(Courtesy to Microsoft Encarta for this photograph.)

George Gamow can be called the originator of the Big Bang. This is because in 1948, he and his team of scientists thought up the idea of the Universe starting from a small object and then suddenly becoming what it is today. George Gamow thought that the Big Bang created all of the matter in the Universe today, but we now know that only hydrogen, helium, and lithium were created in the Big Bang. All of the other kinds of matter were created in nuclear fusion from stars. This theory is what provides the basis of what we understand about the beginning of the Universe.

The Universe started expanding as soon as it was born in the Big Bang. In just he first trillion-trillion-trillionth of a second, the Universe expanded a hundred million times larger than its original size. As the Universe is expanding, it starts to lose density. At first the density of the Universe is a huge 10 billion trillion trillion trillion trillion trillion grams per cubic inch, but it rapidly starts to fall. As the density falls, the temperature does too. The temperature of the Universe dropped to 10,000 trillion degrees from a temperature that was near infinity.

Throughout the Big Bang, the Universe created antimatter and matter. Whenever the antimatter hit matter, they would both annihilate each other. It took energy to create both the matter and the antimatter, so after annihilating each other, they would "return" the energy that they used to create themselves. Why are we made of matter then if the antimatter/matter pairs kept on destroying each other? Find out by click here.