Saturday| 9.25.10
From now on, every week, I'm going to post a summary for each chapter of the book A Brief History of Time by Steven Hawking. The book explains the universe for those of you who don't understand it. Some topics include black holes, the hunt for the grand unification theory, the arrow of time, the expansion of the universe, quantum mechanics, the beginning and the end of the universe, the uncertainty principle, the forces, and, in the newest edition, wormholes and time travel. You can buy the book here.
The first chapter is called Our view of the Universe. It mainly tells the history of the scientists trying to explain the universe. First it reports two reasons why Aristotle thought the Earth was spherical. He said that Earth has to be spherical in order to get a full shadow on the moon, unless if total eclipses only happened when the Sun is directly above the Earth. Otherwise, if the Earth was flat, all eclipses would have elliptical shadows on the moon. He also saw that the North Star was lower in the sky in the Southern Hemisphere which proves this theory.
Then, the book goes on and describes the Ptolemac version of the universe and compares it with the Copernican model. Next, the book briefly describes Isaac Newton's idea of gravity. But if Newton's ideas of gravity are true, and if the universe is finite, then eventually everything would be pulled into one single point -- singularity. Newton countered by arguing that the Universe must be infinite. But in 1823, a German philosopher, Henrich Obairs, said that if the universe was infinite, almost all lines of sight would end in a star making the night sky as bright as the sun. And any intervening matter would heated up by the light until it too, would be glowing as bright as a star making the Earth a very hot place.
Then Hawking talks about theories that explain what happened before the universe began, saying it depends on your religious belief. Then he talks about how Edward Hubble discovered that the universe was expanding. He then explained that physic's goal is to create a unified theory that explains the universe in one go. Since it would be really hard to do that, we have separated it in two partial theories: the theory of relativity (e=mc2 ), and quantum mechanics. We hope to combine both theories into this great theory. That theory should determine everything, even the outcome of the search for this very theory! Then, he tells that this search will might not even affect our lifestyle, but will quench our thirst for knowledge!
