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

[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.

 

[Nugatory]

I read on a forum here recently that an accelerating observer can't be thought of has having an unambiguous frame

Not just accelerating observers. No observer has an "unambiguous" frame, as a frame is just a convention for assigning coordinates to events, and every observer is free to choose whatever convention he pleases - as long as he is consistent about it and careful about getting the coordinate transforms right if he changes frames.

It is true that an observer not undergoing proper acceleration will find the math especially easy by using a frame in which he/she is at rest. But it is careless wording to say that these are "the observer's frames" or that an observer "has" a frame. We can get away with that carelessness for an inertial observer in flat spacetime, but it leads to grief and confusion when we consider accelerated observers, non-inertial coordinates, and the non-flat spacetimes of GR.

 

[1977ub]

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.

Can you explain or point to an explanation?

 

[danR]

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?

Let us go back to your original question, because I think a lot of 'observers A, B' and 'A' and 'B' suddenly parachuted into the discussion from who knows where.

You're proposing there might an alternate theory, which is good, based on an actual 'process', which is better. Science cannot proceed without something concrete to test, so let us go further, but unfortunately, there are a wealth of possible processes that might involve different mechanisms, so we have to try out each one at a time, eg. A good plan might be to start with something that is very analogous to what we already know. Perhaps the universe parsimoniously recycles good mechanisms. For example:

Things slow down in a gravitational field, because the field makes the space things move in denser, and in the same way a pendulum (a time-keeper) will slow down in denser air, and a resonant cavity has a lower frequency, and a vibrating string, etc. so maybe the atoms in clocks' cogwheels and electrons in their orbitals, etc. are slowed down by this 'denser' gravity-stuff. Everything seems to go slower where things are denser, so perhaps gravity does something similar.

Is this perhaps what you're driving at?

(There are some problems, however, as you might already suspect.)

 

[1977ub]

My objection to pure unaccelerated SR clockspeed comparisons doesn't apply to cases where one observer is traveling in a circle. In that case, lorentz/gamma is used to determine the slowing of the traveling/accelerating clock.

 

[Nugatory]

Can you explain or point to an explanation?

Yes, but best to start another thread for that.

 

[dayalanand roy]

Dear dan R
Thanks for understanding my point.

 

[Mentz114]

...

Things slow down in a gravitational field, because the field makes the space things move in denser, and in the same way a pendulum (a time-keeper) will slow down in denser air, and a resonant cavity has a lower frequency, and a vibrating string, etc. so maybe the atoms in clocks' cogwheels and electrons in their orbitals, etc. are slowed down by this 'denser' gravity-stuff. Everything seems to go slower where things are denser, so perhaps gravity does something similar.
...

The problem with this is that it is not the gravitational field that is asociated with time dilation, but the gravitational *potential*. It is therefore possible to have a gravitational potential which slows down time, but causes no motion or 'compression'.

 

[nitsuj]

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.

I find it hard to distinguish between proper time and geometry, so I can't distinguish the two statements above.

The distinction I made was between;

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

Suppose now that this is a discussion on the definition of "time-dependent processes". Which you are calling length a "time-dependent processes".

While I can dispute what you believe, I won't dispute your belief in it.

 

[1977ub]

Aren't all "processes" time-dependent?

 

[nitsuj]

Aren't all "processes" time-dependent?

Which you are calling length a "time-dependent processes".

While I can dispute what you believe, I won't dispute your belief in it. - suppose it's hypocritical to say it twice.

 

[phinds]

While I can dispute what you believe, I won't dispute your belief in it. - suppose it's hypocritical to say it twice.

I don't know ... seems appropriate to me. Sometimes it takes repetition to get a point across and you are making a good point that seems to be ill-received.

 

[cwilkins]

The idea of a spacetime, which is really what I am getting at by suggesting that an observed process can be viewed from either the time or spatial perspective, is one that Einstein based his general theory on. By studying the equations you will find that time and space are equivalent in a dimensional sense; they cannot be separated. There is no need to respond provocatively or pretentiously. I just don't agree with your interpretation of relativity.

 

[1977ub]

Indeed there is: "coordinate-dependent".

For me to calculate my own or a moving traveler's length, I need to establish coordinates.

I also need to do this to determine a traveler's clockspeed.

However, my own clockspeed seems to be the same ("normal") whether I establish coordinates or not. Or is "my location" its own form of "coordinate" system?

 

[nitsuj]

For me to calculate my own or a moving traveler's length, I need to establish coordinates.

I also need to do this to determine a traveler's clockspeed.

However, my own clockspeed seems to be the same ("normal") whether I establish coordinates or not. Or is "my location" its own form of "coordinate" system?

I would hope nature comes Before the model.

 

[danR]

Dear dan R
Thanks for understanding my point.

Keep in mind that the relativity forum is for relativity discussion, and what you are suggesting is an alternative, competing, classical theory. For that reason, unless you start a new thread in the Classical section (I think there's also an Alternative forum), I can't get too much into it. Generally if the authors become too strident about their ideas here, their post gets moved or locked; but you are exceptionally polite.

I will simply say that the vast majority of alternatives wind up more full of holes than a Swiss cheese, once their claims are framed as testable hypotheses.

 

[hairygary]

Wouldn't the most important reason for time itself needing to "slow" stem from the assertion that regardless of the reference frame, and any velocity of one reference frame relative to the other, the speed of light is the same? So if an observer was traveling at a velocity of c/2 away from a light source, the speed of the light relative to the observer would be c, while also being c relative to a second observer stationary relative to the light source. At first this seems contradictory, as the two reference frames will measure different relative Δx between two events, and velocity=Δx/Δt. The only way the speed of light can be the same in both reference frames is if Δt is different. I'm relatively new to the concept though, so there might be a mistake somewhere in my reasoning.

 

[Nugatory]

Wouldn't the most important reason for time itself needing to "slow" stem from the assertion that regardless of the reference frame, and any velocity of one reference frame relative to the other, the speed of light is the same? So if an observer was traveling at a velocity of c/2 away from a light source, the speed of the light relative to the observer would be c, while also being c relative to a second observer stationary relative to the light source. At first this seems contradictory, as the two reference frames will measure different relative Δx between two events, and velocity=Δx/Δt. The only way the speed of light can be the same in both reference frames is if Δt is different. I'm relatively new to the concept though, so there might be a mistake somewhere in my reasoning.

Yes, that's pretty much about right, although it turns out that Δx also has to do some changing to make it all come out consistently.

The relationship between x and t in one frame and another is given by a set of equations called the Lorentz transformations, which are derived directly from the requirement that the speed of light is the same for all observer. There's a pretty decent algebra-only no-calculus derivation of the Lorentz transforms in Einstein's book "Relativity: The special and general theory" which is available on-line... And once you have these equations, all the rest of special relativity, the time dilation and length contraction and relativity of simultaneity and mass-energy equivalence suddenly makes sense... It's really a lot of fun.

 

[JM]

Processes taking place near high gravitation or moving at near light speed are slowed. ?

Roy. Why do you think that time or processes slow down? Is there some book on SpecRel that makes you ask?
JM

 

[dayalanand roy]

Dear dan R
I am trying to keep up with your suggestions.
regards
dayalanand

 

[dayalanand roy]

Roy. Why do you think that time or processes slow down? Is there some book on SpecRel that makes you ask?
JM

Dear JM
No, I have'nt seen any such book. It is the problem of my personal reasoning and my intuition that I wanted to get clarified here.
regards
roy

 

[JM]

Dear JM
No, I have'nt seen any such book. It is the problem of my personal reasoning and my intuition that I wanted to get clarified here.
regards
roy

Perhaps I should have been more clear, by specrel I meant Special Relativity. Your intuition is good though, because slowing of time and processes is commonly mentioned in the SR literature. It is often hard to understand what is meant, so its best to see what the specific calculations are. The idea that 'moving clocks run slow' originated in 1905 when Einstein developed the formula t' = t √( 1 - v²/c^{2). He said that t', the time of the moving frame, when viewed from the stationary frame, is slow. But Feynman showed that the clocks themselves are perfect, and the effect is due to the constant light speed. So the relativity meaning of slow clocks is not the same as the everyday meaning.
But this calculation shows that a process that takes t seconds, when viewed from the stationary frame, takes only the lesser time of t', when viewed from the moving frame. Doesn't that mean that the process has speeded up?
Taylor and Wheeler are emphatic in denying that motion causes any effect on the workings of clocks or human metabolysm. So we can expect that processes here on Earth will continue their normal rates relative to our time standard GMT, whether E.T is watching us or not.
JM}

 

[JM]

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

I know it's late in the discussion, but I wonder if the following might help.
Start in the stationary frame K with x = vt and calculate the corresponding moving coordinates. The result is that the clock at the origin of K' is slow compared with the clocks of K. Then start in the moving frame K' with x' = - v t' and calculate x,t. The rresult is that the clock at the origin of the stationary frame is slow compared with the clocks of K'. This is the symmetrical result.
But the transforms are reciprocal. If x,t transforms to x',t' then x', t' transforms back to x,t. And if x',t' is smaller than x,t then x,t is greater than x', t'. This is the result when both observers are talking about the same clocks.
JM

 

[1977ub]

If I'm sitting on a rock, and you're going by sitting on a rock, and we each judge the other to have greater momentum than ourselves, there is no objective-for-all-observers difference between our momentums. As long as we're using SR and our two observers are traveling in a straight line, then the time dilation each sees for the other seems to be a mere side-effect of adopting inertial frames. If one of us were traveling in a circle near the other, no longer in free fall, then it immediately becomes a case where there is a definite difference in our clocks which we'll both agree on when we pass each other.

 

[dayalanand roy]

Dear JM
Thanks for educating me. Things are gradually becoming clearer.
regards
roy

 

[Dale]

Taylor and Wheeler are emphatic in denying that motion causes any effect on the workings of clocks or human metabolysm.

I think that you are misrepresenting their position here. The fact that the traveling twin is younger at the reunion is incompatible with your statement.