# The speed of time

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Whether Time is linear or cyclical or something else, is the speed of time constant?

What basis do we have to extrapolate time back to t=0 (or very close to 0) and assume it's speed is the same as it today?

I read descriptions of the early universe describing things like "A few millionths of a second (after the big bang), quarks aggregated to produce protons and neutrons"

How would an observer in the early universe measure time when there are only quarks, protons and neutrons?

Is it possible the speed of time is variable?  Could 1 millionth of a second in the early universe be equivalent to a few million years today, relative to that early universe?

If time is accelerating universally, would this not affect any empirical evidence of any experiments performed to date, unless we can time travel?

If time is accelerating, could that explain dark energy and space expansion?

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23 hours ago, AbstractDreamer said:

Is it possible the speed of time is variable?

We know time depends on your motion relative to another observer, and on your gravitational potential

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2 hours ago, AbstractDreamer said:

Whether Time is linear or cyclical or something else, is the speed of time constant?

What basis do we have to extrapolate time back to t=0 (or very close to 0) and assume it's speed is the same as it today?

I guess there are 2 things to consider 1. The measurement of time for any relative observer. 2. The "speed" at which time propagates

1. The measurement depends on what you are comparing to. each frame of reference will measure time to tick away at 1 second per second (a constant rate) however different frames of reference (as swansont stated) may not agree and find that their clock seems to tick away slower or quicker in comparison to the clock in the other frame of reference (variable rate)

2. The speed of time propagation (though makes little sense really), or rather the speed at which change takes place will be C, since time is a measurement of the rate of change, no rate of change happens faster than C so this will be constant (though this rate may have varied during different stages of the evolution of the universe).

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Forgive my ignorance but, what exactly is the "speed of time"?

You cannot define things in a vacuum. How do you measure that speed?

In order to measure a speed, you need a quantity changing. And then you need something else changing in a way regular enough from the perceptual POV to serve as a standard clock.

What is the standard clock against which time is seen to change?

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15 hours ago, joigus said:

Forgive my ignorance but, what exactly is the "speed of time"?

You cannot define things in a vacuum. How do you measure that speed?

In order to measure a speed, you need a quantity changing. And then you need something else changing in a way regular enough from the perceptual POV to serve as a standard clock.

What is the standard clock against which time is seen to change?

16 hours ago, Intoscience said:

The speed of time propagation (though makes little sense really)

Exactly this is why the question makes no sense when worded such a way "the speed of time" I assumed from the rest of the post that the poster was confusing this with the speed at which the rate of change can occur 0 > C.

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31 minutes ago, Intoscience said:

Exactly this is why the question makes no sense when worded such a way "the speed of time"

Yeah. Some nifty definition is needed here. I'm not saying it's impossible to define a "speed of time" in a meaningful way. Cosmology comes to mind.

The second quality standard that a definition worth the name has to satisfy is being useful.

Otherwise, speed of time = rate of change of time with respect to time = change of time / change of time = 1

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23 hours ago, joigus said:

what exactly is the "speed of time"?

You cannot define things in a vacuum. How do you measure that speed?

In order to measure a speed, you need a quantity changing. And then you need something else changing in a way regular enough from the perceptual POV to serve as a standard clock.

What is the standard clock against which time is seen to change?

Well I deliberately avoided any precision in its definition because I really don't know myself.  I have an idea that time propagates.  And if this propagation is with respect to something else, then we can define the rate of propagation (relative to that something else).  Of course, if we cant find anything else, we cant define the rate of propagation.  But that doesn't mean the propagation is constant, it just means it is undefined (possibly meaningless but also possibly meaningful).

If we create a theoretical unit of something, lets just say its called Gap, which is a measurement of time but from outside of time.  We can calibrate Time and Gap arbitrarily, so we can take any moment in time and any period of time as equal to 1 Gap.  So lets take right now as the moment, and a period of 1 hour = 1 Gap.  So we can ask will 1 hour=1 Gap tomorrow, next year, next 13 billion years, 13 billions years ago?  (Lets define 1 hour as something which exists unchanging in all time moments, like some probability of emission decay of some particle.)

We might never be able to empirically show that the speed of time is constant or changing (it might be meaningless).  Whether it is variable or not, it wont ever affect any experimentation as everything we do is "trapped" in the same time and subject to the same changes in the speed of time.   So does it break anything if we assume or not that time has a speed and that this speed is variable?  What if space expansion today, and the inflation model 13 billion years was a manifestation of this?  Could dark energy exist outside of time?

On 8/24/2022 at 2:37 PM, swansont said:

We know time depends on your motion relative to another observer, and on your gravitational potential

Do singularities have infinite or undefined gravitational potential?  Would this mean singularities exist "outside" of time?  Black holes will eventually decay, but what happens to the singularity?

Is there anything (theoretical or otherwise) that has undefined motion relative to another observer?  Space expansion/dark energy?   Would something with undefined motion necessarily exist "outside" of time?  Would that thing need to have undefined motion relative to ALL observers concurrently at one moment in time, or is it enough to be undefined relative to just one observer? If a thing has undefined motion at one moment in time, will it always have undefined motion?

Edited by AbstractDreamer
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Are you really asking whether the 'unit' of time is getting larger, or smaller, as time progresses ?

And further, does it really matter ?

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8 hours ago, AbstractDreamer said:

Well I deliberately avoided any precision in its definition because I really don't know myself.  I have an idea that time propagates.  And if this propagation is with respect to something else, then we can define the rate of propagation (relative to that something else).  Of course, if we cant find anything else, we cant define the rate of propagation.  But that doesn't mean the propagation is constant, it just means it is undefined (possibly meaningless but also possibly meaningful).

If we create a theoretical unit of something, lets just say its called Gap, which is a measurement of time but from outside of time.  We can calibrate Time and Gap arbitrarily, so we can take any moment in time and any period of time as equal to 1 Gap.  So lets take right now as the moment, and a period of 1 hour = 1 Gap.  So we can ask will 1 hour=1 Gap tomorrow, next year, next 13 billion years, 13 billions years ago?  (Lets define 1 hour as something which exists unchanging in all time moments, like some probability of emission decay of some particle.)

We might never be able to empirically show that the speed of time is constant or changing (it might be meaningless).  Whether it is variable or not, it wont ever affect any experimentation as everything we do is "trapped" in the same time and subject to the same changes in the speed of time.   So does it break anything if we assume or not that time has a speed and that this speed is variable?  What if space expansion today, and the inflation model 13 billion years was a manifestation of this?  Could dark energy exist outside of time?

You're living dangerously here. Time propagates with respect to "something else". And what might that be? And how does it relate to everything else that's known?

Feynman bitterly complained about ideas like this: Maybe time is not continuous. Maybe there are other dimensions. Maybe spacetime is a fractal...

Yes. But how does it relate to everything else we know? What the auxiliary hypothesis that gets you out of this arbitrariness/circularity?

I'm not saying that everything we define must be directly measurable. In quantum mechanics, we speak of the wave function, which is not an observable of the theory. But we have ways to check that it's a useful and relevant mathematical construction. In the case of QM, it's Born's hypothesis that the odds of something happening can be calculated from the wave function as quadratic functions of this wave function. Also interference patterns, etc.

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On 8/24/2022 at 4:31 AM, AbstractDreamer said:

is the speed of time constant?

Is not its constancy or periodicity, unless perturbed, its defining characteristic?

14 hours ago, AbstractDreamer said:

(Lets define 1 hour as something which exists unchanging in all time moments, like some probability of emission decay of some particle.)

I have some maths for that?.. Probably not.

14 hours ago, AbstractDreamer said:

I have an idea that time propagates.

Can you explain what that would look like? What is it propagating relative to? An observer outside time?

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Speed is distance in meters divided by time in seconds. So it does apply to time curve f(t')=t.. If time at some point, goes faster or slower, then you need another clock, which will tell how much they differ, when they try to synchronize their clocks once again after re-meeting.

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15 hours ago, AbstractDreamer said:

Is there anything (theoretical or otherwise) that has undefined motion relative to another observer?

If 0 is instead a limit, and our numbers on a line are code for oscillators or vibrational states, is that a Brownian-type motion there? Or are they just a distance from 0? If the former, I'd say their motion is self-contained but I don't know about undefined.

6 hours ago, joigus said:

You're living dangerously here. Time propagates with respect to "something else". And what might that be? And how does it relate to everything else that's known?

Feynman bitterly complained about ideas like this: Maybe time is not continuous. Maybe there are other dimensions. Maybe spacetime is a fractal...

Yes. But how does it relate to everything else we know? What the auxiliary hypothesis that gets you out of this arbitrariness/circularity?

[...]

Could the something else be spatial expanse? Not sure that's a useful or practical theory. If you don't mind, what was Feynman's complaint about--those ideas, or are you listing his complaints?

38 minutes ago, Sensei said:

Speed is distance in meters divided by time in seconds. So it does apply to time curve f(t')=t.. If time at some point, goes faster or slower, then you need another clock, which will tell how much they differ, when they try to synchronize their clocks once again after re-meeting.

So then $time=measure/speed$.

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2 hours ago, NTuft said:

Could the something else be spatial expanse? Not sure that's a useful or practical theory. If you don't mind, what was Feynman's complaint about--those ideas, or are you listing his complaints?

No. It's essentially the same complaint.

People often confuse the dumbed down idea, the metaphor, the motto, with the real idea. Physicists come up with these metaphors to help themselves, and others, remember, understand, and suggest:

Antiparticles are ordinary partlcles going backwards in time.

Virtual particles carry interactions between real particles.

Black holes evaporate.

Etc.

Those are not the ideas. They are motivational instruments. You can't go from the motivational instrument to the actual theory without filling in the details.

That's what I meant.

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21 hours ago, AbstractDreamer said:

We might never be able to empirically show that the speed of time is constant or changing (it might be meaningless).

As I pointed out before, time passes at different rates in different frames of reference, and this has been shown empirically.

Regardless of whatever conjecture you might have, you need to start out from what we have already shown.

21 hours ago, AbstractDreamer said:

Is there anything (theoretical or otherwise) that has undefined motion relative to another observer?

I don't know what "undefined motion" means

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19 hours ago, MigL said:

Are you really asking whether the 'unit' of time is getting larger, or smaller, as time progresses ?

And further, does it really matter ?

Yes, I think that is my question.  And no, I don't think it matters at all to the standard model.  Which is why I'm asking the question... if it doesn't matter, what are the theories that follow if the "unit" of time does or does not change, as time progresses.  And can dark energy exist outside of time.  And in the possibility that dark energy can exist outside of time, could it cause or be caused by time accelerating?

3 hours ago, swansont said:

As I pointed out before, time passes at different rates in different frames of reference, and this has been shown empirically.

Regardless of whatever conjecture you might have, you need to start out from what we have already shown.

I don't know what "undefined motion" means

I accept that the passing of time is relative, and therefore it changes. That is, time dilates.  But this argument does not refute my question.

My question is more:  For a situation where the effect of time dilation due to relative motion is zero, is there no possibility that the rate of change of time is variable -  specifically, a rate that has a denominator value "outside" of time.

Undefined motion akin to gravitational potential at a singularity.  Do singularities have undefined gravitational potential?  Would this mean singularities exist "outside" of time?  Black holes will eventually decay, but what happens to the singularity?

10 hours ago, Sensei said:

Speed is distance in meters divided by time in seconds. So it does apply to time curve f(t')=t.. If time at some point, goes faster or slower, then you need another clock, which will tell how much they differ, when they try to synchronize their clocks once again after re-meeting.

My choice of the word "speed" is poor.   I should have said "rate of change per something else".

Density is mass/volume.  If mass increases, it is denser.

Speed is distance/time.  If distance increases, it is faster.

"rate of change of time per Gap" is time/Gap.  If time increase, it is more "rate of change of time per Gap"

But I don't think it needs to be another clock.  It just needs to be another unit, measureable or not.   But for conceptual purposes, lets call it Imaginary Time or iT, where iT is orthogonal to T.

16 hours ago, joigus said:

Feynman bitterly complained about ideas like this: Maybe time is not continuous. Maybe there are other dimensions. Maybe spacetime is a fractal...

Yes. But how does it relate to everything else we know? What the auxiliary hypothesis that gets you out of this arbitrariness/circularity?

It relates via my wildly speculative question about variable rate of time and space expansion -  that is, whether it is possible that the unit of time changes over time with respect to a unit of something else outside of time. And, if there are entities that exist outside of time (such as an imaginary entity with undefined motion), could they be linked to dark energy somehow.  And ultimately, could something like a variable rate of time be the cause or the effect of space expansion.

Edited by AbstractDreamer
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24 minutes ago, AbstractDreamer said:

I accept that the passing of time is relative, and therefore it changes. That is, time dilates.  But this argument does not refute my question.

I wasn't looking to refute anything (how does one refute a question?)

I was trying to point out that we already know the answer is that time is not a constant. So if you are meaning something else, you need to rephrase the question.

24 minutes ago, AbstractDreamer said:

My question is more:  For a situation where the effect of time dilation due to relative motion is zero, is there no possibility that the rate of change of time is variable -  specifically, a rate that has a denominator value "outside" of time.

There is no theoretical or experimental evidence that this is the case. If there was some universal change in time and it affected everyone, how would we notice it? And if it was not universal, we should notice it.

24 minutes ago, AbstractDreamer said:

Undefined motion akin to gravitational potential at a singularity.  Do singularities have undefined gravitational potential?  Would this mean singularities exist "outside" of time?  Black holes will eventually decay, but what happens to the singularity?

If the black hole decays so that there is no longer a black hole, there is no longer a singularity. (if there ever was one, since they are considered to be unphysical)

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7 minutes ago, swansont said:

There is no theoretical or experimental evidence that this is the case. If there was some universal change in time and it affected everyone, how would we notice it? And if it was not universal, we should notice it.

Right, we can't notice it!  We are all "trapped" in the same rate of change of time.   The unit of time could be doubling, halving, exponential, logarithmic.  We would not be able to observe it, and it would have not consequence to anything within our spacetime.   If there is no theoretical or experimental evidence that this is the case, then why should there be theoretical or experimental evidence that this isn't the case?  What basis do we have to assume the rate of time is constant?

So it doesn't really break any theories to consider the rate of time as non-constant, as it is not measurable.  So why not pick an arbitrary function of this rate of time and tie it into dark energy with undefined motion, to explain space expansion?  What are the main arguments that oppose this approach?

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43 minutes ago, AbstractDreamer said:

Right, we can't notice it!  We are all "trapped" in the same rate of change of time.   The unit of time could be doubling, halving, exponential, logarithmic.  We would not be able to observe it, and it would have not consequence to anything within our spacetime.

I have to disagree. Time is a property that applies to all known matter and energy. It's common to everything in the universe. You say we are all trapped in the same rate of change. That IS time. If your imaginary unit was doubling or halving, that's not a unit of time, because time is what we experience in relation to the rest of the universe, and as you say, we would not be able to detect it. Time is what we CAN detect. You are describing something other than time.

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I find Barbour useful, even when disagreeing with him, on what time could possibly be other than a perceived rate of change that's essentially an illusion.

Warning:  May contain traces of nut.

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2 hours ago, AbstractDreamer said:

Right, we can't notice it!  We are all "trapped" in the same rate of change of time.   The unit of time could be doubling, halving, exponential, logarithmic.  We would not be able to observe it, and it would have not consequence to anything within our spacetime.   If there is no theoretical or experimental evidence that this is the case, then why should there be theoretical or experimental evidence that this isn't the case?  What basis do we have to assume the rate of time is constant?

But if this rate changes for everything, why does it matter? Everything that changes is referenced to that rate. And of it's static, it doesn't matter at all.

2 hours ago, AbstractDreamer said:

So it doesn't really break any theories to consider the rate of time as non-constant, as it is not measurable.  So why not pick an arbitrary function of this rate of time and tie it into dark energy with undefined motion, to explain space expansion?  What are the main arguments that oppose this approach?

Then it's tied to something that's not measurable. If you use an arbitrary rate, it will be some constant multiplicative of the rate we observe, which is just a constant of proportionality that gets lumped in with any other constants of proportionality. It's meaningless from a physical point of view.

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17 hours ago, swansont said:

But if this rate changes for everything, why does it matter? Everything that changes is referenced to that rate. And of it's static, it doesn't matter at all.

Then it's tied to something that's not measurable. If you use an arbitrary rate, it will be some constant multiplicative of the rate we observe, which is just a constant of proportionality that gets lumped in with any other constants of proportionality. It's meaningless from a physical point of view.

It didn't think it does matter.  That's why I'm asking questions. If learned minds can also agree it doesn't matter, I'll take it as a reasonable basis to continue using it as a premise to my end question about dark energy.

It's meaningless perhaps today from anything directly measurable within spacetime.  But theoretically, would you agree there if there is a conceptual idea of the rate of change of time, that there is no basis to assume it is constant at different moments/periods in time?

Something is seemingly stretching the axes of spacetime.  With a leap of faith, it is possible this entity is outside of time?  What if this entity was not directly measurable, but its effect on the measurable universe CAN be observed.  We can observe space expansion occurring in the measurable universe, it is possible that we cannot directly measure what is causing it?

Can we directly measure a singularity? I don't think so.   A singularity exists outside of spacetime as its gravitational potential is undefined.  Can we observe the effects of a singularity?  Maybe not.  What exactly does a singularity do?

Perhaps we cant measure dark energy directly.  Perhaps dark energy is outside of spacetime as it's motion is undefined.  Perhaps its effect can be observed through spacetime expansion.

Is it possible that singularities are the source of dark energy?

Edited by AbstractDreamer
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• 2 weeks later...

So do the equations of General Relativity premise on the propagation of time being constant since the Big Bang?  That is, the premise that the axes of time are uniform between t=0 and t=infinity.

Is there any logical or reasonable basis upon which to assume that the propagation of time is a constant since the Big Bang?

If we accept that the spacetime continuum experiences a stretching of its axes when observing space expansion, why should we assume that its only the axes of space that is stretched, and that the axes of time remain uniform?

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34 minutes ago, AbstractDreamer said:

So do the equations of General Relativity premise on the propagation of time being constant since the Big Bang?  That is, the premise that the axes of time are uniform between t=0 and t=infinity.

Is there any logical or reasonable basis upon which to assume that the propagation of time is a constant since the Big Bang?

If we accept that the spacetime continuum experiences a stretching of its axes when observing space expansion, why should we assume that its only the axes of space that is stretched, and that the axes of time remain uniform?

As I said earlier, we know time depends on your motion relative to another observer, and on your gravitational potential.

What clarification do you need? Time is not absolute, so the notion that time is constant is nonsensical without considering who is doing the measuring, and what the conditions are. To the extent that the question makes sense, we know that the answer is no. As I already said. Time is going to run at a different rate, as compared to some reference clock, depending on where you are and your state of motion.

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48 minutes ago, swansont said:

As I said earlier, we know time depends on your motion relative to another observer, and on your gravitational potential.

So you are saying categorically it (time) cannot depend on anything else, such as for example a function of itself?

53 minutes ago, swansont said:

To the extent that the question makes sense, we know that the answer is no.

Which of my questions is "no" the answer to?

How do the equations in GR allow for Proper Time that has a world line that spans two manifolds between which have observed space expansion?

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6 minutes ago, AbstractDreamer said:

Which of my questions is "no" the answer to?

Both of the ones I quoted in my previous post, both of which asked if time was constant. (the third statement wasn’t actually a question)

8 minutes ago, AbstractDreamer said:

So you are saying categorically it (time) cannot depend on anything else, such as for example a function of itself?

I stated no such thing. Once you know that time depends on certain factors, it answers the question of whether time is constant. Whether there are more variables is a completely different question.

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