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  • The universe has long captivated us with its immense scales of distance and time.

  • How far out does it stretch? Where does it end, and what lies beyond the star fields

  • and the streams of galaxies that extend as far as telescopes can see?

  • These questions are beginning to yield to a series of extraordinary new lines of investigation,

  • and to technologies that are letting us peer not only into the most distant realms of the

  • cosmos but at the behavior of matter and energy on the smallest of scales.

  • Remarkably, our growing understanding of this kingdom of the ultra-tiny, inside the nuclei

  • of atoms, is now enabling us to glimpse the answer to the ancient question:

  • How large is the universe?

  • In ancient times, most observers saw the stars as a sphere surrounding the earth and as the

  • home of deities.

  • The Greeks were the first to see celestial events as phenomena, subject to human investigation

  • rather than the fickle whims of the Gods.

  • One philosopher and sky-watcher named Anaxagorus suggested that meteors are made of materials

  • found on Earth and therefore, might have even come from the Earth.

  • Those early astronomers built the foundations of modern science. But they would be shocked

  • to see the discoveries being made by their counterparts today.

  • The stars and planets that once harbored the gods are now seen as infinitesimal parts of

  • a vast scaffolding of matter and energy that extends far out into space.

  • Just how far began to emerge in the 1920s. Working at the huge new 100-inch Hooker Telescope

  • on California’s Mt. Wilson, astronomer Edwin Hubble, along with an assistant named Milt

  • Humason, analyzed the light of fuzzy patches of sky known then as nebulae.

  • They showed that these were actually distant galaxies located far beyond our own.

  • Hubble and Humason discovered that most of them are moving away from us. The farther

  • out they looked, the faster these objects are receding.

  • This fact, now known as Hubble’s law, suggests that there must have been a time when the

  • matter in all these galaxies was together in one place.

  • Everything that astronomers saw in their increasingly large telescopes would have dated back to

  • a singular beginning, now called the Big Bang.

  • That the universe could expand had been predicted back in 1917 by Albert Einstein, except that

  • Einstein himself didn’t believe it until he saw Hubble and Humason’s evidence.

  • Einstein’s general theory of relativity suggested that galaxies could be moving apart

  • because space itself is expanding. So when a photon gets blasted out from a distant star,

  • it moves through a cosmic landscape that is getting larger and larger, increasing the

  • distance it must travel to reach us.

  • So, how large the cosmos has gotten since the big bang depends on how long its been

  • growing, in addition to its expansion rate.

  • Recent precision measurements gathered by the Hubble space telescope and other instruments

  • have brought a consensus, that the universe dates back 13.7 billion years.

  • In that time a beam of light would have traveled 13.7 billion light years, or about 1.3 quadrillion

  • kilometers.

  • But taking into account the expansion of the universe, the most distant galaxies discovered

  • by the Hubble space telescope are actually 46 billion light years away from us in each

  • direction and almost 92 billion light years from each other.

  • So is that the size of the universe?

  • It’s not, according to a dramatic new theory that describes the origins of the cosmos.

  • It holds that our 92 billion light-year patch is a mere speck within the universe as a whole.

  • The theory is based on the discovery that energy is constantly welling up from the vacuum

  • of space in the form of particles of opposite charge, matter and anti-matter.

  • Back in the 1980s, the physicist Alan Guth proposed that energy fields embedded in the

  • vacuum of space had suddenly tipped into a higher energy state, causing space and time

  • to literallyinflate.”

  • The universe went from atomic size to cosmological size within an infinitesimally short time.

  • As a result, according to Guth’s calculation, the universe as a whole would have grown to

  • some ten billion trillion times the size of the observable universe. That’s a ten followed

  • by 24 zeroes.

  • Put another way, the whole universe is to the observable universe - as the observable

  • universe is - to an atom.

  • The incredible fury of cosmic inflation helps explain the immense size and smoothness of

  • the universe.

  • But to succeed, the theory must also account for how the universe produced what we see

  • around us, all those stars and galaxies and clusters of galaxies, and ultimately us.

  • Scientists are now attempting to piece together the chain of events that launched our universe

  • in its earliest moments by generating what you might call a “little bang.”

  • At the Brookhaven National Lab in New York State, they are blasting gold atoms in opposite

  • directions down tunnels almost two and a half miles long.

  • When these atoms reach velocities just short of the speed of light, they are sent into

  • a violent collision.

  • A fireball erupts, reaching a temperature exceeding two trillion degrees Centigrade.

  • As far as we know, the last time anything in our universe was that hot was about a millionth

  • of a second after its birth.

  • What interests the scientists is the splatter of subatomic particles, a super-hot soup of

  • quarks and gluons that theory says gave rise to matter as we know it.

  • In initial tests, this quark-gluon plasma has shown a crucial property: extremely low

  • viscosity or resistance to flow. Scientists call it a perfect liquid.

  • To grasp its importance, we go back to those primordial energy fields that the theory says

  • spawned the big bang. The thinking is that those fields contained tiny fluctuations that

  • were blown up to huge size during inflation.

  • In the ultra-dense quark-gluon mix, these fluctuations generated pressure waves, or

  • ripples. As the universe evolved, these ripples gave rise to variations in the density of

  • matter.

  • Amazingly, the imprint of those primordial ripples is out there today in a faint signal

  • discovered accidentally back in the 1960s.

  • Working for the Bell Telephone Company, physicists Arno Penzias and Robert Wilson had built a

  • giant horn-shaped antenna. But wherever they pointed, the contraption picked up excessive

  • noise in the microwave portion of the electromagnetic spectrum.

  • That noise turned out to match a prediction made years earlier: that in the wake of the

  • big bang, the universe was filled with a cloud of extremely hot gas that scattered all light.

  • As the universe cooled, the cloud dissipated. Light then shone through

  • Over time the spectral signature of this light would have shifted, as the universe expanded

  • and cooled, to what Penzias and Wilson detected. What they’d heard was the echo of the Big

  • Bang.

  • This image shows the smooth contours of the light recorded by the Bell team. Scientists

  • would have to look closer to find the imprint of cosmic inflation.

  • The Space Shuttle Discovery lifted the Hubble Space Telescope into orbit on April 24, 1990,

  • in one of the most important scientific milestones of our time.

  • Another launch, arguably just as important, took place five months earlier.

  • The Cosmic Observation Background Explorer, COBE for short, was sent up to take a harder

  • look at the microwave radiation discovered by Penzias and Wilson.

  • The results came out two and a half years later. The light of the early universe contained

  • a pattern of hot and cold spots.

  • In this image was nothing less than the origin of all we see around us today, smooth on a

  • large scale, but with significant clumps from which gravity would form gas clouds, then

  • stars, and galaxies.

  • With this cosmic template in hand, astronomers set out to discover how the patterns and the

  • dimensions of the universe evolved over time.

  • In an age of computer controlled telescopes and automated observing, astronomers could

  • now launch huge international collaborations with the goal of mapping a large fraction

  • of the universe in three dimensions.

  • At Apache Point in New Mexico, the Sloan Digital Sky Survey set the standard for mass production

  • astronomy.

  • A series of steel plates are drilled with holes that exactly match the location of galaxies

  • in the night sky.

  • After plugging fiber optic sensors into the holes, the plates capture the light of hundreds

  • of galaxies per night. From that light the astronomers calculate their distances from

  • Earth.

  • Another survey is named the 2 Micron All Sky Survey, or 2Mass, after the frequency of infrared

  • light its detectors are tuned to capture.

  • In this image, the 2Mass data covers a region 60 million light years across. The local group

  • of galaxies, including the Milky Way, are in the center. This is our intergalactic neighborhood.

  • Jump further out to a region about 200 million light years across. Our location is linked

  • to the densely packed Virgo Supercluster, the nearest intergalactic city.

  • Stepping out to a region over 320 million light years across, you can see the full breadth

  • of our local region of the universe. Galaxies line up in walls and arcs. Beyond them are

  • sparsely-populated voids, the rural cosmic countryside.

  • Moving out with the data, this region is over 650 million light years across.

  • Then almost two billion. 3.2 billion.

  • And finally out to a region 6.5 billion light years from end to end: the cosmic continent.

  • In the middle of it all, our galaxy, so immense from our Earthly perspective, is less than

  • a speck.

  • The 2mass study, the Sloan Digital Sky Survey, and the 2 Degree Field in Australia have extended

  • our maps to a quarter of the way back to the beginning of the universe.

  • They have laid out a grand cosmic roadmap.

  • COBE’s successor, the Wilkinson Microwave Anisotropy Probe, orWMAP”, was launched

  • to scan the early universe for the fine-scale origins of this cosmic atlas.

  • WMAP traveled beyond any interference from Earth, to a position balanced between the

  • Earth and the Sun.

  • There, for two years, its detectors took in the pristine light of deep space.

  • This is what WMAP saw: a pattern consistent with the filaments and voids that had evolved

  • in the universe at large.

  • Scientists are poring over the WMAP data for clues to the true dimensions of the universe.

  • One group, for example, looked for repeating patterns that could be evidence of pressure

  • waves that ricocheted through the hot gas of early times.

  • They saw none, which implies that the universe had grown so large during inflation that such

  • waves could not cross it.

  • Then they did the math and reported that the entire universe must have a minimum diameter

  • of 78 billion light years.

  • So what is its maximum size, and what’s beyond that?

  • We will never know for sure what lies beyond our visual horizon, but astronomers are turning

  • up some surprising hints in the universe they can see.

  • To ancient observers, the universe was made of five classical elements: Earth, Water,

  • Air, Fire, and a fifth, Quintessence, or space.

  • Aristotle believed the stars, unchanging and incorruptible, were made of this fifth element.

  • Today, we are finding that space, in fact, has a character of its own.

  • Astronomers have calculated the gravitational pull needed to bind stars as they orbit a

  • galaxy or galaxies as they orbit a cluster of galaxies.

  • They have found that there is simply nowhere near enough visible matter there to hold these

  • structures together.

  • The missing ingredient, its identity still unknown, they call: Dark Matter.

  • In supercomputer simulations of cosmic evolution, dark matter is added in to supply the gravitational

  • tug needed to form the web pattern of filaments and walls; voids and dense clusters we see

  • in the universe at large.

  • But something else appears to be happening </