Who Truly Experiences Slower Time in the Paradox of Time Dilation?

[swerdna]

But swerdna was talking about how an inertial frame is defined, i.e. a single one. A single frame is indeed defined in terms of a set of non-accelerating rulers and clocks which don't move relative to each other.

Thanks for clarifying and confirming.

Well, saying there's "no basis for singling out anyone inertial frame" is the same as saying there's no evidence for a violation of Lorentz-symmetry which would be the only conceivable basis for defining a preferred frame. To put it another way, all the evidence supports the idea that the fundamental laws of physics are locally Lorentz-symmetric, meaning that their equations will remain unchanged when you transform from one frame in SR to another using the Lorentz transformation.

Don’t immediately understand that. Is my second statement also correct? -“all (single) inertial fames move relative to all other (single) inertial frames”
(single) added for clarity.

 

[swerdna]

Ah! Thanks JesseM, and my apologies to you, swerdna!

I made a very silly reading of your text. By "An inertial frame is defined by non-accelerating things that don’t move relative to each other", I had taken you to mean that different non-accelerating things with different frames don't move in relation to each other. My fault for a dumb reading.

Yes, I agree. An inertial frame is defined by a collection of things that are not accelerating and not moving in relation to each other.



Yes. Nicely expressed.

Cheers -- sylas

Thanks - Good to know that I’m not the only one who can make mistakes.

 

[swerdna]

No, it does not "automatically" follow that everything is absolutely moving. There is no absolute, either for absolute movement or for absolute stationary.

You CAN be at rest with respect to something else. REALLY at rest with respect to something else. And your view is just as good as anyone else's... therefore things are not "absolutely moving" either.

In my view, the lack of any absolute frame of reference is a genuine discovery. There's nothing self-evident about it. The ancients considered it "self-evident" that the Earth provided a fixed absolute reference frame. Turns out that this is an arbitrary choice, as far as physics is concerned, which was highly counter intuitive at first.

Much of this is convention. There's nothing to stop someone from defining for some reason a particular reference frame as the absolute basis for deciding what is and is not stationary. What physics says... and this is a discovery; not a self-evident truth ... is that this choice is arbitrary in the sense that the laws of physics can't be used to single out a frame.

Cheers -- sylas

Yes you CAN be REALLY stationary RELATIVE to something else but this is ONLY a RELATIVE stationary and NOT an ABSOLUTE stationary. In other words, RELATIVE stationary isn’t REALLY stationary in an ABSOLUTE or universal sense. Given that there is ABSOLUTELY no evidence that a thing can ever be ABSOLUTELY stationary then (by default if nothing else) it must be concluded that everything is REALLY always moving in an ABSOLUTE sense (IMHO).

Don’t forget - “Written in layman-speak“

 

[Dale]

If object A is at rest relative to object B and is therefore absolutely moving then what is object A's absolute speed?

 

[p764rds]

Yes you CAN be REALLY stationary RELATIVE to something else but this is ONLY a RELATIVE stationary and NOT an ABSOLUTE stationary. In other words, RELATIVE stationary isn’t REALLY stationary in an ABSOLUTE or universal sense. Given that there is ABSOLUTELY no evidence that a thing can ever be ABSOLUTELY stationary then (by default if nothing else) it must be concluded that everything is REALLY always moving in an ABSOLUTE sense (IMHO).

Don’t forget - “Written in layman-speak“

Relativity is a consequence of the speed of light not being infinite. If it were infinite, then
there would be only one reference frame and Lorentz invariance would rule.
But in quantum entangled state correlations, 'things' can move at infinite speed. There is only one reference frame then. But the 'things' are quantum state information and not particels/mass etc.

 

[swerdna]

If object A is at rest relative to object B and is therefore absolutely moving then what is object A's absolute speed?

Absolute movement of any parfticluar thing can’t be measured because there is no absolute stationary to measure it against. A thing is always stationary relative to itself but a single thing alone can’t be used to measure it’s own movement. The only movement that can be measured therefore is relative movement. That relative movement exists proves that movements exists. That nothing can be absolutely stationary establishes that all things move in an absolute or universal sense.

 

[swerdna]

Relativity is a consequence of the speed of light not being infinite. If it were infinite, then
there would be only one reference frame and Lorentz invariance would rule.
But in quantum entangled state correlations, 'things' can move at infinite speed. There is only one reference frame then. But the 'things' are quantum state information and not particels/mass etc.

Sorry but none of that makes any sense to me.

 

[DrGreg]

Yes you CAN be REALLY stationary RELATIVE to something else but this is ONLY a RELATIVE stationary and NOT an ABSOLUTE stationary. In other words, RELATIVE stationary isn’t REALLY stationary in an ABSOLUTE or universal sense. Given that there is ABSOLUTELY no evidence that a thing can ever be ABSOLUTELY stationary then (by default if nothing else) it must be concluded that everything is REALLY always moving in an ABSOLUTE sense (IMHO).

Don’t forget - “Written in layman-speak“

Can't you see that if "absolutely stationary" makes no sense, then "absolutely moving" makes no sense either?

Consider an analogy. Someone on Earth might say "the Moon is above the Earth". An astronaut on the Moon might say "the Earth is above the Moon". Which one is above the other depends on which direction you decide is "up". I hope you will agree, therefore, that the Moon is not absolutely above the Earth. But it doesn't follow that the Moon is absolutely below the Earth.

It is a simple matter of linguistic logic

NOT (absolutely stationary) ≠ absolutely (NOT stationary)​

 

[swerdna]

Can't you see that if "absolutely stationary" makes no sense, then "absolutely moving" makes no sense either?

Consider an analogy. Someone on Earth might say "the Moon is above the Earth". An astronaut on the Moon might say "the Earth is above the Moon". Which one is above the other depends on which direction you decide is "up". I hope you will agree, therefore, that the Moon is not absolutely above the Earth. But it doesn't follow that the Moon is absolutely below the Earth.

It is a simple matter of linguistic logic

NOT (absolutely stationary) ≠ absolutely (NOT stationary)​

The opposite of nonsense is sense. The opposite of absolute stationary is absolute moving . If absolute stationary is “nonsense” then absolute moving is “sense”. If a thing isn’t stationary it’s moving there is no third alternative. That absolute stationary makes no sense establishes that absolutely moving makes sense as it‘s the only thing left.

The relationship between the Earth and the Moon is completely relative. In an absolute or universal sense nothing is ever up, down, faster, slower, etc.

 

[sylas]

... The opposite of absolute stationary is absolute moving. ...

It is a logical fallacy to take the refutation of a certain claim as the affirmation of an opposite claim. It's a false dichotomy.

If you want "opposite", then take the opposite of "absolute"; not of "stationary". You really really want to use the word "absolute" here for some reason, and so you set up two absolute alternatives. Neither one is correct.

The real situation is that the state of being stationary or in motion is not absolute at all. There is no absolute. Not for being stationary, not for being in motion. Whether an object is in motion or stationary is relative.

Cheers -- sylas

 

[swerdna]

It is a logical fallacy to take the refutation of a certain claim as the affirmation of an opposite claim. It's a false dichotomy.

If you want "opposite", then take the opposite of "absolute"; not of "stationary". You really really want to use the word "absolute" here for some reason, and so you set up two absolute alternatives. Neither one is correct.

The real situation is that the state of being stationary or in motion is not absolute at all. There is no absolute. Not for being stationary, not for being in motion. Whether an object is in motion or stationary is relative.

Cheers -- sylas

Seems to be turning into a semantic debate. I’m happy to use the term “universal” rather than “absolute” if that’s more acceptable.

If things didn’t move relative to other things then everything would be universally stationary. The reality is however that things do move relative to other things and that means there is nothing that is universally stationary. Everything is always moving relative to something else universally.

There can be relative movement and relative stationary but there can’t be universal stationary. There is always movement universally regardless that some things are relatively stationary.

 

[sylas]

Seems to be turning into a semantic debate. I’m happy to use the term “universal” rather than “absolute” if that’s more acceptable.

I'll stick with the word "relative". Motion is only meaningful relative to something else.

... Everything is always moving relative to something else universally.

You are much better just to leave out the word "universally". It leads you into inconsistency.

Your first sentence makes good sense if you leave off that redundant word.

Everything is always moving relative to something else.​

The reason you should omit that additional word is because EXACTLY THE SAME THING holds for being stationary.

Everything is always stationary relative to something else.​

There can be relative movement and relative stationary but there can’t be universal stationary. ...

There's your inconsistency. The only sense in which there is "universal motion" applies just as well to say "universal stationary". Just like everything is always moving relative to something else, so too everything is always stationary relative to something else.

 

[swerdna]

The real situation is that the state of being stationary or in motion is not absolute at all. There is no absolute. Not for being stationary, not for being in motion. Whether an object is in motion or stationary is relative.

I'll stick with the word "relative". Motion is only meaningful relative to something else.



You are much better just to leave out the word "universally". It leads you into inconsistency.

Your first sentence makes good sense if you leave off that redundant word.

Everything is always moving relative to something else.​

The reason you should omit that additional word is because EXACTLY THE SAME THING holds for being stationary.

Everything is always stationary relative to something else.​

There's your inconsistency. The only sense in which there is "universal motion" applies just as well to say "universal stationary". Just like everything is always moving relative to something else, so too everything is always stationary relative to something else.

What about acceleration? There’s nothing relative about acceleration.

As diazona said in post #37 - “something can be assumed to be moving in an absolute sense, if it is accelerating”. You seemed to agree with him/her at the time.

 

[sylas]

What about acceleration? There’s nothing relative about acceleration.

Whether you are in motion or stationary is relative.
Whether you are accelerating or inertial is absolute.

This is not hard.

I got to ask, what is the point here? Are you just trying to twist things into contradictions, or are you seriously still not understanding basic relativity?

The measurement of acceleration as a number is still relative to an observer; but you can define a "proper" acceleration as being the acceleration of an object as measured in the inertial frame where it is (instantaneously) with a velocity of zero. That still leaves the direction of acceleration as relative, but it does give an unambiguous absolute magnitude for "proper acceleration".

 

[swerdna]

Whether you are in motion or stationary is relative.
Whether you are accelerating or inertial is absolute.

This is not hard.

I got to ask, what is the point here? Are you just trying to twist things into contradictions, or are you seriously still not understanding basic relativity?

The measurement of acceleration as a number is still relative to an observer; but you can define a "proper" acceleration as being the acceleration of an object as measured in the inertial frame where it is (instantaneously) with a velocity of zero. That still leaves the direction of acceleration as relative, but it does give an unambiguous absolute magnitude for "proper acceleration".

It’s not so much a difficulty of understanding basic Relativity. It’s a difficulty in accepting the validity of one of the basic building blocks that Relativity is founded on. If I could accept that the building block was valid I don’t see that I would have much difficulty in accepting basic Relativity. It’s more to do with accepting than understanding. Although I guess it’s more than likely that my lack of acceptance is a result of my lack of understanding. I’m not trying to be clever or difficult. I’m trying find out what the truth is.

When you are accelerating you are absolutely in motion (no relativeness required).
When you are inertial you are not absolutely stationary.

 

[atyy]

When you are accelerating you are absolutely in motion (no relativeness required).
When you are inertial you are not absolutely stationary.

Are you aware that this is true in Newtonian physics, not just special relativity?

Also, are you aware that the statements mean:
1. When you are accelerating you are absolutely in motion (no relativeness required). = When you are accelerating relative to a particular inertial frame, you are accelerating relative to all inertial frames.
2. When you are inertial you are not absolutely stationary. = When you are stationary relative to a particular inertial frame, you are not stationary relative to all inertial frames.

 

[swerdna]

Are you aware that this is true in Newtonian physics, not just special relativity?

Also, are you aware that the statements mean:
1. When you are accelerating you are absolutely in motion (no relativeness required). = When you are accelerating relative to a particular inertial frame, you are accelerating relative to all inertial frames.
2. When you are inertial you are not absolutely stationary. = When you are stationary relative to a particular inertial frame, you are not stationary relative to all inertial frames.

Yes, but I don’t understand the point of your question. Care to explain it?

 

[atyy]

Yes, but I don’t understand the point of your question. Care to explain it?

So those are the 2 statements you can't accept?

 

[swerdna]

Are you aware that this is true in Newtonian physics, not just special relativity?

Also, are you aware that the statements mean:
1. When you are accelerating you are absolutely in motion (no relativeness required). = When you are accelerating relative to a particular inertial frame, you are accelerating relative to all inertial frames.

Yes.

2. When you are inertial you are not absolutely stationary. = When you are stationary relative to a particular inertial frame, you are not stationary relative to all inertial frames.

Yes. You can only ever be stationary to one particular inertial frame at at time because all inertial frames always move relatrive to all other inerttial frames. This was covered and agreed earlier in the thread.

 

[swerdna]

So those are the 2 statements you can't accept?

No. I fully accept both statements. I made them. I don't accept sylas’s claim that - “Whether you are in motion or stationary is relative”.

 

[atyy]

No. I fully accept both statements. I made them. I don't accept sylas’s claim that - “Whether you are in motion or stationary is relative”.

Oh, I see. I believe sylas's claim is simply the traditional short hand for those two statements.

 

[swerdna]

Oh, I see. I believe sylas's claim is simply the traditional short hand for those two statements.

Doesn't make it any less wrong.

 

[atyy]

Doesn't make it any less wrong.

I thought you accepted the 2 statements? Or are you saying that it is not acceptable short hand for the 2 statements?

 

[swerdna]

I thought you accepted the 2 statements? Or are you saying that it is not acceptable short hand for the 2 statements?

What are you drinking? Doesn’t make Sylas’s statement - “Whether you are in motion or stationary is relative” any less wrong. Nothing to do with the statements I made. Sylas made that statement before I made mine.

 

[atyy]

What are you drinking? Doesn’t make Sylas’s statement - “Whether you are in motion or stationary is relative” any less wrong. Nothing to do with the statements I made. Sylas made his/her statement before I made mine.

Well, if sylas's statements have the same meaning as statements you consider correct, how can you consider them wrong?

 

[swerdna]

Well, if sylas's statements have the same meaning as statements you consider correct, how can you consider them wrong?

“Whether you are in motion or stationary is relative” (sylas) and “When you are accelerating you are absolutely in motion (no relativeness required)” (me) are NOT the “same meaning“. Please read at least some of the thread before commenting on it.

 

[atyy]

“Whether you are in motion or stationary is relative” (sylas) and “When you are accelerating you are absolutely in motion (no relativeness required)” (me) are NOT the “same meaning“. Please read at least some of the thread before commenting on it.

So you disagree with the traditional shorthand, which is fair enough. That means you have no problem with special relativity?

 

[swerdna]

So you disagree with the traditional shorthand, which is fair enough. That means you have no problem with special relativity?

How can sylas’s statement be a shorthand response to my statement when his statement was made first Is he psychic?

Whatever it is that you are drinking I think you really have had more than enough.

 

[swerdna]

Stationary can only exist in a relative sense and not an absolute sense.

Motion can exist in a relative sense and also in an absolute sense in the form of acceleration.

 

[atyy]

Stationary can only exist in a relative sense and not an absolute sense.

Motion can exist in a relative sense and also in an absolute sense in the form of acceleration.

Sure, that's understandable short hand for the 2 statements. So you accept special relativity?

 

[swerdna]

Sure, that's understandable short hand for the 2 statements. So you accept special relativity?

You’re just pulling my leg aren’t you. Very funny.

 

[atyy]

You’re just pulling my leg aren’t you. Very funny.

So which part of special relativity don't you accept?

 

[swerdna]

So which part of special relativity don't you accept?

If you are actually interested read the thread.

 

[atyy]

If you are actually interested read the thread.

Which post? I can only tell you think you disagree with special relativity. I can't tell that you disagree with special relativity.

 

[atyy]

Written in layman-speak . . .

An inertial frame is defined by non-accelerating things that don’t move relative to each other.

Sure. Better: an inertial frame is defined as a frame in which the laws of physics look "pretty", eg. in which Maxwell's equations have their "standard" form. The reason this is better is that you have used "non-accelerating" without specifying whether it is non-accelerating relative to an inertial or a non-inertial frame. Your statement is true if "non-accelerating" is defined relative to an inertial frame. But then you would have used "inertial frame" in the definition of "inertial frame".

No inertial frame can be stationary relative to any other inertial frame. It follows therefore that all inertial fames move relative to all other inertial frames.

Yes.

There is absolutely no evidence that anything can ever be absolutely stationary. It follows therefore that no inertial frame can be absolutely stationary.

Yes, provided "absolutely" means "relative to all inertial frames".

In other words inertial frames are always relatively and absolutely in motion.

Anything wrong with any of this?

This is wrong, if "absolutely" means "relative to all inertial frames", since each inertial frame is not in motion relative to itself, so it is not in motion relative to all inertial frames.

 

[swerdna]

Is the term “a thing is stationary relative to itself” really valid? Relative is one thing compared to another thing. For a thing to be relative to itself wouldn't it have to have multiple existence? How can a thing be relative to itself? A thing is itself. Stationary only exists as a relative situation so how can it be attributed to a situation that isn’t relative? A thing is in motion when it’s accelerating but acceleration isn’t a relative situation. I know I’ve used this term many times myself, but on reflection I thinks it’s nothing more than a nonsense

 

[atyy]

Is the term “a thing is stationary relative to itself” really valid? Relative is one thing compared to another thing. For a thing to be relative to itself wouldn't it have to have multiple existence? How can a thing be relative to itself? A thing is itself. Stationary only exists as a relative situation so how can it be attributed to a situation that isn’t relative? A thing is in motion when it’s accelerating but acceleration isn’t a relative situation. I know I’ve used this term many times myself, but on reflection I thinks it’s nothing more than a nonsense

I think it's ok.

But suppose it's not, that would still not make an inertial frame in motion relative to itself, so an inertial frame would not be in motion relative to all inertial frames, so it would not be in "absolute" motion, where "absolute" means "relative to all inertial frames".

Also, "acceleration is not relative" or "acceleration is absolute" is the traditional short hand for "acceleration is the same relative to all inertial frames".

 

[p764rds]

If I designed a 3D space (a big one) in a computer, then would relativity apply there to the objects I placed in it?
I was trying to work it out in my mind the other night, but got confused. Let's say I designed in a velocity of light (information) too. Probably no takers.. it was just a thought.

 

[atyy]

Is the term “a thing is stationary relative to itself” really valid? Relative is one thing compared to another thing. For a thing to be relative to itself wouldn't it have to have multiple existence? How can a thing be relative to itself? A thing is itself. Stationary only exists as a relative situation so how can it be attributed to a situation that isn’t relative? A thing is in motion when it’s accelerating but acceleration isn’t a relative situation. I know I’ve used this term many times myself, but on reflection I thinks it’s nothing more than a nonsense

BTW, I can't resist - have you heard of the man and his Ba? I think he tells his Ba not to leave him. Naively I understand a man's Ba to be himself, so the man is telling himself not to leave himself - how can that be?

 

[diazona]

If I designed a 3D space (a big one) in a computer, then would relativity apply there to the objects I placed in it?
I was trying to work it out in my mind the other night, but got confused. Let's say I designed in a velocity of light (information) too. Probably no takers.. it was just a thought.

What, you mean like a simulation? Not necessarily... the appeal of simulating things on the computer is that you can program in any physical laws you want. You could make your virtual world follow the laws of relativity if you want, or you could make it follow the laws of nonrelativistic mechanics (but then you'd run into trouble with Maxwell's equations, if EM fields existed in your virtual world).

 

[swerdna]

I think it's ok.

But suppose it's not, that would still not make an inertial frame in motion relative to itself, so an inertial frame would not be in motion relative to all inertial frames, so it would not be in "absolute" motion, where "absolute" means "relative to all inertial frames".

That made me laugh - thanks. You say suppose it's not okay to use the term then you immediately use the term!

Also, "acceleration is not relative" or "acceleration is absolute" is the traditional short hand for "acceleration is the same relative to all inertial frames".

Thanks for the clarification.

 

[swerdna]

BTW, I can't resist - have you heard of the man and his Ba? I think he tells his Ba not to leave him. Naively I understand a man's Ba to be himself, so the man is telling himself not to leave himself - how can that be?

As I walked upon a stair I saw a man that wasn’t there. He wasn’t there again today. I wish that man would go away.

ETA - If you leave me can I come too?

 

[atyy]

As I walked upon a stair I saw a man that wasn’t there. He wasn’t there again today. I wish that man would go away.

ETA - If you leave me can I come too?

 

[swerdna]

But seriously . . . The important thing (to me at least) about it not being valid to say “a thing is stationary to itself” is that you then can’t use a single thing as a definition of stationary.

ETA - This means a non-accelerating thing is always moving in a relative sense.

 

[atyy]

But seriously . . . The important thing (to me at least) about it not being valid to say “a thing is stationary to itself” is that you then can’t use a single thing as a definition of stationary.

But whether or not an inertial frame has 0 or undefined velocity relative to itself, that doesn't make it true that an inertial frame has a defined non-zero velocity relative to all inertial frames, since it would have either 0 or undefined velocity relative to itself.

 

[atyy]

ETA - This means a non-accelerating thing is always moving in a relative sense.

Sure, if relative means "relative to at least one inertial frame, but not relative to all inertial frames".

 

[swerdna]

I understand your laughter but not your confusion.

“have you heard of the man and his Ba? I think he tells his Ba not to leave him. Naively I understand a man's Ba to be himself, so the man is telling himself not to leave himself”

“As I walked upon a stair I saw a man that wasn’t there. He wasn’t there again today. I wish that man would go away.”

“If you leave me can I come too?”

These are all a nonsense. I’m suggesting that “a thing is stationary relative to itself” is no less a nonsense

 

[swerdna]

Sure, if relative means "relative to at least one inertial frame, but not relative to all inertial frames".

If one inertial frame is not moving relative to another inertial frame then they are the same inertial frame.

 

[swerdna]

But whether or not an inertial frame has 0 or undefined velocity relative to itself, that doesn't make it true that an inertial frame has a defined non-zero velocity relative to all inertial frames, since it would have either 0 or undefined velocity relative to itself.

If "a thing is stationary relative to itself" is not a valid statement you can't use it. How can a thing be relative to itself?

 

[atyy]

BTW, there is a very pedantic construction. We don't start by assuming frames to be either stationary or in motion relative to each other. A frame is just a coordinate system for space and time. An inertial frame is a coordinate system in which eg. Maxwell's equations take their standard form. Then one only talks about whether things (like a car, but not a whole frame) are stationary or moving relative to a frame. Consider a thing P that is stationary in inertial frame X, but moving in inertial frame Y. We can assign a velocity to frame X relative to frame Y by saying that it is the velocity of P in frame Y, where P is any thing that is stationary in frame X. In this way, we can define the velocity of a frame X relative to itself by saying that it is the velocity of P in frame X, where P is any thing that is stationary in frame X.