A video about Stephen Hawking, Arthur Clarke and Carl Sagan talking together, Although I don’t understand the extensive details about black holes and what not, I find it fascinating that at one point, they talk about time travel. Hawking says if time travel was invented in the future, there would be much more obvious signs that it would exist. Since there are none, he believes that it is not invented yet some time in the future. This is odd to me, since I believe there is a possibility of time travel existing in the future, yet the future generations would have to enforce rules about going back in the past. There would be guidelines, or general rules which makes it not possible to change the past from the future? It is hard to say, but this idea was my highlight of the video.