# michel123456's relativity thread (from Time dilation dependence on direction)

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19 hours ago, michel123456 said:

At 12:00, the clock T is at rest. For some mysterious reason the Earth goes away at velocity 0,8c.

This is one of your many ideas that cause you so much confusion.  No observers in this scenario are confused about who is changing their frame of reference. The occupants of the rocket feel the acceleration, the occupants of earth do not feel the acceleration.  We all know that the rocket accelerates to a new reference frame from earth.

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19 hours ago, michel123456 said:

At 12:00, the clock T is at rest. For some mysterious reason the Earth goes away at velocity 0,8c.

It’s not a mystery novel. It moves because we’re doing a thought experiment about relativity.

If you like, there was already relative motion at 0.8c, and we set one clock to 12:00 to match the other clock when they are co-located, i.e. when one passes by the other. Whichever introduces less distraction by irrelevant detail.

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6 hours ago, swansont said:
10 hours ago, michel123456 said:

Thank you for the animations, very enlightening.

So let me see if I understand correctly:

If all three are at rest (clock T standing on Earth & planet X at rest) and a missile M is sent from planet X to Earth at 0.8c, how long will it take (as seen from T & Earth) to reach the Earth (and T)?

1:15

It’s no different than the trip in the other direction.

6 hours ago, Eise said:

When you actually mean 'observes' with 'seen': Earth will only see that the missile started from X after one hour, the time light takes to reach Earth. But then, oh shock, the missile arrives only 15 minutes later. So it looks as if the missile took only 15 minutes. But the earth observer is not so stupid. He knows that he got the signal of the missile's start after 1 hour. So he concludes that the trip took 1 hour and 15 minutes. So it all fits.

We all agree that the missile took 1hour and 15 minutes.

Now, replace the missile by planet X itself. Simply change the label M (missile) with Planet X.

How much time does it take, as seen by clock T (at rest) to see planet X come. The answer is the same: Earth Clock T will only see that the missile Planet X started from X after one hour, the time light takes to reach Earth clock T. But then, oh shock, the missile planet X arrives only 15 minutes later. So it looks as if the missile planet X took only 15 minutes. But the earth clock observer is not so stupid. He knows that he got the signal of the missile's planet x start after 1 hour. So he concludes that the trip took 1 hour and 15 minutes. So it all fits.

That is exactly what T clock observes in its FOR. 1:15. that is the time interval  between the departure of the Earth & the arrival of planet X.

And not 45 minutes.

Edited by michel123456
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12 hours ago, michel123456 said:

We all agree that the missile took 1hour and 15 minutes.

No. I know I said it took 1:15h, but I made very clear that this is from the FOR of Earth, X and T (standing still at Earth). Sentences like the above say nothing, unless you say both what event or process, and according to which FOR.  Why can't you stop these imprecise way of speaking. You are just confusing everybody, and most of all yourself.

13 hours ago, michel123456 said:

How much time does it take, as seen by clock T (at rest) to see planet X come.

STOP IT! Again you use this ambiguous 'seen'. If you do not stop this, i.e., if you keep intentionally vague, I will ask this thread to be closed.

So let's repeat it again:

• the missile travels 1:15h according the FOR of Earth, X, and T in your example above
• the missile travels 1Lh according the FOR of Earth, X, and T in your example above.
• the missile travels 0:45h according the its own FOR (i.e. its own clock)
• the missile travels 0.6Lh  according the its own FOR (i.e. its own odometer)*

Exactly the same holds when Planet X travels to Earth (replace 'missile' with 'Planet X' in the above 4 lines).

13 hours ago, michel123456 said:

That is exactly what T clock observes in its FOR. 1:15. that is the time interval  between the departure of the Earth & the arrival of planet X.

Except that you use 'observe' again: T observes Planet X to arrive 0:15h after it observes Planet X starting to move. But because of signal delay, T rightly concludes that the trip took 1:15h.

13 hours ago, michel123456 said:

And not 45 minutes.

But nobody ever said that the trip takes 0:45h from the FOR of Earth and Planet X!!! (except you..)  The '0:45' appears in two (equivalent) ways:

• It is the trip time that T measures on his own clock. For T, he travels only 0.6Lh.
• It is according the FOR of Earth and Planet X the time dilation of T: according Earth's own clock, the trip took 1:15h. But reading the logbook of T, it turns out that T took only 0:45h, i.e. according T's clock. As for the FOR of Earth the distance is still 1Lh, Earth can only conclude that T's clock was slower.

I am wondering how you are thinking. Are you really trying to understand what we write (or animate!!), or do you throw a potential counter example against every step you simply do not understand?

I proposed several times that you concentrate on real scenarios, i.e. scenarios where we really have measurements. It is an empirical fact that many muons that are created in the upper atmosphere reach the earth's surface. But the halftime of the muons is too short to reach the earth's surface, even if they would travel at near light velocity. Or take muons in an accelerator: where given their half life they could maybe not even make one complete turn through the synchrotron, it is measured that it runs about 30 times through it. This is real stuff, not relativity applied to a science fiction scenario.

*So Earth, X, and T on one side, and the missile on the other side, agree about their relative velocity:

• From Earth, X, and T: 60 LMinutes / 75 minutes = 0.8c
• From the missile: (0.6 x 60 LMinutes)/45 minutes = 0.8c.

"Exactly as it should be."

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24 minutes ago, Eise said:

No. I know I said it took 1:15h, but I made very clear that this is from the FOR of Earth, X and T (standing still at Earth). Sentences like the above say nothing, unless you say both what event or process, and according to which FOR.  Why can't you stop these imprecise way of speaking. You are just confusing everybody, and most of all yourself.

STOP IT! Again you use this ambiguous 'seen'. If you do not stop this, i.e., if you keep intentionally vague, I will ask this thread to be closed.

So let's repeat it again:

• the missile travels 1:15h according the FOR of Earth, X, and T in your example above
• the missile travels 1Lh according the FOR of Earth, X, and T in your example above.
• the missile travels 0:45h according the its own FOR (i.e. its own clock)
• the missile travels 0.6Lh  according the its own FOR (i.e. its own odometer)*

Exactly the same holds when Planet X travels to Earth (replace 'missile' with 'Planet X' in the above 4 lines).

Except that you use 'observe' again: T observes Planet X to arrive 0:15h after it observes Planet X starting to move. But because of signal delay, T rightly concludes that the trip took 1:15h.

But nobody ever said that the trip takes 0:45h from the FOR of Earth and Planet X!!! (except you..)  The '0:45' appears in two (equivalent) ways:

• It is the trip time that T measures on his own clock. For T, he travels only 0.6Lh.
• It is according the FOR of Earth and Planet X the time dilation of T: according Earth's own clock, the trip took 1:15h. But reading the logbook of T, it turns out that T took only 0:45h, i.e. according T's clock. As for the FOR of Earth the distance is still 1Lh, Earth can only conclude that T's clock was slower.

I am wondering how you are thinking. Are you really trying to understand what we write (or animate!!), or do you throw a potential counter example against every step you simply do not understand?

I proposed several times that you concentrate on real scenarios, i.e. scenarios where we really have measurements. It is an empirical fact that many muons that are created in the upper atmosphere reach the earth's surface. But the halftime of the muons is too short to reach the earth's surface, even if they would travel at near light velocity. Or take muons in an accelerator: where given their half life they could maybe not even make one complete turn through the synchrotron, it is measured that it runs about 30 times through it. This is real stuff, not relativity applied to a science fiction scenario.

*So Earth, X, and T on one side, and the missile on the other side, agree about their relative velocity:

• From Earth, X, and T: 60 LMinutes / 75 minutes = 0.8c
• From the missile: (0.6 x 60 LMinutes)/45 minutes = 0.8c.

"Exactly as it should be."

No.

27 minutes ago, Eise said:

I know I said it took 1:15h, but I made very clear that this is from the FOR of Earth, X and T (standing still at Earth)

In its FOR, T is at rest. There is NO REASON why it would give a different result.

29 minutes ago, Eise said:

STOP IT! Again you use this ambiguous 'seen'. If you do not stop this, i.e., if you keep intentionally vague, I will ask this thread to be closed.

Cool down.

I am the one who has been insulted, not you.

32 minutes ago, Eise said:

For T, he travels only 0.6Lh.

My understanding is different (let me be wrong). I thought that Relativity gives you the result of what happen in the other FOR, not what happens in your own FOR. IOW for the Earth ,T is time dilated, and for Earth, T is length contracted.

In its own FOR, nothing happens to T. (I am trying to avoid the words "see" & "observe" that annoy you so much).

In the FOR of T :

1. The departure time of the Earth is recorded at 12:00.

2. The departure time of planet X is recorded at 13:00 (1 hour after its actual departure)

3.The arrival time of planet X is recorded at 13:15 (15 minutes after the arrival of the signal from the departure).

In the FOR of T,standing at rest, the travel was 1h15min.

It is not possible that T records only 45 minutes. That would mean that planet X is arriving before the signal.

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1 hour ago, michel123456 said:

In its FOR, T is at rest. There is NO REASON why it would give a different result.

OMG...! What 'it'? Which scenario? This is even less clear!

My guess what your 'argument is pointing at': the missile travelling from planet X to Earth (With T as static guest...).

• From the Earth's FOR it takes 1:15h. (60Lminutes/0.8c)
• T travels a contracted distance, 0.6 x 1 lh = 36 Lminutes. As he is traveling with 0.8c, this takes him 0:45 according his own clock.

Where is this wrong according you? Please always mention in your reactions:

• your scenario (you are introducing new one after new one, only to feed your intuition to find yet another counter argument...)
• which event or process are you looking at?
• According to which FOR's measurements?
• Looking at the clock and ruler of the other FOR or its own FOR?
1 hour ago, michel123456 said:

I am the one who has been insulted, not you.

I do not agree. Your imprecise remarks show that you do not really think through our answers, and this is insulting to the effort Janus, Bufofrog, Swansont, md<somenumberhere>, Markus, and who more. We are all trying to be as precise as possible, and you come with some vague counter argument, shot from the hip.

Tell us e.g. what is wrong with Janus' animations? If nothing, where do you differ in our interpretations of them?

And why do you refuse again and again to take real examples, where we have empirical measurements?

Edited by Eise
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1 hour ago, Eise said:

OMG...! What 'it'? Which scenario? This is even less clear!

My guess what your 'argument is point at': the missile travelling from planet X to Earth (With T as static guest...).

• From the Earth's FOR it takes 1:15h. (60Lminutes/0.8c)
• T travels a contracted distance, 0.6 x 1 lh = 36 Lminutes. As he is traveling with 0.8c, this takes him 0:45 according his own clock.

Where is this wrong according you? Please always mention in your reactions:

• your scenario (you are introducing new one after new one, only to feed your intuition to find yet another counter argument...)
• which event or process are you looking at?
• According to which FOR's measurements?
• Looking at the clock and rule of the other FOR or its own FOR?

I do not agree. Your imprecise remarks show that you do not really think through our answers, and this is insulting to the effort Janus, Bufofrog, Swansont, md<somenumberhere>, Markus, and who more. We are all trying to be as precise as possible, and you come with some vague counter argument, shot from the hip.

Tell us e.g. what is wrong with Janus' animations? If nothing, where do you differ in our interpretations of them?

And why do you refuse again and again to take real examples, where we have empirical measurements?

"Tell us e.g. what is wrong with Janus' animations? If nothing, where do you differ in our interpretations of them?"

You don't want me to do that. But since you asked: almost everything is wrong.

On 10/3/2020 at 9:48 PM, Janus said:

This is how events unfold according to Earth and Planet x.

B and it clock are length contracted and B's clock is time dilated. The length contraction doesn't really play a role in the out come here.

This is the view of some "exterior observer" since it does correspond to no FOR (not the Earth, not Planet X, not clock T)

a.From Earth, when clock T starts it is 12.00 on Earth and 11.00 on planet X

b.From Planet X, when clock T starts, it is 13.00 on planet X

You cannot represent facts a & b on this kind of animation.

The only good thing is that clocks on Earth & on planet X are synchronized. But you cannot extract any information from it, expect that clock T ticks slower than the clocks on Earth & planet X, which means that from T, the clocks on Earth & planet X are ticking FASTER (and where is time dilation then?)

c. There is no length contraction in this animation, which as I stated before is WRONG. If you want to represent time dilation, you must represent length contraction too. By length contraction I do not mean the oval shape of T solely, but also its path 0,6 LH long. Where is it?

IOW this animation 1 above is pure garbage.

Now animation 2.

On 10/3/2020 at 9:48 PM, Janus said:

If we now consider things from B's inertial frame of reference, you get this.

B is at rest while the Earth and planet X move to the left at 0.8c.

In this 2nd animation the Earth is leaving at 12:00, so far so good.

But planet X should be applied the delay: clock T does not get the start signal instantly. So, this animation is wrong. And in this "view from other observer" (that corresponds to animation 1) the clocks on Earth & on planet X are not synchronized anymore.

Edited by michel123456
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16 hours ago, michel123456 said:

We all agree that the missile took 1hour and 15 minutes.

In the earth's frame. You persist in not specifying frames of reference.

16 hours ago, michel123456 said:

Now, replace the missile by planet X itself. Simply change the label M (missile) with Planet X.

How much time does it take, as seen by clock T (at rest) to see planet X come. The answer is the same: Earth Clock T will only see that the missile Planet X started from X after one hour, the time light takes to reach Earth clock T. But then, oh shock, the missile planet X arrives only 15 minutes later. So it looks as if the missile planet X took only 15 minutes. But the earth clock observer is not so stupid. He knows that he got the signal of the missile's planet x start after 1 hour. So he concludes that the trip took 1 hour and 15 minutes. So it all fits.

That is exactly what T clock observes in its FOR. 1:15. that is the time interval  between the departure of the Earth & the arrival of planet X.

And not 45 minutes.

IOW, if you assume relativity is not true, you will get an answer consistent with relativity not being true.

The problem is that we have evidence that relativity is true. You can't disprove it with a thought experiment. So you need to look at actual physical evidence to do this. For example, you could finally address Eise's questions about the muon experiment.

1 hour ago, michel123456 said:

No.

In its FOR, T is at rest. There is NO REASON why it would give a different result.

And the planets are moving, which means the distance between them is contracted.

1 hour ago, michel123456 said:

My understanding is different (let me be wrong). I thought that Relativity gives you the result of what happen in the other FOR, not what happens in your own FOR. IOW for the Earth ,T is time dilated, and for Earth, T is length contracted.

Relativity lets you understand why the other frame disagrees with length and time measurements. If something is moving relative to you, relativity applies.

So in T's frame, earth and X are in a moving FoR, so the distance between them is length contracted. All lengths are contracted in that frame, in the direction of the relative motion.

1 hour ago, michel123456 said:

In its own FOR, nothing happens to T. (I am trying to avoid the words "see" & "observe" that annoy you so much).

And seeing the distance between earth and X is not something that "happens to T" since they are not in its frame.

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7 minutes ago, swansont said:

The problem is that we have evidence that relativity is true. You can't disprove it with a thought experiment. So you need to look at actual physical evidence to do this. For example, you could finally address Eise's questions about the muon experiment.

I firmly believe that the question IS the thought experiment, and ONLY the thought experiment. Not to say that this thought experiment is bad for Relativity, it suggests some weird effect that I think does not take place.

Relativity is OK, no question about that.

8 minutes ago, swansont said:

In the earth's frame. You persist in not specifying frames of reference.

In the frame at rest. In this case, T is at rest. The Earth goes away (say westward) and planet X arrives (say from eastward).

Edited by michel123456
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28 minutes ago, michel123456 said:

Tell us e.g. what is wrong with Janus' animations? If nothing, where do you differ in our interpretations of them?

You don't want me to do that. But since you asked: almost everything is wrong.

I think Eise meant how do they fail to convey the concepts of relativity, rather than how they disagree with your own pet theory. Of course they disagree with your view, since your view is inconsistent with relativity.

Again: you cannot disprove a theory with a thought experiment. You have to look at an actual experiment. Like muons. Or actual moving clocks (e.g. Hafele-Keating)

6 minutes ago, michel123456 said:

In the frame at rest. In this case, T is at rest. The Earth goes away (say westward) and planet X arrives (say from eastward).

There is no unambiguous "frame at rest" since any inertial frame can be taken to be at rest.

Quote

I firmly believe that the question IS the thought experiment, and ONLY the thought experiment. Not to say that this thought experiment is bad for Relativity, it suggests some weird effect that I think does not take place.

Relativity is OK, no question about that

But you keep denying relativity, or failing to use it, so this is not a consistently-applied sentiment.

In the example in play, you fail to apply length contraction to a moving frame.

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12 minutes ago, swansont said:

But you keep denying relativity, or failing to use it, so this is not a consistently-applied sentiment.

In the example in play, you fail to apply length contraction to a moving frame.

Lenght contraction applies instantly for Earth leaving clock T.

But for 1 long hour, for clock T the distance to planet X will not be contracted. Planet X will appear resting at 1LH away. And the signal of departure will appear to come from 1LH away (just like the missile example, in which you had no problem at all to write down that it will be recorded traveling 1 hour & 15 minutes).

You are all very intelligent people here. Why don't you take a rest & take a new look to this thought experiment. There is no danger, and Relativity will not change.

Edited by michel123456
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1 minute ago, michel123456 said:

Lenght contraction applies instantly for Earth leaving clock T.

But for 1 long hour, for clock T the distance to planet X will not be contracted.

You are asserting this, without any physical justification whatsoever. Why don't muons have this problem?

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.edited because of cross posting

Edited by michel123456
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1 minute ago, michel123456 said:

For every observer, the clock of the object moving will tick slower when going away, and faster when coming in.

No, that's what will be seen owing to the Doppler effect. The clock will actually be ticking slower.

Once again, what we see and what we measure are not the same thing.

Why won't you address the muon issue?

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3 minutes ago, swansont said:

Why won't you address the muon issue?

Because we cannot even agree on simple things.

Like : if your clock looks like running slower for me, then my clock must also look like running slower from you. If I read 60 minutes on my clock & 45 minutes on your clock, then reversely you will read 60 minutes on your clock & 45 minutes on my clock.

Not even that.

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59 minutes ago, michel123456 said:

This is the view of some "exterior observer" since it does correspond to no FOR (not the Earth, not Planet X, not clock T)

a.From Earth, when clock T starts it is 12.00 on Earth and 11.00 on planet X

b.From Planet X, when clock T starts, it is 13.00 on planet X

Again mixing up what is really the case, and what observers observe.

Let's first do the clock synchronisation between Earth and planet X: a space station, standing still (so being in the same FOR as Earth and X)exactly in the middle of Earth and X sees that the readings of both clocks are the same. He sends his finding to both Earth and X, who now know that their clocks are really synchronised. This is what Janus' animation shows: both clocks show the same time. However from that it follows that Earth observes X's clock one hour behind, and of course X sees earth's clock one hour behind. But they know that this is just signal delay, so they know their clocks still are synchronised.

a. When it is 12:00h it is 12:00h at X. As shown in Janus' diagram.

b. When T starts, it will take an hour before X sees it. But he knows of the time delay, so he knows T started at 12:00 on both Earth's and X's clock. As depicted in Janus' animation.

59 minutes ago, michel123456 said:

c. There is no length contraction in this animation, which as I stated before is WRONG. If you want to represent time dilation, you must represent length contraction too ). By length contraction I do not mean the oval shpae of T solely, but also its path 0,6 LH long. Where is it shown.

Nowhere, because it is not there. Remember? I said:

On 10/2/2020 at 10:20 AM, Eise said:

Apply md65536's criteria: is it moving?

• no --> no length contraction (the distance between Earth and X is not moving!)
• yes --> that what is moving is length contracted (and time dilated)

And you reacted:

On 10/2/2020 at 11:06 AM, michel123456 said:

I have no much problem with all of that.

Janus' first animation is from the FOR of Earth and X (and my added space station). As per definition of a FOR Earth and X do not move, so there is nothing length contracted. Only T's clock is moving, so it is length contracted.

59 minutes ago, michel123456 said:

IOW this animation is pure garbage.

This is insulting. I don't know ho much time Janus needs for make such an animation, but slowly I getting the idea that all our efforts are useless. You just stick to your wrong intuitions.

36 minutes ago, michel123456 said:

I firmly believe that the question IS the thought experiment, and ONLY the thought experiment. Not to say that this thought experiment is bad for Relativity, it suggests some weird effect that I think does not take place.

What weird effect? PLEASE STOP using ambiguous phrases!

36 minutes ago, michel123456 said:

Relativity is OK, no question about that.

If you believe in your intuitions, you believe that relativity is wrong.

33 minutes ago, swansont said:

I think Eise meant how do they fail to convey the concepts of relativity, rather than how they disagree with your own pet theory.

That is of course what I try to find out, but maybe Michael would show us where his mental block lies. Until now I see two mental blocks, but mentioning them seems not to help:

• he is not able to relate his measurements of time and distance to one single FOR
• he is not able to make the difference between what observers actually observe, and what they conclude

Every suggestion we make to clarify the situation (e.g. my suggestion to use log books instead of remote readings (which introduce signal delays that even confuse Michael more), my suggestion to explain the same phenomena with muons, and last but not least Janus' unambiguous animations) is pushed aside, because Micheal thinks he has a clear view of the situation.

Edited by Eise
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7 minutes ago, michel123456 said:

Because we cannot even agree on simple things.

The muon experiment is arguably the simplest example one could discuss.

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19 minutes ago, michel123456 said:

Like : if your clock looks like running slower for me, then my clock must also look like running slower from you.

Like is shown clearly in Janus' animations? Just look again...

15 minutes ago, swansont said:

The muon experiment is arguably the simplest example one could discuss

Yep. So Michael, do you want to go to the simplest example, with the clear additional advantage that we have precise measurements? In case we can clear up the muon experiment, then we can go back to your thought experiment.

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2 hours ago, michel123456 said:

IOW this animation 1 above is pure garbage.

-1 for willful ignorance.  You deserve a -531 for your performance in this thread IMO.

Let's be honest, you haven't spent 20 researching, you spent 20 years denying... What an odd waste of time and effort.

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On 10/2/2020 at 6:29 PM, swansont said:

IOW, there is no frame of reference where the distance is 1 LH and the described trip takes 45 min

However, that is what is shown in animation 1. Look at B's clock.

On 10/3/2020 at 9:48 PM, Janus said:

This is how events unfold according to Earth and Planet x.

B and it clock are length contracted and B's clock is time dilated. The length contraction doesn't really play a role in the out come here.

You yourself looking at your screen are this observer. Which is wrong ( I mean the animation shows something unphysical)

Say that you are this observer: you are located some LHours away, your distance to Earth is D and to planet X is also D (your position is at the summit of an isosceles triangle),  your clock is synchronized to E and X, and you are at rest with E and X.

For you would B (clock T) be time dilated & length contracted? Knowing that your distance to B remains roughly the same.

Edited by michel123456
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1 hour ago, michel123456 said:

However, that is what is shown in animation 1. Look at B's clock.

B is not in the earth’s frame of reference.

Do you understand what it means to be “in” a frame of reference? It means not in motion with respect to that frame. An animation can show objects that are in multiple frames of reference. (That’s one reason why it has to be animated)

There are two objects shown in the earth’s frame: E and X. In that frame, the trip takes 1:15.  There is no frame of reference where the trip is 1 LH and takes 45 minutes.

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1 hour ago, michel123456 said:
On 10/2/2020 at 5:29 PM, swansont said:

IOW, there is no frame of reference where the distance is 1 LH and the described trip takes 45 min.

However, that is what is shown in animation 1. Look at B's clock.

No again. B is not in the same frame of reference as Earth, X and the 'virtual observer'. These 3 are in the same FOR. B is not.

With other words, this your problem 1:

On 10/5/2020 at 1:02 PM, Eise said:

not able to relate measurements of time and distance to one single FOR

So to extend on Swansont's reaction above:

In the FOR of E and X (and the observer):

• B travels a distance of 1Lh
• It takes B 1:15h to get from E to X.

In the FOR of B:

• B travels a distance of 0.6c
• It takes him 45 minutes
1 hour ago, michel123456 said:

You yourself looking at your screen are this observer. Which is wrong ( I mean the animation shows something unphysical)

No, this is physically perfectly possible. Imagine the observer at my spacestation (see above, it stands still in the FOR of E, and X)), making a movie of what happens. Janus' animation shows exactly what the clocks will look like.

1 hour ago, michel123456 said:

For you would B (clock T) be time dilated & length contracted? Knowing that your distance to B remains roughly the same.

Yes, both. The speed of B in the FOR of E and X is 0.8c. I think you have here problem 2: relativity has nothing to do with delay of signals. In what you really observe delay plays a role. But not in what actually happens. When relativity would be based on signal delays, your argument would make sense. But relativity is not based on signal delay. It does not describe what you see, but what actually happens. So:

On 10/5/2020 at 1:02 PM, Eise said:

not able to make the difference between what observers actually observe, and what they conclude

Edited by Eise
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39 minutes ago, Eise said:

No again. B is not in the same frame of reference as Earth, X and the 'virtual observer'. These 3 are in the same FOR. B is not.

With other words, this your problem 1:

So to extend on Swansont's reaction above:

In the FOR of E and X (and the observer):

• B travels a distance of 1Lh
• It takes B 1:15h to get from E to X.

In the FOR of B:

• B travels a distance of 0.6c
• It takes him 45 minutes

No, this is physically perfectly possible. Imagine the observer at my spacestation (see above, it stands still in the FOR of E, and X)), making a movie of what happens. Janus' animation shows exactly what the clocks will look like.

Yes, both. The speed of B in the FOR of E and X is 0.8c. I think you have here problem 2: relativity has nothing to do with delay of signals. In what you really observe delay plays a role. But not in what actually happens. When relativity would be based on signal delays, your argument would make sense. But relativity is not based on signal delay. It does not describe what you see, but what actually happens. So:

And what is the speed of B in the FOR of the virtual observer?

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6 minutes ago, michel123456 said:

And what is the speed of B in the FOR of the virtual observer?

The observer is at rest wrt E and X, so it’s in the same frame. All of the measured values will be the same.

53 minutes ago, Eise said:

In the FOR of E and X (and the observer):

• B travels a distance of 1Lh
• It takes B 1:15h to get from E to X.

In the FOR of B:

• B travels a distance of 0.6c
• It takes him 45 minutes

In the FOR of B:

• E and X travel a distance of 0.6c
• It takes them 45 minutes

(B is at rest in its frame)

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23 minutes ago, swansont said:
31 minutes ago, michel123456 said:

And what is the speed of B in the FOR of the virtual observer?

The observer is at rest wrt E and X, so it’s in the same frame. All of the measured values will be the same.

You have evaded the question: what is the speed of B in the FOR of the virtual observer?

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