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Time and expanding space.

  1. May 5, 2013 #1
    Hi, I'm new to the forum, and didn't really know where else to ask some questions, and get good answers, I'm fairly poor at mathematics, and grammar, but I have a passion for physics, astrophysics and cosmology. I have some niggling ideas and hypothesis that I can't find answers for, and I hope I don't make myself look foolish, but Einstein said he "visualised" his ideas, and I had a... "visualisation", that the expansion of space, is somehow linked to "arrow of time", in the sense of one way direction of time in large scale, could it be directly linked to expansion? And could it be linked to time dilation? Or does mass have any effect on expansion?
    I'd appreciate any response, and please correct any mistakes I've made.
  2. jcsd
  3. May 5, 2013 #2
    Welcome to the forum.

    Time dilation and expansion are not linked as per se. The expansion does not cause any time dilation. We do see how expansion affects the wavelength of light called redshift. However this is not the same as time dilation. Gravitational time dilation in terms of an overall average mass density isn't sufficient to cause dilation.
    Last edited: May 5, 2013
  4. May 5, 2013 #3
    Thanks, I appreciate the reply.
    Would mass and gravity have any affect on expansion? And does expansion relate in any way to time?
  5. May 5, 2013 #4
    Mass and gravity does affect expansion, so does the vaccuum energy called the cosmological constant. The relation between the two are used to determine the rate of expansion. Time is only a measurement in expansion and not directly related to a direct effect on expansion

    this link is related and has some further information.

  6. May 5, 2013 #5
    Also on time dilation, this is an observer dependant property. An outside observer will see the dilation and inside observer will see time flow normally
  7. May 5, 2013 #6
    Thanks for the clarification.
    One more questions, could time exist without space and motion?
  8. May 5, 2013 #7
    Thats one question that has no clear consensus. There are models that say yes such as multiverse models. Others that say time started at the first moment of that space formed.

    So I cannot give you a definitive answer
  9. Mar 14, 2014 #8
    Some adhere to the Hawking theory - time being the product of our brains, simply. That there is no Newtonian "ticking clock" for the universe progression.

    Could time truly exist without objects? What do current astrophysicist/astronomers have to say about this? Could you ever get indirect evidence for any viewpoint?
    Last edited: Mar 14, 2014
  10. Mar 14, 2014 #9


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  11. Mar 15, 2014 #10

    What area would this be classified under in Astrophysics? That is; space, objects and motions?.. Not just the particles, and not just motion, but also space and time.

    The link was quite interesting!
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