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Quote from: pzkpfw on 20/02/2024 18:27:22Take Alice and Bob passing each other in space, in inertial relative movement.Alice can consider herself at rest, and Bob is passing at 100 kph.Bob can consider himself at rest, and Alice is passing at 100 kph.Alice has a clock that ticks at 1 second per second, but for her, Bob's clock is slow.Bob has a clock that ticks at 1 second per second, but for him, Alice's clock is slow.Thus, their clocks cannot be synchronised. This is basic relativity.Well, yes, you can insert Carol who remains between Alice and Bob, for whom they are both doing 50 kph. For Carol, Alice and Bob's clocks tick at the same rate.Your scenario seems to have the clocks meet at a common event, ...

Take Alice and Bob passing each other in space, in inertial relative movement.Alice can consider herself at rest, and Bob is passing at 100 kph.Bob can consider himself at rest, and Alice is passing at 100 kph.Alice has a clock that ticks at 1 second per second, but for her, Bob's clock is slow.Bob has a clock that ticks at 1 second per second, but for him, Alice's clock is slow.Thus, their clocks cannot be synchronised. This is basic relativity.Well, yes, you can insert Carol who remains between Alice and Bob, for whom they are both doing 50 kph. For Carol, Alice and Bob's clocks tick at the same rate.

... but to generalize a bit, and to remove all unnecessary observers, consider flat spacetime containing two inertial clocks at arbitrary locations, moving at arbitrary velocities, and set to arbitrary times.In exactly one frame C will those clocks be moving in equal and opposite velocities. ...

I do acknowledge that the intended purpose of an observer is often to simply hang a name tag on a frame, so 'according to Carol' becomes shorthand for 'relative to the frame in which Carol is stationary', but 1) it matters not a hoot then where Carol is in that frame, and 2) a rock with 'Carol' painted on it serves the same purpose.

No, I am not forgetting the very thing I am responding to. You tend to throw out snippets that contradict your own previous snippets, or lead to consequences that don't make sense. This is one.Take Alice and Bob passing each other in space, in inertial relative movement.Alice can consider herself at rest, and Bob is passing at 100 kph.Bob can consider himself at rest, and Alice is passing at 100 kph.Alice has a clock that ticks at 1 second per second, but for her, Bob's clock is slow.Bob has a clock that ticks at 1 second per second, but for him, Alice's clock is slow.Thus, their clocks cannot be synchronised. This is basic relativity.Well, yes, you can insert Carol who remains between Alice and Bob, for whom they are both doing 50 kph. For Carol, Alice and Bob's clocks tick at the same rate. (*1)But does that mean Alice and Bob's clocks ARE in an absolute sense (or can be) synchronised?Would Alice and Bob agree?And, if that were true, doesn't that mean you could postulate a Carol for ANY two such clocks? (*2)Do you think it matters to Alice and Bob if there is a Carol there or not?Notes:*1 For Carol, Alice and Bob's clocks will tick slower than hers of course, so you've also just moved the synchronisation issue one step deeper*2 That's why I made my previous post

Quote from: hamdani yusuf on 20/02/2024 12:31:14Both slow down equally, thus they are still synchronized to each other.But each appears to be running slow from the point of view of the other, and neither is in sync with the midpoint observer's clock. So none is synchronised with any other. It just happens that, seen from the midpoint, both departing clocks are equally wrong.

Both slow down equally, thus they are still synchronized to each other.

In exactly one frame C will those clocks be moving in equal and opposite velocities.

It looks like we're talking pass each other. Let's start with the basic common ground. How do you define synchronized clocks?

Let's start with the basic common ground. How do you define synchronized clocks?The same question for Alan.

How do you define synchronized clocks?The same question for Alan.

Two clocks are synchronised if A knows what time B is showing, simply by looking at his own clock.

If the clocks are identical

this can only be the case if there is no relative motion between them.

Where there is relative motion, he must apply a relativistic correction and thus needs additional information to determine the time shown at B.

First, they must tick at the same rate as each other.

Second, some process will have been used to set them to a known start time.

Quote from: Halc on 20/02/2024 20:27:39In exactly one frame C will those clocks be moving in equal and opposite velocities.That's only true if we were living in a one space dimension universe.

I'm giving other members the chance to use their best explanation to answer my questions. When the time is up

One can only know the time the other clock says if it is relatively stationary? Have fun justifying that.

Quote from: hamdani yusuf on 17/02/2024 08:47:23Quote from: pzkpfw on 16/02/2024 22:22:43If the two clocks are in relative movement (the distance between them is changing), will they tick at the same rate (and according to whom)?According to relativity principle, an observers who keep their position right between those clocks should see them synchronized, based on symmetry. Between the clocks is one special case, yes. But does that really mean those two clocks were synchronised?And this is not quite what you earlier said:Quote from: hamdani yusuf on 06/02/2024 09:38:53They can also be achieved when relative position=zero to the observer.And ... how does this apply to GPS?

Quote from: pzkpfw on 16/02/2024 22:22:43If the two clocks are in relative movement (the distance between them is changing), will they tick at the same rate (and according to whom)?According to relativity principle, an observers who keep their position right between those clocks should see them synchronized, based on symmetry.

If the two clocks are in relative movement (the distance between them is changing), will they tick at the same rate (and according to whom)?

They can also be achieved when relative position=zero to the observer.

I am sure that Hamdani will hang on your words, similar to his attraction to hobbyist you-tubes. Clearly he already does, and this will totally reinforce that preference.

I do assure you that I make mistakes.

I don't correct Hamdani because he has no desire to learn. I correct Alan because I disagree with almost everything he says on this subject.

That time has long since come and gone. Based on your other topics going on for years with zero conclusion, the time will never be up.

With enough data, patterns appear.

I'm glad you found one you like. No video is tagged with that name, but I'm guessing the one in post 184.

//www.youtube.com/watch?v=GsMqCHCV5XcWhy twin's paradox is NOT about acceleration?QuoteChapters: 00:00 What is the twin's paradox?00:48 Why acceleration doesn't solve twin's paradox2:24 Twin's paradox without acceleration (Earth's frame)4:42 The traveling frame7:13 My new website - floatheadphysics (ad)8:48 Earth's frame again - with the flag11:38 Travelling frame again - with the flag13:30 The resolution! 14:45 Relativity of simultaneity17:02 Isn't the root cause the acceleration?18:20 What do they 'see'? In this video, we'll intuitively resolve the twin's paradox. This version of the twin's paradox involves no acceleration. And no, you don't need equivalence principle, and you don't need general relativity to solve it. Twin's paradox can be completely solved using special theory of relativity and the correct usage of relativity of simultaneity. Let's see if anyone has objection to the explanation given in this video, which is an improvement of previous video by the same author, Mahesh Shenoy from Floatheadphysics.

Chapters: 00:00 What is the twin's paradox?00:48 Why acceleration doesn't solve twin's paradox2:24 Twin's paradox without acceleration (Earth's frame)4:42 The traveling frame7:13 My new website - floatheadphysics (ad)8:48 Earth's frame again - with the flag11:38 Travelling frame again - with the flag13:30 The resolution! 14:45 Relativity of simultaneity17:02 Isn't the root cause the acceleration?18:20 What do they 'see'? In this video, we'll intuitively resolve the twin's paradox. This version of the twin's paradox involves no acceleration. And no, you don't need equivalence principle, and you don't need general relativity to solve it. Twin's paradox can be completely solved using special theory of relativity and the correct usage of relativity of simultaneity.

and both are moving at the same speed relative to him

I'm giving you the chance to give your best shot.

Perhaps it's just about being human and reconciling how Nature seems to be, or ought to be, compared to how it actually might be.

Quote from: hamdani yusuf on 22/02/2024 13:06:30and both are moving at the same speed relative to himThere's the catch. He needs to know something more than just what the clocks are telling him.