I've answered that many times. No.
Now again, do you accept time dilation and length contraction?
Do you accept SR as already proven beyond a reasonable doubt?
And just to remind you.....
SR Issue
- Thread starter chinglu
- Start date
I've answered that many times. No.
Now again, do you accept time dilation and length contraction?
Do you accept SR as already proven beyond a reasonable doubt?
And just to remind you.....
Neddy Bate
Valued Senior Member
That's good, because clearly they are not the same event. Their t' coordinates are not equal, and their x' coordinates are not equal. So those two events happen at different times, and different locations, according to the M' frame.
Yes, more clearly stated, the M' frame finds the co-location of C' and M event is simultaneous with the light flash event at $$(d',0,0,d'/c)$$.
Your terminology, "using the M frame information," suggests that you are not 100% clear on what that means. The M frame finds the co-location of C' and M event is simultaneous with a different light flash event than $$(d',0,0,d'/c)$$ . That is the very essence of ROS. So it is not a matter of using different information, instead it is a matter of considering a different frame's interpretation of simultaneity. There is nothing wrong with the M frame finding the co-location of C' and M event as simultaneous with $$(d'(1-v/c),0,0,d'(1-v/c)/c)$$ . That is the very essence of ROS.
You cannot make that claim with any validity, because you agreed above that we are talking about two different events which happen at different times, and different locations. Surely a light flash can be located at two different places at two different times. Furthermore, you have not shown any violation of the light postulate, because both events $$(d',0,0,d'/c)$$ and $$(d'(1-v/c),0,0,d'(1-v/c)/c)$$ are in agreement with $$x'=ct'$$ . All you have is an objection to ROS on the grounds that you do not seem to like the idea very much.
I think I'll review this diagram one more time, what the hell.
Previously, I said the purple dots represent events, but I think I should be more precise. The dots along X are things we might assume an observer at (X,t) = (0,0) has "information" about. The observer at rest "sees" three separate locations in their simultaneous space (because they are purple colored dots!). These three objects, whatever they are, appear in X', and the diagram shows how they also lie on a set of hyperbolic curves.
That is, they are the same three "spacelike" locations, but rotated from one frame to the other. The moving frame sees these locations as being further apart.
Along the t axis in the rest frame, there are three more purple dots at different "locations", all in the future of both observers. Again, this is the same three "timelike" points under a rotation.
Ok, so does all that give you a way to describe simultaneous events? Are these points really events, or are they a continuum of events?
Previously, I said the purple dots represent events, but I think I should be more precise. The dots along X are things we might assume an observer at (X,t) = (0,0) has "information" about. The observer at rest "sees" three separate locations in their simultaneous space (because they are purple colored dots!). These three objects, whatever they are, appear in X', and the diagram shows how they also lie on a set of hyperbolic curves.
That is, they are the same three "spacelike" locations, but rotated from one frame to the other. The moving frame sees these locations as being further apart.
Along the t axis in the rest frame, there are three more purple dots at different "locations", all in the future of both observers. Again, this is the same three "timelike" points under a rotation.
Ok, so does all that give you a way to describe simultaneous events? Are these points really events, or are they a continuum of events?
Infract away, but why close the thread?
No, "when" is based on "zu dieser Zeit" -- if you don't know German, then you don't get to have an opinion on what German words are translated into what English words.
| German | Piecewise direct translation | Professional English |
|---|---|---|
| Zur Zeit t = τ = 0 | At time t = τ = 0 | At the time t = τ = 0 |
| von dem zu dieser Zeit gemeinsamen Koordinatenursprung beider Systeme | from the common at this time origin point of both systems | when the origin of the co-ordinates is common to the two systems |
| werde ... aus eine Kugelwelle ausgesandt | ... will sent out a spherical wave | let a spherical wave be emitted therefrom |
| welche sich im System K mit der Geschwindigkeit V ausbreitet. | which propagates in the system K with the speed of V. | and be propagated with the velocity c in system K. |
You didn't define the terms "clock synchronization" or "decidable" or connect your statement with logic to Einstein's 1905 paper, so this is a non sequitur and leaves you looking like a fool.
Incorrect, since Einstein is establishing a convention here. You would have to understand the context of Einstein's 1905 paper in order to know that no frame to frame clock synchronization is implied -- the assumption that (t=0,x=0,y=0,z=0) corresponds to (t'=0,x'=0,y'=0,z'=0) is a selection of the Lorentz transform over the Poincaré transform, but both are discussed in Einstein's paper, even in the part I quoted for you in [post=3205946]post #275[/post].
That's a misuse of online translating tools. "zur Zeit" may be translated as "at the moment" or "now" but "zur Zeit x" means "at time x". In any case, you are looking at the wrong instance of "Zeit" as the second instance ("zu dieser Zeit" -> "when") is the one under discussion.
No clocks are under discussion. My quote of Einstein in [post=3205946]post #275[/post] begins with "it is assumed that at the origin of k, $$\tau = 0$$, when $$t=0$$." because that's one of the underlying assumptions for this section of the paper. By starting a wrong sentence with "clearly" you just look like a blustering empty shell.
You misapply that word.
A transient co-location has no physical meaning at any event which is either elsewhere or else when. You have not demonstrated that line j and line k are not both equally valid definitions of simultaneity.
That's not the definition of relativity of simultaneity and not at issue in the OP. You have committed the fallacy of moving the goalposts. All relativity of simultaneity says is that if one frame says "P and Q are events that happen in different place at the same time" there exist other frames that disagree. Thus $$t_P = t_Q$$ is compatible with $$t'_Q \lt t'_R = t'_P$$, a mathematical fact you calculated in the OP and failed to realize in your ridiculous "conclusions" that you just demonstrated relativity of simultaneity. Like it or not, you calculated the coordinates for events P, Q and R just as I did in [post=3198606]post #2[/post].
Moreover, it was you who [post=3205690]introduced[/post] Einstein's 1905 paper where he wrote:
So we see that we cannot attach any absolute signification to the concept of simultaneity, but that two events which, viewed from a system of co-ordinates, are simultaneous, can no longer be looked upon as simultaneous events when envisaged from a system which is in motion relatively to that system.
All you are doing with your goal-post-moving of "when" to "if" is trying to attach absolute significance to the phrase "at the same time as event P."You have been trolling since your post #1. You contradict your own assumptions, you use contextomy to try and make Einstein say ridiculous things, you redefine terms, you don't label your events and you never discussed lines j and k of [post=3198606]post #2[/post]. You never had a right to demand answers, but you are singularly unrewarding as a conversationalist as well. You have asked questions that contain deceptive wording or contradictory assumptions that need to be corrected not answered. As JamesR said to you:
It might be this [post=2958684]post #28 from July 2012[/post] where you cited an anti-scientific, pro-creationist source. Or [post=2959102]post #37[/post] where the author writes "DARWIN was a crackpot", and by [post=2966782]post #92[/post] used the title Creationist in a way the suggests self-identification.
In this 2010 thread, the author claims "Time dilation false", " Lorentz transforms do not imply time dilation", http://www.physforum.com/index.php?showtopic=28676
Likewise, this 2010 thread, [thread=105498]Time Dilation[/THREAD], was predicated on trying to show that "t ' = ( t - vx/c² )γ " does not lead to a prediction of time dilation.
But I don't know of an example where this author claimed length contraction was wrong.
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Nope, that's incorrect.me said:
The moving observer sees their local frame as "at rest" and the other frame as "moving", so if both observers have identical clocks and measuring rods, the observer "at rest" (whichever frame is chosen) sees the moving frame as having dilated time and space axes. The moving frame has a "slow" clock and a "lengthened" measuring rod relative to the at rest frame. Hence, according to an observer at rest, an observer in motion ages more slowly and sees distances "at rest" as being length-contracted.
Yeah? Nah?
Neddy Bate
Valued Senior Member
No lengths are lengthened. Measuring rods at rest in your own frame are their proper length, and measuring rods at rest in the "other" frame are length-contracted along the axis of motion. The Minkowski diagram can make lengths seem longer, but you have to keep in mind that the units on the skewed axes are larger than the units on the orthogonal axes.
Clocks at rest in your own frame tick at their proper rate, and are all synchronized to each other. Clocks at rest in the "other" frame tick at a slower rate, and are not all synchronized to each other, (not the ones along the axis of motion anyway).
Yes, well. You can see that in the diagram the t' and X' axes have larger units (both are 'dilated' by the transformation). Then to explain what happens to standard measuring rods, the rotation from a rest frame to a moving frame means if the measuring rod is the same length for the moving observer ("at rest" in their local frame) as for the observer at rest, then distances not in the moving observer's local frame must change (i.e contract correspondingly).Neddy Bate said:
Likewise the moving observer's clock will appear to be ticking more slowly relative to the observer at rest's clock; in the diagram the clock along t' takes longer to count up to "2", say.
But this dilation is symmetric--both observers see the other's frame as time dilated and length contracted. Ok. so why is there a difference between the time (clocks are slower in the moving frame relative to the rest frame), and the distance (lengths are shorter in the moving frame relative to the rest frame)? Why does "slower clocks" mean "shorter distances"? Is it just the way we perceive time and distance?
Neddy Bate
Valued Senior Member
Special relativity actually is not about observers or perceptions at all. Imagine a Cartesian coordinate system (sort of like graph paper but 3d) and add a clock to each intersection of the lines on the graph paper. Synchronize all the clocks, and that is a reference frame in SR. You might say that an observer is required to synchronize the clocks, and that is sort of true, even though it does not require any actual humans. The clocks can be photosensitive, like cameras, and they can be programmed to set them selves to the same time displayed on the nearest clock to their left, plus some added time to account for the amount of time required for the light to travel from one camera-clock to the next. In this way, the time displayed on one clock can become the time displayed on all of the clocks.
Let's say you have a second reference frame which happens to be in relative motion to the first. Now any event which happens in the 3d space shared by both systems will have coordinates (x,y,z,t) according to the first system, but coordinates (x',y',z',t') according to the second system. Those coordinates are related by the Lorentz transforms:
t' = γ(t - (vx / c²))
x' = γ(x - vt)
y' = y
z' = z
Where:
γ = 1 / √(1 - v²/c²)
The event really does have the coordinates (x,y,z,t) and (x',y',z',t') which represent the actual location and timing of the event. Someone located far away from the event will perceive the event at a later time, but that does not change the coordinates of the event itself. That is what I mean when I say that special relativity actually is not about observers or perceptions at all. This does not answer your question about "why slower clocks means shorter distances" but I think we can rule out "the way we perceive" as having anything to do with the answer.
Right. It's really about the structure of spacetime, or how to relate changes in distance to changes in time.Neddy Bate said:
However, observers and their perceptions are still useful "abstractions" of the mathematical concepts involved. Einstein in his 1905 paper introduces his "precise definition" of time in terms of light being transmitted to a mirror, then back. This implies the light is generated somehow and that the mirror has been "placed" at some distance from the source of light.
So naturally, we can posit an 'observer' who is intelligent and knows how to transmit light to a mirror, and knows the light is reflected by the mirror. It's a useful heuristic, but the structure of spacetime doesn't "need" observers.
Besides, "the origin" is a single point, and we as observers are not; points trace out lines, lines trace out sheets, sheets trace out volumes. We can't contract ourselves to a single point except in an abstract way. Lastly, I don't know if you can describe SR without using a notion of measurement which is something intelligent observers can do precisely and accurately.
I am not sure how you square that I do not understand the problem and then go on to quote my math in the OP.
And, you have finally happened on the problem. As you agree, the M' frame finds if C' and M are co-located, then the lightning is at the M' frame coordinate $$(d',0,0,d'/c)$$. This is based on the light postulate and everyone agrees.
Next, you agree based on M frame information, if C' and M are co-located, then the lightning is at the M' frame coordinated $$(d'(1-v/c),0,0,d'(1-v/c)/c)$$. Yes, this is ROS. And, that is exactly the point. ROS demands the lightning is at another M' frame coordinate if C' and M are co-located.
Now, let's put it together.
If C' and M are co-located, then the lightning is at the M' frame coordinated $$(d'(1-v/c),0,0,d'(1-v/c)/c)$$.
If C' and M are co-located, then the lightning is at the M' frame coordinated $$(d',0,0,d'/c)$$.
There we have it. If C' and M are co-located, then the M' frame light postulate puts the lightning at one M' frame coordinate and if C' and M are co-located, ROS puts the lightning at a completely different M' frame coordinate.
So, if C' and M are co-located, SR claims the lightning is at two different M' locations along the positive x=axis which is inconsistent with nature.
What about the pair of locations M claims the lightning is at? Shouldn't M also be able to locate the lightning? To be consistent with nature, M should have one location only, right?chinglu said:
If that question is not answered, and along with your past anti SR/Anti Evolution stances on this forum, plus the fact that four rather knowledgable experts have refuted and refuted and refuted your maths, as they have in the past, the forum and its observers can only conclude one thing.
Sure, M has a position for the lightning in its own frame and then translates it to the M' frame. That is what this is all about. But, by ROS, it is not the same place as the M' frame puts it.
Since all this occurs if C' and M are co-located, then if C' and M are co-located the lightning is at 2 different places along the positive x-axis.
I see. And this "translation" means that M' gets to see the lightning there as well, like, M manages to "place" it in the M' frame using this "translation"?
(The x-position of event Q)
The x'-position of event Q
The x'-position of event R.
It's not "if" C' and M are co-located since C' and M are not universally co-located or not, but rather they are only co-located at one event in all of space-time, event P. So you don't want to say "if" but rather "when." Saying "when C' and M are co-located" is the same thing as saying at the same time as event P, which means $$t_P= t_Q$$ and it means $$t'_P = t'_R$$. These two conditions $$t = t_P$$ and $$t' = t'_P$$ are mutually true only at one event in all of space-time, event P. But the propagation of the flash of light does not pass through event P so for the flash of light $$t = t_P$$ and $$t' = t'_P$$ may only be asserted individually and not mutually. Thus Q and R are distinct events.
"when"
"flash of light"
... at two different times. Because while $$x_Q \neq x_R$$ and $$x'_Q \neq x'_R$$ are both true, that is not a violation of any assumption if $$t_Q \lt t_R$$ and $$t'_Q \lt t'_R$$ which chinglu generously calculated for us in the OP.
In fact, $$x_R - x_Q = c ( x_R - x_Q )$$ and $$x'_R - x'_Q = c ( x'_R - x'_Q )$$ which is entirely consistent with us talking about the propagation of a single, particle-like flash of light.
Yes, I know German. As I pointed out, Einstein said when the origins are common and I said when C' and M are co-located. It is the same thing. Try to look at it this way. Assume you are walking through a house and there is a straight path from the front door to the back door. You know when you are at the center and so does an observer in the house. So, the co-location event is one event under SR, which is exactly what I have said all along.
LOLOLOL, SR clock synchronization is in section 1 of the Einstein paper I quoted. Also, decidable is a known term under recursion theory. That means I can write a program that could simulate frame to frame clock synchronization. Uh, are you claiming you know an algorithm to sync arbitrary clocks frame to frame? If so produce it, otherwise, you are forced to accept what I said is true.
Quote the 1905 paper to support this statement. And, I will help you understand what he is saying. First, synch all the clocks in both frames. When the origins are common, assume the current time for all one frame's clocks is 0 instead of xxx. Do this for both frames.
You are wrong. That means you can prove if C' and M are co-located for one frame, then are not for the other. Can you do this yes or no? Otherwise, there is no dispute between the frames for the co-location event, which is my point all along. It is time for you to stop talking and start proving your position.
Now, prove the co-location if C' and M are co-located for one frame, they are not for the other frame.
If you say I moved the goalposts, prove and stop talking because your statement is false. OK, looks like you have the event P as the co-location event. Then you have event Q where M puts the lightning if C' and M are co-located.
You also have event R where M' puts the lightning if C' and M are co-located.
Now, as you have stated time and again, by ROS, $$R \neq Q$$. This is a fact. This is where you are getting confused.
You have already agreed, if C' and M are co-located then by the light postulate in the M' frame, the lightning is at event R.
Now, no logic can contradict this because it is an answer from a postulate.
Yet, by ROS, if C' and M are co-located then by the light postulate in the M frame, the lightning is at event Q where $$R \neq Q$$. So, ROS is contradicting the light postulate in the M' frame and getting the wrong answer if the condition "C' and M are co-located" is met.
That is the deal.
Where you have failed time and again is to show why ROS can contradict the light postulate in the M' frame if the condition "C' and M are co-located" is met.
No theory can contradict its postulates.
BTW, you banned me from your forum for not adhering to the "Christmas spirit". What does that mean?
Your post is based on claiming if C' and M are co-located, then there is some frame that claims that C' and M are not co-located. Prove it.
Otherwise, it is universally true making this post above completely false.