B Is Time Dilation About Particle Motion Rather Than Time Itself?

teacher94
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Hi, i am not a physicist but i have the intuition that time dilation is just slow in the movement of particle's and causality instead of slow in time itself and that this does not affect photons. I understand that there is no way to distinguish between a slow in time and a slow in movement and causality but would the math still work the same if we assume this interpretation of time dilation? Thank you
Hi, i am not a physicist but i have the intuition that time dilation is just slow in the movement of particle's and causality instead of slow in time itself and that this does not affect photons. I understand that there is no way to distinguish between a slow in time and a slow in movement and causality but would the math still work the same if we assume this interpretation of time dilation? Thank you
 
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If you assume that every possible physical process is slowed, then there are a couple of questions:
1) How would you distinguish between that and time dilation?
2) How can you explain every possible physical process slowing down exactly the same amount? That is a lot to explain. On the other hand, you can just say that there is time dilation and everything else follows.
 
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FactChecker said:
If you assume that every possible physical behavior is slowed, then there are a couple of questions:
1) How would you distinguish between that and time dilation?
2) How can you explain every possible physical behavior slowing down exactly the same amount? That is a lot to explain. On the other hand, you can just say that there is time dilation and everything else follows.
Well said, i did say it is impossible to distinguish between a slow in every physical event and a slow in time. That is right i just am saying this is possible interpretation with which the math would still work the same.
 
Time is what your watch measures. Einstein told us it is not as simple as we imagined it to be. Your intuition is up to you but the arithmetic uses what your watch measures.
 
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hutchphd said:
Time is what your watch measures. Einstein told us it is not as simple as we imagined it to be. Your intuition is up to you but the arithmetic uses what your watch measures.
Thank you for your help, so what you aresaying is that it is possible that it's not time that slowing but we have no way of distinguishing between a slow in time and a slow in physical processes?
 
teacher94 said:
i just am saying this is possible interpretation with which the math would still work the same.
Not really. Treating every physical process separately would require a different variable for the amount that every single physical process slowed down. Then you would have to assume that all those factors were equal. How would you justify that? It hurts my head. You would eventually have to admit that it is time itself that has dilated.
 
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It depends upon what you mean by "a slow physical process" but the destinction you seem to be drawing is neither useful nor correct.
What would be an example of such a process?
 
hutchphd said:
It depends upon what you mean by "a slow physical process" but the destinction you seem to be drawing is neither useful nor correct.
What would be an example of such a process?
For example the speed of a chemical reaction or speed of a moving object slow down by the same rate.
 
FactChecker said:
Not really. Treating every physical process separately would require a different variable for the amount that every single physical process slowed down. Then you would have to assume that all those factors were equal. How would you justify that? It hurts my head. You would eventually have to admit that it is time itself that has dilated.
The justification for the slow of evey process by the same factor could be justified by saying that object that move fast have large kinetic energy which in itself is mass since mass and energy are the same this will result in every particle in that object being heavier so it moves slower.
 
  • #10
teacher94 said:
Thank you for your help, so what you aresaying is that it is possible that it's not time that slowing but we have no way of distinguishing between a slow in time and a slow in physical processes?
I would say the point is that "time slowing" is a popsci description that doesn't really capture what's going on. Relativity models time in the sense you mean as "path length" through spacetime, and time never runs slow or fast. It's just that some paths are longer and others are shorter, and when paths aren't parallel the projection of one tick of your clock onto my history isn't the same "length" as one tick of my clock.

Time is just the name we give to the phenomenon.
 
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  • #11
(Proper) time is indeed the name we give it. So? Why "just"?
 
  • #12
thank you
Ibix said:
I would say the point is that "time slowing" is a popsci description that doesn't really capture what's going on. Relativity models time in the sense you mean as "path length" through spacetime, and time never runs slow or fast. It's just that some paths are longer and others are shorter, and when paths aren't parallel the projection of one tick of your clock onto my history isn't the same "length" as one tick of my clock.

Time is just the name we give to the phenomenon.
very much for the explanation.
 
  • #13
hutchphd said:
(Proper) time is indeed the name we give it. So? Why "just"?
I say just to differentiate it from absolute time which is the same everywhere in the universe.
 
  • #14
hutchphd said:
(Proper) time is indeed the name we give it. So? Why "just"?
Because arguing about whether it's "really" time doing XYZ is kind of pointless. Time is, as you said, what watches measure. If my watch/heartbeat/whatever process is running slow (putting aside the issues with that term for now) then time is running slow by definition of the word.
 
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  • #15
teacher94 said:
absolute time which is the same everywhere in the universe.
That definitely doesn't exist.
 
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  • #16
Only if you can define your motion relative to that "absolute" frame. Your "time" will almost always be different. Its relative.
 
  • #17
teacher94 said:
and that this does not affect photons
It seems problematic to make ad hoc exceptions like this. Maxwell’s equations work in every inertial frame, as do the equations of quantum electrodynamics. Doppler shifts follow the relativistic equation, not the Newtonian one. So this exception seems unjustified to me.

Photons don’t have either their own frame or proper time. But time dilation not affecting them seems to be a bit of a stretch.

teacher94 said:
but would the math still work the same if we assume this interpretation of time dilation?
I think you would need to actually derive this to show it. Frankly, I don’t see how your photon exception could even be expressed mathematically. So I would guess “no”.

The thing to do would be to find a peer reviewed paper describing such an approach. I don’t know of one.
 
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  • #18
Well it is impossible for us to observe it because we live in a relative time nad relative movement but thatdoes not mean it does not exist.
 
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  • #19
@teacher94 do you have a peer reviewed reference that describes this approach of yours?
 
  • #20
Dale said:
@teacher94 do you have a peer reviewed reference that describes this approach of yours?
No, your answers convinced me of why my intuition is wrong, thank you all for your time.
 
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  • #21
teacher94 said:
Well it is impossible for us to observe it because we live in a relative time nad relative movement but thatdoes not mean it does not exist.
Then you presumably believe in invisible unicorns because you can't prove they don't exist. Up to you I guess, but it doesn't seem very parsimonious to propose things that you don't need in a model to explain anything, can't detect, and don't do anything except make you add words to your descriptions of things you do need in the model in order to distinguish them from your unnecessary additions.
 
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  • #22
Ibix said:
Then you presumably believe in invisible unicorns because you can't prove they don't exist. Up to you I guess, but it doesn't seem very parsimonious to propose things that you don't need in a model to explain anything, can't detect, and don't do anything except make you add words to your descriptions of things you do need in the model in order to distinguish them from your unnecessary additions.
You are right, science is concerned only with what is observable and measurable. Thank you for your help.
 
  • #23
teacher94 said:
The justification for the slow of evey process by the same factor could be justified by saying that object that move fast have large kinetic energy which in itself is mass since mass and energy are the same this will result in every particle in that object being heavier so it moves slower.
Explanations of this sort fail to explain the symmetry of time time dilation: if A and B are moving relative to one another, A finds that B’s clock is running slow and B finds that A’s clock is running slow.
 
  • #24
teacher94 said:
Hi, i am not a physicist but i have the intuition
Would you go to a medical practitioner who never went to med school and said. "Woo hoo! I can fix your cough! Just cut you right open and yank the bad parts out. 'Cause I got intuition, ya see!!"

"Intuition" is not all that reliable. Uninformed intuition even less so.

You seem to be holding the position that there is One True Time, forever unmeasureable, and every physical process just appears to experience time dilation, With all due respect, that's a personal theory, and a lousy one. Why is it lousy? Because it doesn't allow us to predict anything beyond or better than what SR predicts. It just helps one non-expert feel better.

One last thing - a tree is 10 feet to my left, I turn 45 degrees and now it is 7 feet ahead iof me and 7 feet to my left. Is this a problem? If not, why is doing the same thing for time?
 
  • #25
Nugatory said:
Explanations of this sort fail to explain the symmetry of time time dilation: if A and B are moving relative to one another, A finds that B’s clock is running slow and B finds that A’s clock is running slow.
right the symmetry of time dilation is a different story.
 
  • #26
teacher94 said:
right the symmetry of time dilation is a different story.
Well, that's kind of the point. With a "time is path length through spacetime" interpretation, none of this is a different story. It's all part of one unified (and fairly simple) framework that fits neatly into the broader framework of general relativity, which is what makes it useful.
 
  • #27
Ibix said:
Well, that's kind of the point. With a "time is path length through spacetime" interpretation, none of this is a different story. It's all part of one unified (and fairly simple) framework that fits neatly into the broader framework of general relativity, which is what makes it useful.
Tobe honedt relativity is a simple accurate model with great predictive and explanatory power. I know it's the best we have. But i just donot believe time can be affected or chnged.
 
  • #28
teacher94 said:
But i just donot believe time can be affected or chnged.
As I said, I don't think it's meaningful to talk about time changing, or running slow, or whatever. There are just different paths through spacetime.

I get why people use such terms in layman-friendly presentations, but they aren't accurate.I would advise learning about special relativity as a geometric theory if you are interested.
 
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  • #29
teacher94 said:
The justification for the slow of evey process by the same factor could be justified by saying that object that move fast have large kinetic energy which in itself is mass since mass and energy are the same this will result in every particle in that object being heavier so it moves slower.
The whole system consisting of bouncing quartz clocks has extra rest-mass. And also the whole system consisting of the quartz crystals has extra rest-mass, according to the relativistic addition of masses.

And according to the law that says that harmonic oscillator's ticking rate is inversely proportional to the square root of its mass, there is a slowing down effect, but it's too small. So it's not the whole explanation.
 
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  • #30
jartsa said:
rest-mass
You may mean "transverse relativistic mass". But since that does not match "longitudinal relativistic mass", the concept is of little use.

An object moving at a high rate of speed has the same rest mass as when it is at rest. By definition.
 
  • #31
Most "clocks" use electric forces to tick tock. Therefore they will absolutely agree with the "light clock" of special relativity fame.
 
  • #32
jbriggs444 said:
You may mean "transverse relativistic mass". But since that does not match "longitudinal relativistic mass", the concept is of little use.

An object moving at a high rate of speed has the same rest mass as when it is at rest. By definition.
No I meant the rest-mass of the whole system. I'll go and remove the confusing first sentence.

If we heat up the mass of an harmonic oscillator the oscillation slows down, because of the rest-mass increase.
 
  • #33
teacher94 said:
But i just do not believe time can be affected or changed.
And relativity agrees with this (most clearly in the geometric formulation, and if you are not already familiar with these concepts to at least the level of the early chapters of Taylor and Wheeler's "Spacetime Physics" you are frankly wasting your time and time of the people engaging with you) .

The catch is that time, that thing which cannot be "affected or changed" isn't quite what you're thinking it is. Start with a clear and experimental realizable statement of what is meant by the popular and fuzzy "time slows down for moving objects", do this twice for the the two fundamentally different situations in which this is said (time dilation when A and B are moving relative to one another, twin paradox when A and B separate and reunite), and you will develop a more clearly defined concept of what tIme is.
 
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  • #34
Nugatory said:
And relativity agrees with this (most clearly in the geometric formulation, and if you are not already familiar with these concepts to at least the level of the early chapters of Taylor and Wheeler's "Spacetime Physics" you are frankly wasting your time and time of the people engaging with you) .

The catch is that time, that thing which cannot be "affected or changed" isn't quite what you're thinking it is. Start with a clear and experimental realizable statement of what is meant by the popular and fuzzy "time slows down for moving objects", do this twice for the the two fundamentally different situations in which this is said (time dilation when A and B are moving relative to one another, twin paradox when A and B separate and reunite), and you will develop a more clearly defined concept of what tIme is.
No matter how you look at time boils down to how many events happen in the span of another event, for example how many times the pendulum swings in the span of a free falling motion of a ball. So time is in a sense measure of how many events that we use as measuring ruler(for example the swings of a pendulum) can fit in the span of another event say the free fall of a ball.
 
  • #35
teacher94 said:
No matter how you look at time boils down to how many events happen in the span of another event, ...
Which is to say that it is a comparison of clocks.
Which is to say that time is what clocks measure.
 
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  • #36
jbriggs444 said:
Which is to say that it is a comparison of clocks.
Which is to say that time is what clocks measure.
So time does not exist as an independent concept?!! It exists only in sense of comparing how many cyles of an event fit in one cyle of another event? Therefore relative?
 
  • #37
teacher94 said:
So time does not exist as an independent concept?!! It exists only in sense of comparing how many cyles of an event fit in one cyle of another event? Therefore relative?
We can measure it. With clocks. Proper time exists in that empirical sense.
We can agree on and validate standards of synchronization and extend this notion of time to coordinate systems.

Coordinate time is relative -- to a set of coordinates.
Proper time is invariant.
 
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  • #38
teacher94 said:
So time does not exist as an independent concept?!! It exists only in sense of comparing how many cyles of an event fit in one cyle of another event? Therefore relative?
The reason for calling time "relative" is, that the time-interval ##\Delta t## between two events depends on, which reference frame you choose. Invariant is the spacetime interval between the events. The square of it is, with (+---) convention:
##(\Delta s)^2 = (c \Delta t)^2 - (\Delta x)^2 - (\Delta y)^2 - (\Delta z)^2##
 
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  • #39
teacher94 said:
No matter how you look at time boils down to how many events happen in the span of another event, for example how many times the pendulum swings in the span of a free falling motion of a ball.
Yes, provided that the pendulum and the ball are for all practical purposes colocated, in which case we are measuring proper time along a timelike worldline (strictly speaking, within a sufficiently small timelike worldtube). Everyone agree that this proper time cannot be "affected or changed"; it is also, as Einstein said, what a clock measures.

It gets trickier when we work with events that are not for all practical purposes colocated, as when we conclude that a clock moving relative to us is running slow relative to our own clock. Now the measurement relies on additional assumptions (most crucially, what it means to say that two physically separated events happen "at the same time") that should be stated precisely. The "time slows down...." presentations hide these additional assumptions and obscure what is really going on.
 
  • #40
teacher94 said:
So time does not exist as an independent concept?!! It exists only in sense of comparing how many cyles of an event fit in one cyle of another event? Therefore relative?
Throughout this thread, you have been (as does everyone who hasn't learned relativity, including many people who think they have) using the word "time" to refer to two different things: proper time which is what a clock measures, and coordinate time which is the timestamps that we attach to events ("that firecracker over there exploded at 3:00 PM"). These are completely different things, and confusing them is the root of most relativity confusion. Proper time is "real" in the sense that it is a physical quantity that can be measured, and everyone will agree about the results of such measurements. It's as real and non-relative as any other physical quantity. Coordinate time is relative, in the sense that people in motion relative to one another will naturally assign different coordinate times to the same event.

In normal life we nearly always choose to assign coordinate times in such a way that they are numerically equal to our proper time, and of course we are all moving slowly enough relative to one another that our proper times are pretty much indistinguishable (it takes something like the Hafele-Keating experiment to notice any difference) so it's easy to lump them all together under the single inadequately specified word "time".

We have many older threads here about the difference between the two concepts of time, and I will repeat my earlier suggestion about the early chapters of Taylor and Wheeler.
 
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  • #41
teacher94 said:
The justification for the slow of evey process by the same factor could be justified by saying that object that move fast have large kinetic energy which in itself is mass since mass and energy are the same this will result in every particle in that object being heavier so it moves slower.

Here is a calculation for a simple mass-spring-system in motion, using "relativistic mass":
https://www.mathpages.com/home/kmath068/kmath068.htm

It is better to speak about "energy" (as you did) instead of "relativistic mass" to avoid confusion with "invariant mass".

Here is a similar calculation for a balance-wheel-clock:

The period of oscillation of the balance wheel in it's rest-frame ##S## for non-relativistic angular velocity is:
##T = 2\pi\sqrt{I/\kappa}##

For simplicity assume, that the frame ##S'## moves with relativistic velocity in direction of the wheel axis.

The spring constant in transversal direction must transform in the same way as transversal forces do:
## \kappa' = \kappa/\gamma##

The moment of inertia in transversal direction must transform in the same way as ##E/c^2## does:
##I' = I \gamma##
$$T' = 2\pi\sqrt{I'/\kappa'} = 2\pi\sqrt{\gamma^2 * I/\kappa} = \gamma T$$
The "relativistic mass" ##m_R## and therefore also ##E/c^2## depend on the choosen reference frame and also on the conventional Einstein clock synchronization, as time-dilation does. Their calculation includes the time-dilation factor ##\gamma##:
##m_R = \gamma m_0##
##E/c^2 = \gamma E_0/c^2##
 
  • #42
Suppose Alice passes you, at one-fourth the speed of light. If she could see your clock, she would say it is running slow, by a factor called "gamma."

##\gamma=\frac{1}{\sqrt{1-\frac{v^2}{c^2}}}##

In this case, ##\gamma_{Alice}=\frac{1}{\sqrt{1-0.25^2}} = 1.033##

Now suppose at the same time, Bob also passes you, but he's going one-half the speed of light.
In this case, ##\gamma_{Bob}=\frac{1}{\sqrt{1-0.5^2}} = 1.155##

So how "slow" is your clock? It depends on who you ask! For you, it reads "proper time" since you are carrying it along with you. Alice and Bob disagree on how slow your clock is. This disagrrement has nothing to do with how fast your biological processes are "really" running. There is no "really" except for your proper time.

EDITed to fix up some confusing words.
 
  • #43
Nugatory said:
It gets trickier when we work with events that are not for all practical purposes colocated, as when we conclude that a clock moving relative to us is running slow relative to our own clock. Now the measurement relies on additional assumptions (most crucially, what it means to say that two physically separated events happen "at the same time") that should be stated precisely. The "time slows down...." presentations hide these additional assumptions and obscure what is really going on.

As an example for this, I define a reference frame ##\bar S## (##\bar x, \bar t##) with anisotropic speed of light, given a standard inertial coordinate system ##S## (##x, t##), with ##|k|<1##:

##\bar x = x##
##\bar t = t + \frac{kx}{c}##

https://www.mathpages.com/home/kmath229/kmath229.htm

The spacetime interval between two ticks of a clock moving with velocity ##\bar v = \frac{v}{1+ k\frac{v}{c}}## in positive ##\bar x## direction is:
##\Delta s^2 = c^2 (\Delta\bar t - \frac{k\Delta\bar x}{c})^2 - \Delta \bar x^2##
##\Rightarrow##
##\frac{\Delta \tau}{\Delta \bar t} = \sqrt{(1 - k\frac{\bar v}{c})^2 - \bar v^2/c^2} = \frac{1}{1+ k\frac{v}{c}} \sqrt{1 - v^2/c^2}##

But usually, time-dilation is define with reference to a standard inertial coordinate system, which is based on the Einstein-synchronization (##k = 0##).

Measurement equipment for the transversal Doppler effect to test time-dilation is constructed under the assumption of isotropic one-way speed of light.
 
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  • #44
gmax137 said:
Alice and Bob disagree on how slow your clock is.
All agree on the spacetime-interval between two ticks of my clock.
 
  • #45
teacher94 said:
TL;DR Summary: Hi, i am not a physicist but i have the intuition that time dilation is just slow in the movement of particle's and causality instead of slow in time itself and that this does not affect photons. I understand that there is no way to distinguish between a slow in time and a slow in movement and causality but would the math still work the same if we assume this interpretation of time dilation? Thank you

Hi, i am not a physicist but i have the intuition that time dilation is just slow in the movement of particle's and causality instead of slow in time itself and that this does not affect photons. I understand that there is no way to distinguish between a slow in time and a slow in movement and causality but would the math still work the same if we assume this interpretation of time dilation? Thank you

It's possible to regard a photon as the limiting case of a non-photon (i.e. a massive particle) that moves very very fast. Such a massive particle can't ever quite reach the limiting speed that a photon does, but it can come arbitrarily close.

It's unclear to me exactly what your proposal is, but this might be a useful case to consider. What would you see as the difference between a very fast moving particle, for instance at .9999 c, and a photon moving at 1.0 c? It would be helpful if you could describe some experiment or thought experiment that would illustrate what it is you're trying to describe.

On a somewhat related note, it'd be helpful if you could explain what you think time dilation is. I have to admit that it'd be helpful mostly in criticizing your idea, which you may not want to hear, but that's a separate issue. Discussion is supposed to involve the exchange of ideas, in the end, as opposed to validation. At least, that's the view I take.

I regard time dilation as the ration of proper time (which is the sort of time a clock, such as a wristwatch, measures) to coordinate time, for instance, but I'm not sure saying that will make sense to you. I have a sense (which may be wrong), that you think there is some sort of universal, agreed-upon notion of time, and that you regard time dilation as the ratio of the proper / wristwatch time to this universal underlying time. I would be very critical of this idea, but it'd be somewhat useless to say more if I was totally off the track of what you were trying to ask.
 
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  • #46
teacher94 said:
So time does not exist as an independent concept?!! It exists only in sense of comparing how many cyles of an event fit in one cyle of another event? Therefore relative?
You have to be careful here. The definition of (proper) time is that it is the thing that a clock measures. That is different from saying that time is a clock.

A measuring device measures something. A scale measures mass, a ruler measures length, a clock measures time. Mass is not a scale, it is the thing measured by a scale. Length is not a ruler, it is the thing measured by a ruler. Time is not a clock, it is the thing measured by a clock.

Also, proper time is not relative, it is invariant. All reference frames agree on the reading of any clock, therefore the thing that a clock measures must be an invariant.
 
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  • #47
FactChecker said:
If you assume that every possible physical process is slowed, then there are a couple of questions:
1) How would you distinguish between that and time dilation?
2) How can you explain every possible physical process slowing down exactly the same amount? That is a lot to explain. On the other hand, you can just say that there is time dilation and everything else follows.
It also seems to me that what dilates is the frequency of decay of all particles with mass and not time itself. That would be why people age slower traveling away from earth and coming back to earth, because every atom in them decayed slower than those at earth. Traveling clocks slowed because the caesium atoms decay slowed down taking more time to tick the number of cycles we count to say one second has passed. So it seems speed is affecting matter not time.
 
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  • #48
jkourany said:
So it seems speed is affecting matter not time.
How do you explain the reciprocal nature of this? If I am moving fast with respect to you, you see my clocks slowed but I see your clocks slowed. Which of us is "affected by speed"?

And you can build clocks that work using light bouncing between mirrors. We will both agree that light travels at the same speed, but will both agree that the other's clocks are slow.

The fundamental problem is trying to go down any kind of "time (or whatever other word you think you can use to avoid using the word time) is slowed" route at all. It's a terrible description of the reality of relativity, as I believe I said on the previous page.
 
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  • #49
jkourany said:
So it seems speed is affecting matter not time.
The squared spacetime-interval ##s^2 = c^2 (\Delta t)^2 - (\Delta x) ^2 - (\Delta y) ^2 - (\Delta z) ^2## between two ticks of the clock is invariant. That means, it is the same in each inertial reference frame.

In the inertial restframe of the clock, the squared spatial distance ##(\Delta x) ^2 + (\Delta y) ^2 + (\Delta z) ^2## between the ticks is zero.

In an inertial reference frame, in with the clock is moving, the squared spatial distance between the ticks is greater than zero, therefore, also the (coordinate-)time interval ##\Delta t## between the ticks must be greater than in the rest frame of the clock.
 
  • #50
Ibix said:
How do you explain the reciprocal nature of this? If I am moving fast with respect to you, you see my clocks slowed but I see your clocks slowed. Which of us is "affected by speed"?
Very good point. The central fact is that a stationary person observes the clock of a moving person as it goes from one location to another. It is the difference in synchronized clocks in different locations that forces the reciprocal property. So the slowing of a moving clock is the direct, logical, result of the spacetime distortion of a moving reference frame.
 
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