The History of the Universe
Astronomers have tried to explain what we see in the universe around
us. The simplest explanation for everything we know about the
universe is called the Big Bang theory. This theory says that
in the beginning, everything in the universe was all in one
place. Something unknown caused the universe to begin growing. The universe
began growing very quickly, and the universe is still growing even today.
At the beginning, when all the matter in the universe was contained in a very tiny volume, it was very hot. As the universe started to grow, it cooled off very quickly. When the universe was about 500,000 years old, it had cooled enough that it was possible for the atoms that make up stars and galaxies to begin to form. Energy released when the universe was small and dense, the cosmic microwave background radiation, still fills the universe today. By studying this energy, astronomers can learn what the universe was like when stars and galaxies were first able to form.
So how old is the universe? Astronomers argue about the exact age of
the universe for many reasons. But they do agree that it is somewhere
between 10 and 20 billion years old.
The
History of the Universe in 60 Seconds or Less - Dr. Eric Schulman - streaming
RealVideo (1 min. 16 sec.) from NSF
Einstein's Messengers - LIGO Documentary - streaming
RealVideo (20 min. 12 sec.) from NSF
A Matter of Scale - interactive showing the sizes of things, from very tiny to huge - from NSF
Last modified May 6, 2008 by Randy Russell.
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