Discussion in 'Physics & Math' started by timewarp, Oct 22, 2011.

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1. ### EmilValued Senior Member

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2,801
Try this Wikipedia:Mathematical proof,Proof by contradiction

3. ### PeteIt's not rocket surgeryRegistered Senior Member

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I stand corrected.
If something conflicts with itself, then it must conflict with reality.

I didn't think internal consistency was what timewarp is getting at, but now I'm not sure.

Proof by contradiction means that if some set of premises validly leads to contradictory conclusions, then one or more of the premises must be false.

The classic example is the proof that $\sqrt 2$ is irrational Wikipedia.

Whenever you see a "paradox", that's probably an attempt at proof by contradiction, eg the twin paradox:
• When the twins meet, they can not both be older than the other.
• If a physical theory can be applied to indicate that twin A is older than twin B, and
• The same physical theory can be applied to indicate that twin B is older than twin A, then
• The physical theory is inconsistent, and can't be real

Last edited: Oct 26, 2011

5. ### OnlyMeValued Senior Member

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I did have to look it up but I do understand it.

The quote he provided just sounded like a debate strategy. Oh, and I did hand pick the reference I gave from a ways down the list because of the way it was worded also.

7. ### timewarpRegistered Member

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Originally Posted by timewarp
Repeating my diagram:
Frame A
-------[0]--------------- -->
--------S~~>light
---<--[0]--------------------
Frame B

Frame A
------------[?]-----90m-------[300ns] -->
-------S-------------------------->light
[?]------------150m-----------[500ns]
Frame B

As I said, it is straight out of a relativity book. Surely you have access to
such books. The one you need to look at is "introduction to the theory of
relativity" by Sears & Brehme, p. 16.

It simply shows observers in two frames "measuring" light's one-way speed. What is so difficult about that that you do not understand?

It's standard relativity. Basic, right outta tha book.

Of course, but the plan was to start with the best, and to hope for the rest. Surely, this is not all that difficult. Everybody in the world knows that we do not have absolute time. Therefore, everyone in the world knows that slow transport does not preserve the initial absolute synch. I am beginning to wonder if you are just playing footsie with me.

Hmm... since I invented the diagram, I think I should know what the heck it means. It is an extremely simple diagram, much simpler than those messy space-time diagrams.

Good. Tell us exactly how to experimentally measure light's one-way speed. (And please - no transported or rotating clocks, they runneth sloweth, thereby screwing up the experiment.)

Surely you remember classical physics? Seriously. And there is no need to place scare quotes around the phrase " truly synchronous clocks." We can tell if we have such clocks by the very simple and obvious fact that all observers would get the same time spans between events, and all observers would get a variable light speed.

“ Originally Posted by timewarp
The fact that they are not synchronized is the reason for the no-no. Asynchronous clocks are a no-no. And since Einstein's c invariance calls for asynchronous clocks, his postulate is also a no-no. ”

This is a very strange reply, It seems that you are advocating the use of incorrectly-related clocks.
Do you have any justification?

Speaking of Einstein's one-way light speed invariance (his "postulate"), I am certain that you cannot show it happening either on paper or experimentally.

Go ahead, please show on paper observers in two frames getting c for the one-way speed of light.

Timewarp wrote:
“ If two touching clocks do not read the same time, then one of them is lying. ”

Oh come on. This is getting ridiculous, pardon my French. If two cars crash into each other, which one hit first? I was of course speaking of time in inertial coordinate systems, and was contrasting the current silly scheme with the only correct one. If a clock in one frame passes a clock in another, and they read different times, then something is dead wrong. Similarly, if observers in different frames get different time spans between the same two events, then this is bogus because events occur in only one way fully independently of any and all coordinate systems.

To show you how bad it (the current time system really is, I challenge you to show how we can correctly (with proof) measure the relative speed of a man walking down the road. (You must fully justify each step.)

Timewarp wrote:
“ We need to find a way to (truly) synchronize clocks. How long have you searched so far? (I have searched long enough to think that I have found a way.) ”

You don't really believe that I would tell the whole world how to absolutely synchronize clocks, do you? (Even scientists have stolen from each other.) But I can give you enough hints to probably convince you that I am indeed onto something.

In the first place, we cannot use ordinary inertial objects thrown or propelled to set clocks because (1) they suffer length contractions, and (2) they undergo mass increase. In the second place, we cannot use light rays because, as Einstein stated clearly, we would first need to know the relative speeds of the rays, and this requires (truly) synchronous clocks. (This is what he called a logical circle, ring-around-the-rosie, but not O'Donnell!)

However, we can use objects that are manually or remotely controlled. This completely eliminates the problems of mass increase and length contraction. And to eliminate Einstein's circle, we can use only one clock to time the moving objects.

Hopefully, I have not spilled too many beans.

8. ### AlexGLike nailing Jello to a treeValued Senior Member

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4,304
Timewarp, I think the problem with your diagrams is that they are very badly rendered. I just can't make sense of them.

On edit: For that matter, I can't really make sense of the rest of the post either. You don't seem to know any relativity.

9. ### timewarpRegistered Member

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No one in usenet had any complaints, so you are in the minority. If you think they are indeed "very badly rendered," then why not state what's wrong. As I said, they are infinitely simpler than the standard space-time diagrams.

I know that SR purports to be able to measure one-way relative velocities. But you don't know how to prove this. So whose the real relativity dummy here?

10. ### Neddy BateValued Senior Member

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1,677

If you use an IR or RF remote control, the signal is still restricted to the speed of light. If you use a mechanical linkage of some sort, (i.e., Motor Daddy's method involves pulling a string), then you are restricted to the speed of pressure waves through the linkage. Good luck.

11. ### OnlyMeValued Senior Member

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Being in a minority relative to opinions arrived at "in usnet" is not necessisarily a bad thing. It seems there are a number of individuals here with well established backgrounds in physics that also seem to be confused by the diagrams or at least the diagrams in conjunction with your descriptive statements.

I am not sure anyone could state what is wrong without first a clear understanding of what you think they mean and what your goals are relative to this discussion.

While SR involves hypothetical thought experiments that include oneway measurements of the speed of light, I don't think many here would suggest that a oneway speed of light in vacuum has been experimentally accomplished or is even possible, at present.

There is some possibility that by using fiber optics and a single clock, a oneway speed of light may be experimentally testable, in the medium of the optical fiber. Even experiments attempting this can be challenged as to whether the measurement is truely oneway or two way. There winds up being a number of variables involving emission, detection and timing, each of which can be viewed from more than one perspective.

12. ### originIn a democracy you deserve the leaders you elect.Valued Senior Member

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10,450
I'm sorry but you have to understand that it is really difficult to try and figure out what you are trying to say or ask.

for instance you wrote this about the diagram:

Then 2 paragraphs later you write about the diagram:

Unless your wrote that book that is a really odd couple of paragraphs...

What is it you are having problems with?

Is this an example of a scenario that gives the problem?

2 ships at the same inertial frame acclerate to a new identical inertial frame going in opposite directions. A beam of light is shining along their paths so that one ship is moving in the direction of the beam and the other is moving in a direction opposite to the beam. They both measure the beam to be c. So, how can their clocks be measuring the passage of the time the same, for them to both measure the speed of light at c?

Is this the crux of your questions?

13. ### timewarpRegistered Member

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We know that we cannot throw baseballs or shoot bullets to truly synchronize clocks because - as I said - mass increases with velocity. And, as Einstein saw clearly, we also cannot even use light because we must first have truly synchronous clocks in order to (correctly) measure the relative speeds of the two light signals to make sure that they are equal in both directions. We cannot even start with absolutely synchronous clocks and end up with absolutely synchronous clocks in the case of very slow clock transport (due to time dilation of the nasty sort).

The goal here is to guarantee truly equal relative speeds of the entities that are going to be use to start the clocks. This can be accomplished - as I said - by simply remotely or manually controlling said entities' speeds so we can make sure that they are equal despite mass increase. As you can see, we do not need to actually quantify each entity's relative speed, but we only need to compare them by some means. This mere comparison is much, much easier than direct quantification, and gives us the loophole that allows us to use only one clock to compare the entities' relative speeds.

I hate to say more - trade secret, y'know, ol chap' - but maybe this is enough?

14. ### timewarpRegistered Member

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30
I really cannot possibly make either the descriptions or the diagrams any simpler, sorry.

I have been posting such diagrams for years in the newsgroups and absolutely have had zero complaints.

Have you not thought about the fact that quickly blurting out one's final goal may get one banned on the spot? I need to have patient agreement at each step.

SR has no such thought experiments. What SR does have is Einstein's "assumption" of c invariance. But it is not a valid or scientific assumption because it entails clocks that conflict with reality by reading different times at the same time or by reading the same time at two different times.

I sincerely believe that no one here has the right to complain about either of my diagrams until he or she has taken the effort to see the referenced SR text (which, as I said, was the source of one of the diagrams.) How would you feel if everyone cavalierly ignored your citation whilst bitterly complaining about your diagram which came from the cited source?

"introduction to the theory of relativity" by Sears & Brehme, p. 16

15. ### timewarpRegistered Member

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30
There were two different diagrams, one straight from the book, and the other straight from me. If you would only be kind enough to take a quick look at the cited book, then maybe it would all be clear.

"this" goes to one of my prior posts, was that where it was supposed to go?

16. ### OnlyMeValued Senior Member

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3,914
Since you expect that, to present an honest and complete statement of what you believe your quoted references to be saying.., together with an account of what your goals in the current thread are, would result in a ban...

This suggests that you are intentionally distorting the facts that you believe are important, in an argument intended as a logic trap.

Since this reference is not readily available to anyone who does not already have a copy, and at this point it is even uncertain exactly what of your posts, is actually quoted from the reference and what is your own interpretation or distortion of the original reference, again it appears you are intentially manipulating the discussion and perhaps even the reference to support your position.

A position you have already admitted is one which should get you banned, as noted above.

I am not a moderator but it would seem to me your posts no longer represent any honest attempt to discuss anything and merit at least a warning.

Present your arguement and references in full and in a way that they can be clearly distinguished one from the other. Everyone deserves to be involved in the same discussion.

17. ### PeteIt's not rocket surgeryRegistered Senior Member

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10,166
OK, so you've based your diagram on your understanding of the textbook diagram:
That textbook diagram is not clear at all. Are you sure you reproduced it accurately?
Is that the 1968 or 1979 edition? Not that it matters, it's not in the libraries of either University I have access to. What is the diagram's caption?

Anyway, the difficulty is that it's simply not clear what it is showing.
Either it is showing only one clock, not two, or the "Frame A" and "Frame B" labels don't belong.

Bear in mind that a reference frame is a particular perspective of a series of events... it's not something you can label on a diagram drawn in a different frame. To show different reference frames, you need different diagrams.

Each of the given diagrams seems to have sloppily combined two separate diagrams.

This scenario would be more clearly shown by separating the diagrams and explicitly labeling your clocks.
It is also important to show accurate length contraction to clearly see what's happenning:

Here are the diagrams in Frame A:
Frame A, t=0
Code:
             clock starts          clock (unstarted)
-----------------[A ]---------x-----------[A1]
------------------~~>light
-----------------[B ]-------------?-------------[B1]
--> v                          --> v
clock starts                 clock (unstarted)
Frame A, t=x/c
Code:
          clock reads x/c            clock starts
-----------------[A ]---------x-----------[A1]
-------------------------------------------~~>light
--------------------------------[B ]-------------?-------------[B1]
--> v                          --> v
And here are the diagrams in Frame B:
Frame B, t'=0
Code:
            clock starts                  clock (unstarted)
<-- v                          <-- v
-----------------[A ]-------------?-------------[A1]
------------------~~>light
-----------------[B ]---------x-----------[B1]
clock starts           clock (unstarted)
Frame B, t'=x/c
Code:
  <-- v                          <-- v
--[A ]-------------?-------------[A1]
-------------------------------------------~~>light
-----------------[B ]---------x-----------[B1]
clock reads x/c            clock starts

Last edited: Nov 1, 2011
18. ### PeteIt's not rocket surgeryRegistered Senior Member

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10,166
Truly equal relative speeds? Relative to what?
To guarantee truly synchronous clocks, your actual goal is to guarantee truly equal absolute speeds.

It's a bright idea, but an old one. And on further investigation you will find that it can't be done, unless you first know the absolute speed of some reference object.

Be warned - investigating further involves mathematics. Not awfully hard mathematics - I can do it, and I'm no mathematician - but enough to put most people off.

19. ### PeteIt's not rocket surgeryRegistered Senior Member

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10,166
Some other snippets I should respond to. Sorry for the multiple posts.
Well, your intended meaning is not clearly conveyed in the diagram. See previous post.
Space-time diagrams are much less messy, because they can show you the entire sequence of events in a single diagram, and they are much easier to transform to a different reference frame.

Can't be done without making certain assumptions about clock synchronization.

I'm sure you have a point to make here...?
Doesn't work, timewarp.
If everybody uses clocks synchronized in a particular reference frame (eg UTC clocks), then all observers get the same time span between events and all observers measure variable light speed (unless they also use rulers defined in the agreed reference frame)... but that doesn't make them truly synchronous. They are just synchronized in the agreed reference frame.

"Truly synchronous" clocks conflict with reality, hence the quotes.

Reality requires it.

By "incorrectly-related clocks", you seem to mean that they are not synchronized in some reference frame.
This is the reality of clocks - any clocks synchronized in one reference frame are necessarily not synchronized in other reference frames.

Even clocks synchronized in an absolute rest frame (if one could be identified) are not synchronized in all frames.

This is a simple exercise you should work through on your own.

But you might like to look at this thread where I walked MotorDaddy through the exercise of an observer on a moving train attempting to measure the one-way speed of light:
[post=2753794]Relativity of Simultaneity, post 393[/post]

Well that's what reality says... do you think that Reality is dead wrong?.
Reality seems to disagree with you.

Relative to what? Relative to the road?
It can't be done without making certain underlying assumptions.
For example...
• We can have him walk back and forth, and assume that his speed is the same each way.
• We can synchronize two clocks and move one few metres down the road, assuming that the synchronization changes in a predictable way.
• We can synchronized two separate clocks by measuring the midpoint (assuming our ruler lengths don't vary with position), and sending identical signals in each direction (each pull on a rope, send a constant-speed vehicle), assuming that the identical signals travel at the same speed relative to the road.

As far as we can tell, tw, these are limitations inherent in Reality.

You keep hinting that you have some magic solution, but why should we believe you?

20. ### timewarpRegistered Member

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30
Go to the gymnasium of a large school.

Place a light on a pole.

Get two long, narrow equal-length (by construction) tables.

Place an unstarted clock at each end of each table. (4 clocks)

Align one table's left end with the light pole.

Slide the other table steadily toward the pole from the left.

Whenever the tables' left ends meet at the light, start both left clocks on zero.

According to special relativity theory, each right-end clock must read the time
x/c whenever the light ray reaches it.

I could not care less why this is so in SR (i.e., I don't give a good rip if it's due to some postulate, some hunch, some stipulation, or some off the wall wild ass guess).

What I do care about, and what everyone should care about, is the very simple fact that the light ray will in fact (i.e., in ironclad reality) reach the two right-hand clocks at different times. In fact, it will hit them at absolutely different times. Indeed, it will hit one absolutely before it hits the other.
(This is - irony of ironies - even guaranteed by SR itself due to the fact that the two clock-starting events (the right-hand clock events) are light-like.)

This means that the dadburned clocks are in conflict with this simple reality because they, the stupid things, read the same time when they are started when they are in fact actually and really started at absolutely different times.

There, you have my diagram with no diagram.

As to your "one-way light speed measurement," it seems to contain the dreaded transported clocks, That, sir, is a no-no, as I have tried to make clear.

Anyway, the only correct way to measure any one-way speed, including light's, is by using truly or absolutely synchronous clocks, and no one has such clocks yet.

Believing in Einstein is a certain dead end. He uses rulers that have not been proved to be uncontracted (even in their "rest" frame); he uses clocks that have not been proved to be unslowed (even in their "rest" frame); and to top it off, he has the "stupidity" to use clocks that even he admits that are not truly synchronous. Hmmm... why should you believe me, indeed.

All of this is exactly why no one can correctly or validly measure even the speed of a dog walking down the road (relative to any dang thing you choose).

No one-way speed or round-trip speed has ever been correctly measured in the history of the world, to put it dramatically.

As to my "magic solution," I firmly believe that I have given enough hints to show that I do have something. (No one else has ever even mentioned merely comparing the relative speeds of the clock-starting entities.) (No one else has ever mentioned being able to use only one clock.)

21. ### prometheusviva voce!Registered Senior Member

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2,045
Mod action: thread closed. If anyone has a good reason to reopen it please PM me or another mod and we will consider it.