Is Time Slowing or Are Processes Slowing Near High Gravity and Speeds?

[dayalanand roy]

Processes taking place near high gravitation or moving at near light speed are slowed. General relativity tells that it is due to slowing of time in these conditions. Why can’t we say that this is due to slowing of the process itself in these conditions rather than slowing of the time? Is it not possible that in the atomic clock near high gravity or at high speed, the oscillation of cesium atom itself is slowed down rather than slowing of time? Is it not possible that the physiology and cytology of the twin living near ground or moving at near light speed is slowed down, delaying the ageing phenomenon, rather than slowing the time?

 

[Erich Schoedl]

You're speaking of the general theory of relativity and the special theory of relativity. Yes the process appears "slow" relative to another reference frame. The clock is simply another process.

 

[phinds]

Processes taking place near high gravitation or moving at near light speed are slowed. General relativity tells that it is due to slowing of time in these conditions. Why can’t we say that this is due to slowing of the process itself in these conditions rather than slowing of the time? Is it not possible that in the atomic clock near high gravity or at high speed, the oscillation of cesium atom itself is slowed down rather than slowing of time? Is it not possible that the physiology and cytology of the twin living near ground or moving at near light speed is slowed down, delaying the ageing phenomenon, rather than slowing the time?

What mechanism do you propose to cause the processes to slow down while time moves at the same rate as elsewhere?

 

[cwilkins]

Processes taking place near high gravitation or moving at near light speed are slowed. General relativity tells that it is due to slowing of time in these conditions. Why can’t we say that this is due to slowing of the process itself in these conditions rather than slowing of the time? Is it not possible that in the atomic clock near high gravity or at high speed, the oscillation of cesium atom itself is slowed down rather than slowing of time? Is it not possible that the physiology and cytology of the twin living near ground or moving at near light speed is slowed down, delaying the ageing phenomenon, rather than slowing the time?

What is the distinction between "slowing all time-dependent processes down" and "slowing time down"?

 

[Erich Schoedl]

Time is a measurement of the rate of change of processes. You might be assuming that time should be universal and someone should prove to you that it isn't. Why not look at it the other way around? The measurement of time is only consistent locally. Prove to me instead that this is wrong and why it should be universal. You won't be able to. The arguments go back 100 years to when Einstein first postulated relativity.

 

[dayalanand roy]

You're speaking of the general theory of relativity and the special theory of relativity. Yes the process appears "slow" relative to another reference frame. The clock is simply another process.

Thanks.slowing of a process is easy to conceive. But the phenomenon was suggetsed by Einstein to do away with concept of absoluteness of time, which is hard to conceptualise.
Regards

 

[dayalanand roy]

What mechanism do you propose to cause the processes to slow down while time moves at the same rate as elsewhere?

Thanks for reply. Processes are much easier to be slowed than time. When the gravity of a black hole can interfere with the movement of light, why can't the gravity of a massive body interfere with the oscillation of an atom ( a speculation)?
regards
dayalanand

 

[dayalanand roy]

What is the distinction between "slowing all time-dependent processes down" and "slowing time down"?

Thanks for the reply. When you talk of slowing of a process, it is slowing either in reference to some other process or some reference time. But when you talk of slowing of time, it is slowing in reference to what?
regards
dayalanand

 

[dayalanand roy]

Many thanks for the reply. I fully agree with you..
regards

 

[Vierstein]

Well slowed if you compare it to elsewhere, yes. But you will not notice, seen as time is slowed for you too.

 

[russ_watters]

Thanks for reply. Processes are much easier to be slowed than time. When the gravity of a black hole can interfere with the movement of light, why can't the gravity of a massive body interfere with the oscillation of an atom ( a speculation)?
regards
dayalanand

It can, but what about processes that don't involve physical oscillation? It would be very unlikely for all processes to be slowed by the same amount.

 

[nitsuj]

Processes taking place near high gravitation or moving at near light speed are slowed. General relativity tells that it is due to slowing of time in these conditions. Why can’t we say that this is due to slowing of the process itself in these conditions rather than slowing of the time?

What is the distinction between "slowing all time-dependent processes down" and "slowing time down"?

One thing I think of as a difference between slowing of a "process" and time "slowing down" is the impact on measurement of length.

The simple process of measuring a length more slowly wouldn't result in a contracted measure. i.e. the measure of length isn't time dependent.

Time Dilation is time as a dimension comparatively "slowing down", which precedes any "process" that may happen within this dimension. In turn measure of length too is comparably effected.

Note this is in general with respect to SR, I can't speak for a GR perspective.

 

[cwilkins]

One thing I think of as a difference between slowing of a "process" and time "slowing down" is the impact on measurement of length.

The simple process of measuring a length more slowly wouldn't result in a contracted measure. i.e. the measure of length isn't time dependent.

Time Dilation is time as a dimension comparatively "slowing down", which precedes any "process" that may happen within this dimension. In turn measure of length too is comparably effected.

Note this is in general with respect to SR, I can't speak for a GR perspective.

I don't agree. Length measurement is a time-dependent process in the relativistic sense, since you must have an associated moving frame for length contraction to occur (in SR). If the frames were moving at different rates, you would detect a change in length. The usual way length would be measured with comoving frames would be to start a clock at the instant you first see one end of a meterstick and stop it immediately once it ends. Since you know the elapsed time and relative velocity of your frame, you can compute its length. In that sense it does depend on how slowly you take the measurement.

To clarify my original question, I am asserting that anything which explicitly depends on observed time (or its differential) can be viewed in a way that makes it indistinguishable from the process appearing to be slowed by some other means. For example, in a mechanical clock you would find that the lengths and geometry of the gears/servos are contorted such that the observed clock ticks at a slower rate. Does that mean that time has "slowed down"? Yes, but you could equally (and correctly) argue that it was due to a change in geometry. These interpretations are equivalent, so there isn't really a distinction between the two.

 

[nitsuj]

I don't agree. Length measurement is a time-dependent process in the relativistic sense, since you must have an associated moving frame for length contraction to occur (in SR). If the frames were moving at different rates, you would detect a change in length. The usual way length would be measured with comoving frames would be to start a clock at the instant you first see one end of a meterstick and stop it immediately once it ends. Since you know the elapsed time and relative velocity of your frame, you can compute its length. In that sense it does depend on how slowly you take the measurement.

So...your calculation is time dependent. is it noted in the result? 3m measured in a time interval of 3s with measured objects velocity of 1m/s. No, it's 3m. And you used proper time to measure proper length. A convoluted method as opposed to using a simple measuring stick, which again is not time dependent in any sense. In fact it's complety exlcuisive of time in a relativistic sense. Orthogonally opposed dimensions, +-.

To clarify my original question, I am asserting that anything which explicitly depends on observed time (or its differential) can be viewed in a way that makes it indistinguishable from the process appearing to be slowed by some other means. For example, in a mechanical clock you would find that the lengths and geometry of the gears/servos are contorted such that the observed clock ticks at a slower rate. Does that mean that time has "slowed down"? Yes, but you could equally (and correctly) argue that it was due to a change in geometry. These interpretations are equivalent, so there isn't really a distinction between the two.

Yup kinda what I'm saying. it's a change in geometry that "slows" time and contracts length. Not slowing of processes.

I thought that position was made clear with the statement

Time Dilation is time as a dimension comparatively "slowing down", which precedes any "process" that may happen within this dimension. In turn measure of length too is comparably effected.Does that mean time slowed down? Yes it does, does it mean the processes merely slowed down? No, they haven't the spacetime interval is the same. The geometry is comparatively "different".

 

[dayalanand roy]

Can time be slowed

Dear Cwilkins and nitsuj
Many thanks for for participating in this discussion.
regards
dayalanand

 

[bobc2]

... Why can’t we say that this is due to slowing of the process itself in these conditions rather than slowing of the time?...

This does not work. If it worked this way, then Observer A would see observer B's clock has slowed, but observer B would not see that observer A's clock has slowed. Special relativity has it right: A sees B's clock is slowed, and also, B sees A's clock has slowed.

 

[1977ub]

If all of the slowing/speed of clocks and contracting of matter continues to seem "just wrong," I think it's important to remember that in the case of SR there are a number of assumptions one makes that lead one to conclude that a traveler is slowed and contracted. But the result of measuring / deciding the slowing and contracting can just as easily lead you to question these assumptions - basically the assumption of what events appear to be simultaneous in your own frame. It is very practical in a day-to-day sense to operate with our notion of an extended frame with its simultaneity, and this leads us to have a practical understanding of the longevity of the incoming muon for instance. But in each traveling frame, it is the other fellow's clock/rod which appears slowed, and this cannot logically be literally true. If you hold on to the version of simultaneity that seems normal and practical in your rest frame, you have to let go of the intuitive view that clocks and rods operate without contraction if they are moving. It is just as physically "true" though normally less practical to let go of the intuitive view of simultaneity in our rest frame. Then rods and clocks are free to be uncontracted. I get the impression that in GR there is a similar alternative - an intuitive idea we could "let go of" and keep the clocks all running at the same rate... something related to uncurved spacetime. Something like this: ? "To determine that someone else's clock is running at a different rate at a different altitude, the information from that clock to get to you has to travel through a region of spacetime in which the curvature is constantly changing and this brings about the *seeming* change in clock rates." Again, for practicality's sake I understand it makes more sense to simply think of the clock rates changing, to calibrate GPS satellites and so on.

 

[nitsuj]

But in each traveling frame, it is the other fellow's clock/rod which appears slowed, and this cannot logically be literally true.

It is literally true and because of logic. The situation is symmetrical.

What "cannot logically be literally true" is one frame of reference claiming to be at rest & the other to be moving.

 

[1977ub]

It is literally true and because of logic. The situation is symmetrical.

I just mean in the sense of A>B and B>A not both being literally true logically. It is logical that each "appears" to run slower to the other (similar perhaps to receding travelers viewing each other as shrinking). However, often beginners are scratching their heads and looking for alternate "physical" explanations for slowed time and timepieces. Not only does A not directly perceive his own timepiece to run slower, B does not "perceive" A's timepiece to run slower either... at least not "perceive" without the baggage that the beginner may not be keeping in mind when "perceive" is being casually used by the more experienced.

 

[nitsuj]

I just mean in the sense of A>B and B>A not both being literally true logically. It is logical that each "appears" to run slower to the other (similar perhaps to receding travelers viewing each other as shrinking). However, often beginners are scratching their heads and looking for alternate "physical" explanations for slowed time and timepieces. Not only does A not directly perceive his own timepiece to run slower, B does not "perceive" A's timepiece to run slower either... at least not "perceive" without the baggage that the beginner may not be keeping in mind when "perceive" is being casually used by the more experienced.

Ah I see the perspective, "appears" is kinda misleading imo. it is not merely an appearance but a comparative difference in the geometry of the FoR's. Each literally true, as in relativity of motion - all physics the same in inertial frames.

 

[dayalanand roy]

This does not work. If it worked this way, then Observer A would see observer B's clock has slowed, but observer B would not see that observer A's clock has slowed. Special relativity has it right: A sees B's clock is slowed, and also, B sees A's clock has slowed.

Many thanks for the reply.
regards.

 

[dayalanand roy]

If all of the slowing/speed of clocks and contracting of matter continues to seem "just wrong," I think it's important to remember that in the case of SR there are a number of assumptions one makes that lead one to conclude that a traveler is slowed and contracted. But the result of measuring / deciding the slowing and contracting can just as easily lead you to question these assumptions - basically the assumption of what events appear to be simultaneous in your own frame. It is very practical in a day-to-day sense to operate with our notion of an extended frame with its simultaneity, and this leads us to have a practical understanding of the longevity of the incoming muon for instance. But in each traveling frame, it is the other fellow's clock/rod which appears slowed, and this cannot logically be literally true. If you hold on to the version of simultaneity that seems normal and practical in your rest frame, you have to let go of the intuitive view that clocks and rods operate without contraction if they are moving. It is just as physically "true" though normally less practical to let go of the intuitive view of simultaneity in our rest frame. Then rods and clocks are free to be uncontracted. I get the impression that in GR there is a similar alternative - an intuitive idea we could "let go of" and keep the clocks all running at the same rate... something related to uncurved spacetime. Something like this: ? "To determine that someone else's clock is running at a different rate at a different altitude, the information from that clock to get to you has to travel through a region of spacetime in which the curvature is constantly changing and this brings about the *seeming* change in clock rates." Again, for practicality's sake I understand it makes more sense to simply think of the clock rates changing, to calibrate GPS satellites and so on.

Thanks for the reply. I am encouraged by your last sentence.
regards.

 

[Dale]

I just mean in the sense of A>B and B>A not both being literally true logically.

Nobody claims that. What is claimed is that A>B and A'<B' are both literally true. Length is frame variant so A' is not equal to A. That is the important take-home message.

 

[1977ub]

But in each traveling frame, it is the other fellow's clock/rod which appears slowed, and this cannot logically be literally true.

It is literally true and because of logic.

Nobody claims that. What is claimed is that A>B and A'<B' are both literally true. Length is frame variant so A' is not equal to A. That is the important take-home message.

It is literally true that each clock *appears* slow to the other. It cannot be true of course that each clock is in some objective sense "slower" than the other. As for what someone might claim... I was thinking more in terms of what someone might believe before they understand the subtleties - I wasn't attempting to imply there was any ambiguity in the science.

 

[Dale]

It is literally true that each clock *appears* slow to the other. It cannot be true of course that each clock is in some objective sense "slower" than the other.

Just to be clear, this is not an optical effect. It is not a mater of visual appearances, all of the relativistic effects (except relativistic Doppler) are what remain after correcting for the finite speed of light.

Suppose A is the time between two ticks of clock 1 in the unprimed frame and B is the time between two ticks of clock 2 in the unprimed frame, and suppose A' and B' are the corresponding quantities in the primed frame. Then A>B and A'<B' can both be objectively true, and neither is a statement of appearances or any other optical effect. There is no contradiction in the two statements since the two statements are comparisons of frame variant quantites in two different frames.

 

[1977ub]

Just to be clear, this is not an optical effect. It is not a mater of visual appearances, all of the relativistic effects (except relativistic Doppler) are what remain after correcting for the finite speed of light.

Sorry if I ended up layering additional confusions. What I meant was:

It is literally true that each clock *seems* slow to the other, as determined by each observer in his own inertial frame making observations of the other. It cannot be true of course that each clock is in some objective sense "slower" than the other.

 

[nitsuj]

What I meant was:

It is literally true that each clock *seems* slow to the other, as determined by each observer in his own inertial frame making observations of the other. It cannot be true of course that each clock is in some objective sense "slower" than the other.

they're equally valid FoRs.

The slow in time dilation is an accumulation of sorts. Learned here that's Differential Aging; "accumulation" of dilated time (light just went off thinking this thread, so only fairly sure about this distinction between the terms).

When a clock has elapsed 10 seconds, it is measured by regular time intervals between some "rhythmic" process. An accumulation of some rhythmic physical process is time in the context of aging, and as far as geometry is concerned an artifact of spacetime.

To say it different Time Dilation is time from strictly a geometric perspective.

Differential aging, an "artifact" of this spacetime geometry, aging is more a "property" of matter (or what ever) imo.

Odd that I now find a slight distinction between my watch measuring an 1hr and being 1hr older.

So if you're going the same speed as something, you're in the same time as it. That's proper time from a geometric perspective... oh and it's 300,000 m/s long OR 0.0000000033 s/m long;) it's just elsewhere past that.
"It is literally true that each clock *seems* slow to the other, as determined by each observer in his own inertial frame making observations of the other."

This is time dilation perspective.
"It cannot be true of course that each clock is in some objective sense "slower" than the other."

This is differential aging perspective, and uncertain/unknown/forethought until "side by side" comparison. (assuming just inertial motion)

 

[cwilkins]

So...your calculation is time dependent. is it noted in the result? 3m measured in a time interval of 3s with measured objects velocity of 1m/s. No, it's 3m. And you used proper time to measure proper length. A convoluted method as opposed to using a simple measuring stick, which again is not time dependent in any sense. In fact it's complety exlcuisive of time in a relativistic sense. Orthogonally opposed dimensions, +-.

Yup kinda what I'm saying. it's a change in geometry that "slows" time and contracts length. Not slowing of processes.

I thought that position was made clear with the statement

Time Dilation is time as a dimension comparatively "slowing down", which precedes any "process" that may happen within this dimension. In turn measure of length too is comparably effected.


Does that mean time slowed down? Yes it does, does it mean the processes merely slowed down? No, they haven't the spacetime interval is the same. The geometry is comparatively "different".

Measuring the length is a time-dependent process. To be clear, I am not saying that the rest length of the object changes as a function of time.

If you are moving relative to another frame it is not sufficient to place a meterstick next to the object. The way Einstein thought about it was to use a synchronized series of clocks along the length of the object. The measured time on clocks at the endpoints are then used to determine the length as the object passes by. See the the first paragraph of http://en.wikipedia.org/wiki/Length_contraction#Basis_in_relativity for more on this.

I think I should also clarify what I meant earlier. Say you measured a meterstick moving at some relative velocity to your frame. At this point you might say that the observed length must be contracted as a consequence of time dilation. This is where I don't agree with you. I don't consider time dilation, defined as "dimension of coordinate time changing due to a relative velocity," to be the fundamental cause of this effect. I consider relative velocity combined with a constant speed of light to be the cause. That is what gives rise to time dilation and length contraction simultaneously, not one after the other. This is a subtle distinction but I stand by it.

Edit: the point is if you apply the above reasoning to the original question of whether you can distinguish between time being slowed or the processing being slowed due to changed geometry, it means you can't.

 

[nitsuj]

Measuring the length is a time-dependent process. To be clear, I am not saying that the rest length of the object changes as a function of time.

If you are moving relative to another frame it is not sufficient to place a meterstick next to the object. The way Einstein thought about it was to use a synchronized series of clocks along the length of the object. The measured time on clocks at the endpoints are then used to determine the length as the object passes by. See the the first paragraph of http://en.wikipedia.org/wiki/Length_contraction#Basis_in_relativity for more on this.

I think I should also clarify what I meant earlier. Say you measured a meterstick moving at some relative velocity to your frame. At this point you might say that the observed length must be contracted as a consequence of time dilation. This is where I don't agree with you. I don't consider time dilation, defined as "dimension of coordinate time changing due to a relative velocity," to be the fundamental cause of this effect. I consider relative velocity combined with a constant speed of light to be the cause. That is what gives rise to time dilation and length contraction simultaneously, not one after the other. This is a subtle distinction but I stand by it.

Edit: the point is if you apply the above reasoning to the original question of whether you can distinguish between time being slowed or the processing being slowed due to changed geometry, it means you can't.

The reason they all need to be synchronized is the reason I prefer the meter stick to measure length. It is what those clocks are assumed to be.

 

[Dale]

It cannot be true of course that each clock is in some objective sense "slower" than the other.

Yes, it can. In my frame of reference your clock is measurably slower than mine. Because it is measurable it is objective, not subjective. This is not a psychological issue nor a matter of optics, it is not "appearance" or "seeming" or "subjective". In my frame your clock is objectively, measurably slow even after accounting for any appearances or optical effects.

Time is a frame variant quantity, which means that in order for a duration to have any meaning you must specify the reference frame used. Once you have specified the frame then the time is objective and well-defined, not mere appearance or seeming or opinion or any other "weasel words" you might want to put in. A<B objectively and A'>B' objectively.

My clock is not faster or slower than yours in any frame-invariant sense. But "frame-invariant" is different from "objective" and being objective does not imply frame-invariance.

 

[1977ub]

Yes, it can. In my frame of reference your clock is measurably slower than mine. Because it is measurable it is objective, not subjective. This is not a psychological issue nor a matter of optics, it is not "appearance" or "seeming" or "subjective". In my frame your clock is objectively, measurably slow even after accounting for any appearances or optical effects.

Time is a frame variant quantity, which means that in order for a duration to have any meaning you must specify the reference frame used. Once you have specified the frame then the time is objective and well-defined, not mere appearance or seeming or opinion or any other "weasel words" you might want to put in. A<B objectively and A'>B' objectively.

My clock is not faster or slower than yours in any frame-invariant sense. But "frame-invariant" is different from "objective" and being objective does not imply frame-invariance.

The definition of "frame of reference"... The convention of adopting and using such a thing... while not "optics" it involves assumptions or decisions. There's nothing so fundamental about it that it absolutely *must* enter into an understanding of the world.

If we imagine that somehow it had never occurred to Einstein or anyone else to construct such a thing, then what we would have are measurements taken at our location.

It doesn't even work to construct such a thing for many observers.

Anything that is a "variant" quantity in any way - which cannot be agreed to be the same way for all observers - can be said not to have an "objective" measure. Therefore I really think my statement stands. You're actually making a stronger statement, that *nothing* "objective" can be said of the speed of any clock. Objectively, there's a clock. Everyone agrees on that. Honestly I don't see as quite so fundamental the distinction you're drawing between the view from a point (optics) and the view from an IRF ( optics + convention + methodology).

 

[Dale]

The definition of "frame of reference"... The convention of adopting and using such a thing... while not "optics" it involves assumptions or decisions. There's nothing so fundamental about it that it absolutely *must* enter into an understanding of the world.

Agreed. But that doesn't make it subjective. Will you also claim that momentum and energy are subjective? They are also frame variant. Same with E fields and B fields. The list goes on. Will you also describe them with words like "seems" and "appears".

Anything that is a "variant" quantity in any way - which cannot be agreed to be the same way for all observers - can be said not to have an "objective" measure.

Yes, it can. Suppose some muons' half life was measured to be 10 μs in the lab frame. It is not a matter of personal opinion or any other subjective criteria. It is an objective fact. The half life was objectively 10 μs in the lab frame.

 

[1977ub]

Agreed. But that doesn't make it subjective. Will you also claim that momentum and energy are subjective? They are also frame variant. Same with E fields and B fields. The list goes on. Will you also describe them with words like "seems" and "appears".

There's probably a term somewhere in philosophy to describe this not-fully-objective-bookkeeping category.

Yes, it can. Suppose some muons' half life was measured to be 10 μs in the lab frame. It is not a matter of personal opinion or any other subjective criteria. It is an objective fact. The half life was objectively 10 μs in the lab frame.

The combination of measurement+frame can be the same for all observers, as long as these observers are all agreed regarding protocols and methods of frame-construction.

I read on a forum here recently that an accelerating observer can't be thought of has having an unambiguous frame, since Einstein & Rindler methods don't generate the same framework. That is a case where different attempts to generate a frame would yield different measurements regarding the half life of the muon. Luckily, in inertial frames there is no such ambiguity, and everyone can get into the comfortable habit of doing frame-bookkeeping just as they do momentum or energy bookkeeping.

 

[Nugatory]

There's probably a term somewhere in philosophy to describe this not-fully-objective-bookkeeping category.

Indeed there is: "coordinate-dependent".

A frame is nothing more or less than a method of assigning coordinates to points in spacetime, so any variation from frame to frame of a quantity calculated in terms of coordinates must necessarily be the result of a coordinate dependency - the coordinates are the only thing that change when we move from frame to frame.

Just about all the not-fully-objective (your words, not mine) things that happen in special relativity are the result of a hidden coordinate dependency: We say "simultaneous" when we mean "has the same time coordinate". If we used the latter phrase we wouldn't be so surprised that simultaneity changes with the way that we assign the t coordinate to events, aka change frames. (And because there's an assumption about simultaneity hidden in the definition of a lot of other stuff, such as length, we wouldn't be so surprised by this other stuff being frame-dependent also).

I should add that there is a perfectly good coordinate-free and frame-independent way of defining simultaneity in SR. Using this leads to statements about the physical world that are "objective" (your word again, and I'd prefer "absolute" or "coordinate-independent" or "frame-independent"). However, the procedure for deciding that two events A and B are simultaneous requires three inputs: Not just A and B as our classical intuition expects, but also a worldline.

 

[Dale]

Using this leads to statements about the physical world that are "objective" (your word again, and I'd prefer "absolute" or "coordinate-independent" or "frame-independent").

That is my preference also. Frame variant quantities are not subjective, they simply require the specification of the frame to which they are referenced.