A Brief History of Time is a fascinating book which describes the theories presented by the greatest scientists of the past hundred years concerning space and our existence. Stephen Hawking also poses timeless questions such as how did the universe begin and how big is our universe? Stephen Hawking holds that the universe began with a big bang, an immense explosion which sent the universe in motion. The big bang formed the first building blocks of matter, thus forming his definition of the beginning of time. Edwin Hubble's research gives proof to the theory that we live in an expanding universe. Using redshift comparisons, Hubble was able to deduce that the galaxies are moving away from our galaxy and a steady rate.
Do black holes really exist? According to Stephen Hawking, black holes are long dead stars which have collapsed into a dense ball of matter so strong that light cannot even escape it. A black hole contains an event horizon, which is the radius from which light cannot escape. Thus, anything beyond the event horizon cannot be seen. It is believed by the author that black holes have such an immense gravity field that they can be utilized to transverse long distances of space.
How do stars create such a massive amount of light and energy? The simple answer is Einstein's equation of E=mc2. This equation basically states that energy and mass are equivalent, with light being the conversion factor when squared. In effect, a small amount of matter can be transformed into a huge amount of energy. This explains how lighter atoms fuse into heavier atoms in a star's core to produce light.