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Is there the possibility of absolute time

  1. Jan 9, 2009 #1
    Is there the possibility of "absolute time"

    Is there a theory of absolute time that is compatible with General Relativity?

    (This question inspired by a thread on FRDB. Bob K was encouraged to post here for best results. He did so here.)
     
  2. jcsd
  3. Jan 10, 2009 #2
    Re: Is there the possibility of "absolute time"

    Perhaps the central idea of relativity is that there is no preferred time frame, no absolute time, length, or mass. It seems the only thing that is constant in our Universe is the speed of light. We make do by designating some time frames as being “standard” relative to other time frames. I suppose the first such one to be designated was Greenwich Mean Time. More recently, we have designated the Earth Centered Inertial frame (the ECI frame) as the reference for the GPS system. This type of designating standard times, or absolute times can only be carried so far, of course. Once we are exploring the rest of the solar system, and the galaxy, an Earth centered frame would not have much meaning at all. It would be somewhat presumptuous of us earthlings to think the rest of the galaxy runs on Earth time, let alone the rest of the Universe! But I don’t think we need to be too concerned about that for some time to come! Looking ahead to the day when we may need a true “Universal” time, remember that the speed of light is constant in all reference frames throughout the Universe. Maybe that can be adopted as a true Universal time standard some day?
     
  4. Jan 21, 2009 #3
    Re: Is there the possibility of "absolute time"

    I've been wondering about t/s reference frameworks in an absolute sense on a trans universe scale. We speak of time as relational and relativistic in terms of there being a beginning to time with the beginning of the bb expansion of 'our universe'. Our universe is thought to have had an intitial stage as a static singularity, and then for some as yet unexplained reason its condition changed from static to expanding. Change, as i can make it out, is time. In order for a causal chain of change (a time continuum) to initiate some causal force must act upon it. This force, [ NO. I'm not postulating any form of magical god being. Someone else may postulate that as i have pretty much dismissed the notion. ] in order to be a force acting causally as an agent of change must be operating in a greater t/s continnuum -- a t/s context greater than 'our universe'. Of course, i'm suggesting that necessarily an infinite multiverse of infinite magnitudes is the only way to account for the greater and greater contexts and infinite causal regression. To my mind then, absolute time would be the infinite continnuum of change of the infinite multiverse.
    %?)
     
  5. Jan 21, 2009 #4
    Re: Is there the possibility of "absolute time"

    Well it is a very interesting question, but I don't really think it is possible.

    The main principle of the Theory of Special Relativity is that there is no "absolute time", as different observers have different perceptions of time.
     
  6. Jan 21, 2009 #5
    Re: Is there the possibility of "absolute time"

    That's been a concern that's left me waffling some and still trying to sort this out for my self. Where i'm at in my thinking is that we cannot conceive of time as absolute in as much as we are unable to actually conceive (in the sense of 'grasp') of reality as actual infinity. We can model it and speculate and such, and test for aspects of the 'greater all' but we cannot actually test for or conceive of an actual whole of actual infinity. It seem to follow as clearly that infinity is 'the existent all' while not being an existent thing. "It", reality, cannot be a whole thing any more than infinity can be a whole number. It seems paradoxically to be the set of all sets including the set of all sets.
    So, time being relations of things changing relative to other things, we seem able to conceive of t/s continnuums (t/s finite sets) within reality, but not able to conceive of all of reality. An absolute set of all t/s sets including the set of all t/s sets is beyond the conceiveable for us and therefore not something we can think of as being existent.
    We come down to that common property of all that exists. Anything that exists exists within a framework greater than itself. The twist here is that we end up not being able to prove existence and are forced to either accept or deny that there is something rather than nothing. What would 'all' exist relative to?
    So, in agreement with what you've said about special relativity not allowing for absolute time, it seems that absolute time would be a property of an absolute, exsistent, actual, infinite reality that also may not be allowed for as being existent relative to anything else. We seem to have to either accept or reject this relational property without being able to demonstrate or proove it in the same way as we have to accept or reject that existence is absolute.
    Infinitely perplexing eh?
    I could use some help sorting this out. It's all beyond me.
    %?)
     
  7. Jan 21, 2009 #6

    turin

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    Re: Is there the possibility of "absolute time"

    Can you use the CMBR? Is the CMBR spectrum/isotropy invariant to boosts?
     
  8. Jan 25, 2009 #7
    Re: Is there the possibility of "absolute time"

    In short, according to current accepted theories. . .

    Time IS distance (General Relativity). So if there is no absolute rate of change for distance (velocity) then there is no absolute rate of change for time. Einstein says there is absolute reference frame from which we can measure an absolute velocity. Therefore, there is no absolute reference from which we can measure an absolute time. There is no absolute time.
     
  9. Jan 25, 2009 #8
    Re: Is there the possibility of "absolute time"

    It is strange that there are so many negative responses, when I am sure everyone is aware, at least to some extent, of the standard cosmological timeline:

    http://en.wikipedia.org/wiki/Cosmological_time

    What do we mean when we say that the universe is 13.7 billion years old? The age of the universe that is being quoted is a proper time, which is the time that you would measure if you had been wearing a wristwatch since the beginning of the universe.

    The effect of time dilation only occurs when comparing time measurements between two observers who have been in different states of motion, and or in regions with different gravitational fields.

    No, there is a distinction between euclidean space (++++ metric) and minkowski space (-+++ metric). If time and space were truly interchangeable, then Lorentz boosts would be equivalent to rotations. A Wick rotation into imaginary time is a useful computational device for working with a ++++ spacetime, but one must rotate back into -+++ after the calculation to obtain physical results.
     
  10. Jan 25, 2009 #9
    Re: Is there the possibility of "absolute time"

    I am curious then. How would people in that had been in notably different inertial frames since the big bang determine the "age" of the universe? Would the "age" of the universe be the same for both of them if they were accelerated to the same frame? My understanding of the twin paradox tells me it wouldn't be. And, since they could coexist in the same inertial frame AND have, individually, experienced a different amount time passage since the "beginning" then there is no "absolute" point to measure from.

    I am an amateur though. Please disabuse me of my misconceptions.
     
    Last edited: Jan 25, 2009
  11. Jan 27, 2009 #10
    Re: Is there the possibility of "absolute time"

    Substitute GMT with Big Bang=t(0), substitute GMT time-zones with GR calculated effects of local space-time curvatures? Not that it's as easy as it sounds, LOL...
     
  12. Jan 27, 2009 #11

    Dale

    Staff: Mentor

    Re: Is there the possibility of "absolute time"

    No the CMBR isotropy is not invariant. In fact, the dipole anisotropy of the CMBR is exactly what allows us to determine that we are moving wrt the CMBR.

    Regarding the remainder of the posts. Ages are always determined as the proper time along an object's worldline, which is the coordinate time in their rest frame. This is the same for the universe or for the twin's scenario. In the case of the universe the "rest frame" would be any point at rest wrt the FLRW metric coordinates. An observer moving relative to those coordinates since the beginning of the universe would have aged less than the universe. This is no more a paradox than the normal twin scenario, although understanding that requires a geometric understanding of SR.
     
  13. Jan 27, 2009 #12
    Re: Is there the possibility of "absolute time"

    "Is there a theory of absolute time that is compatible with General Relativity?"
    Not really in the sense you likely mean. Yet time is still the about the most mysterious everyday experience.

    Little in physics is simple,direct and without subtlies:

    Time is absolute: travel with an inertial clock (at constant velocity) and it always ticks off standard intervals.

    Time is relative: accelerate a clock and it will have appeared to slow down when compared with an inertial clock.

    Time is relative: View an inertial clock from an inertial frame in relative motion and it appears slowed.

    Time is space: go inside a black hole and approach the singularity...

    Time can't be absolute: it did not exist before the big bang

    Time is relative: it depends on the existence of space, energy, matter

    Time is discrete: planck time appears to be the minimum interval

    Time is not discrete: Would a minimum planck time look the same from a moving inertial frame?
     
    Last edited: Jan 27, 2009
  14. Jan 27, 2009 #13
    Re: Is there the possibility of "absolute time"

    It was me who told BobK to come here to advance his theory, it's a fair cop governor I am that Dagda. :smile:

    I asked Because, I'm not really an expert, and I couldn't get through to him that he was mistaken about it. If anyone is interested in reading a long winded argument on why mathematically and theoretically there is no absolute time then adventure on the link, I'd be interested if anyone could go through any of my arguments with a fine tooth comb and throw up all the inaccuracies. It was quite fun really talking about it, but it wasn't on a physics forum so I couldn't really explore the maths in any detail.
     
  15. Jan 27, 2009 #14
    Re: Is there the possibility of "absolute time"

    So, in a thought experiment, let us place a clock at the point of the big bang.

    We are in motion relative to the point of the big bang pointed to by the CMBR. Our age-of-the-universe -- our proper time -- our 13.7 billion years -- is different from and less than the proper time of that imagined clock.

    How isn't the center of the CMBR a decent absolute time reference? All time is relative to something. How about taking the Origin of the universe (or our best guess) as the Origin of this reference system. Would intelligent aliens do that?
     
  16. Jan 27, 2009 #15
    Re: Is there the possibility of "absolute time"

    There is no single point in space nor time for the big bang....you can think of it several ways. For one,there was neither at the inception of the big bang: apparently there was nothing,except maybe, a random quantum fluctuation of sorts. For another, inflation caused a ginormous expansion before space and time even formed, faster than the speed of light that created a huge "universe" (at least the basic constituents for one like space,time,mass,energy,time) which is forever beyond our cosmological horizon....in other words, we'll never be able to even detect the vast majority of our universe let alone try to figure out any "point" or "center". And the CMBR originated largely after the inflation occurred and until things settled down to a more stable, lower energy configuration ,there wasn't anything to observe!! That's why after taking into account our relative motion, CMBR is rather uniform all around us...inflation and the CMBR after effects are so expansive they appear uniform everywhere!!!!....just like for every other observer in distant parts of the universe.

    If there were such a "point" I'd agree with your hypothesis.
     
  17. Jan 27, 2009 #16

    Dale

    Staff: Mentor

    Re: Is there the possibility of "absolute time"

    As Naty1 mentioned there is no center of the CMBR. However, you could certainly establish a system of clocks all at rest wrt the CMBR and synchronized according to the time coordinate of the FLRW metric. However, such a system of clocks would simply be a convention and thus would be no more "absolute" than Greenwich Mean Time and the International Date Line. I.e. the laws of physics would not take a different form in your proposed coordinate system.

    I have a hard enough time guessing what intelligent humans will do, I certainly don't feel the need to speculate about intelligent aliens.
     
  18. Jan 28, 2009 #17

    turin

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    Re: Is there the possibility of "absolute time"

    In what experiment?
     
  19. Jan 28, 2009 #18

    turin

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    Re: Is there the possibility of "absolute time"

    If I travel at 0.999999999c w.r.t. to a reference frame that sees a perfectly isotropic CMBR, then how energetic will the CMBR photons be that hit me in the face? Will this tend to slow me down? It seems like a pretty important physical reference to me.
     
  20. Jan 28, 2009 #19

    Dale

    Staff: Mentor

    Re: Is there the possibility of "absolute time"

    IIRC the temperature of a blackbody is directly proportional to the frequency. So just find the Doppler factor and multiply the temperature of the CMBR by that amount to get the "temperature" of the photons you would be facing.

    That still doesn't make the CMBR time "absolute".
     
  21. Jan 29, 2009 #20
    Re: Is there the possibility of "absolute time"

    It does seem odd that the laws of physics should be independent of the matter, radiation, and it's distribution. The way we view it now, there is a disjunction, where we think of the shape of space and time, as dependent upon the distribution of matter, and matter upon the shape of space time. We don't normally consider that either matter, it's form or its distribution, and the nature of the laws of physics should be dependent upon one another.
     
    Last edited: Jan 29, 2009
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