• Question: i learnt that if we could travel faster than light in a train the inside of the train slows down in time and in just 2 weeks in the train you would have traveled over a hundred years outside the train whats your view on that??

    Asked by fistfull6 to Christine, Edd, Jess, Nicolas, Zara on 17 Jun 2011.
    • Photo: Edward Codling

      Edward Codling answered on 17 Jun 2011:

      Hi fistfull! A really good question that is quite hard to explain – you are pretty much correct with your statement!

      This relates to a theory by Einstein known as ‘special relativity’. The idea is that nobody can go faster than light and the time slows down (dilates) if you approach speeds near to the speed of light. However, time continues at normal speed for those who are moving slowly. The theorem has been proved correct – satellites moving really fast around the earth have been shown to experience time very slightly more slowly than how we experience it on Earth. However, the satellite doesn’t move anything near the speed of light so the effect is not very large.

      However the theory of relativity has some odd consequences as I discussed on a different post – time travel may be possible:

      (Copied from earlier post):
      A certain type of time travel IS possible according to Einstein’s theory of relativity. This is why the theory was so incredible at the time he came up with it – people didn’t realise the implications until a while later. However, the theory of relativity does seem to be true and it explains a lot of phenomena we couldn’t explain before.

      The basic idea is that time slows down the faster you move, until time would be standing still if you were moving at the speed of light (and nothing can go faster than this). Hence if you send some astronauts out on a space mission where they are travelling at (say) 1/10th of the speed of light then time for them would move more slowly. Suppose they spend 20 years on their spaceship before coming back to earth. They would have aged 20 years but the people on Earth would have aged hundreds of years in the same time – because time is moving quicker for them. So for the people on earth it looks like the astronauts have gone back in time – but from the astronauts point of view nothing odd has happened to them – everyone else just seems to have aged much more quickly!

      It is very confusing so don’t worry if you don’t understand – I certainly don’t understand the full theory!

      However, at the moment we don’t have the technology to move anything like the speed of light. Some scientists have looked at ways of accelerating space craft by using the gravitational pull of stars and planets though – this could get us up to very high speeds if we were travelling deep into space.

      Do you think it would be odd if you went away to space and when you came back you were younger than your children? In theory this could happen!

    • Photo: Zara Gladman

      Zara Gladman answered on 17 Jun 2011:

      Hey fistfull6! 😀

      That’s a very interesting fact! This question is probably best answered by a physicist (I’m an ecologist so I only study animals). The idea of time travel is fascinating though! I’ll do some searching….

      When I searched for your problem, I found an article by Stephen Hawkings, the famous physicist! Maybe that’s where you heard the fact? He explains it really well. This is what he says in the article:

      1. Firstly, it would be impossible for the train to reach the speed of light…it would only get close to it. The speed of light is like a speed limit (186,000 miles per second) that nobody can break!
      2. Inside the train, time would start to flow slowly compared with outside the train – everything would be in slow motion! This is because if you were to run on the train, then your total speed (when you added it on to the speed of the train) would be greater than the speed of light – and remember, nobody can break the speed limit! So time has to get slower.
      3. When the train stops, after one week they would have travelled 100 years (so I guess 200 years for two weeks?)!

      So overall.. I guess in THEORY if all of that is correct, then time travel is possible! The problem is, I don’t think we’ll ever build a train that can go as fast as that!!

      Would you want to travel to the future?

    • Photo: Jessica Chu

      Jessica Chu answered on 17 Jun 2011:

      already good answers so I won’t repeat.. lol but I would say the same thing – if only we can build a super fast train fast enough to test it out!

Comments