MigL Posted January 25, 2015 Share Posted January 25, 2015 So we have two particles E and P, say an electron and a positron, at a given separation, such that there is a measurable potential between them. The anti-particle of each, positron for the electron E, and electron for the positron P, are brought near, encapsulated in a Faraday cage, such that they do not disturb the pre-existing field. The electron E is allowed to annihilate with its antiparticle, and the positron P is allowed to annihilate with its antiparticle. This is done in a period of time which is much smaller than the propagation time for light between the positions of electron E and positron P. I realize that 'simultaneity' is not possible, but it shouldn't matter. Is this a plausible thought experiment elfmotat ? If not, why not ? If yes, then what happens to the field ? 1 Link to comment Share on other sites More sharing options...
studiot Posted January 25, 2015 Author Share Posted January 25, 2015 Thank you MigL, you have encapsulated the question I posed exactly. +1 Indeed if you only annihilate one of the charges, this still must change the field and the question of what happens to the energy in the field (if there is any) before the 'change' signal has arrived from the destroyed charge. Link to comment Share on other sites More sharing options...
Sensei Posted January 25, 2015 Share Posted January 25, 2015 So we have two particles E and P, say an electron and a positron, at a given separation, such that there is a measurable potential between them. The anti-particle of each, positron for the electron E, and electron for the positron P, are brought near, encapsulated in a Faraday cage, such that they do not disturb the pre-existing field. The electron E is allowed to annihilate with its antiparticle, and the positron P is allowed to annihilate with its antiparticle. This is done in a period of time which is much smaller than the propagation time for light between the positions of electron E and positron P. I realize that 'simultaneity' is not possible, but it shouldn't matter. Is this a plausible thought experiment elfmotat ? If not, why not ? If yes, then what happens to the field ? Are you aware of Positronium exotic atom.. ? http://en.wikipedia.org/wiki/Positronium Link to comment Share on other sites More sharing options...
studiot Posted January 25, 2015 Author Share Posted January 25, 2015 Are you aware of Positronium exotic atom.. ? What bearing does this have on the question posed in the OP? Link to comment Share on other sites More sharing options...
Sensei Posted January 25, 2015 Share Posted January 25, 2015 This is what happens to electron and positron prior their annihilation. Link to comment Share on other sites More sharing options...
studiot Posted January 25, 2015 Author Share Posted January 25, 2015 Sensei prior their annihilation Thank you. But the question is about what happens after annihilation. Wiki : the two particles annihilate each other to produce two or three gamma-rays Perhaps I made the scenario too dramatic. If I just said that the charges are moved further apart, no one would bat an eyelid about the signal that ensues. But the question of what happens to the energy in the field, before the signal arrives, still remains unanswered. Link to comment Share on other sites More sharing options...
Sensei Posted January 25, 2015 Share Posted January 25, 2015 Thank you. But the question is about what happens after annihilation. While asking my question, I was concerned about this part of post "This is done in a period of time which is much smaller than the propagation time for light between the positions of electron E and positron P. I realize that 'simultaneity' is not possible, but it shouldn't matter." Link to comment Share on other sites More sharing options...
studiot Posted January 25, 2015 Author Share Posted January 25, 2015 While asking my question, I was concerned about this part of post "This is done in a period of time which is much smaller than the propagation time for light between the positions of electron E and positron P. I realize that 'simultaneity' is not possible, but it shouldn't matter." I see no problem with this part of MigL's post. We know from experiment that annihilation is both possible and takes finite time. However long that time is the charges can be separated by a greater distance than light can cover in that time. Link to comment Share on other sites More sharing options...
Sensei Posted January 26, 2015 Share Posted January 26, 2015 I see no problem with this part of MigL's post. Transfer of information with speed greater than speed of light is not a problem?? We know from experiment that annihilation is both possible and takes finite time. Without doubt. However long that time is the charges can be separated by a greater distance than light can cover in that time. Positron and electron that are at greater distance are not annihilating.. Otherwise we would not be able to hold positrons in magnetic trap. About what distances you're talking about? Travel of distance equal to f.e. Compton wavelength would take 8.07*10-21 s at speed of light. Positronium has decay mean-life time that it's >10-10 and >10-7. Electron-positron pair with parallel spins have different half/mean-life than electron-positron with anti-parallel spins. Did you actually read article I gave? Link to comment Share on other sites More sharing options...
studiot Posted January 26, 2015 Author Share Posted January 26, 2015 SenseiPositron and electron that are at greater distance are not annihilating.. No one said they were, in fact that is the whole point. Yes I did look at your link, but I couldn't see anything relevent. That is why I asked studiot What bearing does this have on the question posed in the OP? sensei Transfer of information with speed greater than speed of light is not a problem?? No one is suggesting superluminal transfer, that is the issue. Since other (Einstinian) Physics forbids superluminosity my original question explores was happens beyond that transfer horizon? I honestly don't know the answer to my original question, that is why I posted the OP in the first place. A universe with a single charge does not have any energy in its field. The energy arises when a second charge is introduced. So if there is now energy in the field of two charges what happens if one is destroyed or removed to the energy in the field that is further away from the destroyed charge than light can reach in the time to destroy the charge? Link to comment Share on other sites More sharing options...
Sensei Posted January 26, 2015 Share Posted January 26, 2015 (edited) A universe with a single charge does not have any energy in its field. The energy arises when a second charge is introduced. I don't think so that's true. Charged particle is existing regardless of opposite charged particles. Intergalactic space is filled with relativistic accelerated protons emitted by stars in the all directions, that are f.e. one per thousand km3 And their kinetic energy and charge remain unchanged even though the closest galaxy can be hundred thousands light years far away.. If I will take Stirring rod, start rubbing, and charging f.e. electrostatic plume, electrons-charges will gather on its branches and they will be repelling.. I can take positively charged source (that lost electrons to charge plume) to airplane, and fly to 2nd side of Earth. It won't make difference. Plume still will be charged, and its branches pointing up.. Edited January 26, 2015 by Sensei Link to comment Share on other sites More sharing options...
studiot Posted January 26, 2015 Author Share Posted January 26, 2015 sensei I don't think so that's true. So explain how you would calculate this energy and what form it takes, please? Link to comment Share on other sites More sharing options...
Sensei Posted January 26, 2015 Share Posted January 26, 2015 So explain how you would calculate this energy and what form it takes, please? Inability of calculation doesn't guarantee something is true or false. It's lack of data to calculate/measure. This is similar problem as with flying in airplane without windows with constant velocity (assuming no sound of engines etc) (so we don't have acceleration). What speed it has? Is it flying or waiting in queue on the ground? One would say "use GPS", other "use compass", but assume we don't have such cheating devices (not to mention their data might be wrong and misleading).. How would you calculate velocity (so also kinetic energy) of such airplane.. ? Link to comment Share on other sites More sharing options...
studiot Posted January 26, 2015 Author Share Posted January 26, 2015 (edited) The difference is that in your examples the aircraft is not the only mechanical object in your test universe so you would have a mechanical reference, if you choose to use it. I specifically said that there is only one charge in the universe (as you noted that could mean sufficiently remote from other charges). So you say that there is definitely energy, but that it can't be calculated, and can't offer a physical law to describe it. Sounds like witchcraft. Edited January 26, 2015 by studiot Link to comment Share on other sites More sharing options...
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