Absolute Reference Frame

Discussion in 'Physics & Math' started by Prosoothus, Mar 27, 2006.

1. PeteIt's not rocket surgeryRegistered Senior Member

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Hi CANGAS,
I guess you're referring to this?
My impression is that Dale was talking about the case introduced by Prosoothus: "What if you replace the two wires with two parallel beams of electrons travelling through a vacuum. Would they attract each other, or not?"

Your example is quite clearly a case where the electrons are travelling through a conductor. So the question is "what difference does the conductor make?", I guess.

Personally, my first reaction would be to think that the presence or absence of a conductor wouldn't make a difference... but I'm no expert in electromagnetism.

If I were gong to make strong statements one way or the other, I'd take Dale's suggestion and work it out properly. You haven't done that, have you?

Yes, if you can show a situation in which SR predicts an unambiguous event to happen in one frame but not another, then SR is disproved.

But just saying it isn't enough... you've got to be rigorous or no one will believe you. So why don't you work it out? Show me the money!

Last edited: Mar 31, 2006

3. Billy TUse Sugar Cane Alcohol car FuelValued Senior Member

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Nor am I, but I know the conductor makes a HUGE difference in that it is electrically neurtal, even when carrying large currents.

That is for every electron (at least to extemely high order) there is a positive charge. There is a slight tendence for the electrons to travel on the "skin" as they can get farther from each other that way, but they mainly "like" to stay near the positive charge, (and this love is mutual), so metals actually hold together rather well.

BTW, if you apply a large enough electric field to a metal (fine point makes the required voltage reasonable) you can pull some electrons out into a vacuum. If your voltage was stored in a highly-charged, low-inductance, condensor, that charge (and almost the double because of inducive effects) will rapidly flow (large, brief current) Because of the magnet field circling this current makes a radial inward pressure on the electrons moving in the vacuum, the region in the vacuum carrying the current becomes smaller in cross section diameter. (Well named as "the pinch effect.")

Very high temperature can be produced this way - so hot that in a high energy pinch, you can get so hot that the Black Body radiation temperature is making X-rays!)

Last edited by a moderator: Mar 31, 2006

5. CANGASRegistered Senior Member

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You All:

This situation is so simple that it would be a genuine waste of time to make it any more complicated.

We have a test fixture in which are two charged particles, two electrons. They are initially restrained from any movement. We have three observers. One observer will be standing still directly in front of the test fixture. A second observer will be travelling past the test fixture at a specific velocity. A third observer will be travelling past the test fixture at a higher velocity. The transits of the observers are planned so that they will all be directly in front of the test fixture at the same time. The initialization of the experiment is planned so that the restraint will be removed from the charged particles when the the observers are all directly in front of the test fixture.

In honor of Special Relativity we recognize that the observers each may elect to observe as if they were prime, or, stationary, even we know that they might be really moving. Of course, any observer choosing to believe that they are stationary will force the test fixture to act as if it were performing the movement.

One observer seeing two initially stationary charged particles of like sign will observe a mutual repulsion which will immediately drive the particles apart at high velocity due to the great electrostatic forces in effect between charged particles.

A second observer, at exactly the right relative velocity, will observe the electrostatic force exactly balanced by a magnetic force resulting from the apparent movement of charged particles through space.

A third observer, at a higher relative velocity, will see the two charged particles apparently travelling at a high enough velocity that the resulting attractive magnetic force is great enough to overpower the repulsive electrostic force, and the two particles will move toward each other.

Special Relativity has permitted us to have three observers obtain three completely contradictory reports about the movement of the same two particles at the same time. This is because SR permits, indeed forces, us to consider the actually moving observer to be stationary, and the actually stationary test fixture to be moving.

The reciprocity of observer and observed reference frames causes this paradox, and this paradox is of such a blatant nature that it simply cannot be believed.

It is not unnoticed that cajolers have replied with diversionary tactics rather than specific argument.

Perhaps I am wrong and am making such a huge logical blunder that I will find it hard to fathom when it is specifically pointed out to me. But vague statements and requests for me to do the critic's homework are not very convincing rebuttal against my stated position.

7. PeteIt's not rocket surgeryRegistered Senior Member

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If Dale is correct and if I've understood him correctly (two big IFs, I know

), then all three observers will observe a mutual repulsion which will drive the particles apart (at different rates of acceleration according to time dilation).

8. CANGASRegistered Senior Member

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Dale cannot speak for himself?

Pete cannot speak for himself?

CANGAS is (sometimes) not afraid to speak for CANGAS.

Last edited: Mar 31, 2006
9. PeteIt's not rocket surgeryRegistered Senior Member

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Just saving you some time.

Here's my opinion, for what it's worth. I don't trust it a great deal myself, for reasons stated earlier. If I wanted to make a strong statement, I'd spend the time to do the calculations.

In my opinion, your predictions about your scenario are incorrect. I think that all three observers will observe a mutual repulsion which will drive the particles apart.

10. CANGASRegistered Senior Member

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Pete:

Your distrust of your opinion, in my opinion, is very well founded.

The definition of the ampere is based upon the two centuries old observation that electrons in parallel wires, moving parallel at a small velocity, produce a magnetic field that overpowers the intrinsic mutual electrostatic repulsion and attracts the two wires.

How can you refute this?

11. PeteIt's not rocket surgeryRegistered Senior Member

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You're assuming that the case of current through parallel wires is the same as electrons moving in vaccuum.

Are you sure that's the case, or is it just your intuition?

12. CANGASRegistered Senior Member

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Pete:

Within a wire, a thermal electron travels an average distance of several hundred lattice atoms before briefly taking lodging and then travelling on to the next atom. Between atoms, is the electron moving in vacuum, or, in pea soup?

Does your sarcasm have no limit?

13. PeteIt's not rocket surgeryRegistered Senior Member

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It just doesn't feel right to pretend the wire doesn't exist. I can't help thinking of all those other charges in the wire, and how they affect and are affected by the moving electrons, you know?

Have you really thought this through? Perhaps tried looking up some theory and running some calculations?

14. CANGASRegistered Senior Member

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PETE:

It is painfully obvious that you are thrashing about because you obviously do not know what you are talking about. It is also painfully obvious that you are "running the clock out" to get my explicit post so far back that many readers will miss it and not become aware of the very real criticism of SR.

If you knew even a smidgeon about SR or electrodynamics in general, you would have immediately destroyed my position if it was vulnerable. Instead, you have desperately tried to create doubt in my mind, in the vain hope that I was faking.

I am not faking. I know what I am talking about.

If I have suffered a monumental lapse of logic, all you, or anyone, has to do is to point out precisely where my lapse of logic is. I have been wrong before and I may be wrong again. Show us where I am wrong.

Please, do not keep on pussy footing around and beating around the bush.

Last edited: Mar 31, 2006
15. PeteIt's not rocket surgeryRegistered Senior Member

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CANGAS, I have no doubt that you know just as much about electrodynamics as I.

16. CANGASRegistered Senior Member

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Pete:

Perhaps even more.

17. PeteIt's not rocket surgeryRegistered Senior Member

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Here are two easy questions for you CANGAS, to demonstrate the difference between your particles and two parallel wires:

Why do your particles need to be restrained before the experiment begins?
Why would two parallel wires in the same situation not need to be restrained?

18. CANGASRegistered Senior Member

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The particles are initially restrained so that the observers can get to their planned observation place before the experiment begins.

Who said parallel wires would not need to be restrained? Was it Pete?

CANGAS needs some Zs and is leaving the building to lay it down. Manyana.

19. PeteIt's not rocket surgeryRegistered Senior Member

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Two stationary electrons without wires need to be restrained or they are forced apart.
Two stationary electrons in parallel wires are not forced apart... clearly the wires themselves cancel that repulsion in some way.

Clearly, the wires make a difference for stationary electrons.

Perhaps there's a difference for moving electrons as well?

Goodnight, see you tomorrow. I enjoy our chats

Last edited: Mar 31, 2006
20. CANGASRegistered Senior Member

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Pete, you are a dirty little sleep-depriving fellow.

The parallel wire case will be covered when I wake up and feel like skirmishing with a hard bitten skeptic who refuses to think for himself.

21. PeteIt's not rocket surgeryRegistered Senior Member

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Sorry, CANGAS... I didn't mean to do that to you.
I've also just edited my message (before reading yours) because my original had such a nasty tone.

I hope I'll be more polite after a night's sleep.

22. DaleSpamTANSTAAFLRegistered Senior Member

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Excellent, I am glad to know that you have some good solid mathematical background and that I was mistaken about our being in disagreement on this point.

That someone was indeed me. Having the mathematical background in the material I am sure that you will easily be able to determine the large difference between an electrically charged stream of particles and the same current in a neutrally charged conductor.

You are correct, if SR predicted that two charges were in three contradictory states of movement simultaneously then that would definitely indicate a fatal flaw in SR. I therefore strongly encourage you to work out the math.

-Dale

23. Billy TUse Sugar Cane Alcohol car FuelValued Senior Member

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CANGAS has proposed the strongest paradox to challenge to SR I have ever seen. (Much better than the twin paradox, which is easily shown to be only a paradox.)
I am confident that someone well versed in SR and Maxwell's equations can show that it is only a paradox, not a hammer smashing SR, but I can not. (It sure looks like a hammer to me.) I have shortened CANGAS’s version to one paragraph, as follows:

We have a test fixture in which are two charged particles, two electrons. They are initially restrained from any movement. We have three observers. Observer 1 is standing still, directly in front of the test fixture. Observer 2 will be traveling past the test fixture at a later specific velocity. Observer 3 will be traveling past the test fixture at a higher velocity. The transits of the moving observers are planned so that all three will be "side-by-side" and adjacent to the test fixture, exactly when the restraint are removed from the charged particles. (NO "simultaneity problems" as to "when" charges are released from constraint.)

It seems SR forces:
Observer (1) sees two stationary charges. So, charges move apart, when restraint is removed.

Observers (2) & (3) also consider themselves to be stationary, and see two like charges, moving parallel to each other, forming a current which is making a magnetic field.

Observer (2) see magnetic force exactly balance the electric static one. So, charges do not move, when restraint is removed.

Observer (3)sees more magnetic attraction that repulsion. So see charges move together, when restraint is removed.

DOES DISTANCE BETWEEN CHARGES CHANGE WHEN THE RESTRAINTS ARE REMOVED? (IF "YES," WHICH WAY?)

SR’s reciprocity of observer and the observer’s reference frames causes this paradox, and this paradox is of such a blatant nature that it simply cannot be believed. Is SR false? Or am I (and CANGAS) lacking in math skills (with SR & Maxwell’s Equations)?

Last edited by a moderator: Mar 31, 2006