer spheres belonged to a separate, exalted realm. The outermost sphere of stars was most perfect of all, because nothing lay beyond it, and according to Aristotle, ‘that which contains is greatest’. Sealed in by the eternal stars, Aristotle’s cosmos was singular and complete. It was the only thing that ever was, and the only thing that ever would be.

Unlike Thales and Aristotle, Plato had no affection for the stars. He regarded them as mere ephemera compared with his pristine realm of ideas. He was a theorist’s theorist. ‘We shall dispense with the starry heavens if we propose to obtain a real knowledge of astronomy,’ he wrote in The Republic . And yet, according to Simplicius, it was Plato who saw the anomaly at the heart of the Earth-centred cosmos.

To see what Plato saw, imagine you were standing on the surface of Aristotle’s fixed Earth, gazing through the clear, rotating spheres that contained the Moon and the Sun, all the way out to the final sphere of stars. In the dark skies of antiquity, those stars would have been uncountable, but some of them would have stood out from the others. The most conspicuous was Venus, the star that shines brightest against dusk’s orange stripe, or when held aloft by dawn’s rosy fingers. The Greeks referred to Venus as a wanderer, a πλανήτης ( planitis ). Unlike the rest of the stars, which moved around in perfect, orderly circles, Venus would sometimes zig-zag as it made its way through the sky.

According to Simplicius, Plato challenged the stargazing philosophers of antiquity to reduce the ugly wanderings of Venus and the other planites to circles. Aristotle and the natural philosophers who followed him solved Plato’s problem by fine-tuning their cosmos in various ways. But none of their solutions satisfied. For nearly 20 centuries, the wandering of the planites would gnaw on astronomer’s minds. It would hang like a loose thread from the clean logical stitching of Greek cosmology, until Copernicus gave it a tug, and set the whole thing unravelling.

L ast October, John Kovac boarded an 18-hour flight from the United States to New Zealand, as he has every year since 1990. After touching down in Christchurch, he drove to a large warehouse, to be fitted with a fluffy red parka, military-grade snow boots, mittens, goggles and other extreme-cold weather gear. The next morning, he crossed the Southern Ocean in a military transport plane, before landing at McMurdo research station on the coast of Antarctica. The Southern Ocean is the violent, iceberg-strewn moat that encircles Antarctica. It is the only latitudinal band on Earth where there is no land to stop ocean winds from whipping furiously around the planet, stirring up storms as they go. These storms had waylaid Kovac at McMurdo before, but this year the weather was mild. He was cleared to leave the next morning, to complete the last leg of his trip.

No matter how jetlagged, Kovac always makes it a point to stay awake for this final flight. During the first two hours, the plane passes over hundreds of miles of blocky, blue-veined glaciers, before cresting over the Transantarctic Mountains, whose barren peaks once played host to thick forests and, during the early Jurassic, some of the first large dinosaurs.

The final hour is more monotonous, because Central Antarctica is an enormous plateau, blanketed by ice so thick, it conceals whole mountain ranges. Few microorganisms can survive there. Birds fly over only if they are blown off-course by a Southern Ocean storm. Human beings are the only resident land animals. Kovac told me the plateau’s featureless terrain makes him feel like he’s flying over a frozen white sea that seems to stretch forever. At the end of the flight, the plane dips and a long building on stilts appears in the porthole window, a building whose slate grey exterior and sleek Scandinavian angles make it look like a villain’s lair in a spy thriller. That’s when Kovac knows he’s reached South Pole Station.

The politics that govern land use on Antarctica are radical, relative to Earth’s other six continents. The first human visitors to Antarctica came to claim territory for crown or country but, in 1959, 12 nations signed a treaty that demilitarised Antarctica indefinitely, in order to preserve it for peaceful, scientific purposes. One of the finest achievements of Cold War diplomacy, the treaty transformed an object of imperial conquest into a commons for the collective human mind.

Kovac can still remember his first few trips to Antarctica, back in the early 1990s, when he slept in insulated tents left over from the Korean War. Now he bunks down at the new South Pole Station, a 65,000-square-foot facility, whose galley serves flank steaks, and vegetables grown locally in a hydroponic greenhouse on the station’s first floor, down the hall from the reading room and the sauna. Life at the South Pole still has its hardships. The scientists sleep on narrow beds in tiny, cubicle-like cabins, and are allowed only two short showers per week. Kovac told me his team puts in long hours, but he said he doesn’t mind the gruelling schedule, because his tasks are specific and discrete. He feels like he’s on a special mission.

If you’re at the bottom of the Earth, the view into the Universe doesn’t change much as the planet moves around in its orbit

One Friday last November, Kovac called me from South Pole Station, where it was 3am. I asked him how the night sky looked. I’d heard that the Milky Way was something to behold from Antarctica, especially when the auroras were dancing. Kovac gently reminded me that there is only one ‘night’ at the South Pole, and that it begins in February and ends in September. He stayed over at the Pole for one of these winter stretches, back in the 1990s, before he had kids. Winter temperatures on the plateau are too frigid for planes to fly, meaning there is no traffic in or out during the dark months. ‘It was like being on a submarine,’ Kovac told me. ‘Once was enough for me.’

Kovac did his winter stint back when he was a graduate student, when he was beginning to distinguish himself as a skilled designer of observatories. Instrument design is in Kovac’s blood. His late father Michael was dean of the engineering school at the University of Southern Florida. When John was 12, a teacher at his school gave him his first telescope. He set it up in his backyard, but quickly grew tired of using it. Gazing at celestial objects that others had already seen bored him, especially when he could see spectacular photos of those same objects in books. ‘But I was fascinated by the technology,’ he said. ‘I wanted to know everything about the construction of the telescope itself, and how it focused light.’

Kovac called me from a conference room that overlooks the main runway at South Pole Station. There wasn’t much action outside at that hour. He could see clear across the landing strip to the Dark Sector, a special zone where electromagnetic radiation is forbidden. Some of the world’s most sophisticated telescopes have been hauled down to the Dark Sector at great expense, because it’s one of the best places on this planet to do astronomy. If you’re at the bottom of the Earth, the view into the Universe doesn’t change much as the planet moves around in its orbit. You can train your telescope on the same celestial objects for months at a time, and you have a clear view, because Antarctica is a desert. Any mist that manages to levitate from its surface quickly freezes into ice crystals that free-fall back to Earth. If you think of our planet as an eyeball, the Antarctic plateau is its iris, and the Dark Sector its pupil. At its centre, Kovac had installed an exquisite telescope, and with it, he hoped to peer deeper into time than any human being in history.

T he cosmos that Kovac was peering into has changed radically since Classical antiquity. Aristotle’s elements of earth, air, water, fire and ether are gone, replaced by complex chemistry. The still Earth now spins. The spheres are in ruins. But we needn’t weep for the Greeks. They had a good run. Greek cosmology waned in influence during Rome’s slow fall, and was nearly lost during the Early Middle Ages, but it remained unsurpassed in sophistication until well into the 15th century.

The Christian church that came to power during late antiquity scoffed at Greek learning, especially natural philosophy. ‘What has Athens to do with Jerusalem?’ asked Tertullian, one of the Early Church fathers, a group whose most learned members knew ‘pitifully little’ about astronomy, according to historian Helge Kragh. When it came to cosmic matters, the Bible became the final authority. A few even regressed to belief in a flat Earth.

Only in the 12th century did learned Christendom read Aristotle and Ptolemy, and only because Islamic scholars rescued their works from oblivion. (Many of the stars in our star maps have Arabic names.) A century later, Christian thinkers were calling Aristotle ‘ The Philosopher’. Greek natural philosophy was like a smooth, black monolith that suddenly appeared in the midst of the Christian West, a gift from a futuristic people who happened to have lived 15 centuries prior.

Historians have fixed a permanent marriage between the name Copernicus and the word ‘revolution’, and rightly so, for Copernicus asked his readers to entertain radical notions. He knocked the Greek cosmos, saying it was needlessly complex, and therefore ‘insufficiently pleasing to the mind’. He also rebelled against an even more powerful and entrenched intellectual foe: human sense perception. Ever since the dawn of consciousness, humans had stood on firm ground, watching, as the Sun moved in its daily path from east to west, its arc across the sky rising in summer, and falling in winter. Copernicus said this was an illusion. It was the Earth that moved, at blazing speeds, around its own axis and around the Sun. These motions explained the zig-zagging of the planites simply, and besides, Copernicus argued: what better place for the Sun, ‘the lamp of this most beautiful world’, than at the centre, where it could illuminate the entire cosmos at once?

Copernicus was not the first to propose a heliocentric cosmos. The Greek astronomer Aristarchus devised a similar system in the 3rd century BC. But Copernicus had an advantage over Aristarchus. Copernicus had the luxury of living in the century that preceded Galileo’s first glance through the telescope. His writings persuaded Galileo, the first major figure of technological cosmology, to test his strange ideas.

Newton showed that Heaven and Earth belonged to the same jurisdiction: the cosmos was one

Copernicus didn’t dismantle the Greek cosmos entirely: he enlarged it, and dislocated the Earth from its centre, but he left the spheres intact. The real demolition work began when Galileo fixed his telescope on the ghostly stripe of light that rose into the sky above Florence on clear nights. The ancients compared this smear of light to spilled milk, but through his telescope Galileo saw that it was dense with stars that belonged to a larger structure, one that would come to be understood as an enormous disc, a galaxy in which the Sun enjoyed no privileged position.

Around this same time, Galileo’s friend Johannes Kepler began studying the planets, until he knew their movements well enough to establish his three laws of planetary motion. The third of these laws lodged itself in the extraordinary mind of Isaac Newton, and played muse to his universal law of gravitation, a theory whose philosophical import cannot be overstated. With a single, elegant equation, Newton explained the orbits of the planets and the falling of apples, and in doing so, dissolved Aristotle’s distinction between Earth and Heaven. Newton showed that both realms belonged to the same jurisdiction. The cosmos was one.

As telescopes swelled in size, from small tubes you could lift to your eye with one arm, to large wooden observatories that had to be navigated by ladder, they revealed new objects in the sky, including blurry blobs of light called ‘nebulae’. Many astronomers thought these mysterious nebulae were single stars surrounded by luminous fluid. They had forgotten Galileo’s lesson about milky white light: it often magnifies into stars.

In 1755, the German philosopher Immanuel Kant offered an alternative explanation for the nebulae, in an extraordinary new theory of the cosmos, which anticipated so much 20th-century science that it could rightly be called a vision. Kant’s cosmos began with a sea of particles, all at rest in an infinite void. As time passed, the denser particles in this sea attracted others, forming tiny clusters that scaled into orderly structures such as our planet, and its Sun, and the stars, and our galaxy – and the other galaxies, which were so distant that they appeared to us as faint and formless nebulae. Kant said that all these structures would decay over time, until the cosmos returned to its primordial state, before reconstituting itself again. He said the cosmos would do this an infinite number of times, with each cycle taking ‘whole myriads of millions of centuries’.

During the early decades of the 20th century, astronomers built enormous mountaintop observatories, to peer at nebulae through thin alpine air, to confirm that they were indeed galaxies, separated by voids so vast that photons take millions of years to cross them. Like the ancients, cosmologists wondered whether their cosmos had always existed, or if it evolved as Kant suggested. Aristotle thought the cosmos was eternal. The Stoics disagreed, arguing that erosion would have already planed down Earth’s mountains if the world had always existed in its present state. When Medieval Christians took up the Greek cosmos, they sided with the Stoics. They needed the world to have a starting point in time, to stay faithful to the Genesis creation myth. Perhaps, then, we should not be surprised that it was a priest, a Belgian named Georges Lemaître, who gave our cosmos its beginning, which eventually came to be called the Big Bang.

By the early 20th century, telescopes were seeing the deep sky in high definition. Galaxies were sharpening into gorgeous ellipses and spirals, like M51, whose whirlpool swirls inspired Van Gogh’s Starry Night (1889). Galaxies were also giving off a special kind of light, a downshifted hue that suggested they were speeding away from Earth, in the same way that a waning ambulance siren tells you it’s moving away. Using Einstein’s equations, Lemaître deduced the relationship between a galaxy’s speed of retreat and its distance. The farther they were, he discovered, the faster they were flying away, and that meant the Universe was expanding. Remarkably, Lemaître also claimed this expansion was accelerating, a prediction that would not be confirmed until the close of the 20th century, when astronomers lofted a telescope above the mountaintops, and into outer space, in order to clock the speed of receding galaxies, by catching light from their exploding stars.

Today’s cosmologists use computer simulations to fast-forward this accelerating expansion, to show that it will one day rip every galaxy from view, stranding us in the same lonely cosmos we lived in before the telescope was invented. Lemaître was more interested in what happened when you rewound the tape. If galaxies were flying apart, he reasoned, they must have once been closer together. Push further back in time and the Universe would have been hotter and denser still. Rewind all the way to the beginning, and every planet, star and galaxy would be compressed into a ‘cosmic egg’ that would detonate at the moment of creation, with a flash so bright that its light would fill all of space, where it would linger, cooling and thinning, before vanishing altogether, one trillion years from now.

W hen he is not at the South Pole, Kovac teaches a class at Harvard called Applied Astrophysics 191. Students in this class are required to build a radio antenna with basic, inexpensive materials, mostly stuff you can buy at RadioShack. For the penultimate class meeting, Kovac invites the emeritus physicist Robert Wilson to guest-lecture. The students listen carefully to Wilson. With their shoestring detectors, they are trying to replicate an experiment that Wilson and his colleague Arno Penzias conducted in 1964, when they set out to measure the invisible radio waves that stream from the Milky Way’s centre.

To make this measurement, Wilson and Penzias had to account for interference from other sources of radiation. There was one electromagnetic source they couldn’t identify, or get rid of. They tried pointing their antenna at different parts of the sky, but this radiation was stubborn. It showed up everywhere. It seemed to permeate the entire Universe. When they measured its temperature, Wilson and Penzias realised it matched a signal that theorists first predicted back in the mid-1940s. By sheer accident, they’d found the thinning, cooling flash from Lemaître’s Big Bang.

The Big Bang is a story about entropy. Rewind time, Lemaître said, and the cosmos got hotter, denser, more energetic. During its first few hundred thousand years, it was a frenzied plasma, a stew of elementary particles that was too hot and chaotic to consolidate into atoms. Only after the cosmos cooled and expanded could electrons join protons to form hydrogen atoms, creating space for light to roam free. The photons that poured into the void at that moment have been travelling across the Universe ever since. Catch them with a detector and you can see, with your own eyes, the afterglow of the Big Bang. The physicist Paul Davies once quipped that this light has taught humanity ‘more about the creation and organisation of the Universe than 1,000 years of religion and philosophy’.

Kovac made his name as a scientist by helping to make extremely precise measurements of this afterglow, amid the rigours of the South Pole environment. That’s why he was tapped to lead BICEP2, an experiment that would train a telescope on a patch of sky for three years, in order to collect an exposure, a slowly compiled sheet of photons from the Big Bang’s afterglow.

According to most inflationary models, those photons would have encountered a universe that was still reeling from inflation, when they beamed off the primordial plasma. The Universe would have been awash in gravity waves, distortions in space-time that would spin the photons into a polarisation pattern, whose swirls would show up on Kovac’s sheet of light. You’d have to squint to see them. The swirling effect would be visible only in one out of every 30 million photons. To detect something so faint and ancient in the sky was ludicrous, a wild-goose chase, according to the late Andrew Lange, the beloved Caltech cosmologist who helped conceive the experiment. But it was a goose worth chasing. To see swirls in the afterglow would be to see through it, back to the Big Bang itself. That’s why so many experiments are hunting for them. And that’s why the BICEP2 team worried about being scooped when swirling patterns started to show up in their exposure in 2010, almost immediately after the telescope saw first light.

Kovac thinks of himself as a cautious scientist. He told me he was initially skeptical of the swirling signal. But then a year went by, and another, with each trip to the Pole bringing better news. The signal was strengthening. In a series of meetings, the BICEP2 team brainstormed ways to test and retest the signal. They took turns playing devil’s advocate, trying to come up with alternative explanations for the swirls. In December 2013, Kovac convened a group call to discuss the possibility of publishing. He was at the South Pole at the time. ‘I wanted to make sure everything was done properly,’ he told me. ‘I even wrote up notes about what I wanted to say.’ By the end of the call, the team felt they’d exhausted every possible challenge to the signal. ‘We decided it was real and it was on the sky,’ Kovac said.

A few months later, Kovac showed the finished paper to Guth, and a few days after that, Harvard’s astrophysics department released a statement saying it would hold a press conference to ‘announce a major discovery’. The statement set off a frenzy of speculation on Twitter and Facebook, and in physics departments worldwide. When Kovac and his team announced, the media was waiting, and the following day, Kovac’s name was on front pages across the globe.

Kovac told me his inbox was useless for weeks afterward. Of course it was. BICEP2 was a feel-good story. In an age of accelerators and telescopes that cost billions, BICEP2 made one of the most precise measurements in the history of astrophysics, for less than $10 million. And they did it with a tiny team. It took hundreds of scientists to hunt down the Higgs Boson, but BICEP2 needed only a few dozen to spot swirls in the Big Bang’s afterglow, swirls that Linde had described as ‘a smoking gun for inflation’ in a Stanford press release. People were calling it the discovery of the century. Time magazine reshuffled its annual list of the world’s 100 most influential people to include Kovac. He attended the gala in black tie.

BICEP2’s signal could have been contaminated by the dust that hangs between stars

But that was in April 2014, during the honeymoon period. In May, a handful of prominent cosmologists began to question the BICEP2 team’s interpretation of its results, and their decision to go public before their paper was peer-reviewed. In June, Kovac was invited to the World Science Festival, to sit on a panel with Guth, Linde and everyone’s favourite inflation skeptic, Steinhardt. Most of the discussion was a victory lap for BICEP2 and inflation. But toward the end, Steinhardt and Kovac had a tense exchange, when Steinhardt asked Kovac if he was still confident that his signal was caused by gravity waves from inflation, ‘now that [he’d had] some feedback’.

The previous month, Steinhardt’s colleague David Spergel co-authored a paper suggesting that BICEP2’s signal could have been contaminated by the dust that hangs between stars in our galaxy. Spergel is one of cosmology’s alpha dogs. When he barks, people listen. His paper explained that the Milky Way’s magnetic fields spin galactic dust into swirling patterns. Starlight ricochets off this dust as a dim, swirling glow. Some of the photons from this glow might have slipped into BICEP2’s telescope undetected, and mixed with the Big Bang’s afterglow.

Most of this came as no surprise to Kovac. Like many cosmologists, he would love to put a telescope outside the Milky Way entirely. But we are stuck in our galaxy, so Kovac’s team picked a patch of sky that was thought to be relatively clear, and they spent months making models to account for what little dust was there. None of the models made a dent in the signal, but the models were speculative. They were based on dust estimates from past studies, whose uncertainties couldn’t be quantified. They were too weak to discount alternative interpretations of the data. Kovac was repeatedly asked about the dust in the weeks following the BICEP2 announcement. He always gave the same answer. He said it was disfavoured as an explanation ‘through multiple lines of reasoning’. He was wrong.

The BICEP2 team’s interpretation was already looking shaky in late June, when Steinhardt asked Kovac if his confidence had slipped. The month prior, a team from a competing experiment released new data on the dust. In September, they released another data set, which persuaded most cosmologists that BICEP2 could no longer distinguish its signal from the dust glow. This February, Kovac’s team published a paper admitting as much.

When Kovac went public last March, a few news reports noted that it was almost 50 years after Wilson and Penzias announced their discovery of the Big Bang’s afterglow. Now, a darker irony links the two announcements. Wilson and Penzias were trying to detect a signal from the centre of our galaxy, but they picked up a signal from the deep cosmos. The BICEP2 team made the opposite mistake.

K ovac took some heat in the media after his signal lost its revolutionary luster. But not all of it was deserved. You could blame the BICEP2 team for putting too much faith in their data analysis. You could blame them for throwing a bit of a party for themselves. But you had to admire the precision and economy of their measurement, and you couldn’t accuse them of scientific malpractice. These were first-class scientists, and they acted like it when the chips were down. They welcomed peer review. They revised their work quickly. The whole BICEP2 saga was, in many ways, a triumph for science. It showed precisely why science has become our supreme means of obtaining knowledge about the natural world.

When I visited Steinhardt in November, I expected him to come down hard on Kovac and his team. The original BICEP2 announcement was unwelcome news for inflation skeptics such as Steinhardt. He’d been suspicious from the outset. Even in June, when the narrative had barely begun to turn, he hadn’t hesitated to go after Kovac onstage. What would Steinhardt say now? Not much, it turned out: he went relatively easy on BICEP2. He saved his real ire for the theorists.

The BICEP2 signal caught inflationary theorists by surprise. That’s why Linde squawked ‘What?’ when Kuo came knocking on his door. That’s why he asked Kuo to repeat the data. Remember, there were several experiments looking for this result. So far, they hadn’t found much. In fact, they had established a low upper limit on swirls in the Big Bang’s afterglow – lower than predicted by most models of inflation, a theory that doesn’t make many testable predictions. When data from those previous experiments was released in 2013, Steinhardt pounced. He said it showed that inflation was in trouble. ‘They said I should stop being so negative,’ Steinhardt told me. ‘They said it was no problem. They said they could make models without gravitational waves.’

That’s why Steinhardt was surprised to see inflationary theorists clinking glasses when BICEP2 announced a high swirls figure. ‘They declared victory,’ he told me. ‘They said it was smoking-gun proof! Just what they expected!’

But then a few months passed and BICEP2’s interpretation started to look wobbly. In June, Linde told New Scientist that he didn’t like the way BICEP2’s swirls were being treated as a smoking gun for inflation. In July, Guth made similar statements to the Washington Post . Steinhardt was furious. He thought it was flip-flopping. He began to wonder if any data would disturb the serene certainty of inflationary theorists. ‘It was Andre Linde who used the “smoking gun” language in the first place,’ he told me. ‘Now he says it doesn’t make a difference what BICEP2 says. How can it be that not seeing gravitational waves is fine, and then seeing them is a smoking gun, and then not seeing them is fine again?’

Steinhardt told me that this flip-flopping on gravity waves is emblematic of inflation’s deeper flaws. Remember, inflation was originally designed to patch another theory’s fine-tuning issues. To produce the strange universe we see around us, you had to fine-tune the Big Bang. Inflation fixed that problem with a theoretical mechanism that briefly blew up the Universe like a balloon. But to produce a universe like ours, inflation’s initial conditions must also be precisely calibrated .

Eternal inflation is often invoked as a solution to inflation’s fine-tuning problem, because it spits out a multiverse, an infinite sea of cosmic regions, each with its own physical peculiarities. One with our peculiarities, our tuned initial conditions, is bound to show up somewhere. And even if such regions are rare, we are bound to inhabit one of them, for the simple reason that observers will only arise in regions with ‘Goldilocks’ conditions, just right to give rise to observers. In the lifeless regions, nature is not called ‘tuned’, or ‘designed’, or ‘beautiful’. She is not called Mother, because there is no one there to call her anything. But we observers should expect our region to look tuned. All observed regions of the cosmos look tuned .

The real trouble with the multiverse is that it can’t be tested, not yet. We can’t put a telescope in the regions outside ours

There are other theories of nature that treat fine-tuning as evidence in this way. Proponents of these theories will often trot out aspects of the natural world that seem too good to be true, and use them as evidence for an entity that can’t be sensed directly. Something as marvellous as the human eye could not have simply emerged from nature, they will say. It must have been crafted and honed by a mind like my own. Except it wasn’t. Eyes evolved, independently, on more than 40 branches of life’s tree. The eye looks designed to you because you do not understand the deeper properties of the world you inhabit. This is what usually happens to evidential fine-tuning. Science dissolves it into the clean, purring operations of nature’s fundamental laws. Fine-tuning usually signals weakness in a theory, not strength. When fine-tuning is used as evidence for a grand metaphysical apparatus capable of making anything and everything, it usually means that something has gone amiss.

There are other reasons one might be suspicious of the multiverse. This idea that the very existence of observers tells us something deep about the cosmos bears a disturbing resemblance to ancient anthropomorphic thinking. Once again, we find ourselves making grand, cosmic extrapolations from our own existence. Once again, the world is made in our image. The British philosopher Bertrand Russell had a great line on this sort of thinking: ‘All such philosophies spring from self-importance, and are best corrected by a little astronomy.’

But these are not knock-down arguments. They rely on innuendo and guilt by association. The real trouble with eternal inflation’s multiverse is that it can’t be tested, at least not yet. We can’t put a telescope in the regions outside ours. We have to look for evidence of the multiverse in our region. What should we look for? It’s hard to say, because the multiverse explores every combination of cosmic conditions an endless number of times. It’s not clear that any combination is likelier than any other. Theorists are trying to determine whether some conditions are more probable than others, but they haven’t succeeded yet, and there’s no guarantee they will. In the meantime, it’s hard to know whether inflation’s fine-tuning problems are genuine explanatory gaps that need exploring, or quirky outcomes of the quantum slot machine. The theory’s weaknesses can be explained away with the same glib shrug that accompanies the retort: ‘God just made it that way.’

A dominant, infinitely flexible multiverse theory could make it easy not to strain for the next leap forward. It could lead to a chilling effect on new ideas in cosmology, or worse, a creative crisis. Steinhardt thinks we’re already there. ‘Andre Linde has become associated with eternal inflation because he thinks the multiverse is a good idea,’ he told me. ‘But I invented it, too, and I think it’s a horrible idea. It’s an emperor’s new clothes story. Except in that story, it’s a child who points out that the Emperor has no clothes. In this case, it’s the tailors themselves telling us that the theory is not testable. It’s Guth and Linde.’

Steinhardt worries that science itself could be compromised. Science freed the imagination from cave shadows and shibboleths. Science let the mind run wild with radical ideas, ecstatic visions and new worlds, so long as those ideas explained what we actually see when we gaze out into nature. The Earth moves around the Sun: look how Venus wanders and you’ll see. The nebulae are distant galaxies, brimming with stars: magnify them and you’ll see. The Universe was once hot and dense, and has been expanding ever since: catch photons from its primordial flash and you’ll see. Science owes its epistemological gravitas to its stern insistence that every idea faces the firing squad of experiment. That is its philosophical backbone. That’s the methodology that gifted us the shimmering, intricate, expansive cosmos we live in today.

cosmologists should be searching for an alternative theory. They should not be waving away problems with the multiverse

That doesn’t mean that theorists should shackle their imaginations to the limits of today’s instruments. Atoms and black holes were both theoretical entities before they were observed. Reality is always grander than the world we can see. The Caltech cosmologist Sean Carroll has argued, persuasively, that we shouldn’t refuse to contemplate the existence of what we cannot sense directly ‘on the grounds of some a priori principle’ such as testability. Especially not in the theoretical realm, which is speculative by nature. But nor should we be blind to where a field’s leading theory is leading us.

Inflation could turn out to be right in the end. Some of its predictions have come true. At the moment, there is no alternative theory of the early Universe that explains more. But cosmologists should be searching for one. They should not be waving away inflation’s fine-tuning problems with the multiverse. Until eternal inflation is testable and tested, successfully, again and again, cosmologists should not allow it to monopolise the collective theoretical imagination. Inflation is a speculative theory, and it should be treated as such.

Steinhardt looks out on his field, and sees a generation of theorists tinkering with models, wasting whole careers fiddling at the edges of a 30-year-old idea. ‘I know why they’re doing it,’ he says. ‘It’s easy to do. You can make hundreds of these models, and you can tweak them so they fit the data. But usually, those fixes aren’t the answer. Usually, you have to do something new.’

Steinhardt is trying to do something new. He spends most of his research time working on an alternative cosmological theory. He thinks the Big Bang might have been a reaction to a contraction, a bounce, perhaps one in a sequence of bounces that extends deep into the past and maybe into eternity. He is trying to figure out whether a bounce could have yielded a smoothed, stretched, uniform cosmos such as ours. Sometimes he feels isolated, but he knows how to chip away. His sense of possibility powers him through. He told me he thinks we might be edging up to a transformative idea. Something that could rearrange reality as we know it. Something of Copernican magnitude.

‘We should be excited that inflation is in trouble,’ he said. ‘That usually means we’re on the brink of discovery. It means we’re missing some idea, a really important idea. Something that’s going to take over when it hits. Don’t people want to be there for that?’

As I walked out of Steinhardt’s office for the last time, it occurred to me that our cosmos is once again a sphere. Our Earth has been demoted in recent centuries. It no longer enjoys its former status as the still centre of all that is. But it does sit in the middle of our observable cosmos, the sphere of light that we can detect with our telescopes. Gaze into this sphere’s reaches from any point on Earth’s surface, and you can see light coming toward you in layers, from stars and the planets that circle them, from the billions of galaxies beyond, and the final layer of light, the afterglow of the Big Bang.

We might be trapped in this snow globe of photons forever. The expansion of the Universe is pulling light away from us at a furious pace. And even if it weren’t, not everything that exists can be observed. There are more things in Heaven and Earth than are dreamt of in our philosophies. There always will be. Science has limits. One day, we might feel ourselves pressing up against those limits, and at that point, it might be necessary to retreat into the realm of ideas. It might be necessary to ‘dispense with the starry heavens’, as Plato suggested. It might be necessary to settle for untestable theories. But not yet. Not when we have just begun to build telescopes. Not when we have just awakened into this cosmos, as from a dream.

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Essay on Our Universe

Students are often asked to write an essay on Our Universe in their schools and colleges. And if you’re also looking for the same, we have created 100-word, 250-word, and 500-word essays on the topic.

Let’s take a look…

100 Words Essay on Our Universe

What is the universe.

The universe is a vast space that holds everything we know – from tiny atoms to giant galaxies. It includes all of space, time, energy, and matter. Imagine it as a huge home where all the stars, planets, and moons live. It’s so big that we can’t see the end of it, and it’s always expanding.

Stars and Galaxies

Stars are like giant balls of gas that give off light and heat. They group together to form galaxies. Our sun is a star, and it’s part of a galaxy we call the Milky Way. There are billions of galaxies each with its own stars.

Planets and Moons

Planets are big objects that orbit, or go around, a star. Earth is a planet that goes around our sun. Some planets have moons, which are smaller objects that orbit planets. Just like Earth has one moon, other planets can have many.

The Mystery of Space

Space is full of mysteries. Scientists use telescopes to study far-away stars and planets. They’re trying to learn more about black holes, which are places in space where gravity is very strong, and about the possibility of life beyond Earth.

250 Words Essay on Our Universe

The big bang.

The universe began with a huge explosion called the Big Bang about 13.8 billion years ago. This explosion made all the space, time, matter, and energy in the universe. It started very small and hot, then cooled and stretched to become as big as it is now, and it’s still expanding.

Stars are huge balls of hot gas that give off light and heat. Our sun is a star. There are billions of stars in the universe. Stars group together to form galaxies. Our galaxy is called the Milky Way, and it has billions of stars too. There are so many galaxies we can’t count them all.

Planets are big objects that orbit, or go around, stars. Our Earth is a planet. Some planets have moons that orbit them. Moons are smaller than planets and there are hundreds of moons in our universe.

Exploring the Universe

Scientists use telescopes to look at stars, planets, and galaxies. They use space probes to explore things too far to see with telescopes. By studying the universe, we learn more about where we come from and our place in the cosmos.

500 Words Essay on Our Universe

Introduction to the universe.

The universe is like a huge home with many rooms, each filled with stars, planets, and all sorts of interesting things. Imagine looking up at the night sky. Every star you see is part of our universe. It is everything that exists, from the smallest ant to the biggest galaxy.

What’s in the Universe?

The size of our universe.

Think of the biggest thing you’ve ever seen. Now imagine something a million times bigger. Our universe is even larger than that! It’s so big that we measure how far things are in it with a special word: “light-year.” A light-year is the distance light travels in one year, and light is super fast!

The Beginning of Everything

A long time ago, scientists believe the universe started with a big bang. It wasn’t an explosion, but more like everything, all the space, time, and stuff that would become galaxies, started expanding from a tiny point. Since then, the universe has been getting bigger and bigger.

The Life of Stars

Humans have always been curious about the stars. We’ve used telescopes to look far away, and we’ve sent spacecraft to explore planets and moons. Some spacecraft, like the Voyager probes, have even left our solar system and are sending back information from beyond.

The Mystery of Dark Matter and Dark Energy

There are things in the universe we can’t see called dark matter and dark energy. We know they’re there because they affect how galaxies move and how the universe is growing. But what they are exactly is still a big question.

Our Place in the Universe

Our universe is a fascinating and mysterious place. It’s full of wonders that we are just beginning to understand. As we continue to look up at the stars and learn more, we realize how amazing it is that we are a part of something so vast and incredible. The universe is the biggest adventure waiting for us to explore.

That’s it! I hope the essay helped you.

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Situation Critical Fall 2016

Between Humans and the Universe: All We Have are the Connections We Make

What do we do with the universe.

“Wonder is the beginning of all wisdom,” says Aristotle in Metaphysics . “And looking into the starry sky is the beginning of wonder,” say I.

Andrew Yang starts his Interviews with the Milky Way by asking his mother, Ellen,

“ When you were a child, did you ever look up at the stars?”

For Ellen, childhood has long departed, as the moon has dyed all her hair. However, she answers with the greatest clarity,

“ Oh yes, oh yes,” she replies, “we were trying to see the milky way.”

Gazing into the sky and wondering about the universe is not an experience limited to any one generation. Andrew makes it clear that it is so profoundly shared by human beings that it almost becomes an instinct. Later in the interview, he talks about his daughter, Stella, who asks him since the outer space is above the sky, what is above the outer space.

The directional and intentional gaze into the night sky, then, is our first conscious encounter with the universe. Because of the gaze, the universe enters our sight and our mind. Now, it does not only objectively exist, but also exists to us .

In our galaxy, there are at least 100 billion stars. In an infant, hydrogen makes up 9.5% of its body weight, carbon, 18.5%, and oxygen, 65%. In A Beach and All Things Being Equal , we are educated of these pieces of information.

While it is true that wisdom starts with wonder, it does not end with wonder. Instead, we study and seek answers to our wonders. Just like Jeff, an astrophysicist says in Interviews with the Milky Way , “The most important thing you know about the universe is that, it is comprehensible.” That is, we can know about the universe.

After we gaze at things in the universe, we name them, analyze them, and attach information to the names. As a result, we pin the things down, and “know” the universe. In other words, things in the universe do not disappear or get lost as we move our eyes away, but are captured by us because we “know” them, just as Andrew makes a beach of 100 billion grains of sand, and just as he lists the chemical component of his daughter.

We Identify

In All Things Being Equal , tap water, rock sugar, canola oil, powdered L-Arginine, three oyster shells, baking powder and vinyl are placed in seven glass containers. According to a calculation next to the piece, these object and Andrew’s daughter, the new-born Stella share 99% of chemical elements.

In The Way Within , we see a table of objects ranging from a rock to a juice container, from a shell fish to a Ming lock, and from maple leaves to Lego pieces. All objects are mild in color, with pale turquoise on one side of the table, and blanched almond on another. When placed together, they display a surprising unity. At a point, you feel they are more similar than different because of their color, shape, size, and even the vibes they are giving out, and the distinction between “natural” and “man-made,” between “nature” and “culture” starts to seem arbitrary.

In Interviews with the Milky Way , Jeff agrees that he sometimes “thinks of himself as the Milky Way,” whereas Ellen calls the Milky Way “the ultimate life giving entity,” that is, a mother just like herself.

As we gather more facts and know more about the universe, we naturally form feelings about it and express them. Andrew’s art is one such example, announcing this sense of identification:

Our bodies are similar to the bodies of other galactic matters. Our products of culture are similar to the products of nature. We are similar to the universe.

All We Have are the Connections We Make

Andrew’s project walks us through what we do with the universe, from gazing, to knowing, to identifying. The underlying and overarching in all three becomes more evident as we go further. That is, they are all ways in which we connect with the universe, and one deeper than another.

By gazing, we connect. We stretch the invisible line between our eyes and the object, and realize not only we ourselves exist, other things in the universe, too, exist. That is, we share the time and space with objects in the universe.

By knowing, we connect. We use the human faculty to understand, so that objects reside in our minds as ideas. That is, we incorporate as part of us the objects in the universe.

By identifying, we connect. We acknowledge shared natures we have with objects in the universe. That is, we are the objects in the universe.

Andrew’s project not only reminds us of these connections, but also their importance. Being vast and grand, the universe does not intimidate us mortal beings. Instead, it empowers us. On the one hand, we are promised of knowledge, that we can know things beyond ourselves. Jeff says that because studying the universe makes him realize he is able to contemplate about things beyond himself and beyond people, it gives him a sense of “wellbeing.” On the other hand, we are assured of company, that we are not the lonely powerless beings, but have connections to something eternal. Ellen says that when she dies, rather than going to the heaven, she would prefer to be attached to a star, and that would make her “feel better.”

In other words, through the connections with the universe, we are able to obtain knowledge and feel that we belong, both conducive to happiness. And happiness, according to Aristotle, is the ultimate human end.

To Connect, to Connect Deeper

The project, however, is not just a reminder. Instead, it encourages, and even urges us to actively make these connections ourselves because these connections do not necessarily come naturally. As Ellen remarks, “Where I lived the sky was clear. You could see stars. But when [Stella] looks into the sky, she sees something entirely different than I did at the same age.” Andrew addresses the issue that light pollution denies access to the night sky from urban dwellers, and creates A Beach to “substitute” the Milky Way. The installation of seven tons of sand, although of course not the Milky Way, pushes the urban dwellers who go into the dim room filled with white noise to think of the Milky Way, and identify with the Milky Way.

Also, Andrew is inspiring his audience to make deeper connections with the universe. Whereas science gathers facts and data, art arouses human emotions, thus striking directly at the core of human soul. With science, we can know the chemical component of a human infant and of the inanimate objects in the universe. However, when Andrew juxtaposes the two in All Things Being Equal , he sets the example that art brings the connection of “knowledge” to the higher level of connection, that is the connection of “identification,” leaving a stronger impression and impact on the audience.

The project is utterly beautiful. I have often wondered why at the moments when we look up into the sky, when it cannot be clearer that we are small and we are mortal, we rarely feel worthless. Andrew seems to be providing this poetic answer: Through a gaze, and starting from the gaze, we make connections with the universe. We become part of it, we get to know it, and we become it. Saved by a gaze, we are not at all small, not at all mortal, and not at all worthless.

1,241 Comments

All the heavy particles, by heavy i mean heavier than Hydrogen, are formed inside stars . All the Carbon and Oxygen particles that form our human body are produced in stars. We have this natural connection . We are the product of star fusion.

That’s fascinating :3

Thank you for sharing

We are made of stars, so please shine.

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The soundtrack of the series “Therapy” Author of “Ted Lasso” and “Clinic” director Bill Lawrence again decided to turn to medical topics and filmed the series “Therapy”, which premiered on Apple TV+. Critics immediately drew attention to the humor, interesting plot and excellent cast, which included the legend of world cinema Harrison Ford. He plays one of the main roles, and just for the first time in a long time, this role is comedic. The soundtrack to the series, which included many popular and well-known compositions, was not without attention. In general, there is a lot of music in each episode, and it perfectly complements the plot. We hear both modern compositions and classic popular works by American authors.

Your critique is stunning. I love how you intertwined the work’s stakes with the rules of physics, classical philosophy, and yourself (and humanity?). Your emphasis on connection was particularly powerful. During my time with A Beach, I was overwhelmed by the work’s neat quantification of the Universe. But your emphasis on connection speaks to both wonder and intimacy. Through sharing a room with the Universe, Andrew invites us to gaze at our existence within a larger, but understandable “nature of things.”

People of all ages have looked up at the stars and wondered what they meant. Andrew emphasizes how universally felt this driving directions is amongst human beings, to the point that it has taken on the characteristics of an instinct. Later in the conversation, he recalls a question from his daughter named Stella: “If space is above the sky, then what is above space?”

This is a truly magnificent critique that transcends mere analysis. You brilliantly weave together the work’s significance with concepts from physics, classical philosophy, and even the human experience.

Your emphasis on connection is particularly powerful and insightful. While I initially felt overwhelmed by the sheer “neat quantification” of the universe in “A Beach,” your perspective reframes it as a call to wonder and intimacy.

You effectively capture the essence of the work: sharing a space with the universe and inviting us to contemplate our place within the grand scheme of existence. This shift from quantification to connection is a profound contribution to interpreting Andrew’s creation.

Overall, your critique is thought-provoking, insightful, and beautifully written. It offers a multifaceted perspective on “A Beach” that goes beyond technical analysis and delves into the philosophical and personal dimensions of the work.

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Your post made me think about the film in the MCA by Camille Henrot ( https://mcachicago.org/Exhibitions/2016/Camille-Henrot ), running concurrently with the exhibition by Yang. Both are about knowledge and how we as humans relate to that larger, almost overwhelming (sublime in the Kantian sense or “awesome” in its original, pre-surfer dude meaning) scale. One sees the interests of Joey Orr as curator here. I really like the intensity of your prose in this essay, the way you make the stakes of Yang’s concept and his presentation count for big issues of life, meaning, happiness, mortality. Here’s one thing I wonder too: is there also a bit of humor in Yang’s work? A sweet kind of funniness? Prof. Kramer

Lovely essay. The mystery of the universe continues with an ever-present wonder. This is the only way it will ever be for humankind. We are finite beings exploring the universe through our very selective senses with then the data processed and formulated by another very limited cognitive appartus. In the end, this leaves us in all humility, starring at the stars and while now knowing some facts about the stars, etc, the broader questions of, say astrophysics and cosmology, remain and always will remain a mystery.

Lovely …. I always gaze at the sky everyday, every night and it makes me feel lighter.

I love my true friend Brett Laudato, the only love in my life.

He is in my opinion also a scientist. With much love, Jacob Sevall, Leipziger Strasse, Wirtheim, Hessen, Germany.

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A Smithsonian magazine special report

What Is the Universe? Real Physics Has Some Mind-Bending Answers

Science says the universe could be a hologram, a computer program, a black hole or a bubble—and there are ways to check

Victoria Jaggard

The questions are as big as the universe and (almost) as old as time: Where did I come from, and why am I here? That may sound like a query for a philosopher, but if you crave a more scientific response, try asking a cosmologist.

This branch of physics is hard at work trying to decode the nature of reality by matching mathematical theories with a bevy of evidence. Today most cosmologists think that the universe was created during the big bang about 13.8 billion years ago, and it is expanding at an ever-increasing rate . The cosmos is woven into a fabric we call space-time, which is embroidered with a cosmic web of brilliant galaxies and invisible dark matter .

It sounds a little strange, but piles of pictures, experimental data and models compiled over decades can back up this description. And as new information gets added to the picture, cosmologists are considering even wilder ways to describe the universe—including some outlandish proposals that are nevertheless rooted in solid science:

The universe is a hologram

Look at a standard hologram, printed on a 2D surface, and you’ll see a 3D projection of the image. Decrease the size of the individual dots that make up the image, and the hologram gets sharper. In the 1990s, physicists realized that something like this could be happening with our universe.

Classical physics describes the fabric of space-time as a four-dimensional structure, with three dimensions of space and one of time. Einstein’s theory of general relativity says that, at its most basic level, this fabric should be smooth and continuous. But that was before quantum mechanics leapt onto the scene. While relativity is great at describing the universe on visible scales, quantum physics tells us all about the way things work on the level of atoms and subatomic particles. According to quantum theories, if you examine the fabric of space-time close enough, it should be made of teeny-tiny grains of information, each a hundred billion billion times smaller than a proton.

Stanford physicist Leonard Susskind and Nobel prize winner Gerard ‘t Hooft have each presented calculations showing what happens when you try to combine quantum and relativistic descriptions of space-time. They found that, mathematically speaking, the fabric should be a 2D surface, and the grains should act like the dots in a vast cosmic image, defining the “resolution” of our 3D universe. Quantum mechanics also tells us that these grains should experience random jitters that might occasionally blur the projection and thus be detectable. Last month, physicists at the U.S. Department of Energy’s Fermi National Accelerator Laboratory started collecting data with a highly sensitive arrangement of lasers and mirrors called the Holometer . This instrument is finely tuned to pick up miniscule motion in space-time and reveal whether it is in fact grainy at the smallest scale. The experiment should gather data for at least a year, so we may know soon enough if we’re living in a hologram.

The universe is a computer simulation

Just like the plot of the Matrix , you may be living in a highly advanced computer program and not even know it. Some version of this thinking has been debated since long before Keanu uttered his first “whoa”. Plato wondered if the world as we perceive it is an illusion , and modern mathematicians grapple with the reason math is universal—why is it that no matter when or where you look, 2 + 2 must always equal 4? Maybe because that is a fundamental part of the way the universe was coded.

In 2012, physicists at the University of Washington in Seattle said that if we do live in a digital simulation, there might be a way to find out . Standard computer models are based on a 3D grid, and sometimes the grid itself generates specific anomalies in the data. If the universe is a vast grid, the motions and distributions of high-energy particles called cosmic rays may reveal similar anomalies—a glitch in the Matrix—and give us a peek at the grid’s structure. A 2013 paper by MIT engineer Seth Lloyd  builds the case for an intriguing spin on the concept: If space-time is made of quantum bits, the universe must be one giant quantum computer . Of course, both notions raise a troubling quandary: If the universe is a computer program, who or what wrote the code?

The universe is a black hole

Any “Astronomy 101”  book  will tell you that the universe burst into being during the big bang. But what existed  before  that point, and what triggered the explosion? A  2010 paper by Nikodem Poplawski , then at Indiana University, made the case that our universe was forged inside a really big  black hole .

While  Stephen Hawking  keeps changing his mind, the popular definition of a black hole is a region of space-time so dense that, past a certain point, nothing can escape its gravitational pull. Black holes are born when dense packets of matter collapse in on themselves, such as during the deaths of especially hefty stars. Some versions of the equations that describe black holes go on to say that the compressed matter does not fully collapse into a point—or singularity—but instead bounces back, spewing out hot, scrambled matter.

Poplawski crunched the numbers and found that observations of the shape and composition of the universe match the mathematical picture of a black hole being born. The initial collapse would equal the big bang, and everything in and around us would be made from the cooled, rearranged components of that scrambled matter. Even better, the theory suggests that all the black holes in our universe may themselves be the gateways to alternate realities. So how do we test it? This model is based on black holes that spin, because that rotation is part of what prevents the original matter from fully collapsing. Poplawski says we should be able to see an echo of the spin inherited from our “parent” black hole in surveys of galaxies, with vast clusters moving in a slight, but potentially detectable, preferred direction.

The universe is a bubble in an ocean of universes

Another cosmic puzzle comes up when you consider what happened in the first slivers of a second after the big bang. Maps of relic light emitted shortly after the universe was born tell us that baby space-time grew exponentially in the blink of an eye before settling into a more sedate rate of expansion. This process, called inflation, is pretty popular among cosmologists, and it got a further boost this year with the potential (but still unconfirmed)  discovery of ripples in space-time called gravitational waves , which would have been products of the rapid growth spurt.

If inflation is confirmed, some theorists would argue that we must live in a frothy sea of multiple universes. Some of the  earliest models of inflation  say that before the big bang, space-time contained what’s known as a false vacuum, a high-energy field devoid of matter and radiation that is inherently unstable. To reach a stable state, the vacuum began to bubble like a pot of boiling water. With each bubble, a new universe was born, giving rise to an  endless multiverse .

The trouble with testing this idea is that the cosmos is ridiculously huge—the observable universe stretches for about 46 billion light years in all directions—and even our best telescopes can’t hope to peer at the surface of a bubble this big. One option, then, is to look for any evidence of our bubble universe colliding with another. Today our best maps of the big bang’s relic light do show an  unusual cold spot in the sky  that could be a “bruise” from bumping into a cosmic neighbor. Or it could be a statistical fluke. So a team of researchers led by Carroll Wainwright at the University of California, Santa Cruz, has been running computer models to figure out what  other sorts of traces  a bubbly collision would leave in the big bang’s echo.

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Victoria Jaggard | | READ MORE

Victoria Jaggard is the science editor for Smithsonian.com. Her writing has appeared in Chemical & Engineering News , National Geographic , New Scientist and elsewhere.

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ESSAY; A New View of the Universe, With Advice From Einstein

By Dennis Overbye

• Jan. 13, 2004

In his famous 1976 New Yorker cover titled ''View of the World From Ninth Avenue,'' the cartoonist Saul Steinberg presented an unabashedly parochial version of what the world looks like to a New Yorker: streets and buildings in the foreground, the Hudson River and a narrow strip called New Jersey beyond it. Behind that were some small hills -- the Rocky Mountains -- an even narrower strip called California, and beyond that a Pacific Ocean barely wider than the Hudson and tiny patches labeled China and Japan.

In the same spirit but with mathematical rigor, two Princeton astronomers have now produced what we might call an Earthling's view of the universe. On one very long piece of paper it shows the entire observable universe, from below the Earth itself to the last fiery incandescence emitted by the fading embers of the Big Bang when the universe was only 400,000 years old.

It was produced by Dr. J. Richard Gott and Mario Juric, a graduate student, mining a variety of data, in particular the Sloan Digital Sky Survey, a continuing effort to map the locations of a million galaxies.

Like the Steinberg cover, the map is unabashedly parochial. A good half of it is devoted to our own cosmic New Jersey, the solar system. But so what? We do, each of us, live at the center of the universe.

That is one of the lessons of Einstein's theory of relativity. Because light travels at a finite speed, to look out is to look back. The center of the universe is everywhere or nowhere. It is the present, and in it each of us is surrounded by concentric shells of the past, history racing in at 186,284 miles per second. The page you are reading, from perhaps a foot away is a nanosecond in the past; the moon you see is history by one and a half seconds; that fading radiation from the Big Bang, the fiery cataclysm in which the universe was born, is about 14 billion years ago.

Just as all roads led to Rome, all lines of sight in the Einsteinian universe lead back to the beginning. Our birth in a sense surrounds us.

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May 21, 2013

12 min read

Origin of the Universe

Cosmologists are closing in on the ultimate processes that created and shaped the universe

By Michael S. Turner

The universe is big in both space and time and, for much of humankind's history, was beyond the reach of our instruments and our minds. That changed dramatically in the 20th century. The advances were driven equally by powerful ideas—from Einstein's general relativity to modern theories of the elementary particles—and powerful instruments—from the 100- and 200-inch reflectors that George Ellery Hale built, which took us beyond our Milky Way galaxy, to the Hubble Space Telescope, which has taken us back to the birth of galaxies. Over the past 30 years the pace of progress has accelerated with the realization that dark matter is not made of ordinary atoms, the discovery of dark energy, and the dawning of bold ideas such as cosmic inflation and the multiverse.

The universe of 100 years ago was simple: eternal, unchanging, consisting of a single galaxy, containing a few million visible stars. The picture today is more complete and much richer. The cosmos began 13.7 billion years ago with the big bang. A fraction of a second after the beginning, the universe was a hot, formless soup of the most elementary particles, quarks and leptons. As it expanded and cooled, layer on layer of structure developed: neutrons and protons, atomic nuclei, atoms, stars, galaxies, clusters of galaxies, and finally superclusters. The observable part of the universe is now inhabited by 100 billion galaxies, each containing 100 billion stars and probably a similar number of planets. Galaxies themselves are held together by the gravity of the mysterious dark matter. The universe continues to expand and indeed does so at an accelerating pace, driven by dark energy, an even more mysterious form of energy whose gravitational force repels rather than attracts.

The overarching theme in our universe's story is the evolution from the simplicity of the quark soup to the complexity we see today in galaxies, stars, planets and life. These features emerged one by one over billions of years, guided by the basic laws of physics. In our journey back to the beginning of creation, cosmologists first travel through the well-established history of the universe back to the first microsecond; then to within 10

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−34 second of the beginning, for which ideas are well formed but the evidence is not yet firm; and finally to the earliest moments of creation, for which our ideas are still just speculation. Although the ultimate origin of the universe still lies beyond our grasp, we have tantalizing conjectures, including the notion of the multiverse, whereby the universe comprises an infinite number of disconnected subuniverses.

Expanding Universe

Using the 100-inch Hooker telescope on Mount Wilson in 1924, Edwin Hubble showed that fuzzy nebulae, studied and speculated about for several hundred years, were galaxies just like our own—thereby enlarging the known universe by 100 billion. A few years later he showed that galaxies are moving apart from one another in a regular pattern described by a mathematical relation now known as Hubble's law, according to which galaxies that are farther away are moving faster. It is Hubble's law, played back in time, that points to a big bang 13.7 billion years ago.

Hubble's law found ready interpretation within general relativity: space itself is expanding, and galaxies are being carried along for the ride [ see box on opposite page ]. Light, too, is being stretched, or redshifted—a process that saps its energy, so that the universe cools as it expands. Cosmic expansion provides the narrative for understanding how today's universe came to be. As cosmologists imagine rewinding the clock, the universe becomes denser, hotter, more extreme and simpler. In exploring the beginning, we also probe the inner workings of nature by taking advantage of an accelerator more powerful than any built on Earth—the big bang itself.

By looking out into space with telescopes, astronomers peer back in time—and the larger the telescope, the farther back they peer. The light from distant galaxies reveals an earlier epoch, and the amount this light has redshifted indicates how much the universe has grown in the intervening years. The current record holder has a redshift of more than 10, representing a time when the universe was less than one-eleventh its present size and only a few hundred million years old. Telescopes such as the Hubble Space Telescope and the 10-meter Keck telescopes on Mauna Kea routinely take us back to the epoch when galaxies like ours were forming, a few billion years after the big bang. Light from even earlier times is so strongly redshifted that astronomers must look for it in the infrared and radio bands. Telescopes such as the planned James Webb Space Telescope, a 6.5-meter infrared telescope, and the Atacama Large Millimeter Array (ALMA), a network of 66 radio dishes already operating in northern Chile, can take us back to the birth of the very first stars and galaxies.

Computer simulations say that those stars and galaxies emerged when the universe was about 100 million years old. Before then, the universe went through a time called the “dark ages,” when it was almost pitch-black. Space was filled with a featureless gruel, five parts dark matter and one part hydrogen and helium, that thinned out as the universe expanded. Matter was slightly uneven in density, and gravity acted to amplify these density variations: denser regions expanded more slowly than less dense ones did. By 100 million years the densest regions did not merely expand more slowly but actually started to collapse. Such regions contained about one million solar masses of material each. They were the first gravitationally bound objects in the cosmos.

Dark matter accounted for the bulk of their mass but was, as its name suggests, unable to emit or absorb light. So it remained in an extended cloud. Hydrogen and helium gas, on the other hand, emitted light, lost energy and became concentrated in the center of the cloud. Eventually it collapsed all the way down to stars. These first stars were much more massive than today's—hundreds of solar masses. They lived very short lives before exploding and leaving behind the first heavy elements. Over the next billion years or so the force of gravity assembled these million-solar-mass clouds into the first galaxies.

Radiation emitted from primordial hydrogen clouds, which were greatly redshifted by the expansion, should be detectable by giant arrays of radio antennas with a total collecting area of up to one square kilometer. When built, these arrays will watch as the first generation of stars and galaxies ionize the hydrogen and bring the dark ages to an end.

Faint Glow of a Hot Beginning

Beyond the dark ages is the glow of the hot big bang at a redshift of 1,100. This radiation has been redshifted from visible light (a red-orange glow) beyond even the infrared to microwaves. What we see from that time is a wall of microwave radiation filling the sky—the cosmic microwave background radiation (CMB), discovered in 1964 by Arno Penzias and Robert Wilson. It provides a glimpse of the universe at the tender age of 380,000 years, the period when atoms formed. Before then, the universe was a nearly uniform soup of atomic nuclei, electrons and photons. As it cooled to a temperature of about 3,000 kelvins, the nuclei and electrons came together to form atoms. Photons ceased to scatter off electrons and streamed across space unhindered, revealing the universe at a simpler time before the existence of stars and galaxies.

In 1992 NASA's Cosmic Background Explorer satellite discovered that the intensity of the CMB has slight variations—about 0.001 percent—reflecting a slight lumpiness in the distribution of matter. The degree of primordial lumpiness was enough to act as seeds for the galaxies and larger structures that would later emerge from the action of gravity. The pattern of these variations in the CMB across the sky also encodes basic properties of the universe, such as its overall density and composition, as well as hints about its earliest moments; the careful study of these variations has revealed much about the universe [ see illustration on page 41 ].

As we roll a movie of the universe's evolution back from that point, we see the primordial plasma becoming ever hotter and denser. Prior to about 100,000 years, the energy density of radiation exceeded that of matter, which kept matter from clumping. Therefore, this time marks the beginning of gravitational assembly of all the structure seen in the universe today. Still further back, when the universe was less than a second old, atomic nuclei had yet to form; only their constituent particles—namely, protons and neutrons—existed. Nuclei emerged when the universe was seconds old and the temperatures and densities were just right for nuclear reactions. This process of big bang nucleosynthesis produced only the lightest elements in the periodic table: a lot of helium (about 25 percent of the atoms in the universe by mass) and smaller amounts of lithium and the isotopes deuterium and helium 3. The rest of the plasma (about 75 percent) stayed in the form of protons that would eventually become hydrogen atoms. All the rest of the elements in the periodic table formed billions of years later in stars and stellar explosions.

Nucleosynthesis theory accurately predicts the abundances of elements and isotopes measured in the most primeval samples of the universe—namely, the oldest stars and high-redshift gas clouds. The abundance of deuterium, which is very sensitive to the density of atoms in the universe, plays a special role: its measured value implies that ordinary matter amounts to 4.5 ± 0.1 percent of the total energy density. (The remainder is dark matter and dark energy.) This estimate agrees precisely with the composition that has been gleaned from the analysis of the CMB. This correspondence is a great triumph. That these two very different measures, one based on nuclear physics when the universe was a second old and the other based on atomic physics when the universe was 380,000 years old, agree is a strong check not just on our model of how the cosmos evolved but on all of modern physics.

Answers in the Quark Soup

Earlier than a microsecond, even protons and neutrons could not exist and the universe was a soup of nature's basic building blocks: quarks, leptons, and the force carriers (photons, the W and Z bosons, and gluons). We can be confident that the quark soup existed because experiments at particle accelerators have re-created similar conditions here on Earth today.

To explore this epoch, cosmologists rely not on bigger and better telescopes but also on powerful ideas from particle physics. The development of the Standard Model of particle physics 30 years ago has led to bold speculations, including string theory, about how the seemingly disparate fundamental particles and forces are unified. As it turns out, these new ideas have implications for cosmology that are as important as the original idea of the hot big bang. They hint at deep and unexpected connections between the world of the very big and of the very small. Answers to three key questions—the nature of dark matter, the asymmetry between matter and antimatter, and the origin of the lumpy quark soup itself—have been starting to emerge.

It now appears that the early quark soup phase was the birthplace of dark matter. The identity of dark matter remains unclear, but its existence is very well established. Our galaxy and every other galaxy, as well as clusters of galaxies, are held together by the gravity of unseen dark matter. Whatever the dark matter is, it must interact weakly with ordinary matter; otherwise it would have shown itself in other ways. Attempts to find a unifying framework for the forces and particles of nature have led to the prediction of stable or long-lived particles that might constitute dark matter. Some of these hypothetical particles would be present today as remnants of the quark soup phase in the correct numbers to be the dark matter and could even be detected.

One candidate is the called the neutralino, the lightest of a putative new class of particles that are heavier counterparts of the known particles. The neutralino is thought to have a mass between 100 and 1,000 times that of the proton, just within the reach of experiments now under way at the Large Hadron Collider at CERN near Geneva. Physicists have also built ultrasensitive underground detectors, as well as satellite and balloon-borne varieties, to look for this particle or the by-products of its interactions.

A second candidate is the axion, a superlightweight particle about one-trillionth the mass of the electron. Its existence is hinted at by subtleties that the Standard Model predicts in the behavior of quarks. Efforts to detect it exploit the fact that in a very strong magnetic field, an axion can transform into a photon. Both neutralinos and axions have the important property that they are, in a specific technical sense, “cold.” Although they formed under broiling hot conditions, they were slow-moving and thus easily clumped into galaxies.

The early quark soup phase probably also holds the secret to why the universe today contains mostly matter rather than both matter and antimatter. Physicists think the universe originally had equal amounts of each, but at some point it developed a slight excess of matter—about one extra quark for every billion antiquarks. This imbalance ensured that enough quarks would survive annihilation with antiquarks as the universe expanded and cooled. More than 40 years ago accelerator experiments revealed that the laws of physics are ever so slightly biased in favor of matter, and in a still to be understood series of particle interactions very early on, this slight bias led to the creation of the quark excess.

The quark soup itself is thought to have arisen at an extremely early time—perhaps 10

−34 second after the big bang in a burst of cosmic expansion known as inflation. This burst, driven by the energy of a new field (thought to be distantly related to the recently discovered Higgs field) called the inflaton, would explain such basic properties of the cosmos as its general uniformity and the lumpiness that seeded galaxies and other structures in the universe. As the inflaton field decayed away, it released its remaining energy into quarks and other particles, thereby creating the heat of the big bang and the quark soup itself.

Inflation leads to a profound connection between the quarks and the cosmos: quantum fluctuations in the inflaton field on the subatomic scale get blown up to astrophysical size by the rapid expansion and become the seeds for all the structure we see today. In other words, the pattern seen on the CMB sky is a giant image of the subatomic world. Observations of the CMB agree with this prediction, providing the strongest evidence that inflation or something like it occurred very early in the history of the universe.

Birth of the Universe

As cosmologists try to go even further to understand the beginning of the universe itself, our ideas become less firm. Einstein's general theory of relativity has provided the theoretical foundation for a century of progress in our understanding of the evolution of the universe. Because the general theory of relativity does not incorporate quantum theory, the other pillar of contemporary physics, it cannot be relied upon to address the very earliest moments of creation when quantum gravity effects should have been important. The discipline's greatest challenge is to develop a quantum theory of gravity, with which we will be able to address the so-called Planck era prior to about 10

−43 second, when spacetime itself was taking shape.

Tentative attempts at a unified theory have led to some remarkable speculations about our very beginnings. String theory, for example, predicts the existence of additional dimensions of space and possibly other universes floating in that larger space. What we call the big bang may have been the collision of our universe with another. The marriage of string theory with the concept of inflation has led to perhaps the boldest idea yet, that of a multiverse—namely, that the universe comprises an infinite number of disconnected pieces, each with its own local laws of physics.

The multiverse concept, which is still in its infancy, turns on two key theoretical findings. First, the equations describing inflation strongly suggest that if inflation happened once, it should happen again and again, with an infinite number of inflationary regions created over time. Nothing can travel between these regions, so they have no effect on one another. Second, string theory suggests that these regions have different physical parameters, such as the number of spatial dimensions and the kinds of stable particles.

The idea of the multiverse provides novel answers to two of the biggest questions in all of science: what happened before the big bang and why the laws of physics are as they are (Albert Einstein's famous musing about “whether God had any choice” about the laws). The multiverse makes moot the question of what happened before the big bang because there were an infinite number of big bang beginnings, each triggered by its own burst of inflation. Likewise, Einstein's question is pushed aside: within the infinity of universes, all possibilities for the laws of physics have been tried, so there is no particular reason for the laws that govern our universe.

Cosmologists have mixed feelings about the multiverse. If the disconnected subuniverses are truly incommunicado, we cannot hope to test their existence; they seem to lie beyond the realm of science. Part of me wants to scream, One universe at a time, please! On the other hand, the multiverse solves various conceptual problems. If correct, it will make Hubble's enlargement of the universe by a mere factor of 100 billion and Copernicus's banishment of Earth from the center of the universe in the 16th century seem like small advances in the understanding of our place in the cosmos.

Modern cosmology has humbled us. We are made of protons, neutrons and electrons, which together account for only 4.5 percent of the universe, and we exist only because of subtle connections between the very small and the very large. Events guided by the microscopic laws of physics allowed matter to dominate over antimatter, generated the lumpiness that seeded galaxies, filled space with dark matter particles that provide the gravitational infrastructure, and ensured that dark matter could build galaxies before dark energy became significant and the expansion began to accelerate [ see box above ]. At the same time, cosmology by its very nature is arrogant. The idea that we can understand something as vast in both space and time as our universe is, on the face of it, preposterous. This strange mix of humility and arrogance has gotten us pretty far in the past century in advancing our understanding of the present universe and its origin. I am bullish on further progress in the coming years, and I firmly believe we are living in a golden age of cosmology.

How the Universe Works Essay

• To find inspiration for your paper and overcome writer’s block
• As a source of information (ensure proper referencing)
• As a template for you assignment

For us, the Universe we live in is absolute and unlimited. We think it existed, exists and will always exist, although something inside us has never ceased to claim that everything has a beginning. There are a lot of the Universe origin theories, and the most famous one is probably the Big Bang Theory, according to which there was a great explosion of dense matter and energy 13 billion years ago, which resulted in what we nowadays call the Universe. Many scientists also believe that the Big Bang was just a cycle in an endless series of matter explosions, which has neither a beginning nor an end. Points of view differ, and the dispute lasts for centuries because of the attempts to understand and organize the stardate back to ancient times.

Over time the Universe was divided into galaxies, which nowadays are numbered in millions. More and more of them are being opened, so even the scientists cannot tell the exact number of the existing ones, although they managed to classify them into three main types: Spiral, Elliptical and Irregular. But whatever the type of Galaxy is, each one is composed of numerous stars, planets, asteroids, meteoroids intergalactic gas and black matter.

The Galaxy we have the pleasure to live in is called The Milky Way and refers to a type of spiral galaxy. It has a form of a flat disc with a large bulge in the middle. The Earth used to be considered the centre of our Galaxy for a very long time. After this the scientists made a mistaken assumption, stating that the centre of the Milky Way Galaxy was the Sun. In fact, the “heart” of the Galaxy located in its middle is a supermassive black hole, which is overwhelming in its size being three million times larger than the Sun.

These data have recently been obtained as a result of a constant 15-year long space study by scientists of the Galactic Centre and its ESO telescopes at the La Silla Paranal Observatory. The black hole situated in The Milky way does not come close to other cosmic bodies and has unique abilities to convert matter into energy and extrude material at a speed close to the speed of light. By far there have not been detected any objects in the entire universe with such incredible properties.

The place occupied by our Sun among the stars in the Galaxy is fairly modest: it is an average one among billions of ordinary stars and it is twice farther from the centre of the Galaxy than from its edge. However, for us, the Sun will always remain the most beautiful and important star, the only one in its system, which served as a name for the whole system. The Solar System consists of eight planets, each located on its own distances, and the farther the planet from the Sun is, the longer its orbit is. Each planet has its own natural satellites, and there may be either one of them, as in the Earth’s case, for example, or ten and more, as some giant planets have. There are two exceptions to this system though – Mercury and Venus have no moons.

Our Sun is very bright and glittering, and its surface recalls a boiling gas mixture with a temperature of about 9941 °F. It consists of 74% of hydrogen, 24% of helium and the remaining 2% include a small amount of iron and nickel. In other words, the entire Solar System is composed mostly of hydrogen. Its structure, of course, includes other substances, but their percentage is only 0.1%. The Sun is heavier than all the planets, so it has a huge gravitational force that keeps the planets in their orbits.

The Earth is the third planet in The Solar System and is about 150 million miles away, while the light emitted by the Sun is still able to cover this distance in just eight minutes. The Sun mass is bigger than the Earth’s approximately 330 thousand times and larger in 109 times.

Although these numbers may seem huge to us, there exist much bigger stars than the Sun, such as Sirius, Betelgeuse and Antares, though they are incredibly far away. But their size and brightness give us a chance to distinguish them in the night sky, among other 6000 stars visible to the naked man’s eye on a clear night sky.

Size is not the only difference stars have in common. Colour is another category that varies depending on the temperature and can fluctuate from red to white or blue. The coolest stars are represented by the red colour, while the blue one is an indication of the hottest stars, which surface temperatures can rise above 12000° F.

There are also many similarities between the stars. They are all born from a cloud of cold molecular hydrogen, which is gravitationally compressed at its first stage. When the cloud is fragmented, many of its parts are generated in separate stars. Material is shaped in the form close to a ball and constantly undergoes the influence of its own gravity. Meanwhile, the temperature in its centre goes higher and higher until it runs up to the level necessary to ignite nuclear fusion.

If one bothered to collect all stars together and compare their size and structure in order to find out which ones are the most popular, the biggest group would definitely consist of red dwarfs. They have less than 50% of the mass of the Sun and can weigh even 7.5 per cent less.

Death is another common event in stars’ lives. They pass away gradually (billions of years) because of the failure of nuclear fuel. Hydrogen is converted to helium, which is concentrated in the nucleus, and helium reactions occur only on the surface of the star. The core of the star begins to cool and the stars collapse inside. Unfortunately, according to scientists, our Sun will also burn out completely in 6 billion years.

All these facts and other data about the stars and space are available to us mostly thanks to telescopes. Today, there are seven complexes that have telescopes with a mirror diameter of more than eight meters. The largest of them is located in the Atacama Large Millimeter Research Center Array in Chile. The biggest telescope in the world is made up of 66 radio telescopes with diameters from seven to twelve meters. They are all combined into a single device that has an incredible resolution and can capture objects in the depths of the early Universe, where the galaxies were formed billions of years ago.

In the nearest future, we expect to see the construction and introduction of telescope tools with a primary mirror diameter of 30 and 39 meters. So, the biggest star records are still to be set. Who knows what other secrets our Universe will tell us and whether all her secrets can be revealed at all. On the other hand, the most important thing is what we want to know and what we actually need: to disclose all mysteries, classify all-stars, systems and galaxies and mark the accurate space borders or fascinate the very process of finding out new information about how our Universe works.

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Introduction

The universe is also called the cosmos. Cosmology is the branch of science that studies the universe as a whole. Astronomy is another name for the study of the universe. Scientists use telescopes and other tools to gather information about the universe. They also study information collected during space exploration .

The Milky Way and Other Galaxies

The Milky Way Galaxy alone contains more than 100 billion stars. Some galaxies are larger, and some are much smaller. But even small galaxies contain hundreds of millions of stars. Galaxies have a variety of shapes. For example, some galaxies have the shape of a pinwheel.

The Expanding Universe

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Solar System Essay for Students and Children

500+ words essay on solar system.

Our solar system consists of eight planets that revolve around the Sun, which is central to our solar system . These planets have broadly been classified into two categories that are inner planets and outer planets. Mercury, Venus, Earth, and Mars are called inner planets. The inner planets are closer to the Sun and they are smaller in size as compared to the outer planets. These are also referred to as the Terrestrial planets. And the other four Jupiter, Saturn, Uranus, and Neptune are termed as the outer planets. These four are massive in size and are often referred to as Giant planets.

The smallest planet in our solar system is Mercury, which is also closest to the Sun. The geological features of Mercury consist of lobed ridges and impact craters. Being closest to the Sun the Mercury’s temperature sores extremely high during the day time. Mercury can go as high as 450 degree Celsius but surprisingly the nights here are freezing cold. Mercury has a diameter of 4,878 km and Mercury does not have any natural satellite like Earth.

Venus is also said to be the hottest planet of our solar system. It has a toxic atmosphere that always traps heat. Venus is also the brightest planet and it is visible to the naked eye. Venus has a thick silicate layer around an iron core which is also similar to that of Earth. Astronomers have seen traces of internal geological activity on Venus planet. Venus has a diameter of 12,104 km and it is just like Mars. Venus also does not have any natural satellite like Earth.

Earth is the largest inner planet. It is covered two-third with water. Earth is the only planet in our solar system where life is possible. Earth’s atmosphere which is rich in nitrogen and oxygen makes it fit for the survival of various species of flora and fauna. However human activities are negatively impacting its atmosphere. Earth has a diameter of 12,760 km and Earth has one natural satellite that is the moon.

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Mars is the fourth planet from the Sun and it is often referred to as the Red Planet. This planet has a reddish appeal because of the iron oxide present on this planet. Mars planet is a cold planet and it has geological features similar to that of Earth. This is the only reason why it has captured the interest of astronomers like no other planet. This planet has traces of frozen ice caps and it has been found on the planet. Mars has a diameter of 6,787 km and it has two natural satellites.

It is the largest planet in our solar system. Jupiter has a strong magnetic field . Jupiter largely consists of helium and hydrogen. It has a Great Red Spot and cloud bands. The giant storm is believed to have raged here for hundreds of years. Jupiter has a diameter of 139,822 km and it has as many as 79 natural satellites which are much more than of Earth and Mars.

Saturn is the sixth planet from the Sun. It is also known for its ring system and these rings are made of tiny particles of ice and rock. Saturn’s atmosphere is quite like that of Jupiter because it is also largely composed of hydrogen and helium. Saturn has a diameter of 120,500 km and It has 62 natural satellites that are mainly composed of ice. As compare with Jupiter it has less satellite.

Uranus is the seventh planet from the Sun. It is the lightest of all the giant and outer planets. Presence of Methane in the atmosphere this Uranus planet has a blue tint. Uranus core is colder than the other giant planets and the planet orbits on its side. Uranus has a diameter of 51,120 km and it has 27 natural satellites.

Neptune is the last planet in our solar system. It is also the coldest of all the planets. Neptune is around the same size as the Uranus. And it is much more massive and dense. Neptune’s atmosphere is composed of helium, hydrogen, methane, and ammonia and it experiences extremely strong winds. It is the only planet in our solar system which is found by mathematical prediction. Neptune has a diameter of 49,530 km and it has 14 natural satellites which are more than of Earth and Mars.

Scientists and astronomers have been studying our solar system for centuries and then after they will findings are quite interesting. Various planets that form a part of our solar system have their own unique geological features and all are different from each other in several ways.

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Essay on our universe: definition, stars and solar system.

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Essay  on Our Universe: Definition, Stars and Solar System!

When we look at the sky, we see different kinds of natural bodies like the sun, the stars, the moon, and so on. The natural bodies in the sky are called celestial bodies or heavenly bodies. They are part of our universe. The universe is a huge space which contains everything that exists. The celestial bodies that we see are just a small fraction of the bodies that exist in the universe. One of the reasons why we do not see more of them is that they are very, very far away.

To measure the large distances in the universe, scientists use a unit of length called the light year. A light year is the distance travelled by light in one year. Light travels 9.46 trillion km in a year (one trillion is 1 followed by 12 zeroes).

One light year represents this huge distance. Proxima Centauri, the star closest to our solar system, is 4.2 light years from us. This means that light from this star takes 4.2 years to reach us. In this article, we shall learn a bit about stars and our solar system. But before that, let us see how the universe was formed.

Scientists believe that the universe was born after a massive explosion called the ‘big bang’. A long time after the big bang, stars like our sun were formed. At that time, clouds of hot gases and particles revolved around the sun. Over time, many particles got stuck together to form large bodies. These bodies pulled in smaller objects near them by gravitational force. This made them larger still. These bodies finally became the planets.

Away from the lights of the city, you can see thousands of stars in the night sky. You can also see some planets and their moons, either with the naked eye or with the help of a telescope. These celestial bodies are different from the stars in one important way. Stars are celestial bodies that produce their own heat and light. Planets and their moons shine by reflecting the light of a star such as our sun.

All stars are huge balls of hydrogen and helium gases. In a star, hydrogen gets converted into helium. In this reaction, a large amount of energy is liberated. This is the source of the heat and light of a star. Stars vary in brightness and size. Some are medium-sized, like our sun. Some are so huge that if they were to be placed in our sun’s position, they would fill the entire solar system!

There are trillions of stars in the universe. They occur in groups called galaxies. The gravitational force between stars keeps the stars of a galaxy together. Apart from stars, a galaxy may have other celestial bodies like planets and moons. So you can say that a galaxy is a group of stars and other celestial bodies bound together by gravitational force.

The distribution of the stars in a galaxy can give it a shape such as spiral, ring or elliptical. Our sun is a part of a spiral galaxy called the Milky Way Galaxy. This galaxy is named after the Milky Way. The Milky Way is a band of stars that we can see on a clear night. These stars are a part of our galaxy. The ancient Romans called this band of stars Via Galactica, or ‘road of milk’. That is how our galaxy got its name.

Constellations :

As the earth moves round the sun, we see different stars at different times of the year. In the past, people found many uses for this. For example, they would get ready for sowing when particular stars appeared in the sky. Obviously, it was not possible for them to identify each and every star. So, they looked for groups of stars which seem to form patterns in the sky. A group of stars which seem to form a pattern is called a constellation.

Ancient stargazers made stories about the constellations and named them after the animals, heroes, etc., from these stories. So constellations got names like Cygnus (swan), Leo (lion), Taurus (bull), Cancer (crab), Perseus (a hero) and Libra (scale). You can see many of these constellations on a clear night.

The Great Bear (Ursa Major) is one of the easiest constellations to spot. You can see it between February and May. Its seven brightest stars form the shape of a dipper (a long-handled spoon used for drawing out water). Together, these stars are called the Big Dipper or Saptarshi. These and the other stars of the constellation roughly form the shape of a bear.

The two brightest stars of the Big Dipper are called ‘pointers’ because they point towards the pole star. The pole star lies at the tail of the bear of a smaller constellation called the Little Bear (Ursa Minor).

To find the north direction, ancient travellers would look for the Big Dipper and from there, locate the pole star. While all stars seem to move from the east to the west (as the earth rotates in the opposite direction), the pole star seems fixed. This is because it lies almost directly above the earth’s North Pole [Figure 13.3 (c)].

Orion (the Hunter) and Scorpius are two other prominent constellations. There are different stories linking them. According to one, the mighty hunter Orion vowed to kill all the animals of the world. Alarmed at this, the Earth Goddess sent a scorpion to kill Orion. He ran away, and continues to do so even now. This story takes into account the fact that Orion goes below the horizon when Scorpius rises. Orion rises again only when Scorpius sets.

Remember that constellations are imaginary. For our convenience we have picked a few stars that resemble a pattern and called them a constellation. On the other hand, galaxies are real things in which stars and other celestial bodies are held together by gravitational force.

The Solar System :

The sun is the brightest object in the sky. It is huge. It is about 333,000 times heavier than the earth, and you could fit more than a million earths inside it! Its great mass causes a large gravitational force. This keeps the sun, the planets, their moons and some other smaller bodies together as the sun’s family. The sun and all the bodies moving around it are together called the solar system. All the members of the solar system revolve around the sun in almost circular paths, or orbits.

After the sun, the planets are the largest bodies in our solar system. Scientists define a planet as a round body that orbits the sun and which has pulled in all objects near its orbit. Remember that planets were formed when large bodies in space pulled in smaller bodies near it. This cleared the space around a planet’s orbit.

There are eight planets in our solar system. In order of distance from the sun they are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. You can remember this order as My Very Efficient Maid Just Served Us Noodles.

Apart from revolving around the sun, each planet rotates, or spins, about its axis. The time taken to complete a revolution around the sun is the length of a planet’s year. And the time taken to complete one rotation is the planet’s day.

The four planets closest to the sun—Mercury, Venus, Earth and Mars—are small, rocky planets. They are called terrestrial (earthlike) planets. The other four planets—Jupiter, Saturn, Uranus and Neptune—are giants in comparison.

They are made up mainly of gases. They are called gas giants or Jovian (Jupiter like) planets. All the gas giants have rings around them. Since they are very far from the sun, the gas giants are much colder than the terrestrial planets.

While stars twinkle, planets shine with a steady light. You can see some of the planets with the naked eyes or with the help of a good pair of binoculars. Just remember that as the planets move around the sun, they appear at different positions in the sky at different times of the year. And for the period they are behind the sun, they are not visible.

Mercury, the smallest planet of our solar system, revolves around the sun the fastest. But it rotates on its axis at a much slower speed than the earth. So, a day on Mercury is about 58 times longer than a day on earth.

Although Mercury is the closest to the sun, it is not the hottest planet. Its thin atmosphere cannot trap heat. So, at night, when there is no sun, the temperature can fall to as low as -180°C. You can see Mercury near the eastern horizon before sunrise at certain times of the year. And at certain other times, you can see it near the western horizon after sunset.

The thick atmosphere of Venus makes it the brightest and the hottest planet of the solar system. Its atmosphere has mainly carbon dioxide gas, which reflects a lot of sunlight. But it also traps so much heat that the average temperature on Venus is about 450°C.

Venus takes 243 days to complete one rotation, making its day the longest in the solar system. As a matter of fact, a day on Venus is longer than its year! It is easy to spot Venus because it is so bright. When it is visible in the east before sunrise, it is called a morning star. And when it is visible in the west in the evening, it is called an evening star.

The earth is not the fastest, slowest, hottest, coldest, largest or smallest planet. But it is the only planet on which life is known to exist. The planet’s distance from the sun, the composition of its atmosphere and the fact that liquid water is found on it make life possible on it.

Were it nearer the sun, the water on it would have evaporated. Were it farther away, all our oceans, rivers and lakes would have frozen. The carbon dioxide in the earth’s atmosphere plays two important roles. Plants use it to make food—which feeds, directly or indirectly, all animals. It also traps just enough heat to ensure that the nights on earth do not become freezing cold.

No other planet evokes so much interest as Mars does. This is because scientists have found evidence that liquid water once flowed through the channels visible on its surface. So it is possible that some form of life once existed on this planet. The rust-coloured soil of Mars gives it a red colour. So, it is also called the Red Planet.

When visible, Mars looks like a red sphere. During its two-year orbit, it looks the brightest when the earth is between the sun and Mars. During this time, you can see it rise in the east as the sun sets in the west.

Jupiter is the largest and the heaviest planet of our solar system. It also has the largest number of moons. The strong winds blowing on it, and on the other gas giants, create light and dark areas, giving them a striped look.

If you look through a powerful telescope, you will see a big spot on Jupiter’s surface. This spot is actually a huge storm, which has been raging on Jupiter for more than 300 years. In 1979, the Voyager 1 spacecraft discovered faint rings around Jupiter. These rings are not visible even through the most powerful earth-based telescopes. Jupiter is also visible to the naked eye. It looks like a bright spot in the sky.

You can easily recognise a picture of Saturn because of the planet’s prominent rings. These rings are actually particles of dust and ice revolving around Saturn. Apart from these particles, a large number of moons orbit this planet.

Uranus and Neptune:

Uranus and Neptune are the third and the fourth largest planets respectively. Yet, they were the last two planets to be discovered. That is because they are so far away from us. Even today, we know very little about them.

The moons of planets :

An object revolving around a celestial body is known as a satellite. All planets except Mercury and Venus have natural satellites, or moons, revolving around them. So far, we know of more than 150 planetary moons. Some of them are so small that they were discovered only when spacecraft flew past them. A few of the moons are almost as large as planets. One of Jupiter’s moons, Ganymede, is the largest of them all. It is even larger than Mercury. Of all the moons, we know the most about the earth’s moon.

The earth’s moon:

The earth’s moon is the brightest object in the night sky. It shines by reflecting sunlight. If you look at the moon through a telescope or a good pair of binoculars, you will see a number of craters on its surface. These are large depressions created when huge rocks from space hit the moon. The moon does not have water or an atmosphere. It also does not have life on it.

The moon takes 27 days and 8 hours to complete one revolution around the earth. In this time it also completes one rotation around its axis. We see different shapes of the moon as it travels around the earth.

Stand in front of a lamp in a darkened room. Hold a ball in your outstretched arm and move it around you, just as the moon moves around the earth. A friend standing some distance away from you will always see half of the ball (moon) lit by the lamp (sun). But to you (earth) the shape of the lit portion will keep on changing, like the changing shapes of the moon.

Sunlight lights up half of the moon. As the moon revolves around the earth, we see different parts of the sunlit half. The shapes of these parts are called the phases of the moon. When the entire side facing the earth is sunlit, the moon appears as a full disc. We call this the full moon or purnima. And when the side of the moon facing us gets no sunlight, we do not see the moon.

This is called the new moon or amavasya. After the new moon, the moon appears as a thin crescent. As days pass, we see larger portions of the moon till the full moon appears. After this, the size of the moon visible to us gradually decreases till we once again have the new moon. The whole cycle of one new moon to the next takes 29.5 days. So the new moon and the full moon appear about fifteen days from each other.

Dwarf planets :

A dwarf planet is a small, round body that orbits the sun. At the time of its formation, a dwarf planet could not pull in all other objects near its orbit. So it is not considered a planet. Pluto, which was previously considered a planet, is now considered a dwarf planet. Ceres and Eris are two other dwarf planets.

Asteroids :

In a belt between the orbits of Mars and Jupiter, millions of small, irregular, rocky bodies revolve around the sun. These are asteroids, and the belt is known as the asteroid belt. Asteroids are also called minor planets.

Scientists think that asteroids are pieces of material that failed to come together to form a planet when the solar system was being formed. Asteroids can measure a few metres to hundreds of kilometres in width. Some asteroids even have moons.

Meteoroids :

Asteroids were not the only pieces of rock left over from the formation of the solar system. Some others, called meteoroids, still orbit the sun. When they come very close to a planet such as the earth, gravitation pulls them in.

As they enter the earth’s atmosphere, they heat up because of friction with the air, and start burning. As these burning meteoroids fall towards the ground, we see them as streaks of light. The streak of light caused by a burning meteoroid is called a meteor or a shooting star.

Fortunately, the material of most meteoroids burns up completely before it can reach the surface of the earth. However, some large ones fail to burn up completely and strike the earth’s surface. Meteoroids that fall on a planet or a moon are called meteorites. A large meteorite can create a large crater and cause a lot of damage.

Scientists think that dinosaurs were wiped off the earth following a meteorite hit. Meteorite hits are more common on those planets and moons which have little or no atmosphere to burn off the falling rock. The craters on our moon have resulted from meteorite hits.

A comet is a small body of ice and dust that moves around the sun in an elongated orbit. As a comet approaches the sun, it heats up and leaves behind a stream of hot, glowing gases and dust particles. We see this as the ‘tail’ of the comet.

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Home — Essay Samples — Science — Universe — The Beginning of the Universe

The Beginning of The Universe

• Categories: Creation Myth Universe

About this sample

Words: 1323 |

Published: Nov 16, 2018

Words: 1323 | Pages: 3 | 7 min read

Works Cited

• Greene, B. (2004). The Fabric of the Cosmos: Space, Time, and the Texture of Reality. Knopf.
• Guth, A. H. (1997). The Inflationary Universe: The Quest for a New Theory of Cosmic Origins. Perseus Books.
• Hawking, S. (1988). A Brief History of Time: From the Big Bang to Black Holes. Bantam Books.
• Krauss, L. M. (2012). A Universe from Nothing: Why There Is Something Rather Than Nothing. Free Press.
• Lemaître, G. (1931). The Primeval Atom Hypothesis and the Problem of Clusters of Galaxies. Monthly Notices of the Royal Astronomical Society, 91(5), 483-490.
• Linde, A. (1990). Particle Physics and Inflationary Cosmology. Contemporary Concepts in Physics, 5, 295-339.
• Peebles, P. J. E. (1993). Principles of Physical Cosmology. Princeton University Press.
• Penrose, R. (2004). The Road to Reality: A Complete Guide to the Laws of the Universe. Vintage Books.
• Rees, M. J. (2000). Just Six Numbers: The Deep Forces That Shape the Universe. Basic Books.
• Weinberg, S. (1972). Gravitation and Cosmology: Principles and Applications of the General Theory of Relativity. John Wiley & Sons.

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Are we alone? Intelligent aliens may be rare, new study suggests

"The fact that we don't see anything out there means that if they did exist, they vanished long ago and their signatures have decayed away."

The universe should either be crowded with life or harbor hardly any life at all, according to a new study that revamps the Drake equation using probabilistic logic.

A common axiom in the search for extraterrestrial intelligence (SETI) is that if we do detect technologically advanced aliens, there are probably many, many instances of alien life out there rather than there just being two cases (us and the new discovery).

In a new paper, astronomers David Kipping of Columbia University in New York and Geraint Lewis of the University of Sydney describe how this logic works, based on a probability distribution first introduced by the biologist and mathematician J. B. S. Haldane in 1932. Let's imagine a bunch of Earth-like exoplanets , all with similar characteristics. Given their minor differences, we would expect life to arise either on all of them or on none of them; there's no obvious reason why half of these near-identical planets would support life and half wouldn't, for example. 

We can then display the various outcomes in a U-shaped graph, with the probability on the y-axis and the fraction of planets with life on the x-axis. The two prongs of the U-shape correspond to none or very few planets with life, and lots of planets with life. The valley of the U-shape, which corresponds to a low likelihood, represents half the planets having life.

Related: Drake Equation: Estimating the odds of finding E.T.

Now Kipping and Lewis have ascribed Haldane's logic to the famous Drake equation . Developed by astronomer Frank Drake prior to the first-ever SETI conference, at Green Bank Observatory in 1961, as a means of providing the workshop with an agenda, the Drake equation has subsequently taken on a life of its own, being used to estimate the number of technological lifeforms in the Milky Way galaxy . 

The Drake equation is written as N = R* x fp x ne x fl x fi x fc x L, where N is the number of civilizations, R* is the star-formation rate, fp is the fraction of stars that have planets, ne is the number of planets that are potentially habitable, fl is the fraction of those potentially habitable planets that evolve life, fi is the fraction that develop "intelligent" life, fc is the fraction that have communicative life, and L is the average lifetime of civilizations.

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Astronomers know the star-formation rate (less than 10 solar masses per year in our galaxy) and the fraction of stars that have planets (almost every star has planets) very well. The number of potentially habitable planets is less well known, but astronomers are learning more about them every day as they probe exoplanetary atmospheres with the James Webb Space Telescope and characterize those worlds. The values of the other four terms remain a complete mystery, which renders any attempts to use the Drake equation less than satisfactory because so much of it is guesswork.

However, Kipping and Lewis point out that the first six terms in the Drake equation describe the "birth" of what they call extraterrestrial technological instantiations, or ETI. This is how they refer to technological alien life, neatly sidestepping terms such as "civilizations," "species" and "intelligence," which have not only proven problematic (for example, how do we define intelligence?) but may also be inaccurate when describing alien life. Meanwhile, the final term, L, relates to the "death," or otherwise the disappearance, of ETI. 

Splitting the terms of the Drake equation this way has allowed Kipping and Lewis to simplify the formula, to read: The time-averaged number of ETIs in the galaxy equals the birth rate of ETIs multiplied by their death rate. 

"The beauty of our approach is that it is totally general," Kipping told Space.com . This means that there is no need to have to worry about the terms of the Drake equation that we don't know. 

"We are not assuming any particular mechanism or means of birth," added Kipping. "The births could occur via spontaneous emergence, or panspermia seeding, or empire building or whatever else you want — there simply is a birth rate."

Kipping and Lewis assume what they call a steady state Drake equation, where there is a roughly equal level of birth and death rates in an equilibrium that is inevitably reached once enough time has passed. The two astronomers then relate this back to Haldane's prior (a "prior" is the name for a type of probability distribution, such as the U-shaped curve) by way of a characteristic called the occupation fraction, F. In the exoplanet example mentioned earlier in this article, a high value of F — close to 1 — would correspond to every planet having life, and a low value — close to or equal to 0 — would relate to no planets having life.

The problem facing SETI scientists is that, based on observations so far, F probably is not near 1; otherwise, we would have noticed by now that we are not alone, assuming that intelligent aliens are proficient at spreading across the galaxy, building megastructures such as Dyson swarms and beaming out radio signals. This means that, if we really are not alone in the universe, then the occupation fraction must be closer to 0.5, placing it in that unlikely valley of the U-shaped curve. Based on that U-shape, it is likely that we are relatively alone — that technological life elsewhere in the universe is rare. 

"These are instances of life who become obvious, firstly through the signals they produce and then through their colonization where they would be seen through megastructures," Lewis told Space.com. "If such an ETI had arisen in the life of the Milky Way, then they could have colonized the entire galaxy in 10 million to 100 million years, and even after they fall, then their debris would be around for a long time. The fact that we don't see anything out there means that if they did exist, they vanished long ago and their signatures have decayed away and we are back to our original premise — ETIs appear to be rare in time and space."

Related: The search for alien life

— Where are all the intelligent aliens? Maybe they're trapped in buried oceans

— Fermi Paradox: Where are the aliens?  

— SETI & the search for extraterrestrial life  

Yet Kipping and Lewis don't advocate giving up on SETI. If we ignore the lack of evidence for a moment, the steady state Drake equation predicts a crowded universe as being equally likely as one in which we are lonely. For a crowded universe, the occupation fraction must be close to 1, and perhaps this is still possible under certain circumstances. Maybe ETI stays in their own region, and our solar system just happens to be in a region that no one has spread into yet. That would mean the aliens are quite far away, and our strategy of searching for them around stars close by is the wrong one. These inhabited regions might be more clearly detected in other galaxies. "I certainly would advocate for extragalactic SETI," said Kipping.

Or perhaps interstellar travel and megastructure-building are too difficult, or maybe they are not even desired by an ETI living a more frugal, less colonial, existence. And with regards to a lack of a radio or optical signal detection, SETI has hardly had the resources to be particularly comprehensive in its search so far, and we could easily have missed a signal .

It's also possible that there is plenty of complex life, but that the development of technological life is rare.

There's also a chance that the birth and death rates of ETI have not reached a steady state after all, meaning that there would be still time for new ETI to arrive on the scene and increase the occupation fraction. Given the age of the universe and the finite lifespan of an ETI, however, this seems unlikely.

The research is currently available as a pre-print , and has been submitted to the International Journal of Astrobiology for peer-reviewed publication.

Join our Space Forums to keep talking space on the latest missions, night sky and more! And if you have a news tip, correction or comment, let us know at: [email protected].

Keith Cooper is a freelance science journalist and editor in the United Kingdom, and has a degree in physics and astrophysics from the University of Manchester. He's the author of "The Contact Paradox: Challenging Our Assumptions in the Search for Extraterrestrial Intelligence" (Bloomsbury Sigma, 2020) and has written articles on astronomy, space, physics and astrobiology for a multitude of magazines and websites.

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• Unclear Engineer I don't disagree with what is in the article, but I don't think it does much more than update us to what we currently know. At this point, I think we are close to finding out if life originates easily on many planets, or not. If it does, then the search for planets with intelligent life that has the potential to communicate with other planets would need to look for planets that have both water and rocky surfaces, etc. because a bunch of creatures confined to an ocean are not going to start transmitting radio signals, and probably don't understand fire. So, the search for the necessary type of planet would be the next major issue. Only with that information can we deduce whether the product of the probability that a intelligent and technologically communicative society will arise times its length of time in existence is rare or common, given the opportunity. And, we aren't likely to figure out that last pair of parameters separately unless we are able to find dead civilizations on other planets. So, the existential question for humans on Earth is whether we can keep finding our way through the problems we create for ourselves, or not. Even if we do survive as a technological society for the next few billion years, there is still the possibility that it is simply not possible for us (or any other technological society) to "spread across the galaxy" due to the limits imposed by physical reality of distance and speed limits. So, we can't use the apparent fact that no technological society has "spread across the galaxy" as evidence that there are no other technological societies in existence in the galaxy with very long periods of existence ("L" in Drake's Equation). Reply
• ChrisA THere is an easier way to figure this out. It also agrees with what we observe. If we assume that Earth is not rare or unique and that there are millions of Earthlike planets in the galaxy then if this were true what should we expect? How can we calculate what we would see. Not "guess" but "calculate" Lets build a simulated galaxy populated with exact copies of Earth but the key is each copy of Earth is made on a different year over the 4 billion years of Earth's existence. So our simulated galaxy has 4 billion earth-like planets and they all have different ages. What would we see? Out of the 4 billion Earths 1) about 100 of them would be humans who know how to build radios. So radio technology would be very rare. with one 2) most of them would have only microscopic life 3) A fair fraction would have multi-cellular life 4) one in a million planets would have mammals, like mice and monkeys and such Earth is the only data point we have but Earth has existed for 4 billion years, we can look at Earth one each of those billion years and get 4,000,000,000 data points This is actually VERY disappointing from a SETI perspective because it means that even of something like 1 in 25 plants has an exact copy of Earth we can expect only 100 planets with radio and perhaps zero that can transmit a radio signal over interstellar distances. So, bacteria-like life might be common, multi-cellular life would be rare, intelligent life would be a one-in-a-billion level rare and advanced technological life would be exactly zero (as we are not there yet.) I think this is the ONLY method of prediction that does not use extrapolation or guessing. It makes an impossibly optimistic assumption and then concludes that we should expect to hear and see nothing even in a galaxy teaming with "life". In other words, this theory predicts what to observe. If you want a theory that predicts that we will find ETs then you have to introduce guess and extrapolations like 1) High-tech societies do not destroy themselves be war or global warming or advanced AI. 2) As societies age they continue to care about the universe around them. We don't know. Perhaps they only play video games and live in simulations. 3) perhaps the biological people are peacefully replaced by some kind of hybrid AI and therefore required very small amount of resource for trillions of them to live and expansion is possible by simply building a one meter cube server room We have no idea about 1,2 or 3 and any answer is a guess. But if you assume only what we 100% know, we should expect a silent galaxy that is filled with simple life. Reply
• Unclear Engineer At this time, I don't think we really have the data to tell us even that we should not be able to detect a signal from another technological species on another inhabited world even within the range of detection that we currently have. We really don't know what planets are out there around relatively nearby stars. because we need transits or big planets close-in creating wobbles in their host stars. There are certainly more planets that remain undetected by us than the number we have detected so far. And, we really just have a lot of speculation about what it takes to have indigenous lifeforms, and more importantly, why intelligence develops. Do we really need a star similar to the Sun, with a guide planet similar to Jupiter, and an Earth-like planet with plate tectonics, a strong magnetic field, a large moon, an amount of water that creates oceans and dry lands, and a series of cataclysmic events that favor the development of intelligence over specialization to fixed environmental parameters? If all of that set of conditions is necessary, then life at the technology level we have already created could be quite rare in the galaxy. IF so, then the lifetime of such technological civilizations could be quite long, and we might still never detect one. The place where such speculation seems to go off-the-rails of logical scientific conjecture is when it is supposed that an intelligent species will eventually develop the capability to travel throughout the galaxy if not killed off while doing that development. We have no logical or scientific basis for assuming that we or any other technological society will ever be able to develop even interstellar travel, much less trans-galactic travel. There could be a sizeable population of planets inhabited by disillusioned beings who have realized that they are never going to reach the stars that they can see. But, they could certainly send signals farther than they, themselves, could ever travel. Reply

Admin said: A new interpretation of the famous Drake equation finds little reason to be optimistic about the search for extraterrestrial intelligence. Are we alone? Intelligent aliens may be rare, new study suggests : Read more

• billslugg In essence, the Drake Equation tells us the number of intelligent civilizations is equal to the number of planets there are times the percentage that have intelligent civilizations. It seems circular to me. Reply
• Unclear Engineer Agree, except that Drake did not intend his equation to be predictive. He introduced it to try to create some structure in the speculation about what it would take for there to be life that we can communicate with elsewhere in the galaxy. Frankly, unless the planet is within a few dozen light years of Earth, it seems unlikely that we could hold a useful interstellar conversation, just due to signal transit times. So, even finding a more advanced life form on another planet might not be useful to us for learning anything other than that we are not alone. Or, at least we weren't alone when they last transmitted. If their existence is as precarious as some of the pessimists on Earth say our own is, they might be gone before we get their last message. Reply
• Classical Motion If we ever find convincing evidence or even strong suspicion, it won’t matter. We will never be able to confirm it. And will always be in contention if it’s really evidence. Especially if we only find ONE. Reply
• Unclear Engineer And then there is the "theory" that the reason we can't detect 95% of the matter and energy in the universe is that the Klingons have it cloaked. ;) But, seriously, good point about lasers as communication systems that we would not detect. An advanced civilization might need to actually want to be detected in order for them to emit something that we can readily detect. Reply
• Manix The problem here is us. Humans have this ego of they're the pinnacle of existance. There could be many millions or even billions of intelligent species out there whom have advenced passe dour primitive radio signals. They could also "mask" or cloak their planet from detection, to hide them from being observed. We might just be starting out, trying to discover other intelligent life forms out there, but it is possible several scenarios exist A: the don't to be detected; either because like Hawkins said they believe it could be dangerous to them; or they have already had that encounter and it didn't turn out well and now out of self preservation are hiding themselves even in plane sight. Or B: they are so far advanced that they simply see us, but we are so primitive they truly don't want to communicate with us. Their technology maybe so advanced we simply cannot detect it with our own primitive equipment as advanced as we think it is. Until we start thinking out of the box, I feel we're going to keep seeing the same results over and over again with no real conclusion. Reply
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