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Conditons at Big Bang, comparison with Light Speed travel

  1. Feb 18, 2016 #1
    According to Einsteins Theory of relativity if an object traveled at the speed of light, it's mass would become infinite, time would seem to stop relative to others and it length would become absolute zero. The same conditions were thought of at the Big Bang, when time didn't seem to have existed ( correct me on this on terms of language ), the density of the universe was infinite and it was all contracted into total profound nothingness. like Everything in nothing.
    Do the conditions I seem to be comparing have anything in common, something that mathematically can be worked out from them or is it just anything else ?

    p.s. - ( Please keep in mind while answering i'm just in High School )
     
  2. jcsd
  3. Feb 18, 2016 #2

    Ibix

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    Welcome to PF.
    None of this is correct, I'm afraid, although it's a popular meme in pop sci presentations. It is, in fact, impossible to travel at the speed of light for anything other than a massless particle; describing what the world would look like when you are doing something impossible (even in principle) is impossible. Why? You always see light travelling at 3x108m/s by definition. If you were travelling at the speed of light it would be travelling at 0m/s relative to you. It can't be doing both...
    I don't think this is a great description of the Big Bang, either, although I'll defer to others with more knowledge on that.

    However, there is a basic difference between travel at the speed of light (which is explicitly forbidden by relativity) and the Big Bang singularity which is where the equations of relativity give up. Einstein's theory predicts something it cannot describe at the origin of the universe. Opinion here seems to be that a theory of quantum gravity ought to describe the actual origin of the universe better. But we haven't managed to develop one yet...

    In short, I don't think the situations have much in common at all, I'm afraid.
     
  4. Feb 18, 2016 #3
    This is simply where the theory reaches the limits of reality. Massive objects are never seen reaching "lightspeed" or appearing infinite, and time never stops for anything!
    As a "starting point" to arrive at what we see from where we are... very slight adjustments "from the beginning" have tremendous consequences when you get to where "now" would be in the timeline.
    Once you get into special relativity, which is the "high-energy, high-velocity extension" of general relativity, you see how light speed is the "universal" speed limit.
     
  5. Feb 18, 2016 #4
    Thanks for the reply
    I was kind of skeptical like comparing apples and oranges, but with a bit of assumption that the laws of science break down during the instance of big bang. Yes, It did seem quite Sci-Fi to me and actually is a lot in reality too. And on the point of Quantum gravity I definitely agree that the model that one ' beautiful ' theory would give should be just enough to answer this silly question too ( i hope i do publish something like that later-on :-) )
     
  6. Feb 18, 2016 #5
    Just wondering if those massive objects were the universe itself in a multiverse situation . It's too Sci-Fi to think like this but yes i am lacking some better math for it. Too Sci-Fi for me too.
     
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