Is traveling back in time possible?



This is one of the most Frequently asked questions at Science Conferences held for amateurs. Being an amateur in Science with not much liking for it I finally decided to find out if its practically possible to travel back in time or is just one of the many things Hollywood has been feeding us. This is what I found:

For a really longtime it was believed that it is possible to travel back in time. Or atleast roughly something on those lines based on Sir Issac Newton's theory of Absolute Time. According to his theory of Absolute Time someone sitting on the North Pole will experience the same time as someone on Mars. He also accepted the fact that human measurement of time is inaccurate and he therefore named that as Relative Time. According to Newton time throughout the universe was same and therefore by that logic time was the Fourth Dimension of the universe. This discovery was one of the greatest of its time and gave the later generations a framework to work on around Physics and formed the basis of Classical Mechanics. As we can go back and forth in the three dimensions, Newton assumed that we would be able to do that in the fourth dimension too. The difference is that the dimension of time is unidirectional and therefore one cannot go back and forth in it and another great Scientist later proved this. 

Albert Einstein in one of his papers put forward the Special Theory of Relativity. This article on How stuff works explains Special Relativity really well. The main postulate of the theory was that no information could travel faster than the speed of light in a vacuum. It also put forward the second postulate that all laws of physical world show remain the same in any inertial reference frame.  What this basically means is that irrespective of which reference frame a person is in the time for two reference frames can never be the same. This is exactly opposite of what Newton said. According to Einstein's theory of Special Relativity time is not absolute but rather it is relative. This idea and through applicable physics Einstein forced the world to abandon the idea of Absolute Space and Time and brought in the idea of Relative Time.

As I said earlier time is a unidirectional Dimension unlike any other dimensions and one can only travel forward than backward in it. This protects the idea of causality that cause should precede effect and not other way around. This is called the Law of Cause and Effect. Therefore traveling back in time is not possible because you cannot have an effect and than have the cause of it felt. For now and maybe for eternity traveling back in time will be just one of those Sci-fi things we would want to do but cannot. 


Your post about time travel reminded me of todays class. It was so interesting to listen to the Dean of Eberly College of Science, Daniel Larson, as he discussed in detail about Space to our class. I have always been fascinated with space so I really enjoyed the discussion. Mr. Larson mentioned about the theory of time travel through a black hole and I also found an interesting article of Stephen Hawking's perception of time travel through a black hole. Mr. Larson had also brought up that when we see the light of some stars we could actually be seeing light that came from a star over thirteen billion years ago as the light took so long to reach Earth. So we're actually seeing the past in the present. I thought that was a really cool fact to grasp!

It actually was really interesting about the stuff Dr. Larson said in class today. It pretty much means that light is the fastest traveling medium and there can be nothing faster than it. In my blog I answered the question (not very well) if we can travel in the past and I guess it is not possible. It is easier to understand this in the same way that the light which came from a star billions of light years ago, if we want to get back to the source of it we need to travel back to that star faster than the speed of light and I do not think that is really possible. So that clearly rules out traveling back in time. According to some theories it might even be possible to travel faster than the speed of light if it was possible to have negative mass. It is called the Alcubierre Drive. Here is a better explanation to it: I do not fully understand physics or even partially but I am not sure how plausible it is to make a spacecraft have negative mass to make it travel faster than light

Time travel, teleportation, and hover crafts have always seem to have been major scientific topics that at this point seem more like science fiction. I don't think we will see any of these things in our lifetime especially not time travel. These concepts seem so far fetched to me to be realistic. I cant't ever picture a world with time travel no matter how many cheesy movies like this one(still a great movie),, try to portray it.

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