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Time Travel, Relativity

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I’ve just watched “Faster than the speed of light” programme on ITV. There is one assumption that these people always have that I have never understood. Why does travelling faster than the speed of light have to mean “time travel”??. The only reasoning i ever hear is that “You would arrive before you left”. This just doesn’t make sense to me. Why is light any different to sound? In theory, you can make a sound then travel faster than the speed of sound to hear your own voice in another location.
If they mean Einstein’s theory about time slowing down as you reach the speed of light, why not say that? Why state that “it’s impossible to go faster because you “would arrive before you departed”? Do you know what I mean??

Thanks
Russell

Answer:

According to Einstein’s assumptions in the theory of relativity, the velocity of light in vacuum is a constant and no particle can travel faster than light. The theory of relativity is based on this central concept. So, if we imagine to travel faster than light, time will reverse (As per theoretical results) and we may go back in time. That is why travel with or above the speed of light is referred to as “Time Travel”.

Light is an electromagnetic wave and is different from sound as it is a mechanical wave which requires a medium to travel. Sound cannot travel through vacuum.

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