October 19, 2009
The mind-blowing answer comes from a theory describing the birth of
the universe in the first instant of time.
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
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
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
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
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
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
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