Is there the possibility of absolute time

[G Hathaway]

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 http://www.freeratio.org/showthread.php?p=5740883#post5740883".)

 

[schroder]

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?

 

[0zyzzyz0]

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.
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[Je m'appelle]

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.

 

[0zyzzyz0]

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.
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[turin]

Can you use the CMBR? Is the CMBR spectrum/isotropy invariant to boosts?

 

[MackBlanch]

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.

 

[confinement]

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.

Time IS distance (General Relativity).

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.

 

[MackBlanch]

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:

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.

 

[abvgd]

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?

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...

 

[Dale]

Can you use the CMBR? Is the CMBR spectrum/isotropy invariant to boosts?

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.

 

[Naty1]

"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?

 

[The Dagda]

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

(This question inspired by a thread on http://www.freeratio.org/showthread.php?p=5740883#post5740883".)

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

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.

 

[G Hathaway]

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.

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?

 

[Naty1]

So, in a thought experiment, let us place a clock at the point of the big bang...
How isn't the center of the CMBR a decent absolute time reference?

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.

 

[Dale]

How isn't the center of the CMBR a decent absolute time reference?

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.

Would intelligent aliens do that?

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

 

[turin]

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

In what experiment?

 

[turin]

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.

 

[Dale]

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".

 

[Phrak]

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.

 

[turin]

That still doesn't make the CMBR time "absolute".

Doesn't the CMBR provide an absolute 4-vector? What I mean is that, in our frame of reference, can we define the 3-vector direction as the direction of the CMBR isotropy, and then determine the boost needed to remove the isotropy, so that we can determine the components of an absolute 4-vector in our frame of reference? Then, could we define absolute time as the proper time in the direction of that 4-vector? Is the CMBR a fundamental part of our universe, or can it really be ignored without physical consequence?

 

[Dale]

Doesn't the CMBR provide an absolute 4-vector? What I mean is that, in our frame of reference, can we define the 3-vector direction as the direction of the CMBR isotropy, and then determine the boost needed to remove the isotropy, so that we can determine the components of an absolute 4-vector in our frame of reference? Then, could we define absolute time as the proper time in the direction of that 4-vector?

No, the CMBR would only provide a 4-vector relative to the CMBR.

Is the CMBR a fundamental part of our universe, or can it really be ignored without physical consequence?

The Himilayas are a part of our planet that cannot be ignored without physical consequence (particularly for pilots who wish to avoid a "controlled flight into terrain"), but that does not mean that they are "absolute" in the usual physics meaning, i.e. the laws of physics are the same in an inertial frame where Mt. Everest moves and one where it is at rest. Similarly with the CMBR.

 

[hartlw]

An isolated particle emits a pulse of light. If you can associate a distance (dimension) with the particle you can define time as the distance between the particle and the light pulse, assuming the particle remains at the center of the light pulse envelope, which is reasonable in the case of an isolated particle.

By this definition the speed of light is constant wrt the particle. There are no other clocks around.

Finally, time is distance (travelled by the light pulse envelope).

The envelope of the first pulse of light ever emitted is still out there, keeping time.

 

[confinement]

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.

In fact I did make an error, I should have stated that the 13.7 billion years is the least upper bound for the proper time of any observer.

 

[turin]

I am having some profound trouble separating the concept of the universe from the concept of the stuff in the universe. I suppose this is what Phrak was alluding to. I also don't know exactly what someone means when they say "law of physics"; in these kinds of discussions, it seems like they mean "law of free space". I cannot deny the physical consequences of relativity that seem so mundane now. But, I also cannot imagine literally empty space. It almost seems like an oxymoron.

 

[ckollerer]

An isolated particle emits a pulse of light. If you can associate a distance (dimension) with the particle you can define time as the distance between the particle and the light pulse, assuming the particle remains at the center of the light pulse envelope, which is reasonable in the case of an isolated particle.

By this definition the speed of light is constant wrt the particle. There are no other clocks around.

Finally, time is distance (travelled by the light pulse envelope).

The envelope of the first pulse of light ever emitted is still out there, keeping time.

I am another amateur, as the OP is. To me, you make the most sense. Because the constant, speed of light, must be the answer to what Absolute Time is. We just have to substitute meters and years with "universal" units of measurement, is all. Let's not trip over our yardsticks defining it.

Einstein said the speed of light had to remain constant, and all the rest of physics had to be changed to be consistent with this fact.

 

[The Dagda]

I am another amateur, as the OP is. To me, you make the most sense. Because the speed of light must be the answer to what Absolute Time is. We just have to substitute meters and years with "universal" units of measurement, is all. Let's not trip over our yardsticks defining it.

Einstein said the speed of light had to remain constant, and all the rest of physics had to be changed to be consistent with this fact.

This fact is also why there are no preferred reference frames, it's also why photons don't theoretically experience time. Absolute time is a fairy tale, there is no way to determine such a thing even if it existed given the limitations of space and time, and their intrinsic inter-relation.

 

[hartlw]

OK, now suppose we have two identical particles in the universe, and no matter where they are the distance between them changes due to some form of interaction, "gravity." Unit distance is the size of the particle.

Assume they each emit an identical pulse of light which has a spherical envelope, as determined by our definition of distance. This spherical envelope has a center, which permanently marks a point in space and exists forever. For example, the envelope of light emitted by the "big bang" is still out there expanding and its center defines a point which is the "center" of the universe.

Note time is defined at any center of light by the distance of the light envelope from the center.

Each of our two particles emit a pulse of light. The options then are:

1) They drag the light with them, ie, the light always and instantly centers itself on the "gravitational" field of the particle. But then it will be influenced by the "gravitational" field of the other particle and become complex in shape. Unlikeley scenario.

2) The two centers of light remain fixed.

3) The two centers of light move with respect to each other due to having the speed of the particle at the time of the light pulse.

My inclination is toward 3) because That's what would happen if the other particle didn"t exist, and the existence of the other particle shouldn't change this. (Flimsy reason. You really just have to accept this as a possible alternative.)

In practical terms, this means that if a ight wave "hit" a particle and triggered the emission of a light pulse, the center of the triggered light pulse would have the speed of the particle from which it was emitted at the instant it was triggered. This has interesting implications.

The next step is the viewpoint of a real observer and what he can actually measure, and how he interprets the measurements to decide between 2) and 3), and the implications. Sorry, we have reached the limits of my little brain.

 

[matheinste]

Hello hartlw.

When considering flat, no gravity spacetime your number 1 scenario probably best describes what happens. Whether it applies in GR i do not know.

In SR, if a particle emitted a light pulse that particle would remain central to the expanding sphere of light. If two separated particles, moving inertially relative to each other emitted a light pulse each, they would both remain central to their respective expanding sphere of light. If both particles, moving with respect to each other were present at a point where a light pulse was emitted, they would BOTH remain central to the expanding sphere of light although they would be moving apart. This is a direct consequence of the speed of light being the same for all observers.

Matheinste

 

[hartlw]

Thanks Matheinste,

I believe you have to distinquish between what actually happens (the disembodied abstract observer), and what the real observer can actually "see" (measure) and logically conclude from that. SR and GR.

 

[matheinste]

Hello hartlw.

The above is what is actually predicted by SR and so is what happens. I have no idea how physicists observe it.

Matheinste

 

[hartlw]

My answer to the question:

Absolute time is the distance of a spherical light wave from its center measured by an observer at the center.

Distance is the size of the particle which emitted the light wave at the time it emitted the light wave. It is assumed that distance can be preserved by the observer at the center of the light wave.

 

[The Dagda]

My answer to the question:

Absolute time is the distance of a spherical light wave from its center measured by an observer at the center.

Is the point where you are standing stationary, is it expanding? If so how can you tell?

Distance is the size of the particle which emitted the light wave at the time it emitted the light wave. It is assumed that distance can be preserved by the observer at the center of the light wave.

How exactly, and how could we use this to measure anything but that single point where he stands at that given time, even sending the information would make it useless as a reference, that is the point.

That point is no more discreet than any other point, it cannot be and SR remain a viable theory.

 

[hartlw]

It would be nice to dispense with the size of the particle and just say that absolute time is the size of the light wave with respect to its center. But you can't quantify this unless you can uniqueley identify a particular position of the light wave.

 

[The Dagda]

It would be nice to dispense with the size of the particle and just say that absolute time is the size of the light wave with respect to its center. But you can't quantify this unless you can uniqueley identify a particular position of the light wave.

Or a discreet frame of reference, or a stationary point. It's a hypothesis that could not be verified practically, think carefully how you'd test it, or how you'd use this so called AT. Thus SR survives another day.