They are for people in our rest frame, they are not for people moving relative to us.

You seem unwilling to accept that both of these things can be true at once.

Yes, he sees it happen wen his clock reads 2.5m years, knows that the light took 2.5m years to get there from the event, and so knows that the event happened when his clock read zero.

You seem to be getting confused by the fact that he knows that it took the light some time to reach him, you need to separate when he saw it from what time he claculates that it happened. These things are not the same.

Do you understand this point? For an observer, you see the event at time t, and you then need to subtract the time of flight from t to work out when the event hapened. It seems that you do not, which is possibly why you have managed to convince yourself that with no formal education in the subject, you can overthrow a century of well established physics.

And yes, I have several degrees in physics. This does not prove that what I am writing is true, of course, but is hopefully indicative of me being a decent source for information on what the mainstream says.

Do you genuinely believe that you have spotted something that no-one else saw before? Do you not concede that there is possibly just a little chance that the rest of the world's scientists are right, and that you might have made a bit of a silly mistake?

A question which you clearly refused to answer. Why is this?

And the other posters are agreeing with me, that in the rest frame of the light source, the observers clocks are synchronised.

No-one is saying otherwise, except you.

Can you please tell me why you think that the clocks are not synchronised?

So, you are agreeing, that you believe that both our motionless observers here, that their "Now's" are together/simultaneous?

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RussT
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Everything is, as it should be, otherwise, it wouldn't be!

Wait...Now we have to back up to here.
The whole point to adding the "Stationary" light source, halfway bewteen here and M31, was so that when each beam arrived at our respective "at rest" locations, we could both calibrate our clocks to 0........right? How does that add movement?

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RussT
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Everything is, as it should be, otherwise, it wouldn't be!

You do not set the rules of this forum. Fortis answered your question. You are the ATM poster, and you are obliged to answer questions. Talking of which, would you kindly answer the questions I posed?

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“He who asks a question is a fool for five minutes; he who does not ask a question remains a fool forever”
Chinese proverb
"All you need in this life is ignorance and confidence - and then success is sure." - Mark Twain.

Yes. How many times do you want this repeated?

Now how about you tell us why you think that they are not?

And just to make this explicitly clear (again), there are observers who DO NOT see these two as having synchronised clocks. That is he whole point of relativity; synchronised clocks in one frame are not synchronised in another.

For the umpteenth time, everything here is stationary: observers and light source, all are in the same inertial reference frame, SR does not apply, Lorentz equations do not apply.

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“He who asks a question is a fool for five minutes; he who does not ask a question remains a fool forever”
Chinese proverb
"All you need in this life is ignorance and confidence - and then success is sure." - Mark Twain.

Are you seriously asking this? M31 is not stationary with respect to us. It is very, very far from stationary.

Did you not know this?

You keep missing off very important points from your definition, and asking for a yes or a no, which is dishonest. You cannot use the word simultaneous without stating to which observer you are referring. A and B can both see that, for them, their clocks are simultaneous. Observer C may not agree that A and B have simultaneous clocks.

Are you doing this on purpose? Do you not understand that you always need to add "as observed by observer X" in SR? It makes no sense otherwise.

I'll ask you again, and hope that you'll grace me with a reply this time, do you believe that all of the physicists for the last hundred years have overlooked something that you have found, and have you made this discovery without a formal education in the subject?

Great,,,,,,,,,,,this is the whole point...but hang on a sec.........there is something we have to straighten out first.

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RussT
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Everything is, as it should be, otherwise, it wouldn't be!

Okay, let's be sure we are on the same page here...I am not trying to be difficult...really I am not, I have just seen things switched around so many times, and I am very pragmatic!

Why won't you stick to one situation?

I am...By saying that for a scientist in our "Earth Rest Frame" to a scientist on a planet's "Rest Frame" in M31, if we put an isotropic light source halfway between as you suggested, then when that beam reaches both earth and M31, simultaneously, we both set our clocks to 0...does that scenario work?

I mean, here we hold the earth stationary, as usual from "Earth's frame", and we know M31 is moving relative to us, BUT, that light that left there 2.5 million years ago, IS from where it was then, when it was emitted...Right?

and, if you don't agree that that is okay...then is this...


If you are going to insist on using M31, then let's at least change the universe around and make it stationary with respect to us. You do understand, don't you, that you cannot argue about stationary observers otherwise?

Still completely legitimate Relativity?

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RussT
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Everything is, as it should be, otherwise, it wouldn't be!

Sorry, gzhpcu, for the delay!

actually it is non-inertial........but being stationary to begin with is the whole point just like Einstein did...

He had two observers A and B on two horizontal lines, representing observer A on the Railroad platform and observer B on the second horizontal line, with a light source halfWay between each.



_____________________________________B____________ _______________



------------------------------------------LS



_____________________________________A____________ _____________



So, here is the problem right here…A and B are both “Motionless”...

“Assumes” a full Lorentz Transform of A and B’s “Nows”, just because there is a light source halfway between them. That imaginary light source halfway between two observers is meaningless as pertaining to their “Nows”!!!

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RussT
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Everything is, as it should be, otherwise, it wouldn't be!

"Light in it's own frame" IS a singularity....it is going from 0 to infinity, because there is division by zero, it is actually undefined...unless of course you make the 0 'mean something' and use the infinity to go from point A to point B anywhere, even 1000 billion ^1000 billion Light years, in the Universe."Instantanseously"...

ETA: OR, Contract this...1000 billion ^1000 billion Light years, down to 0 "Instantaeously"

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RussT
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Everything is, as it should be, otherwise, it wouldn't be!

Okay, here you are starting to confuse things, RussT, because now we are dealing with 2 rest frames and it is not clear whether the to frames are the same rest frame (i.e. whether our planet and the other M31 planet are at rest with respect to eachother). If this is not the case, than the clocks are not synchronized anymore by this experiment.

So, no this does not work unless you specifically write down that both rest frames are the same rest frame.

What do you want to get out of this silly discussion. First you want to synchronize two observers in the rest frame of the light bulb, and thus both observers at rest with respect to the light bulb and thus in rest with respect to eachother. Now you want to have M31 moving with respect to our planet. that is a whole different situation and your synchronization comments, on which every one was agreeing does not hold anymore.

Different situation, different kind of clocks, start over again.

Yes and no, it all depends on whether the two observers are at rest with respect to each other or not. Is that so difficult to understand?

If you want to overthrow relativity, at least you need to have a grasp about which rest frames are the same and which are different.

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善數, 不用籌策 (shàn shù, bù yòng chóu cè)
He who is good at counting, uses no counting tools
“A good scientist has freed himself of concepts and keeps his mind open to what is”
道德經, 二十七 (dào dé jīng, 27)

How can you have a Lorentz transform for two stationary observers?????????????????????????????????????????????????? ????????????????????????????????
It just does not make sense!!!!!!!!!

Lorentz transform, from Alonso & Finn: Physics, an undergraduate physics book, transformation between two obeservers with relative velocity v in the x-direction:

[latex]
x' = \frac{x - vt}{\sqrt{1 - \beta^2}}
y' = y
z' = z
t' = \frac{t - vx/c^2}{\sqrt{1 - \beta^2}}
[/latex]

Now plug in that both observers are at rest with rrespect to each other, which means v=0 and you find that x' = x and t' = t.

Now, what exactly do YOU mean with a Lorentz transform between the two stationary observers A and B. Unless you clear this up, it is useless to continue this ridiculous discussion.

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Any comments in glorious red are to be considered in ModeratorMode.


善數, 不用籌策 (shàn shù, bù yòng chóu cè)
He who is good at counting, uses no counting tools
“A good scientist has freed himself of concepts and keeps his mind open to what is”
道德經, 二十七 (dào dé jīng, 27)

No, not at all. This is now a totally different situation to that which you were describing earlier, and to the one in the desert that you used just up above. These two observers are in different rest frames, their clocks will move at different speeds.

Why don't you please just stick to the example you began with, where the observers are stationary with respect to one another, and stop this flip-flopping?

This is what I have been saying more than once, but I never get a response...

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“He who asks a question is a fool for five minutes; he who does not ask a question remains a fool forever”
Chinese proverb
"All you need in this life is ignorance and confidence - and then success is sure." - Mark Twain.

Well you didn't provide sufficient information. Are the two clocks moving relative to each other? Are they moving relative to the light source? Without that information, all I can do is say that both clocks read 0 in the rest frame of the light source at the same time. Anything after that depends on the information that you failed to provide.

As an aside, weren't you aware that exclamation marks are in short supply, and that we must do our best to conserve them?

That is exactly what I am saying...it doesn't make a bit of sense, 0 sense, nada, zilch, none what-so-ever!

And yet, for over 100 years now, it has gone completely unnoticed, that the distance from observer A to observer B, 'has been contracted to 0', by assuming that if the light beam sinks their clocks to 0, that because both clocks say 0, that their "Nows" are together/simultaneous, even though they are completely motionless/stationary!!!That is it in a nutshell.

So Instead of this...

“Assumes” a full Lorentz Transform of A and B’s “Nows”

I probably should have said...

Illegitimately 'contracts the distance to 0' OR Illegitimately uses a Lorentz transform to contract the distance to 0!!!

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RussT
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Everything is, as it should be, otherwise, it wouldn't be!

And I even cover this in the next line in my OP...

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RussT
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Everything is, as it should be, otherwise, it wouldn't be!

Actually, you are correct here Fortis...my opologies...

I assumed that everyone would simply understand that we were standing stationary in the salt flats... My Bad.

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RussT
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Everything is, as it should be, otherwise, it wouldn't be!

Now, wil show how this is false!

If you are going to insist on using M31, then let's at least change the universe around and make it stationary with respect to us

Okay, M31 and the Milky Way are stationary to each other 2.4 million light years distant.

For a scientist In "Earth's Frame" and a scientist in their/M31's planets "Rest Frame"
we put a light source halfway between us...1.2 million light years away from each other.

Turn on the light, and 1.2 million years later we will both set our clocks to 0, when those beams reach each of us simultaneously.

Now, a Super Nova explodes in M31 right when that beam halfway between us reaches that scientist, and his clock reads 0 as the SN explodes, and so our clock Must read 0 too...there is no way around that...

Then the light/photons from that SN take 2.4 million light years to reach us.

A light source, halfway between to observers at any distance is meaningless to sinking "Nows"

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RussT
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Everything is, as it should be, otherwise, it wouldn't be!

RussT, people are not saying that SR makes no sense, they are saying that your posts do not make sense. You know this, so why the disingenuous reply above? This is like the scholground retort "I know you are, but what am I", and has no place here.

You keep leaving out details about which observers are at rest relative to various others, and then trying to get people to give a definitive answer in this undefined scenario. This is sowing confusion unnecessarily.

In the situation where both observers are stationary with respect to the light source, everyone on here, except you, agrees that they will both see their clocks as being synchronised.

In this situation, can you please, please, try to explain why you disagree? Stop switching it to a situation where the observers are not in the same rest frame (the one whee you use M31 as one observer has more than one rest frame, why don't you get this?), and just explain why you do not agree that the clocks are synchronised. Please also stop trying to make your proof more "real" by insisting on 250m light years as being any more useful a distance than, say 1 metre.

Because of how you write (leaving out critical details), it is almost impossible to follow your line of "argument", and it is starting to look deliberate on your behalf. If you are doing this just for a laugh, please stop.

If you genuinely do want to have your ideas explored, stick to stationary observers, and stop underspecifying your examples to the point where no-one knows the pertinent facts.

To be explicitly clear on this, you have posted queries where everyone is on one frame (your desert example), and where we are telling you that the clocks are synchronised IN THAT FRAME, and you have posted ones where observers are in relative motion (the one involving M31), and where we all agree that the clocks are asynchronous IN ALL FRAMES.

If you had not realised that these situations are very different, and that this is actually the essence of SR, then might I suggest that you go back and read the standard texts on the subject?

You still owe me an answer to my question of whether you have any degrees in physics. It is pertinent in that I still have no idea how best to pitch to you that you'll end up learning something.

What is sinking? Are we on a boat?

You keep talking about two different frames, you do it again up there. Do you not understand that there is only one rest frame here?

Secondly, why this bizarre assertion that it is the existence of the light source that causes the "now" to match for both observers. The light source is used as part of the proof, but there is absolutely no requirement that there really be a light source. If I wanted to show you that two angles on a figure were identical, I might draw lines between vertices, but you don't then get to say that the proof is flawed because these lines are not real.

Again, to be clear, the light source between the two is not the reason that the clocks are synchronised. It is used to allow a method for both people to set their own clocks to read zero at the same time.

To give you another analogy, if I want to work out if my friend across the valley has his countour line at the same height as me, we can run a tube full or water along the valley floor, and fill it until the water is at my height. He can then check that it is also at his height. The tube in no way suddenly made the heights match, it was just a measuring device, exactly as the light source in the centre is.

I have never said that the clocks are not sychronized!

Just that the "Nows" are not and cannot be together as a result of that Syncing.

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RussT
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Everything is, as it should be, otherwise, it wouldn't be!

Yes, and you have not proved it. Not even close. You have asserted it.

You need to explain what you mean by their "nows" not being together. Physics involves itself only with what we can measure. You seem, suddenly, to wish to switch to a metaphysical or philosophical point that synchronised clocks is different to your desired state of having matching nows.

So, I'll ask you this. If both observers agree fully that the supernova happened at time t=0, for each of them, why do you assert that their nows are not the same?

what does that even mean? the 'Nows'?

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This is a really important point that RussT is overlooking. It seems he has a feeling that there exists some kind of undefined "nowness", that he has introduced, but not defined.

RussT, if you want to introduce a new quantity into physics, you need to define it first.

Your original post claimed that Einsteing was trying to synchronise the "now" for various observers. In fact, he was trying to synchronise their clocks.

Other posters obviously assumed that you were using "synchronised nows" to mean synchronised clocks, as that is what the argument to which you referred was doing.

If you are actually making another argument, and "synchronised now" is not the same as "synchronised clock", then you need to defin what you mean by synchronised now.

If it is your own concept, and if you have defined it to be unsynchronised for any observers not at the same spot as one another, then it has nothing to do with SR, nothing at all.

And you still owe me an answer on whether you have any physics degrees. please can you respond on this?

I'm off to motorbike to Goodwod, for the festival of speed now, so will respond later.

So what does this mean?
Not the reason.....huh......it is the very method by which you set both clocks to 0.

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RussT
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Everything is, as it should be, otherwise, it wouldn't be!