You might be on to something. Perhaps if he addressed my post that included that scenario it would have been identified.

If this is the case then it has nothing really to do with SR. Its like saying 2 people 100m apart don't hear everything at the same time. Well no duh and who cares. You don't even need SR to work out the differences.

That is exactly what RussT is claiming (e.g. with respect to A and B and the supernova near B), which naturally is totally ridiculous. I think I even pointed that out to him, only to get his drawing of A, B and the light again.

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善數, 不用籌策 (shàn shù, bù yòng chóu cè)
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“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)

And his confusion about proper time isn't helping.

Could it be, that RussT considers "now" as being when things actually occur and not when they are actually seen by the observer?

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RussT.
Still interested in SR and struggle with sync ? then PAY ATTENTION to THIS :
Is the key for :
Finally ......... "WHEN .. ACTUALLY OCCUR" ! what a strange childish concept !
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Declaimer: Words are tailored to human ears , not all statements are extirely correct to the math.

I only have a few minutes to answer a few of these tonight...

No, of course I don't think...according to SR[/i] that they need to see every event at the same time,

I am simply saying that the halfway light source is meaningless to A and B's NOWs, even though I do and am agreeing that you can set both clocks to 0 using that method........BUT A and B are still the same distance away from their "Nows" being together, even though both of their clocks have been set to 0.

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

Oh, ok. I thought that was what you were getting when you pointed out that an event near A is seen by A before it's seen by B as if it proved your point.

So, presumably you agree that if A and B are in the same rest frame then an event that is closer to A will be seen by A before it is seen by B according to their synchronized clocks (assuming they can synchronize their clocks somehow).

Conversely, presumably you also agree that an event closer to B will be seen by B before A.

And those events which are closer to neither will be seen by neither first according their synchronized clocks. That's all that light source in the middle is doing: defining a convention for their clocks to be synchronized.

I don't understand what same distance away from their "Nows" being together means at all, sorry.

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If logic doesn't work, then surely it does.

Maybe it would be helpful RussT, if you would define exactly what you understand under "now"...

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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.

No RussT they aren't because if they come together at the same rate of acceleration their clocks will be the same.

Please address my post found
here - #120

What is your problem with the first scenario. The light is used to zero the clocks and at the end of the test both clocks read the same.

"Now", as usual, is when a 'light source' flashes/turns on...IE: Super Nova in M31, helmet on B's head, ETC

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

Actually, I have continually used the SN in M31/Oberver/scientist B, at rest, on his home planet, when both clocks are set at 0, because the beam from the Halfway LS reached him at the same time it reached our Earth Frame.


The halfway clock synching 0's is once again 'meaningless' here...

If we, in the Milky Way saw an event 500,000 light years away from us, in the direction of M31, we of course would see it first, and say it was 500,000 light years distant. A scientist in M31, would see it much later than us, and first light for him/her would be ~1.9 million light years distant.

Again, synching those clocks is Meaningless!


The "Now" for the SN/M31 was 2.5 million years ago, from OUR current NOW.

M31, and that SN that happened 2.5 million years ago, have moved, based on M31's relative speed to the Milky Way, to where M31 is today, in our now....all we can really do is "Extrapolate" where that is, based on sound physics....

Which is exactly what Tim Thomspon says Here...

Quote:
Originally Posted by RussT
I am just trying to make sure that you/MS (Mainstream) does not have some 'special way' of 'showing' that we/science can see/detect photons, say from M31, that would show that we/science can see M31 as it is "Now", and where it is "Now", as seen from our 'Now' here in the Milky Way.

Quote:
Originally Posted by Tim Thompson
OK, is this what I am supposed to be answering? Haven't I already done that several times? How many different ways do you want to see the same answer? We detect photons in our "now", and that tells us what M31 looks like in our "now". Realizing that it took photons 2.5 million years to make the trip, and that our "now" is 2.5 million years after the "now" of M31 we see, we can then derive from physics how M31 would have changed over the intervening 2.5 million years. That way we can synthesize a picture if what M31 would look like if photons made the trip instantaneously, and that the two "now"s were simultaneous. RussT's Bold/Red
Further...

Quote:
Originally Posted by RussT
In other words, when we send a light beam to the moon, as in the lunar ranging project, it travels to the moon at "c" and Back at "c", for a ~2.5 second round trip, right.

Quote:
Originally Posted by Tim Thompson
Always.

Quote:
Originally Posted by RussT
So, is light/photons ever traveling 'instantaneously' away from us towards any distant object?

Quote:
Originally Posted by Tim Thompson
Never.

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

The reason I haven't answered/responded to this particular scenario is quite simple...it is beyond what I said I was defending...but the other reason is because this....No RussT they aren't because if they come together at the same rate of acceleration their clocks will be the same.

Contains a glaring error, according to Relativity, as does your scenario in post # 120....

I will ask this, so it is up to you to figure it out...

You and any SR buddy you choose, jump in your spaceships, your brand new Enterprize Mark X's...you start at Alpha Centauri, 4 light years away, coming at Earth accelerating at 50% "c", and your buddy starts at earth, accelerating at 50% "c", when you meet at the halfway point, compare clocks, what do they say?

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

So, just to be clear, is "now" for you when the event really happens and emits photons, and not when the photons from the light source reach the observer's eye?

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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”
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"All you need in this life is ignorance and confidence - and then success is sure." - Mark Twain.

How does one accelerate at 50% c?

Wasn't this thread originally about people at rest with respect to each other?

Wouldn't the answer to this depend on what their clocks said before they began accelerating?

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Earth and Alpha Centauri are not at rest in respect to each other. The respective clock rates will be different. Their clocks do not show the same time, and tick at different rates. The spaceships do not accelerate a 50% c. 50% c is a velocity and not a rate of acceleration. You mean they travel a 50% c towards each other. This 50 % c will be in respect to their respective inertial frames of reference. Complicated calculation.

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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.

So, it would appear that you are agreeing with my/RussT and Jeff Root's{I will pull his quotes out too, if necessary} claim, that Relativity is not and cannot be applied, when it comes to known distances, in the Local Neighbothood, because Relativity did not and cannot determine those distances?

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

I think you don't understand the rules of ATM forum. Please read them.
So what part of my scenario are you trying to defend? I've started from the begining of your scenarios except I, unlike you, didn't leave out crucial information that is needed to do the thought experience.


Once again you fail to set up the entire scenario. Which is why I layed out the entire scenario. Also if my scenario
Then why ask me something that I've already gave you the answer to at the end of scenario #1
So you are just avoiding answering my question and obfuscating what you feel is the problem with SR.

Given the entire scenario in post #120

Please quote and bold where you think I've missed something. Because the above covers your

They would say/read the same thing as long as they where synchronised by a source that was 1/2 way between me and my buddy and me and my buddy where in the same rest frame even though the rest frames where 4ly apart.

So stop your games and properly address Post #120

This is why I layed out the entire scenario from start to finish and RussT waves his hand, says it doesn't cover what he has a problem with with out saying what that is and then tries to ask a question that I explicitly answered in my scenario.

RussT seems to recognise he has no real arguement because I didn't leave him any wiggle room and now wants to pretend that he's still right and we are all greatly confused.

He needs to stop his childness and address the full scenario. It would be very easy for him to point to exactly where he thinks there is a problem and state what problem he has with that point.

You are so confused it isn't funny. What makes it worse is when everyone keeps explaining that it doesn't matter that in a photon's frame there is no time or distance. We aren't interested in time and distance in the photon's frame of reference because they are undefined and have no bearing on the frames of reference of 2 observers in the universe.

Please address my post #120

I've layed out the entire scenario with no wiggle room for you to hide like you have been trying to do by constantly changing scenarios.

I'd be happy for you to fully explain your own scenario with all peaces of infromation present needed to do the calculations then point to where you think the calculations break down.

What exactly do you think special relativity is?
It is a "transformation mechanism" for observations between observer A and observer B who has a relative velocity with respect to A.
I have not got the foggiest how you would want to use SR to determine distances. It is not what is it made for, and it cannot be used for that because it makes no sense. It can say that when A measures a length X, then B will measure a length Y and the relation between the two is given by the Lorentz transform.

If that, finally, is your whole point, that you cannot use SR to do something for which it was not developed, then congratulations on this miraculous find, that apparently no physicist has found before.

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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)

So, to what end?

So you keep saying, but why?

Assuming the guy on M31 isn't moving relative to us,w hy is synching those clocks meaningless? Just because they might see some other event (not the halfway LS) at different times?

And he explained it perfectly. Now-over-there can only be computed from what we see now-over-here of what happened over-there in the past (along with a definition of what we mean by now-over-there, of course).

"now" doesn't travel from the LS to each guy thus bestowing "nowness" on them. It's just a way for them to synchronize their clocks by both observing the same event from the same distance knowing that the time lag will then be the same for both. Where's the problem?

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There are 10 types of people in the world. Those who understand ternary, those who don't, and those waiting for a bus.
If logic doesn't work, then surely it does.

No. I am saying that SR is not used to determine distances, and am extremely puzzled as to why you are bringing up distances with respect to SR.

You can apply SR anywhere in space. I dont know why you would want or need to apply it to any motions in the local group, since all those motions are so slow that the relativistic adjustments are tiny percentages of the total movement.

It looks like all those quote you added to your post are incomplete. At least I couldnt tell what you are discussing.

SR is used to find the changes to classical mechanics due to the finite speed of light. It is concerned with objects moving with respect to one another and how time and space look different to different observers due to the finite speed of light. The only reason I could see to use SR in the local group is if you were extremely fussy about exact motions. An example would be the few thousand years difference that it would take Andromeda to reach the Milky Way if you calculated it with and without the SR adjustments.

I would like for you to please explain what it is you have a problem with in SR. We seem to be very confused as to what your problem is.

Er, one of the two postulates of SR is that the speed of light measured in any inertial reference frame is always the same, i.e. c. This is built into SR.

Please tell us what the problem is. You seem to be dancing around it by asking us questions, yet I suspect that I'm not the only one having problems understanding your issue.

c is a velocity, not an acceleration.

That's like saying that the theory of coordinate rotations cannot be applied to the same application and for the same reasons.

What are you trying to show?

What do you think Special Relativity is?

It is the method, but not the reason. If a river marks the full flow height at the same level on both sides of a valley, then the river is not the reason that two particular trees are both at the full flow level, it is just the way of measuring this equivalence.

It is disappointing that RussT is now insisting on arguing in circles, and using all of the cranks's armoury of avoiding the point under contention.

RussT, if you would like any more input from me, please try, just this once, to actually explain why you believe SR is wrong. Please reference the actual paper. If you don't want to, please say so. You seem to be playing an unfunny semantic game at present, or you seem unable to make a point concisely.

I had this argument with Tommac. He was under a big misconception on how much the proper motion of galaxies and their gravity wells have on their frames of reference. I couldn't get it through Tommac's head that in the grand scheme of things, IE when we are measuring how long ago something happened in a galaxy 1 billion ly away, the 1.000002000006 time dilation due to the milky way moving at ~600km/s relative to the CMB meant nothing. Even if 2 galaxies where moving in opposite directions at 600km/s relative to the CMB the dilation is only 1.000008000096

For everything we do right now we can basically say that we are in the same rest frame locally and these numbers are even more meaningless when you get into higher redshift.

Yes, sorry, I did leave out the appropriate synching at the start...

BUT, that is not the problem......the problem is...

That, according to Relativity, because they are 'accelerating/decelerating', they would be nowhere near 'side by side', since they are coming together from opposite directions...

But, now you will just switch to 'instantaneous constant speed' for your 'alien in a spaceship', which is impossible in nature (Accept for Neutrinos and photons) to try to prove your point.

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

No game, no semantics...the real problem is that TWO Truths are being held to 'simultaneously'!

You said in post #37...

The Bold simply means, that you are waiting for that light to travel that distance to get from event X to us, the observer...

That automatically says that there is a "Light Travel Time", from a distance X....

For the SN in M31, when you use the halfway light to synch M31 to the Milky Way, where the SN explodes when that halfway light gets to M31 and M31's clock reads 0, as our clock reads 0 because the light beam hit us at the same time it hit M31, it then simply and automatically takes 2.5 million lys to travel to us, as the observers in the Milky Way.........there simply can be no "Simultaneity" of first light there to absorption here...what is so hard to understand about that?

All the rest is the Circular reasoning!~

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