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

Time relative to inflation?

  1. Mar 4, 2012 #1
    does inflation affect time?

    my question arises from @ ~7:30min. if space itself can be used as a reference point for speed, is it an omnipresent observer? is it therefore not excepted from SR if space is moving relative to space?

    I have searched the forums already, im trying not to double post or bother people with the same questions. if its answered elsewhere please indulge me with perhaps a simpler explanation, as its probably likely i have already found the answer to my questions but failed to understand completely what I was reading.

    thanks in advance for your time.
    Last edited by a moderator: Sep 25, 2014
  2. jcsd
  3. Mar 4, 2012 #2
    Your question seems not related to your title, and I'm not sure what you are asking.
  4. Mar 4, 2012 #3
    Basically if space is can be considered an observer and if space is 'stretching', is it moving relative to itself? or if objects are moving relative to the stretched space, is time not affected? also at the big bang, if objects are moving relative to space at relativistic speeds, would time be affected?

    Rather, to simplify my question further - as i am not trying to elicit specific answers to each "?", does the process of inflation itself have any affect on time?

    *edit, upon reflection I apologize if my title was misleading or not worded properly. I will exercise due prudence in title selection in the future.
  5. Mar 4, 2012 #4
    Just to help you out here, inflation refers specifically to the very earliest phase of the universe's life (as we currently understand it). The more general expansion is refered to simply as "expansion".

    As far as your question goes, the answer is pretty much no. Velocity and Gravity are the two ways in which time dilation occur. Since both are at their minimum out in deep space, time will be as unaffected as you can get it.
  6. Mar 4, 2012 #5
    First, in GR only spacetime is an unambiguously defined object. Space and time are derived concepts and they depend on how you decompose spacetime. This makes your questions confusing.

    When you understand, you may reformulate your question.
  7. Mar 5, 2012 #6
    Thank you for your answer.

    If I may with a follow up question, at the beginning, was time affected by inflation, or was the inflation itself the primary cause of the relative motion of anything that existed?

    also, please let me know if I should be posting elsewhere with such ignorant questions (perhaps homework forum though im not in school, 4 chan, or entertainment weekly's forum) please believe I have done lots of reading on my own; ineptitude is the cause of my ignorance, not laziness.
  8. Mar 5, 2012 #7
    Although I stated inflation refers to a specific, early period, understand that inflation is still expansion. It was far more extreme than modern expansion, however. But the answer above still stands - inflation would have no impact on time.

    The second half of the sentence is tricksy. The answer is "yes and no". Relative motion of all the inanimate objects of our universe are largely caused by gravitational influences. However, the imbalance of matter distribution that allowed gravity to do its work can be traced back to the effect inflation had on quantum fluctuations in the vaccum.

    If you're satisfied with the questions about time, but wish to pursue questions about inflation, you may want to hop over to the cosmology forum and start a new thread. Keep in mind that the period of inflation is a speculative area still.
  9. Mar 5, 2012 #8
    In the video, all he is trying to say is that space is something because the skater could be seen to spin and know it has a spin even though it wasn't measured relatative to another object. I don't think distant stars or galaxies have been shown to increase in mass due to their relative velocity due to inflation, so then it wouldn't experience any time dialation due to it either. It has also been said that inflation allows for objects to travel faster than the speed of light, so it is like an object can accelerate due to inflation and be immune to the effects of relativity, although I don't know how this is possible. I may be wrong, but I haven't heard any source saying that an object seen in space was affected by relativistic effects that was just moveing along with the expansion of the universe. It would seem like every galaxy on the edge of the visable universe would be seen as a black hole or something if it did occur...
  10. Mar 9, 2012 #9
    dooces, you can think of it in form of 'relative motion'. Relativity states that there is no way you can define an 'absolute' uniform motion (speed/velocity) for any object, relative something else. Only accelerations give you that unique evidence of what is 'moving' relative what, and that in the form of 'gravity'.

    One might assume that if 'space' is expanding, and nota bene, 'accelerating' between galaxies then there could be a larger 'time dilation' between two frames of reference, as between two galaxies, loosely speaking now. But a time dilation is a very difficult thing to prove, and, it is also so that at no time will any of those galaxies find themselves 'living slower' or 'faster'.

    You would need a twin experiment to prove that thesis.

    But as all galaxies then could be defined as constantly 'accelerating', relative each other, we might notice more 'gravity', which we haven't, as far as I know? But it is a interesting question, what you seem to be asking is if 'space' exist on its own, as a measurable quantity (a modern 'aether' sort of). I don't think so myself, the metric (gravity) defines space, but that's my very own view.

    A time dilation is on the whole nothing you ever will notice locally, it is only a effect between 'frames of reference'. None of the twins in the twin experiment will ever find their time change. Only as the accelerating 'moving' twin is back at Earth will the time dilation be provable. And if you think of it gravitational time dilations are everywhere on Earth at very small scales, and we have no problems with them.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook