Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

A few simple questions.

  1. Jan 15, 2008 #1
    Hey, there are a few things I would like to clear up in my mind.

    I was talking to a mate today at school, and he was talking about the speed of light. He was saying that if you could travel the speed of light you could arrive somewhere before you left? He then went on to say that if you were travelling at the speed of light you would actually be going back in time?

    This raised a few questions in my mind.

    - Firstly, does that hold any truth? I can't picture that in my head, he could possibly have been talking about thta in terms of any image that you could see (If slowed down considerably)

    - The whole going back in time idea, I am very sure holds no truth but I have seen some theory similar using light and mirrors or something?

    - Is it actually possible for something to move at the speed of light? Obviously excluding light itself, I thought I read somewhere that before something reached that speed something happenned and it could never actually reach that speed.

    Any explanation would be great. Thanks.


    Just another two questions.

    Ok I've heard that if you continue travelling in space you will eventually end up where you started? If so is there an explanation to this?

    I've also heard that if you go far enough into space, you will eventually be able to see the formation of the universe, or the big bang? As the light is still travelling through space, so if you "could catch up with it" could you see the big bang?

    Pretty random questions, and not all really related, but they've been playing on my mind =]
    Last edited: Jan 15, 2008
  2. jcsd
  3. Jan 15, 2008 #2


    User Avatar
    Science Advisor
    Homework Helper

    If you could go faster than the speed of light you could arrive before you left!
    This is one of the reasons you can't go faster than light!
    Nothing with mass can travel at the speed of light.
  4. Jan 15, 2008 #3

    Is there an explanation for why mass cannot travel at the speed of light? It would be interesting to read a bit into it, the answer is probably an obvious one to most, but I'm not really sure?
  5. Jan 15, 2008 #4


    User Avatar
    Science Advisor
    Homework Helper

    The simple explantnation is that the equations of Special Relativity say that mass increases as it reaches the speed of light and reaches infinity at the speed of light, so it would take an infinite amoutn of energy, but this is ather arguing in circles.

    Strictly speaking no information can travel faster than light because this would lead to problems with causality, effects happening before causes!
    There are a lot of good books and articles about Special Relativity.
  6. Jan 15, 2008 #5
    Thanks, that has helped alot with that question. The only problem I have with reading into some of these things is that, they seem very complex. :/
  7. Jan 15, 2008 #6
    Ok thanks, I understand it now cheers for all the help! =]
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook