SR Issue

[Neddy Bate]

do you realize there's a contradiction on your part ?

No, I do not realize that. Where is the contradiction on my part?

If I had to guess, I'd say you are referring to these two statements:
1. Merely saying "two observers in relative motion" does not describe any event, because there is no specific occurrence of zero duration, and there is no specific location or time of occurring. Thus it would not be correct to call "two observers in relative motion" one event or two events. Neither is the case.
2. Yes, that sounds correct, because every point on a worldline represents an occurrence of zero duration, which has a specific spacial location, and a specific time of occurring.


Note that #2 is in the context of a worldline for each of the moving observers. A worldline necessarily implies that a specific location of the moving observer is known at any specific time. In #1 there is no specific information regarding specific locations of the observers at any specific times. Of course the trajectory of the moving observers represents an infinite number of events, but I did not find any of those events to be specified in #1. I suppose I should have been more generous and just said that #1 could represent an infinite number of events, assuming the specific locations of the moving observers are known at specific times.

 

[krash661]

why would i expect anything else stated,
(shrugs)

and no, look again,.
but also there's no point to get involved in this,
because you will continue to say ," no there is not " and i'll continue to say " yes there is ",
then i'll point it out, then you will just have some argumentative excuses of why it is not.
it's a pathetic game.
no need to escalate it.
there are some here who it is obvious to see.

 

[chinglu]

RPenner

RPenner, we now both agree where the M' frames places the lightning flash on the positive x-axis of the M' frame.

Since LT correctly translates, specifically where does the M frame place the lightning flash in M' frame coordinates when C' and M are co-located?

You did not answer.

 

[chinglu]

Thread readers.

Is the co-location event of C' and M a single SR event given both frames agree on the clock times?

If you think it is not s single event explain why as compared to Einsteins's statement,

"At the time $$t=\tau=0$$, when the origin of the co-ordinates is common to the two systems, let a spherical wave be emitted therefrom,"

https://www.fourmilab.ch/etexts/einstein/specrel/www/

 

[chinglu]

This thread appears to have propagated the question of what's needed to demonstrate that simultaneity is relative.

Every example I've seen has two observers and at least one event in it. Simultaneous events implies that you need at least two events for each observer to compare; in examples with two observers seeing one event, the other event is the co-location of the observer's frames.

But relativity of simultaneity doesn't depend on co-location of two observers, only that they have relative motion.

The universe provides lots of simultaneous events, so arguably the observers won't see just one "external" event in each of their simultaneous frames, they will see, well, a universe of events, but they won't agree on which ones are simultaneous, so therefore any single event (common to both frames) "demonstrates" that simultaneity is relative.

So what's needed is two observers in relative motion and a universe where information transfer is limited by, well, you know.

Can you explain specifically why the co-location event of C' and M are 2 events? Otherwise, agree it is one event.

 

[chinglu]

Then I guess I have to ask this: Are two observers in relative motion one event, or two events? If the two observers have intersecting worldlines, is the point of intersection one event or two events?

I think the answer to the first question is that every point on each of the observer's worldlines is an event, and the answer to the second question is that the point of intersection is a different event for each observer, since they assign different times to it.
So what can be said to be simultaneous for either observer when they intersect?

So, when LT translates, since it arrives at a different time as output from the input coordinates, that is 2 different events?

Is that correct?

 

[Neddy Bate]

why would i expect anything else stated,
(shrugs)

and no, look again,.
but also there's no point to get involved in this,
because you will continue to say ," no there is not " and i'll continue to say " yes there is ",
then i'll point it out, then you will just have some argumentative excuses of why it is not.
it's a pathetic game.
no need to escalate it.
there are some here who it is obvious to see.

You seem like you have a bad attitude regarding web forums. Why do you bother to post at all? Anyway, thanks for sparing me from having to suffer through a conversation with you.

 

[paddoboy]

Thread readers.

If you think it is not s single event explain why as compared to Einsteins's statement,

Can you explain specifically why the co-location event of C' and M are 2 events? Otherwise, agree it is one event.

Chinglu, as you know, I cannot validate or invalidate your maths. But I do observe two or three reasonably well respected experts doing that anyway.
So please, don't ask me to move on, when I ask a couple of questions relevant to SR, which is afterall what your mathematical problem is concerned with.
OK, now that is out of the way, here are the questions chinglu.

You have participated in many threads on SR and in all of those threads you have claimed SR to be false.
Correct? Good.
Taking that into consideration, isn't it reasonable of me to assume that this supposed mathematical problem you present, [which experts have shown how you have drawn the wrong conclusion] is for the express purpose of invalidating SR?
Logically and objectively, I see the answer to both questions as yes.
So my next question is why?...Why are you so anti SR/GR, when the whole world accepts and operates under those assumptions. Why do you defy and misinterpret evidence that even school children could interpret correctly.

Is it some sort of Creationist/God/Deity agenda?
Do you see SR and consequently GR and the BB, plus the standard acceptable cosmological model, as making this mythical God/Deity defunct?

Your maths has been shown to be in error, and the associated assumptions you make with it.
But you refuse to accept that, just as you have continued to refuse to accept time dilation and length contraction as real and frame dependant.
Again,to clarify your position re SR, I ask, are you claiming SR is false?
The answer to that question is the crux of the matter, and probably will decide whether this thread is moved to alternative section.
And has been shown, the answer is a resounding yes!

 

[arfa brane]

I don't know what to say.

If you can understand one of these you should be able to understand special relativity.

 

[Neddy Bate]

If you can understand one of these you should be able to understand special relativity.

How many events are shown there?

 

[krash661]

point in space of objects are same location only as shared, separate, but whiled shared, co locations is required. both occurring simultaneously.
light does not change under any frame nor circumstances.

everything has it's own time.
everything has an element of it's own time being shared , at times.
everything shares it's time in an overall time.
the significance of time and what kind of time(believe it or not) is very important.

 

[arfa brane]

How many events are shown there?

The diagram shows two frames: (t,X) and (t',X') with an angle $$ \Phi $$ between them. So (t,X) is the "at rest" frame and (t',X') has a velocity relative to (t,X).

Look at the lines labelled X and X'. There are three points (purple dots), connected by three curves. Each point is an event in the two simultaneous hyperplanes.
The curves are representations of the functions that transform events from X to X'; these are all hyperbolic.

There are three events lying along t and t', with similar curves connecting them.

Ok, so which are the spacelike separated, and which are the timelike separated events? What does the red curve passing through the origin represent, what about the black arrow, the yellow rectangle and the parallelogram? The three purple dots lying along X are simultaneous in (t,X) because t and X are at right angles. What about the three "connected" dots on X'? Are these simultaneous in (t',X')? How does the diagram convey the answers to those kinds of question?

...etc

 

[Neddy Bate]

The diagram shows two frames: (t,X) and (t',X') with an angle $$ \Phi $$ between them. So (t,X) is the "at rest" frame and (t',X') has a velocity relative to (t,X).

Look at the lines labelled X and X'. There are three points (purple dots), connected by three curves. Each point is an event in the two simultaneous hyperplanes.
The curves are representations of the functions that transform events from X to X'; these are all hyperbolic.

There are three events lying along t and t', with similar curves connecting them.

Ok, so which are the spacelike separated, and which are the timelike separated events? What does the red curve passing through the origin represent, what about the black arrow, the yellow rectangle and the parallelogram? The three purple dots lying along X are simultaneous in (t,X) because t and X are at right angles. What about the three "connected" dots on X'? Are these simultaneous in (t',X')? How does the diagram convey the answers to those kinds of question?

...etc

Could you please provide the value of the relative velocity v, the three values of X, the three values of X', the three values of t, and the three values of t'? I think they might help me understand it better. Thanks.

 

[arfa brane]

Could you please provide the value of the relative velocity v, the three values of X, the three values of X', the three values of t, and the three values of t'? I think they might help me understand it better. Thanks.

I don't really understand your request. There are three points along X, three along X' and these must have three values. If you're asking what they are, well that's arbitrary and depends on units of distance. The thing to realise is that the diagram describes a geometry which every point in spacetime must have, regardless of the units of time or distance we apply. I would guesstimate the velocity of the moving frame to be about 1/3 of c, given the size of the angle subtended by t,t'.

This is what the caption of the diagram says:

Minkowski diagram with resting frame (x,t), moving frame (x′,t′), light cone, and hyperbolas marking out time and space with respect to the origin.

You could refer back to some of rpenner's fairly detailed posts on what the lines and points on them represent (try starting with #48).

Here is a question for you: why are there no events on the line labeled "v = c" in the Minkowski diagram? Did they forget to put some there maybe, or is it possible to locate events along this line, and why or why not?

 

[chinglu]

RPenner and arfa brane & the relativity of simultaneity

RPenner and arfa brane have taken the position that the co-location event of C' and M alone is sufficient to invoke the relativity of simultaneity (ROS).
Yet, the times on the clocks of C' and M were decided by LT as one can see in the OP.

Here is a quote from Einstein.

"To any system of values $$x, y, z, t$$, which completely defines the place and time of an event in the stationary system, there belongs a system of values $$\xi, \eta, \zeta, \tau$$, determining that event relatively to the system k."

https://www.fourmilab.ch/etexts/einstein/specrel/www/

Since LT was used to decide the times on the clocks of C' and M then by Einstein's quote above, the co-location of C' and M is a single SR event.

 

[chinglu]

We can now completely understand this experiment. We try to use SR to decide the distance the lightning is from C' and M in M' frame measurements Then, we can use LT to decide the distance in M' frame measurements that the M frame claims the lightning is from their common location.

1) M' Frame calculation. C' is at $$(\frac{-vd'}{c},0,0)$$ relative to the M' origin and the lightning is a distance $$d'$$ from the origin. So, the total distance of the lightning from the common location of C' and M is $$d'+\frac{vd'}{c}=d'(1+\frac{v}{c})$$ in M' frame measurements.

2) M Frame calculation. C' is at $$(\frac{-vd'}{c},0,0)$$ relative to the M' origin and the lightning is a LT calculated distance in M' frame measurements of $$d'(1-v/c)$$. Add the 2, $$\frac{vd'}{c}+d'(1-v/c)=d'$$. Therefore, the M frame claims the lightning is a distance of d' from the common location of C' and M in M' frame measurements.

Hence, SR claims the lightning is a distance $$d'(1+\frac{v}{c})$$ and $$d'$$ from the common location of C' and M.

Note how ROS no longer matters.

 

[paddoboy]

I have asked a few questions pertaining to SR which your mathematics do also chinglu.
In light of that common point, those questions deserve a truthful answer.
If you are unable to, or refuse to answer them, then this forum, will conclude [as has been aptly shown anyway] , that your mathematical interpretations and conclusions are in error.
Therefor SR stands as it has for more than a 100 years, unchallenged, and part and parcel of everyday life.

 

[chinglu]

I have asked a few questions pertaining to SR which your mathematics do also chinglu.
In light of that common point, those questions deserve a truthful answer.
If you are unable to, or refuse to answer them, then this forum, will conclude [as has been aptly shown anyway] , that your mathematical interpretations and conclusions are in error.
Therefor SR stands as it has for more than a 100 years, unchallenged, and part and parcel of everyday life.

My answers are above.

 

[paddoboy]

My answers are above.

So you prefer not to answer?
The forum then can obviously make its own objective conclusions.
That your mathematical interpretations and conclusions are simply wrong, and therefor SR stands as it has for more than a 100 years, unchallenged, and part and parcel of everyday life.

 

[arfa brane]

RPenner and arfa brane have taken the position that the co-location event of C' and M alone is sufficient to invoke the relativity of simultaneity (ROS).

Well, I certainly haven't taken that position.
I've said you need two observers in relative motion plus a universe in which simultaneous events occur, and that a single event is sufficient. But this "single" event is different for each observer so, . . . I should say it's a pair of events, connected by a velocity transform.

Yet, the times on the clocks of C' and M were decided by LT as one can see in the OP.

This is nonsensical. Observers decide what the times on their clocks are, these are again "connected" by Lorentz transform. That doesn't mean if you know the time on one clock (i.e. you are that observer), then you know the time on the other clock by "LT".

Since LT was used to decide the times on the clocks of C' and M then by Einstein's quote above, the co-location of C' and M is a single SR event.

Except this single event is a different event for each observer; more exactly this colocation event has a single location, but two observer-dependent times.