There is no time dilation (split from The twin Paradox revisited)

[Genady]

10 minutes ago, Boltzmannbrain said:

Sorry, I meant that the time dilation does not happen for the people on Earth even though it appears that way from the ship.  The Earth (not the traveler) experiences a long 10 years.  In other words, nobody experiences time dilation; it is only an observation from a different POV.  

From the event of the ship leaving to the event of the ship returning, everyone on Earth experiences 10 years, and everyone on the ship experiences 1 week. What is confusing about it? 

[studiot]

43 minutes ago, Boltzmannbrain said:

Time dilation only happens to a POV.  It does not happen for the object being viewed.  This is widely understood; it is not controversial at all, at least for mainstream physics.

I understand what you are getting at but

Trying to play the smartass with everybody has led you to post some ridiculous English.

Nothing 'happens to points of view'. They do not change.

However the muon experiment is really good in that it allows comparison of effects in two different frames and introduces of the second fundamental point of relativity.

 

36 minutes ago, Boltzmannbrain said:

This is also widely misunderstood.  The muon experiences the same amount of time as the observer.  The muon *does not* experience different time than the observer, even though I see that term written everywhere.  

Of course it does. That is exactly your point and it is correct as far as it goes. But it is not complete because there are two different frames involved.

The ground or laboratory observer measures different times in his laboratory for the same effect to occur when the muons with him in the laboratory, and when they are approaching it at speed.

 

[Boltzmannbrain]

1 minute ago, Genady said:

From the event of the ship leaving to the event of the ship returning, everyone on Earth experiences 10 years, and everyone on the ship experiences 1 week. What is confusing about it? 

Yes, there shouldn't be anything confusing about that.  I made a mistake.  But it can get confusing in other situations. 

[joigus]

51 minutes ago, Boltzmannbrain said:

This is also widely misunderstood.  The muon experiences the same amount of time as the observer.  The muon *does not* experience different time than the observer, even though I see that term written everywhere.  

It's perfectly understood. It's called proper time, and @Markus Hanke gave you the recipe to calculate it. The observer on the ground, who is aware of the theory of relativity, can use it to infer how much time has ellapsed in the frame associated to the muon. She, OTOH, can use her own coordinate time and observe the difference. You've been told:

14 hours ago, swansont said:

How do clocks (such as used in the Hafele-Keating experiment)  “perceive” time?

It's been measured. It's common knowledge. Misunderstood only by people who haven't studied physics. So maybe you're right about the 'widely misunderstood.' For the wrong reasons, of course.

[Boltzmannbrain]

40 minutes ago, studiot said:

I understand what you are getting at but

Trying to play the smartass with everybody has led you to post some ridiculous English.

Nothing 'happens to points of view'. They do not change.

That's right.  There is no dilation of either twin for themselves.  

Quote

Of course it does.

Are you saying, of course it does experience less time?  

 

26 minutes ago, joigus said:

It's perfectly understood. It's called proper time, and @Markus Hanke gave you the recipe to calculate it. The observer on the ground, who is aware of the theory of relativity, can use it to infer how much time has ellapsed in the frame associated to the muon. She, OTOH, can use her own coordinate time and observe the difference.

You've been told:

Are you saying that a fast moving muon experiences less time than a muon at rest?

Edited February 21, 2023 by Boltzmannbrain

[studiot]

6 minutes ago, Boltzmannbrain said:

That's right.  There is no dilation of either twin for themselves.  

Are you saying, of course it does experience less time?  

 

You said

45 minutes ago, studiot said:

The muon experiences the same amount of time as the observer.

To which I replied

46 minutes ago, studiot said:

Of course it does. That is exactly your point and it is correct as far as it goes.  ...etc

Yes if the lifetime is 1 second* the muon expeience 1 second of 'life'.

But the rest of what I said means that the lab observer sees (measures, experiences) the moving muon taking much longer than this to die, whilst the muon in his hand take exactly 1 second to die.
 

*(Actually the time is about 2 microseconds, not 1 second)

[joigus]

55 minutes ago, Boltzmannbrain said:

That's right.  There is no dilation of either twin for themselves.  

Are you saying, of course it does experience less time?  

 

Are you saying that a fast moving muon experiences less time than a muon at rest?

I've never interviewed a muon. And nobody is saying that. Please, read @studiot's answer and ponder what he' saying.

[swansont]

6 hours ago, Boltzmannbrain said:

No, it definitely does not happen to the astronaut or anything.  Time flows at the same rate for everyone/everything. 

The clocks in the Hafele-Keating experiment did not run at the same rate as the ground clocks. As such, they accumulated a different amount of elapsed time.

GPS oscillators are adjusted to run slow on earth so that they run at the correct rate in space, to match the ground clocks.

 

Time does not flow at the same rate for everything.

 

[Boltzmannbrain]

4 hours ago, swansont said:

The clocks in the Hafele-Keating experiment did not run at the same rate as the ground clocks. As such, they accumulated a different amount of elapsed time.

GPS oscillators are adjusted to run slow on earth so that they run at the correct rate in space, to match the ground clocks.

 

Time does not flow at the same rate for everything.

 

Last time I asked this I got a mouth full, but I have to ask again because I really don't know.  Are you saying that some things experience less time than others? 

I have read many times that time passes the same for everything in special relativity, but I am not totally sure about general relativity.  

[Lorentz Jr]

5 hours ago, swansont said:

Time does not flow at the same rate for everything.

Does anyone on this thread realize that @Boltzmannbrain's use of the term "time dilation" is different from its usual meaning in relativity? He doesn't mean external observers see a moving clock as ticking slowly, he means a comoving observer either perceives or can detect some kind of objective slowness in the clock's behavior. (And he's saying that doesn't happen.)

22 hours ago, Boltzmannbrain said:

For any object, time runs the same, 1 second per second. 
the twin with the longer beard is actually still perceiving his/her own time in the past (with a short beard) at 1 second per second. 
No time dilation actually occurs for the object that is perceived to have dilated time.

20 hours ago, Boltzmannbrain said:

It is only perceived by an outside observer.

12 hours ago, Boltzmannbrain said:

Time flows at the same rate for everyone/everything. 

11 hours ago, Boltzmannbrain said:

If you only experience 1 week in the ship, then shouldn't your clock/calendar show 1 week?

11 hours ago, Boltzmannbrain said:

Time dilation ... does not happen for the object being viewed.  This is widely understood; it is not controversial at all, at least for mainstream physics.

10 hours ago, Boltzmannbrain said:

There is no dilation of either twin for themselves. 

58 minutes ago, Boltzmannbrain said:

I have read many times that time passes the same for everything in special relativity

Edited February 22, 2023 by Lorentz Jr

[sethoflagos]

12 minutes ago, Boltzmannbrain said:

Last time I asked this I got a mouth full, but I have to ask again because I really don't know.  Are you saying that some things experience less time than others? 

I have read many times that time passes the same for everything in special relativity, but I am not totally sure about general relativity.  

I'm no expert in this but I'll say it anyway. 

My understanding is that in SR the spacetime interval between two events is invariant for all inertial reference frames.

The minimum spatial separation occurs for the observer who sees the events as simultaneous.

All other observers see a greater spatial separation and an increasing temporal separation per s² = x² + y² +z² - (ct)² = constant.

Local clocks and measuring rods must vary accordingly. 

[Genady]

38 minutes ago, Boltzmannbrain said:

I have read many times that time passes the same for everything in special relativity, but I am not totally sure about general relativity. 

A passage of the proper time of an observer does not change. This is so in SR and in GR.

(Proper time is time in a reference frame in which observer is at rest.)

[Boltzmannbrain]

19 minutes ago, Genady said:

A passage of the proper time of an observer does not change. This is so in SR and in GR.

(Proper time is time in a reference frame in which observer is at rest.)

Ok, that's what I thought, but I found it difficult to find a good source to explain this the way that we are talking about it.  I wonder now if it even makes sense to ask if my proper time runs slower.  How would that even make sense since time is relative?  But anyway, maybe that's a philosophical question; I don't know.

[Genady]

7 minutes ago, Boltzmannbrain said:

Ok, that's what I thought, but I found it difficult to find a good source to explain this the way that we are talking about it.  I wonder now if it even makes sense to ask if my proper time runs slower.  How would that even make sense since time is relative?  But anyway, maybe that's a philosophical question; I don't know.

It makes sense to compare proper times of different observers. That was what we did in the twins exercise. The proper time of one observer advanced 10 years while the proper time of another observer advanced 1 week. It is very physical result.

[Boltzmannbrain]

7 minutes ago, Genady said:

It makes sense to compare proper times of different observers. That was what we did in the twins exercise. The proper time of one observer advanced 10 years while the proper time of another observer advanced 1 week. It is very physical result.

I meant a different proper time in general.  But I don't think that makes sense since I think that would mean that absolute time exists.

[Genady]

4 minutes ago, Boltzmannbrain said:

I meant a different proper time in general.  But I don't think that makes sense since I think that would mean that absolute time exists.

Yes. No absolute time. Each observer has its own proper time.

[Lorentz Jr]

34 minutes ago, Genady said:

The proper time of one observer advanced 10 years while the proper time of another observer advanced 1 week. It is very physical result.

10 minutes ago, Genady said:

No absolute time.

But absolute ratios, at least. Clocks (and everything else) on the spaceship ran 500 times more slowly than identical clocks (and everything else) on Earth, even if the astronauts didn't notice it during the voyage. That's a real physical result.

Edited February 22, 2023 by Lorentz Jr

[Genady]

1 minute ago, Lorentz Jr said:

But absolute ratios, at least. Clocks on the spaceship ran 500 times more slowly than clocks on Earth. That's a real physical result.

Why do you call it absolute? Isn't it specific for two observers and two events (start and finish of the duration)?

[Lorentz Jr]

3 minutes ago, Genady said:

Why do you call it absolute? Isn't it specific for two observers and two events (start and finish of the duration)?

Because it's frame-invariant. It's not specific to those observers. All observers will agree that 500 times more time elapsed on Earth than on the spaceship. Their calculations will be different, but their results will all be the same.

Edited February 22, 2023 by Lorentz Jr

[Genady]

2 minutes ago, Lorentz Jr said:

Because it's frame-invariant. It's not specific to those observers. All observers will agree that 500 times more time elapsed on Earth than on the spaceship. Their calculations will be different, but their results will all be the same.

Oh, I see. Got it.

[swansont]

9 hours ago, Boltzmannbrain said:

Last time I asked this I got a mouth full, but I have to ask again because I really don't know.  Are you saying that some things experience less time than others? 

Yes. "Relativity" means that some quantities, like time, are relative to the frame you are in. IOW, what you measure and what someone in another frame will measure, will disagree.

 

9 hours ago, Boltzmannbrain said:

I have read many times that time passes the same for everything in special relativity, but I am not totally sure about general relativity.  

In your own frame, your own clock ticks once per second. Your meter stick is a meter long. But there will be disagreement on how many seconds passed, and how far you traveled, when comparing to some other frame, because these are relative measurements. 

[Boltzmannbrain]

2 hours ago, swansont said:

Yes. "Relativity" means that some quantities, like time, are relative to the frame you are in. IOW, what you measure and what someone in another frame will measure, will disagree.

 

In your own frame, your own clock ticks once per second. Your meter stick is a meter long. But there will be disagreement on how many seconds passed, and how far you traveled, when comparing to some other frame, because these are relative measurements. 

I should have said proper time instead of "experienced" in my question.  But you answered it anyway.