If you label the picture as M' stationary, then I will agree with it.
You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an alternative browser.
You should upgrade or use an alternative browser.
Relative Velocity Measurement – Frame and photon
- Thread starter geistkiesel
- Start date
If you label the picture as M' stationary, then I will agree with it.
But Jack, you've defined the situation in the rest frame of M, and that is what informs us what the situation is in the rest frame of M'.
You have used the setup in M to derive a measurement in M'.
And right now, we're disagreeing about that setup, are we not? So, perhaps we should agree about what the setup is in M before we decide what happens in M'?
No, I accepted the conditions of rest M and constructed an environment for M' to decide the problem.
I cannot see how we would disagree on the setup in M.
Are you also agreeing to the first part of that post?
You agree that if lightning strikes A' in one frame of reference, it can't miss A' from another point of view, right?
And you agreed that in the rest frame of M', when the lightning strikes at A, A' is there as well, right?
So, it clearly follows that in the rest frame of M, when the lightning strikes at A, A' is there as well, right?
I really do not care what other reference frames see.
If you wnat to look at MM' and then conclude that M will have diffrerent conclusions about the strikes at say A', that is SR's problem and not mine.
In fact, I believe you are finally see some inconsistencies in SR.
When M and M' are co-located, M' will conclude the observer, A' is co-located with A because of length contraction.
Now, M will not conclude A' and A are co-located when M and M' are co-located. Seems like an error in the theory.
However, the relativity postulate allows me to operate with M' stationary and use all the tools of SR like length contraction of a moving frame's length.
So, I did that.
That is SR. If you disagree, take it up with Einstein.
If you label the picture as M' stationary, then I will agree with it.
OK... I'm trying to get a handle on how exactly you decide where to place A' and B'.No, I accepted the conditions of rest M and constructed an environment for M' to decide the problem.
I cannot see how we would disagree on the setup in M.
We start with the conditions of rest M:
A and B are equidistant and stationary with respect to M. Lightning strikes at A and B simultaneously with M' passing M.
Now, you want to switch to working in the rest frame of M', right?
You said: "assume there were M' observers co-located at B and A when the lightning strikes occurred at A and B and call them A' and B'."
So, making that explicit:
A' and B' are at rest with respect to M.
A' is placed so that lightning strikes at A' as A passes by.
B' is placed so that lightning strikes at B' as B passes by.
Good so far?
Last edited:
OK... I'm trying to get a handle on how exactly you decide where to place A' and B'.
We start with the conditions of rest M:
A and B are equidistant and stationary with respect to M. Lightning strikes at A and B simultaneously with M' passing M.
Now, you want to switch to working in the rest frame of M', right?
You said: "assume there were M' observers co-located at B and A when the lightning strikes occurred at A and B and call them A' and B'."
So, making that explicit:
A' and B' are at rest with respect to M.
A' is placed so that lightning strikes at A' as A passes by.
B' is placed so that lightning strikes at A as B' passes by.
Good so far?
B' is placed so that lightning strikes at A as B' passes by.
Do you mean B?
Last edited:
Yes, thank you. I'll edit my previous post to fix that.
Next, you said: "Therefore, when M and M' are co-located, the distance from M' to B' is d/λ and the distance from M' to A' is d/λ."
It seems that you are assuming that the lightning strikes are simultaneous in the rest frame of M'. ie you are assuming that when M is colocated with M', A is colocated with A' and B is colocated with B'.
I suggest that this assumption is unwarranted. In fact, SR says that (if A, M, and B are all moving in the direction from B' to M' to A'):
B will pass B' first, then M will pass M' a little later, then A will pass A' a little later again.
Next, you said: "Therefore, when M and M' are co-located, the distance from M' to B' is d/λ and the distance from M' to A' is d/λ."
It seems that you are assuming that the lightning strikes are simultaneous in the rest frame of M'. ie you are assuming that when M is colocated with M', A is colocated with A' and B is colocated with B'.
I suggest that this assumption is unwarranted. In fact, SR says that (if A, M, and B are all moving in the direction from B' to M' to A'):
B will pass B' first, then M will pass M' a little later, then A will pass A' a little later again.
Last edited:
Running the transforms:
A passes A' at:
x = -d
t = 0
x' = -λd
t' = λvd/c²
M passes M' at:
x = 0
t = 0
x' = 0
t' = 0
B passes B' at:
x = d
t = 0
x' = λd
t' = -λvd/c²
Note the time order in the rest frame of M':
B' is colocated with B when t' is negative, M meets M' at t'=0, and A' meets A at positive t'.
Before I did this, I had the time order around the wrong way in my previous post. This shows why doing the formalism can be important to getting it right.
A passes A' at:
x = -d
t = 0
x' = -λd
t' = λvd/c²
M passes M' at:
x = 0
t = 0
x' = 0
t' = 0
B passes B' at:
x = d
t = 0
x' = λd
t' = -λvd/c²
Note the time order in the rest frame of M':
B' is colocated with B when t' is negative, M meets M' at t'=0, and A' meets A at positive t'.
Before I did this, I had the time order around the wrong way in my previous post. This shows why doing the formalism can be important to getting it right.
Yes, thank you. I'll edit my previous post to fix that.
Next, you said: "Therefore, when M and M' are co-located, the distance from M' to B' is d/λ and the distance from M' to A' is d/λ."
It seems that you are assuming that the lightning strikes are simultaneous in the rest frame of M'. ie you are assuming that when M is colocated with M', A is colocated with A' and B is colocated with B'.
I suggest that this assumption is unwarranted. In fact, SR says that (if A, M, and B are all moving in the direction from B' to M' to A'):
B will pass B' first, then M will pass M' a little later, then A will pass A' a little later again.
Well, once you get to the facts, I will prove they are simultaneous. Unlike Einstein, I prove things.
No, I dont assume anything.
Of course, you do as we can see above.
Oh, can you prove the above from M' stationary?
Show me.
I want to see the proof.
Again, assume M' is stationary.
Running the transforms:
A passes A' at:
x = -d
t = 0
x' = -λd
t' = λvd/c²
M passes M' at:
x = 0
t = 0
x' = 0
t' = 0
B passes B' at:
x = d
t = 0
x' = λd
t' = -λvd/c²
Note the time order in the rest frame of M':
B' is colocated with B when t' is negative, M meets M' at t'=0, and A' meets A at positive t'.
Before I did this, I had the time order around the wrong way in my previous post. This shows why doing the formalism can be important to getting it right.
The above bold are wrong in the frame of M' stationary.
Yes, you do. Your statement:Well, once you get to the facts, I will prove they are simultaneous. Unlike Einstein, I prove things.
No, I dont assume anything.
"Therefore, when M and M' are co-located, the distance from M' to B' is d/λ and the distance from M' to A' is d/λ."
Is not a logical conclusion from your premises unless you assume simultaneity in the rest frame of M'.
What specifically do you want proven?Oh, can you prove the above from M' stationary?
All I can prove is that for any scenario you describe, SR when applied correctly does not lead to contradictions.
For example, I just proved that correctly applying SR to your little experiment demonstrates that in the rest frame of M':
when M and M' are co-located, the distance from M' to B' is dλ and the distance from M' to A' is dλ.
Not according to SR, Jack.The above bold are wrong in the frame of M' stationary.
x' = (x - vt)λ
t' = (t - vx/c²)λ
Whatever model you are thinking of is clearly not SR, and I'm not surprised that it's self-contradictory.
Not according to SR, Jack.
x' = (x - vt)λ
t' = (t - vx/c²)λ
Whatever model you are thinking of is clearly not SR, and I'm not surprised that it's self-contradictory.
Here are your bold
x' = -λd
t' = λvd/c²
x' = λd
t' = -λvd/c²
Note you hsve a v term in the time but not in the x' coords.
And, no this is not correct.
LT is used to describe light travel from co-location to a receiver. We are taking simple distance measurements which are length contracted frame to frame.
So, we must first understand how and when to use LT.
Hence, any conclusions you draw above are completely invalid.
Yes, you do. Your statement:
"Therefore, when M and M' are co-located, the distance from M' to B' is d/λ and the distance from M' to A' is d/λ."
Is not a logical conclusion from your premises unless you assume simultaneity in the rest frame of M'.
This is the correct application of SR
I do not know ewhat to tell you.
If you think it is wrong, try to explain why except make sure you use SR.
Thanks.
What specifically do you want proven?
All I can prove is that for any scenario you describe, SR when applied correctly does not lead to contradictions.
For example, I just proved that correctly applying SR to your little experiment demonstrates that in the rest frame of M':
when M and M' are co-located, the distance from M' to B' is dλ and the distance from M' to A' is dλ.
You are claiming if d is the rest distance in M and we take M' as stationary, then M' will see the distance as dλ?
:roflmao:
Yes, that's correct. It's elementary arithmetic, Jack. I know you can do it.Here are your bold
x' = -λd
t' = λvd/c²
x' = λd
t' = -λvd/c²
Note you hsve a v term in the time but not in the x' coords.
x = -d
t = 0
x' = (x - vt)λ = -λd
t' = (t - vx/c²)λ = λvd/c²
x = d
t = 0
x' = (x - vt)λ = λd
t' = (t - vx/c²)λ = -λvd/c²
No, the lorentz transform is used to transform event coordinates from one reference frame to another. Look it up on Wikipedia.LT is used to describe light travel from co-location to a receiver. We are taking simple distance measurements which are length contracted frame to frame.
Length contraction is a consequence of applying a lorentz transform to particular events - events that occur at different times in the original reference frame, and at the same time in the target reference frame. You can always use a lorentz transform, but you can't always apply length contraction.
Jack, you're telling me very clearly that you are unable to correctly apply SR.This is the correct application of SR
I do not know ewhat to tell you.
If you think it is wrong, try to explain why except make sure you use SR.
You know why it's wrong - you're getting inconsistent results. You have successfully proven that your conception of SR is inconsistent.
Look at what I'm doing, Jack. I can consistently apply a model to get consistent results. You seem to think that the model I'm using is not SR, but so what? It works. You so hung up on proving that the model you have in your head is wrong, that you're not interested in seeing a model that is right.
No, Jack. The distance from M' to A' is a "moving distance" in M. It is at rest in M'.You are claiming if d is the rest distance in M and we take M' as stationary, then M' will see the distance as dλ?
The lorentz transform says that if d is the distance between A' and M' in M and we take M' as stationary, then M' will see the distance as dλ?
See how length contraction is a consequence of the lorentz transform?
Yes, that's correct. It's elementary arithmetic, Jack. I know you can do it.
x = -d
t = 0
x' = (x - vt)λ = -λd
t' = (t - vx/c²)λ = λvd/c²
x = d
t = 0
x' = (x - vt)λ = λd
t' = (t - vx/c²)λ = -λvd/c²
No, the lorentz transform is used to transform event coordinates from one reference frame to another. Look it up on Wikipedia.
Length contraction is a consequence of applying a lorentz transform to particular events - events that occur at different times in the original reference frame, and at the same time in the target reference frame. You can always use a lorentz transform, but you can't always apply length contraction.
http://www.fourmilab.ch/etexts/einstein/specrel/www/
Check chapter 4
Here is the correct way to do it.
First M' is stationary, so you must use
x = (x'+vt')γ
With t' = 0,
x = x'γ
Now given from the M frame a value of d for x, we have
d = x'γ
So,
x' = d/γ.
When you use
x' = (x - vt)γ, you are operating from the view that M is the stationary system.
Jack, you're telling me very clearly that you are unable to correctly apply SR.
You know why it's wrong - you're getting inconsistent results. You have successfully proven that your conception of SR is inconsistent.
Look at what I'm doing, Jack. I can consistently apply a model to get consistent results. You seem to think that the model I'm using is not SR, but so what? It works. You so hung up on proving that the model you have in your head is wrong, that you're not interested in seeing a model that is right.
No, Jack. The distance from M' to A' is a "moving distance" in M. It is at rest in M'.
The lorentz transform says that if d is the distance between A' and M' in M and we take M' as stationary, then M' will see the distance as dλ?
See how length contraction is a consequence of the lorentz transform?
Here you are again, frame mixing sometimes claiming M' is stationary and other times claiming M is stationary.
Remember, we are operating from the position that M' is stationary and trying to work the problem.
Jack, you begin describing this scenario by specifying events with M stationary, remember? You specified that the distance with M stationary from A to M and M to B is d, and you specified that with M stationary, lightning strikes A and B simultaneously when M and M' are colocated.http://www.fourmilab.ch/etexts/einstein/specrel/www/
Check chapter 4
Here is the correct way to do it.
First M' is stationary, so you must use
So, you know x and t for three events. You don't yet know x' and t' for those events.
Wrong.x = (x'+vt')γ
With t' = 0,
x = x'γ
Now given from the M frame a value of d for x, we have
x=d when t=0, not when t'=0.
You're doing it wrong, Jack. You don't understand how SR works, and that's why you're getting inconsistent results.
We're transforming coordinates from M to M'. We have to do that because we know what they are in M, and we want to know what they are in M'.x' = (x - vt)γ, you are operating from the view that M is the stationary system.
Jack, you begin describing this scenario by specifying events with M stationary, remember? You specified that the distance with M stationary from A to M and M to B is d, and you specified that with M stationary, lightning strikes A and B simultaneously when M and M' are colocated.
So, you know x and t for three events. You don't yet know x' and t' for those events.
Wrong.
x=d when t=0, not when t'=0.
You're doing it wrong, Jack. You don't understand how SR works, and that's why you're getting inconsistent results.
We're transforming coordinates from M to M'. We have to do that because we know what they are in M, and we want to know what they are in M'.
First, post #53 clearly demonstrates I am talking about M' as stationary.
Second, if d is the rest distance in M, then when M' is stationary and M is the moving frame, that distance is d/γ = d√( 1 - v²/c²) in the M' frame. It is called length contraction.
If you do not believe me ask AN or something.
I gave you the link for the 1905 paper and I have no interest in debating length contraction in SR. In fact, I can give you links to the BAUT forum and even they understand that.
Yes, that's correct.First, post #53 clearly demonstrates I am talking about M' as stationary.
Second, if d is the rest distance in M, then when M' is stationary and M is the moving frame, that distance is d/γ = d√( 1 - v²/c²) in the M' frame. It is called length contraction.
However, you are not being careful about which distances are rest distances in which frames.
The distance from A to M will be length contracted in the rest frame of M'.
The distance from A' to M' will be length contracted in the rest frame of M.
See? But perhaps we're still confused about the setup. Let's go back a few steps.