Journeys in Space and Time

This episode of Cosmos (the eighth) deals with relativity, space time, and lots of other things but presents them in a simple and cohesive way that nobody should have trouble understanding. Dr. Sagan starts out by says something to the effect that a handful of beach sand contains about ten thousand grains, which is more than the number of stars we can see on a clear night. But that there are in fact so many stars that there are more than all the grains of sand on all the beaches of the world.

When I first heard this I can remember being amazed by what he said. I was in high school at the time, so I already had a decent grasp of astronomy, but to have it described this was was quite eye opening. He goes on to describe the distances in space with various examples such as M31 being two million lightyears away which means that the light we see from it today left M31 before there were any humans on earth. I spoke a little bit about Voyager 1 and 2 a couple of days ago, but he used them as examples as well in this segment by saying they are the fastest spacecraft ever launched from earth, but that they are still going about ten thousands times slower than light.

He then gave a series of demonstrations regarding time dilation, and it effects and spoke about Einstein's early years and how his high school teacher had told him he wouldn't amount to anything so that he might as well drop out of school. He gave these demonstrations and spoke about Einstein while in the town of Vinci, and then went on to speak a bit about Leonardo da Vinci and his passion for flight. He made sure the viewers knew that Leonardo's inventions were good ones, but they failed because of the technology not the design.

The episode concluded by him speaking about time travel, and it various issues and possibilities. Another great episode.



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