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Bob3141592
- 236
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Sometimes I think I'll never understand anything about photons. In isolation things seem to make sense, but put together they seem impossible. Here's what I'm thinking.
A photon is a particle with energy and momentum but no mass. Or it is a varying electromagnetic wave. Presumably there's a way to see it so these are the same thing. Let's go with the electromagnetic wave notion. You can't have a stable electric field without a charge to anchor it, so the photon's electric field quickly decays, which induces a magnetic field. But there is nothing to anchor this magnetic field either, so it also decays, producing an electric field. And so on and so on.
Since the photon has momentum, there must be some asymmetry to these fields to give the photon a particular direction to travel in. I presume there must be some spatial asymmetry in each field itself, and not simply in their relationship to each other, otherwise the photon could also be traveling in the opposite direction at the same time (with opposite phase), which seems clearly nonsensical. I suspect this asymmetry could have come about from the electron configuration in the excited atom when the photon was first emitted, but I digress.
Nothing can travel faster than c. That's a given. Now consider two photons traveling in the same direction side by side. Can one photon be "aware" of the other? I think not, by simple geometry. Form a triangle with A being the position of the left photon at time t-zero, B the position of the right photon at at t-zero, and C being the position of the left photon at t-one. Information about the right photon would have to travel along a hypotenous to meet the other photon at t-one, but that distance is longer than AC, so the first photon is gone before that information can get there. Thus there can be no information exchanged between these two photons. In a romantic sense, each photon is a universe unto itself, but I digress again. Suffice it to say that this isolation exists no matter how close or far away these two photons are.
Now, if no information spatially separated from the photon traveling parallel to the photon can communicate with it, how can the spatially extent electromagnetic field of the photon keep up with itself? How can the varying electric field "know" the configuration of the magnetic field? It seems it can't, so I can only conclude that all this electromagnetic varying occurs at a single point. But that destroys the notion of asymmetry, so how can the photon move at all?
Perhaps, from the photon's perspective, it isn't moving. Again, in a romantic sense, time stops for an object moving at c. Unfortunately, looked at this way, a photon can't interact with anything or be affected by anything, and one glance in the mirror tells you this inference can't be right.
Still, the photon cannot move at greater than nor les than c, so it must be moving with constant velocity. But objects moving at constant velocity seem at rest from their own reference frame. When moving at constant velocity, you can't tell you're moving except in relation to external objects, which the photon can't "see", and even then it would "feel" like it was the external objects that were moving. Since a photon at rest makes no sense, I conclude the photon can't seem to be at rest even from it's own frame. From all this I can only conclude that the very notion of a reference frame for a photon is nonsensical (they are called inertial reference frames, and photon's don't have inertia, do they? even though they have momentum?)
And how can a any field be compressed into a point? Isn't that self contradictory by definition, even though it seems necessary? The more I think about this the more confused I get. Either I'm terribly wrong about something(s) fundamental, or these's a question in here that would be interesting to know. The answer might be something else, but for now I'd be happy to just know the question.
Can anybody help?
A photon is a particle with energy and momentum but no mass. Or it is a varying electromagnetic wave. Presumably there's a way to see it so these are the same thing. Let's go with the electromagnetic wave notion. You can't have a stable electric field without a charge to anchor it, so the photon's electric field quickly decays, which induces a magnetic field. But there is nothing to anchor this magnetic field either, so it also decays, producing an electric field. And so on and so on.
Since the photon has momentum, there must be some asymmetry to these fields to give the photon a particular direction to travel in. I presume there must be some spatial asymmetry in each field itself, and not simply in their relationship to each other, otherwise the photon could also be traveling in the opposite direction at the same time (with opposite phase), which seems clearly nonsensical. I suspect this asymmetry could have come about from the electron configuration in the excited atom when the photon was first emitted, but I digress.
Nothing can travel faster than c. That's a given. Now consider two photons traveling in the same direction side by side. Can one photon be "aware" of the other? I think not, by simple geometry. Form a triangle with A being the position of the left photon at time t-zero, B the position of the right photon at at t-zero, and C being the position of the left photon at t-one. Information about the right photon would have to travel along a hypotenous to meet the other photon at t-one, but that distance is longer than AC, so the first photon is gone before that information can get there. Thus there can be no information exchanged between these two photons. In a romantic sense, each photon is a universe unto itself, but I digress again. Suffice it to say that this isolation exists no matter how close or far away these two photons are.
Now, if no information spatially separated from the photon traveling parallel to the photon can communicate with it, how can the spatially extent electromagnetic field of the photon keep up with itself? How can the varying electric field "know" the configuration of the magnetic field? It seems it can't, so I can only conclude that all this electromagnetic varying occurs at a single point. But that destroys the notion of asymmetry, so how can the photon move at all?
Perhaps, from the photon's perspective, it isn't moving. Again, in a romantic sense, time stops for an object moving at c. Unfortunately, looked at this way, a photon can't interact with anything or be affected by anything, and one glance in the mirror tells you this inference can't be right.
Still, the photon cannot move at greater than nor les than c, so it must be moving with constant velocity. But objects moving at constant velocity seem at rest from their own reference frame. When moving at constant velocity, you can't tell you're moving except in relation to external objects, which the photon can't "see", and even then it would "feel" like it was the external objects that were moving. Since a photon at rest makes no sense, I conclude the photon can't seem to be at rest even from it's own frame. From all this I can only conclude that the very notion of a reference frame for a photon is nonsensical (they are called inertial reference frames, and photon's don't have inertia, do they? even though they have momentum?)
And how can a any field be compressed into a point? Isn't that self contradictory by definition, even though it seems necessary? The more I think about this the more confused I get. Either I'm terribly wrong about something(s) fundamental, or these's a question in here that would be interesting to know. The answer might be something else, but for now I'd be happy to just know the question.
Can anybody help?