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

Time speeding up?

  1. May 23, 2005 #1
    Ok, so the universe is expanding at an accelerating rate. The further we look into the past the slower things are receding from us, no?
    Could it not be that time is speeding up? Has this being discounted, ie is there any other way to tell if time is passing by more quickly now than it was it the past?

    (I'm not trying to taut a theory here, just interested to know if it's possible or not)
     
  2. jcsd
  3. May 23, 2005 #2

    pervect

    User Avatar
    Staff Emeritus
    Science Advisor

    What would time be speeding up with respect to? Normally one says that time flows at the rate of 1 second / second, which is a tautology. The idea needs some additions before it says anything that makes a testable statement about reality.
     
  4. May 24, 2005 #3
    Well, it speeds up in relation to itself in the past, in much the same way as a metre on earth isn't the same as a metre that's close to a black hole (from our perspective).
    Of course, if we occupied that metre close to a black hole, we wouldn't be able o tell the difference (assuming no gradient..ok a blackhole was an extreme example, lol). In the same way, 1 second a billion years ago would still seem like a second. But measured against our current second, it might be 1.2 seconds.

    Hope I'm making sense here. Is the analogy accurate?
     
  5. May 24, 2005 #4
    If the universe were expanding at a constant rate, but at the same time have a constant effect on time, that could explain the apparent accelerating expansion, could it not?
     
  6. May 26, 2005 #5
    Ok, let me put it another way. Why is the concept of 'dark energy' even remotely favourable to this idea? Neither are unfalsible. Although I've yet to think of a way to test it, at least I know where to start.
     
  7. May 26, 2005 #6
    Practically speaking

    Time is normally something is measured with respect to. The second is defined in terms of a period relating to the cesium atom. So, if time were changing in any meaningful way, one could measure it by measuring a second via a cesium atom, storing that length, and then measuring the period again, and comparing. Although, if the effect were uniform, the changing of time would affect the storage device, and one would get perfect agreement no matter what. If there is another dimension that time is changing with respect to, we'd probably need to find a way there before measuring any change in time.
     
  8. May 27, 2005 #7
    As I said, time changes with respect to itself. I see no problem with this since time is treated similar to other dimensions in relativity.

    For instance, how do you measure 1 metre? With a ruler? That ruler is a different size under different spacial configurations. In order to determine if a metre here is the same as a metre somewhere else, we need a measure it from our frame of reference. Likewise we can only measure time with respect to past-times from our frame of reference.
    The atomic clock example you gave is just like trying to use a ruler, it's doomed to failure.

    The 3 spatial dimensions of the universe are literally changing, expanding. I see no reason not to think that time isn't changing as well. Indeed, it seems to me that suggesting it's static is the more extreme position.

    Although it's difficult to prove(impossible maybe?) I'm starting to think that the apparent expansion is evidence for it, rather than the concept of dark energy(which flies in the face of accepted physics).
     
  9. May 27, 2005 #8
    True, the space is expanding.Yet, I believe our REAL TIME doesn't speed up with that but VIRTUAL TIME ( this theory hasn't be proved yet but is an imagination time ). It is claimed that the farther the object in the space from the Earth, the faster it is going away from the Earth. That means these objects are expanding in a greater acceleration.
     
  10. May 28, 2005 #9
    That's not quite how it works. True, objects further away are receding faster, that's basic humble stuff due to the expansion of the universe. But, those galaxies furthest from us are expanding slower than they should be and those closest are expanding faster. It's this that suggests the universe is undergoing accelerating expansion. Link.

    I contend it's due to an altering of our speed through time, thus the galaxies furthest from us are expanding slower only because time is passing more quickly for us.

    (the issue of imaginary time is something unrelated and has to do with complex maths afaik.)
     
  11. May 30, 2005 #10
    This is what I have concluded in the past. After much thinking, I once concluded that if indeed the 3 spacial dementions are expending (becoming less dense) that the demention of time must run faster (WRT the past). But it seems that everybody here rejected this notion, so I guess they must be right. Although, I have seen numerous contradictions here so maybe I was right :uhh:
     
  12. May 30, 2005 #11

    Garth

    User Avatar
    Science Advisor
    Gold Member

    The question is; if time is 'speeding up' how would you measure it? With a clock that is also speeding up? If the two clocks are spatially separated then how do you convey the measurement of time at one location with that at the second location? Perhaps that method of conveyance also changes the measurement?

    We can only talk about that which can be measured and observed. The observation of gravitational and cosmological red shift may be thought of as the observation that time has speeded up. It is often said that gravitational red shift shows that a clock at the bottom of a gravitational potential well is observed to run more slowly than one at the 'top'. Therefore it might be said that 'time speeds up', as observed by another person, as you climb out of such a well.

    The same might be said of cosmological red shift as well. All you can say is that we observe atomic (spectral line frequencies) and other processes (such as the decay rate of a S/N) proceeding more slowly at high red shift, z, than locally - such as in the laboratory (spectra) or in a nearby stellar system (S/N).

    Therefore time might be said to 'speed up' cosmologically as well.

    But does this mean that there are two components to cosmological red shift? One due to 'time speeding up, as the photon has climbed out of an earlier universe when the average cosmological gravitational field was greater than at present, and one due to a recessional Doppler effect? No, because these are the same cosmological space-time effect, interpreted in two different ways.

    Garth
     
    Last edited: May 30, 2005
  13. May 30, 2005 #12

    Aether

    User Avatar
    Gold Member

    Some of the best experimental evidence for a possible cosmological "acceleration of time" is to be found in Doppler residuals of the Pioneer anomaly.
     
  14. May 31, 2005 #13
    So then what happens (please ignore how) when we develop FTL technologies and travel to another galaxy? It seems to me that this could have interesting consequences, especially in how we determine the age of the universe. If time is not a constant, we are likely to be way off, especially if it expands faster some places than others.
     
  15. May 31, 2005 #14

    Aether

    User Avatar
    Gold Member

    I suppose that one might be able to rack-up a ton of frequent flyer miles on such a trip...anything else?
    That's right, guevaramartyr.
     
  16. May 31, 2005 #15
    has anyone ever thought of the notion that time flows at a rate that is propotional to the magnitude of the gravitational field in that region. If the rate of time were to be measured by how fast a photon appears to travel, this would suggest that in order for a photon to move at the speed of light, which im assumingto be a constant. This means time flows slower around large gravitating bodies and fastests when we are infinitely far away from any bodies. Isn't this consistent with relativity, that as we speed up we gain mass an our time flows slower with respect to an inertially fixed observer?
     
  17. Jun 1, 2005 #16
    To determine if time speeds up one has to first define timespeed.
    One definition of timespeed in SR is [tex]cd\tau/dt[/tex] where [tex]d\tau=dt\sqrt{1-v^2/c^2}[/tex], so the timespeed [tex]v_{time}=\sqrt{c^2-v^2}[/tex].
    It's clear that any variation in the constancy of timespeed should then come from the [tex]c[/tex].
    In GR a possible definition of timespeed is [tex]v_{time}=c\sqrt{1-2GM/(rc^2)}[/tex]. Here the variation may come from [tex]c[/tex] or [tex]G[/tex] ([tex]r[/tex] is just a coordinate).
    So the real question is in fact if the physical constants are changing over time.
    This is indeed a topic that often leads to heavy debate. Nobody seems to have found the answer so far.
     
    Last edited: Jun 1, 2005
  18. Jun 3, 2005 #17
    that clock idea would literaly take 5million years to get a minute adjustment
     
    Last edited: Jun 3, 2005
  19. Jun 3, 2005 #18
    What you have mentioned is something ive been toying with a while. this would induce the belief that the speed of light is botha constant and a not. if you were measuring the speed of light as it travels near a gravitational body, the location of your observation would induce varying results. speed is only a measurment of how far something travels in the time measured.

    disatance/time... if time flowed at different rates through out the universe that would impact the formula. Einstein already proved that motion can effect time as measured.
     
  20. Jun 3, 2005 #19

    Garth

    User Avatar
    Science Advisor
    Gold Member

    Be careful - if you allow the standard constants of physics to vary you open a Pandora's box, how do you measure anything? SR & GR allowed previous constants to vary only in a consistent manner and hence they were plausible theories. The fact that Barrow and others are working on a VSL theory today is an indication that perhaps something has to give in the standard theory, but at what price and how are measurements to be made? In particular how do you measure time? With what kind of clock??

    Garth
     
  21. Jun 3, 2005 #20

    pervect

    User Avatar
    Staff Emeritus
    Science Advisor

    If you interpret the rather ambiguous phrase "the rate of time flow" as the metric coefficient g_00 (sometimes called g_tt) in General Relativity, your idea more or less works. Note that distances also change by a factor of g_rr with this interpretation, so a meter close to a planet isn't the same as a meter far away. 'c' will always be a constant number of meters/second for someone deep in a gravity well or far away, by definition.

    But you run the risk of confusing someone versed in relativity by talking about the rate of time flow, if you say you are talking about g_00 or g_tt he'll probably understand. (The opposite could be true for a lay audience, but I suspect that they may also be somewhat confused by what you mean by "the rate of time flow").

    One technical point: g_00 depends not on the gravitational field, but on the total gravitational potential energy.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Time speeding up?
  1. Time speeding up ? (Replies: 4)

  2. Is Time Speeding Up? (Replies: 8)

  3. Speeding up time? (Replies: 7)

  4. Speeding Up Time (Replies: 4)

Loading...