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Author Topic: Why am I having trouble with Tolman's paradox?  (Read 12886 times)

Offline paros

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Why am I having trouble with Tolman's paradox?
« on: 22/06/2014 20:03:43 »
Reference material:

http://www.ejtp.com/articles/ejtpv6i21p1.pdf [nofollow]  (see diagram on page 5)

___

I still cannot see how a tachyon that merely moves faster than light necessarily reverses the order of events. I have been drawing Minkowski diagrams for several hours and I am still not seeing it.  All the diagrams that propose to demonstrate reverse causality merely draw in a tachyon moving backwards in time.  Thus as far as I am concerned they are inserting the conclusion into the premise.  The diagram from page five above is incorrect as far as I am concerned.  All signals traveling from B to A,  (be they tachyon, photon, or sound wave) must traverse from right-to-left going upwards.  Not downwards as tachyon2 was drawn in the PDF. 

Here is the original diagram followed by my correction:



Upon asking a non-expert, I was informed that I must have an accelerated frame whose future contains the past of a stationary observer.   So I did that exact thing.   I see no reverse causality again. Only that the tachyon will arrive prior to the light signal from A0.   The diagram below shows a stationary observer `"A"` and an observer `"B"` in an accelerated reference frame:



I still do not see how reversal of events can happen here. Only when we presume that tachyons "move backwards in time"  does this manifest. But I cannot see how that is asserted merely by a tachyon traversing a more shallow slope on the diagram than the light cone. 

More precisely:  Please explain why the tachyon from observer B to observer A must necessarily move backwards  in time in  ('downwards') the reference frame of A.



« Last Edit: 25/04/2015 17:12:09 by chris »


 

Offline yor_on

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Re: Trouble with Tolman's paradox
« Reply #1 on: 21/04/2015 00:38:54 »
This might come a little late, don't blame me though, I just saw your question :) So it is now as far as I'm concerned, (or was 'now' at least, depending on observer of what I write, or rather wrote?)

You could try this for a suggestion on how to see it.

Spacetime, Tachyons, Twins and Clocks.

That said I think I will agree with you anyway. They are a figment of imagination :)
==

You could add causality to the description, assuming it possible to receive it 'inside our SpaceTime', which is a added improbability, to 'lock' its behavior relative the three observers. Causality is what we use to define the commonality of SpaceTime, proving that even though we see locally different events (observer dependencies), space and time wise, they still are one and the same.

Defining your local clock to 'c' they can't exist. Not to us anyway. Just as I could propose pink elephants to propagate faster than 'c'. So using this logic, defining 'c' as equivalent to your local arrow, there will be no arrow for my elephants and those tachyons. Which makes them both probable, in theory, but practically impossible to measure on. A photon could be seen as 'locally timeless' using my proposal, which then naively could be seen as become some sort of symmetry, or opposite if you like, to the idea of of a far away 'clock' at a event horizon 'stopping', according to ones local definition of a clock rate.

The point with defining a photon as locally timeless depends on how you think of zero. As a beginning? Belonging to natural numbers, or not? Because where no arrow exist the idea of it also being able to go backwards, passing that definition, becomes rather improbable to me, although mathematically possible. If there exist such a thing as something without a arrow there is no need for it to go backwards. Because that is where everything coexist, and defining it through the idea of arrows becomes meaningless to me.
« Last Edit: 21/04/2015 01:59:51 by yor_on »
 

Offline yor_on

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Re: Trouble with Tolman's paradox
« Reply #2 on: 21/04/2015 11:17:35 »
The point with using causality is simple. That is our common SpaceTime, the gold standard telling you that we all are here together. And tachyons would not fit.
=

that give one some choices.

Time is an illusion? Sure, and so must causality be if that is correct, and so you, and me too, become a illusion.
Time exist? Then causality is what I wrote above, a proof of our 'common SpaceTime', but tachyons have no place in it.

Time is not like a ocean having different undercurrents. Time is a direction, locally defined, and equivalent to 'c'.  There is only one direction for you, not several.
« Last Edit: 21/04/2015 11:53:01 by yor_on »
 

Offline jeffreyH

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Re: Trouble with Tolman's paradox
« Reply #3 on: 22/04/2015 12:17:54 »
The point with using causality is simple. That is our common SpaceTime, the gold standard telling you that we all are here together. And tachyons would not fit.
=

that give one some choices.

Time is an illusion? Sure, and so must causality be if that is correct, and so you, and me too, become a illusion.
Time exist? Then causality is what I wrote above, a proof of our 'common SpaceTime', but tachyons have no place in it.

Time is not like a ocean having different undercurrents. Time is a direction, locally defined, and equivalent to 'c'.  There is only one direction for you, not several.

Rates of change are limited by the speed of light. That includes velocity and angular momentum. To move faster than the maximum rate of change indicates a stepping outside of the normal parameters of the universe. It violates the limitations of the Planck scale. This would mean moving to points in the universe where the past light cone exists.
 

Offline PmbPhy

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Re: Trouble with Tolman's paradox
« Reply #4 on: 22/04/2015 20:45:19 »
Quote from: Jeff


I still do not see how reversal of events can happen here.
Are you saying that you can't see from the diagram how event A occurs before event B in frame S1 while event A occurs after event B in frame S2? If not then take a closer look, this time keeping in mind that lines of constant time are those lines which are parallel to the spatial axis. Thus to visually determine when an event occurs simply draw a line parallel to the x-axis until it intersects with the time axis. Do this for both events in both frames. You'll see that when a signal can travel faster than the speed of light the sequence of causal events can change.
 

Offline yor_on

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Re: Trouble with Tolman's paradox
« Reply #5 on: 22/04/2015 21:00:20 »
One of the really big problems, leading people astray is the assumption of 'c' as being solely a speed. If it is a speed, then why can't there be stuff moving 'faster'? In my view it is a constant, what defines causality, it is also what defines your local arrow. It is SpaceTime, described from a container model. And the container model is what makes us able to communicate. So thinking of it as a speed is a rather meaningless definition, although that was the point of origin for our definition of it as a constant.
=

one might want to argue "And the container model is what makes us able to communicate." though, assuming that speeds can be 'infinite', even if using causality. But causality is what orders events in SpaceTime logically, making us able to communicate, and 'grow up'. Using the limits the constant sets we break causality by assuming infinite speeds. Assuming it to be correct we then lose ordered events. If you think of a entanglement, it is around 'zero' (time wise) to me, a photon is locally around 'zero'  too, so is that clock you define (relative your own) at a event horizon. But they don't, in any circumstances, 'tick backwards'. They are all limits.
« Last Edit: 22/04/2015 21:23:45 by yor_on »
 

Offline PmbPhy

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Re: Trouble with Tolman's paradox
« Reply #6 on: 22/04/2015 22:21:12 »
Quote from: yor_on
One of the really big problems, leading people astray is the assumption of 'c' as being solely a speed.
That’s not the least bit of a problem. And c is most definitely a speed. In fact, by definition it’s the speed of light.
Quote from: yor_on
If it is a speed, then why can't there be stuff moving 'faster'?
The answer is very simple; In 1905, in his paper which stated what has become known as the principles of special relativity, Einstein showed that the work done in accelerating a particle of proper mass m0 from rest to the speed v it requires doing an amount of work equal to the change in kinetic energy of the particle. Since the particle started off from rest it started with zero kinetic energy. So the final kinetic energy equals the work done to accelerate the particle to the speed v and has the value
K = 6d1c5fcc7a8742cf5ae8d85ac086eb8d.gif
where
5ab2e981227adc050617550b3e9c86f2.gif
Notice what happens as the speed. v, increases. As v -> c,  K -> infinity. Therefore, since no particle existence can have an infinite amount of kinetic energy it follows that no particle can be accelerated to or past the speed of light. However, that doesn’t mean that particles can’t be “born” moving at the speed of light. A discussion of the existence of particles was published in the following article
Possibility of Faster-Than-Light Particles by G. Feinberg, Physical Review, Vol. 159 (5), July 25, 1967.
You can download and read it from this link: http://einsteinrelativityphysicstheory.com/images/superluminal_velocities/possibility_faster_than_light.pdf
Quote from: yor_on
In my view it is a constant, …

Einstein beat you to it in 1905 in his paper on the electrodynamics of moving bodies, what most physicists now refer to as paper on special relativity. The Second Postulate of Special Relativity states that the speed of light in a vacuum is invariant, i.e. has the same value in all frames of reference.
Quote from: yor_on
…what defines causality, it is also what defines your local arrow.
The speed of light most certainly does not define causality.
Quote from: yor_on
It is SpaceTime, described from a container model.

I can’t even figure out what that statement means! The term container model is not a term used in physics.
Quote from: yor_on
And the container model is what makes us able to communicate.

Keep it civil, guys... Moderator
« Last Edit: 23/04/2015 19:51:20 by evan_au »
 

Offline yor_on

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Re: Trouble with Tolman's paradox
« Reply #7 on: 22/04/2015 23:35:15 »
Well Pete, to me it is :)
For the rest of, I wasn't answering your post writing the above. I was just thinking in my own terms.
 

Offline yor_on

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Re: Trouble with Tolman's paradox
« Reply #8 on: 23/04/2015 00:21:47 »
When it comes to my definitions then I define 'c' as a speed from SR, also define it as equivalent to ones local arrow, splitting it, and argue that it can be seen as what defines causality. The last is new, didn't think of it that way before and can be seen several ways depending on how you define it, I define it through what I call 'useful information' which then is 'c'. If you have a proof of Tachyons existing I'll be pleased to see it.
 

Offline PmbPhy

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Re: Trouble with Tolman's paradox
« Reply #9 on: 23/04/2015 02:29:17 »
Quote from: yor_on
When it comes to my definitions then I define 'c' as a speed from SR, also define it as equivalent to ones local arrow, splitting it, and argue that it can be seen as what defines causality.
Complete nonsense.
 

Offline phyti39

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Re: Trouble with Tolman's paradox
« Reply #10 on: 25/04/2015 15:28:24 »
A performs an experiment inside a space ship, sending a tachyon (magenta) at 2c a distance of 1 unit to a reflector and back. The tachyon is always sent at t=.5, ship time. The detection of a light signal (blue) from event R is td. The time of event R is assigned per the SR  convention as (td-.5)/2. The axis of simultaneity is green.

case 1. The ship is docked at the station. Speed v=0. R is assigned t=1.00.
   R occurs .50 after emission.

case 2. Speed v=.5. R is assigned t=.50. R occurs at emission (instantaneous).

case 3. Speed v=.8. R is assigned t=0. R occurs .50 before emission.

In the Minkowski graphic, a thing moving instantaneously would be represented by a horizontal line. This would also be equivalent to not moving at all since the time duration is zero. It would also be ambiguous since the number of movements could not be determined. If instantaneous is the limit of speed, a line directed downward would have no meaning.

The second graphic is case 2 as described by A. The tachyon path is not symmetrical as  described by the docking station.
A faster than c entity still moves in the positive ct sense. The problem is assigning time via the SR synch convention, using light speed messaging that is slower than the cause of the events. If the same tachyons were used for communications, the anomaly would disappear. Tachyon speed would be the new 'c', the blue lines would become magenta, and the reciprocity of relativity would be restored.

 

Offline yor_on

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Re: Trouble with Tolman's paradox
« Reply #11 on: 25/04/2015 16:46:36 »
Well Pete, big words and postures aside. Present one original thought here, please :)
 

Offline PmbPhy

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Re: Trouble with Tolman's paradox
« Reply #12 on: 25/04/2015 16:53:11 »
Well Pete, big words and postures aside. Present one original thought here, please :)
In post #4 I explained why tachyons can lead to reverse causality. What else do you want to know?
 

Offline yor_on

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Re: Trouble with Tolman's paradox
« Reply #13 on: 25/04/2015 16:56:47 »
And you want that to count as a original thought from you?

Give me something, or stop acting as a sage.
 

Offline yor_on

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Re: Trouble with Tolman's paradox
« Reply #14 on: 25/04/2015 17:11:59 »
And Phyti, you're wrong. 'c' is 'c', you can test it, it's one of the most tested ideas that exist. So that 'proof' of yours is just conjecture. I base mine on simplicity, not fantasy.
 

Offline yor_on

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Re: Why am I having trouble with Tolman's paradox?
« Reply #15 on: 25/04/2015 17:27:27 »
Although Phyti, you can get to Superluminal motion just by assuming a field, then assuming light to be defined not by motion but by rules. To do that you need some other principle though, equivalent to 'c'. If you do it 'c' will become a pattern defining information, creating a common SpaceTime.
 

Offline yor_on

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Re: Why am I having trouble with Tolman's paradox?
« Reply #16 on: 25/04/2015 17:38:56 »
The point, to me then, with this last proposition is that it it doesn't simplify anything. It doesn't matter how we want to define superluminal motion if we have no standard for it, and we don't. We have a standard for 'c' though, that works in all experiments. that doesn't state that this idea must be wrong. It seems more a matter of how one expect, or think, 'it' works, than how 'it' might be to me.
=

and yes, I do use experiments, not theory. You don't have a experiment proving your point? then you redefine it.

(And to be clear, I do question motion too, in that you're not alone. And if you do that all standards for what it means change. But 'useful' information must still be transfered at 'c' to me. And what happens outside the limits is of no use to us normally, although QM may open some windows of application to us.)
« Last Edit: 25/04/2015 17:56:17 by yor_on »
 

Offline PmbPhy

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Re: Trouble with Tolman's paradox
« Reply #17 on: 26/04/2015 02:36:41 »
Quote from: yor_on
And you want that to count as a original thought from you?
I never claimed it was original. I was merely saying that was my contribution to this thread.

Quote from: yor_on
Give me something, or stop acting as a sage.
People don't come up with original thoughts on demand. That's a creative process which comes about when working on a problem, if it happens at all.

However all of my thoughts in my paper on relativistic mass are quite original. You've known that the paper has existed for a long time but you've chosen not to read it.

Keep it civil - Moderator.
« Last Edit: 26/04/2015 12:43:33 by evan_au »
 

Offline phyti39

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Re: Trouble with Tolman's paradox
« Reply #18 on: 26/04/2015 19:55:19 »
And Phyti, you're wrong. 'c' is 'c', you can test it, it's one of the most tested ideas that exist. So that 'proof' of yours is just conjecture. I base mine on simplicity, not fantasy.
You missed the point. 'c' is the new speed of communication using tachyons, which move faster than light.
It's only conjecture to the same extent as tachyons.
 

Offline yor_on

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Re: Why am I having trouble with Tolman's paradox?
« Reply #19 on: 02/05/2015 13:04:39 »
Pythi, there is no point missed. Both are theoretical conjectures, coming from mathematical propositions without experimental proofs.
 

Offline yor_on

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Re: Why am I having trouble with Tolman's paradox?
« Reply #20 on: 02/05/2015 13:06:40 »
I know you don't Pete, but if you want to write here you better accept that this is a forum for everyone, not only a few selected. You want it otherwise you better move to your own.
 

Offline phyti39

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Re: Why am I having trouble with Tolman's paradox?
« Reply #21 on: 02/05/2015 19:58:49 »
Pythi, there is no point missed. Both are theoretical conjectures, coming from mathematical propositions without experimental proofs.

In your previous posts you use 'c' exclusively for light speed, and I wasn't with "new c". For clarity note tachyon speed as q. Assuming the discovery of an exotic particle named tachyon, it just replaces the role of the photon.
The constant speed of light is a postulate based on experiment. Am not clear on what "both" is referring to.
 

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Re: Why am I having trouble with Tolman's paradox?
« Reply #21 on: 02/05/2015 19:58:49 »

 

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