ASTR 1020 NOTES

Einstein’s special theory of relativity (1905) contains two postulates. The first is that we cannot measure our absolute speed in the universe. We can only measure our relative speed, with respect to some other object in space. Einstein used the visualization of two passing trains to describe this postulate. If, from inside one train, one’s only reference point is the other train, it is impossible to know whether you are the one moving, or the other train. A relative speed between the two trains can be determined, but not the absolute speed of either train on the track. The second postulate says that whenever you measure the speed of light, you will find V = C = 300,000 km./sec. = 186,000 m./sec.

Einstein used visualizations more so than math when theorizing about the universe. With his general theory of relativity of 1915, he visualized an intergalactic elevator, being pulled at an accelerating speed, to explain his ideas. If a person standing in the elevator had an object in each hand, and dropped them at the same time, they would observe the objects dropping the same way they would under the effects of gravity. In fact it would be the elevator floor moving toward the objects at an accelerating rate, rather than the objects falling. With this visualization of the elevator, he also noticed that light being emitted from the elevator would appear to curve as a result of the elevator’s accelerating motion. This is what helped him to understand that light would be curved in the vicinity of a mass as a result of gravity.

Einstein worked until the day he died on his Unified Field Theory which was intended to describe gravity and electrical force as two aspects of one greater single force. He discovered eventually that he didn’t know enough mathematics to do what he wanted to do so he began hiring mathematicians to work with him. He never succeeded in unifying the two forces and died a frustrated man. Stephen Hawking has made remarkable progress in the direction Einstein was heading. Because of his disability, Stephen Hawking has been forced to learn how to manipulate complex geometry in his head. This has given him an advantage because he can solve problems no one else can solve.