The universe has long captivated us with its
immense scales of distance and time.
How far does it stretch? Where does it end...
and what lies beyond its star fields... and
streams of galaxies extending as far as telescopes
can see?
These questions are beginning to yield to
a series of extraordinary new lines of investigation...
and technologies that are letting us to peer
into the most distant realms of the cosmos...
But also 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, permits us to glimpse the largest
vistas of space and time.
In ancient times, most observers saw the stars
as a sphere surrounding the earth, often 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 sky-watcher, for example, suggested that
meteors are made of materials found on Earth...
and 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 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 extending
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 his assistant
named Milt Humason, analyzed the light of
fuzzy patches of sky... known then as nebulae.
They showed that these were actually distant
galaxies far beyond our own.
Hubble and Humason discovered that most of
them are moving away from us. The farther
out they looked, the faster they were 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.
That time... when our universe sprung forth...
has come to be called the Big Bang.
How large the cosmos has gotten since then
depends on how long its been growing... and
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.
Its radius, then, is the distance a beam of
light would have traveled in that time ...
13.7 billion light years.
That works out to about 1.3 quadrillion kilometers.
In fact, it's even bigger.... Much bigger.
How it got so large, so fast, was until recently
a deep mystery.
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.
In 1995, the orbiting telescope named for
Edwin Hubble began to take the measure of
the universe... by looking for the most distant
galaxies it could see.
Taking the expansion of the universe into
account, the space telescope found galaxies
that are now almost 46 billion light years
away from us in each direction... and almost
92 billion light years from each other.
And that would be the whole universe... according
to a straightforward model of the big bang.
But remarkably, that might be a mere speck
within the universe as a whole, according
to a dramatic new theory that describes the
origins of the cosmos.
It's 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 suddenly tipped into a higher
energy state...
causing space and time to literally "inflate"...
...to go from atomic size... to cosmological
size within an infinitesimally short time.
As a result, according to one calculation,
the universe as a whole...
...would have grown to some ten billion trillion
times the size of the observable universe.
That's ten followed by 24 zeroes.
Put another way, the complete universe is
to the observable universe... as the observable
universe is... to an atom.
The fury of this period 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 seeking 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... particles that 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 this 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
led to variations in the density of matter.
Amazingly, the imprint of those primordial
ripples is out there today... first seen 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 it shifted... as the universe expanded
and cooled... to just the noise signature
detected by Penzias and Wilson. 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
our time.
Another launch, arguably just as important,
took place five months earlier.
This was 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 early universe contained a pattern
of hot and cold spots.
One COBE scientist called it the fingerprint
of creation... for it showed the origin of
the universe 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, and that light determines
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.
Here, these data go out to a region 60 million
light years across. You can see the local
group of galaxies, dominated by Andromeda
and the Milky Way in the center. This is our
neighborhood.
Jump further out to a region about 200 million
light years across.
Our galactic neighborhood merges into the
densely packed Virgo Supercluster... which
is 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... that
bound an array of 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...
and gravitational routes.
Now COBE's successor, the Wilkinson Microwave
Anisotropy Probe, or "WMAP", was ready to
scan the early universe for the fine-scale
origins of this cosmic atlas.
WMAP was launched 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... and with the tiny-scale
structures sketched by inflation at the very
birth of the cosmos.
Scientists at Brookhaven National Lab in the
U.S. and the new Large Hadron Collider in
Europe will be probing ultra high-energy collisions
in the coming years to tease out more details
of the early universe.
Others are poring over the WMAP data for evidence
of its true dimensions.
One group looked for repeating patterns that
could be evidence of pressure waves that might
have 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... the entire universe
has a minimum diameter of 156 billion light
years... not quite twice the size of everything
out there that we can see: the "observable"
universe.
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
on these large scales.
Astronomers have been making refined measurements
of the cosmic expansion rate with a new type
of distance marker.
They wanted to know if gravity was slowing
down the pace at which the universe is spreading
out.
But what they've found comes as a shock:
The markers they use, type IA supernovae,
are thought to burn at uniform intensities
throughout the universe.
By measuring changes in the brightness of
these so-called standard candles at various
distances, the researchers have been hunting
for changes in the rate at which the Cosmos
is expanding.
They have shown that while local regions or
the universe are drawing together, the universe
as a whole is not only expanding, it's accelerating
outward!
The culprit is thought to be energy welling
up from the vacuum of space... similar to
what occurred in the early moments of the
Big Bang, causing cosmic inflation.
Now it's happening in minute quantities across
vast regions.
Over time, this so-called "Dark Energy" has
grown to an astonishing three-fourths of all
the matter and energy in the universe.
With data like this pointing to an underlying
dynamic within our universe, some scientists
have suggested its part of an even larger
cosmic dynamic... much broader and deeper
than we've ever thought.
There is a version of inflationary theory
that suggests we live in one of many universes....co-existing
side by side but out of touch with one another.
Like bubbles, they are continually rising
up... and expanding across the oceans of infinity.
Just 500 years ago many people looked out
into space and saw a universe of lights...
small and nearby... centered on the Earth.
The birth of astronomy revealed stars far
from our planet...
Galaxies... clusters of galaxies... then vast
walls and filaments of matter.
Newer ideas about the size of the universe
amount to a quantum leap in our sense of scale,
by extending these structures far, far beyond
our horizon.
Do these discoveries push us, on our tiny
out-of-the-way planet, into a smaller and
smaller corner of Creation?
Or does our ability to comprehend and imagine
the far limits of time and space expand our
importance... in the grand scheme of things?
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