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| How does the electron make a photon in an antenna? |
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| T3sl4co1l:
--- Quote from: Rick Law on February 13, 2017, 06:44:38 am ---[This was going to be a quick reply, but to be clear I had to add more and more words. Hope I don't lose you half way.] --- End quote --- I appreciate the long form discussion! So many lengthy posts go unchallenged, or probably even unread. Few people seem to appreciate that 140 characters simply cannot communicate the complexity, detail and subtlety that encompasses... most everything! --- Quote ---I see where we are out of sync. You are talking about adopting a different (in your word, "more appropriate") methodology of doing analysis. Whereas, I am simply describing the inability of scaling math to the limit (not in the mathematical sense of limit but in the practical sense) and consider that as applicable to the physical world. --- End quote --- So what you're getting at is, not just the simple matter of analysis (which I see more often, hence my focus on that), but more fundamental. --- Quote ---So however similar sound the question, this is a real non-silly question: If a particle is mathematically evaluated not to decade in 10E40 years, and I am not talking half-life, I am talking non-probabilistic hard number of 10E40 years. The question is: does it decade? Based on current rate of acceleration of expansion, in 10E30 years or so our universe is energy-dead. At 10E40 years, the particle has a life longer than the expected life of the universe. At 10E30 years, there would be no energy to use, no matter visible, no matter interaction since there is no matter left within reachable distance (rate of expansion>c)... --- End quote --- NB: decay? Some theories suppose the proton will decay, in some unimaginably long time scale; still, for the vast number of them in the universe, perhaps one could stand the chance of observing such an event, within that time scale. But that's a probabilistic decay; you mean a fixed, known decay time? There is no mechanism to conceive of such a thing, within the Standard Model as we know it. This supposed particle is very alien indeed, and making any hard statements about, say, its mass or energy or internal state, is quite undefined! So, proposing a simple thought experiment about one property, really strains the understanding of many more properties within present theory! I'm not sure that this was the intended effect... --- Quote ---The universe in 10E40 years is an unknown condition. We don't know what physical laws will apply. We also know that the act of measurement itself affects what we are measuring... I would not consider the question "does it decade" a question of physics but instead it is a philosophical question. In other words, it is outside the domain I think of as Physics since it is in a domain where I don't know if our physical laws apply. --- End quote --- Yeah, physics is a very practical science: if you can measure it, if it comes out of the math of established (read: measurement-supported) theory, there's something there. If you can't measure it, maybe it's there, maybe not, it doesn't really matter in that case, does it? (This is sort of the problem that string theory has: my limited understanding of it is, it's a superset of earlier theory, so it suffers from the problem of being too general -- indeed, that many of the new variables can't be measured. More of a framework than a physical theory. When we finally obtain new experimental data, we have plenty of choice of framework to fit them into -- but for now, it's kind of just a plaything.) So, given that it's unlikely the study of physics (at least, as we know it) will persist for 10^30 years, say -- I would be more than happy to answer "no, it doesn't decay*". The implication is: *for all intents and purposes. But if you have reason to believe it decays (such as the theories which suggest proton decay, if proven), then who knows, you might measure it some day, and you can say "yeah sure, why not?" instead. Or, if you've somehow determined that a particle will go off like a time bomb at exactly 1e40, you probably have a very good reason to believe that, in which case the "Yes!" is as resounding as the strength of the theory behind that result, and the sigmas of its supporting data! And, since these things always cut both ways -- whatever mechanism you've discovered, that gave rise to this timebomb-ino, as it were -- likely has profound effects on other particles or relationships within the theory! If this one particle is deterministic, there must be a companion that's also deterministic? Or is there even less determinism (more chaos, or randomness) in other events? Besides proton decay, a more practical example might be double-beta decay: it was hypothesized for some time, and expected to be very unlikely, but it has in fact been observed in a number of quite long half-life nuclides. This is, of course, a probabilistic decay, not a time bomb, which makes it practical to measure, despite the half-life being on the order of (age of universe)^2. Is it useful to know? Yes -- it validates our theories about the weak force. Is it practical, in and of itself? Probably not; anything with a half-life that long is pretty well "stable" for all intents and purposes, outside maybe a very sensitive detector (don't accidentally get any 100Mo in your neutrino detector tank!). --- Quote ---We can hypothesize that our known physical laws still apply at the extremes, but we don't know. In fact, we don't know even today how our physical laws apply beyond near our own solar system. 96% of the universe is dark matter and dark energy. We don't even know what they are let alone form laws that may apply to that extend. So, I tend to think physics as what we can have a prayer of forming laws that we can describe and perhaps prove directly or indirectly. So, bottom line (in my view), you can choose whatever way you choose to look at it, all we can say is "well, we think it does, but we really don't know for sure." If you say the particle WILL decade in 10E40 years, I can accept that too. You have more faith in the robustness of our physical laws than I do. --- End quote --- So to sum up, it seems like we're in agreement. Physics, as a field of study, is only as certain of its results as it can measure. No need for faith, just soft fuzzy error bars! Tim |
| T3sl4co1l:
--- Quote from: RoGeorge on February 13, 2017, 08:27:01 am ---So, who's making a photon in an antenna? One electron jumping from a higher to a lower energy state? No. --- End quote --- BTW, note that the antenna is only a guide for the EM field. The EM field extends from within the cable (or waveguide, or whatever), through the radiating structure, out into space. If you wish to use photons in your reasoning, then they can be present in all these locations. Ultimate photon interactions (creation and absorption) -- not just scattering, occurs at sources and sinks. Really, anything with resistance, or equivalent resistance. Tim |
| T3sl4co1l:
--- Quote from: John Heath on February 13, 2017, 03:57:11 pm ---I would add that waves leaving of the surface of the water outward become smaller and smaller through distance but photons do not as seen in the photoelectric effect. Green light will force an electron off metal but red light no matter how strong will not. The waves are quantified into energy packets of E=hv for reasons unknown. --- End quote --- Honestly: the photoelectric effect is far more complex (surface physics, yay!..) than its traditional origin story suggests. It's remarkable to me that any research on the subject could be eligible for a Nobel prize! Though to be fair, it's generally been said that Einstein was honored, not so much for that particular paper (On The Photoelectric Effect), but more generally, because, well, Einstein. Familiar examples are phototubes, with sensitivity curves seemingly much longer in wavelength than the materials used would suggest. (But, they use compounds, selected for wideband sensitivity, which might not obey the same rules as pure metals.) But also of note -- EVERYTHING is nonlinear, to some degree. Some crystals exhibit multi-photon mixing (essentially: upconversion due to a locally-quadratic field response). Such phenomena are uncommon, both because of material properties (only specialized crystals are chosen for applications), and because of small probabilities (the likelihood of two photons being in the same location, phase and polarization, is small; however, laser light is quite luminous and coherent, so the effect can be usefully applied). A more banal example: simply heating something, with any radiation source sufficiently intense. Induction heating achieves up-conversion from 60Hz (~coherent) to ~400THz ("white" noise -- oh, wait, white indeed!), and that's just in ordinary industrial steelmaking! :) In the extreme, space itself is nonlinear: the kugelblitz is a black hole, created from a sufficient density of pure light at a point. The mass of a black hole, summoned purely from energy! Of course, you need a truly astronomical amount of light, converging on an exact point, which might not be possible given optical limitations; but there's nothing prohibiting it on the lowest physical levels, that we know of. Tim |
| John Heath:
--- Quote from: T3sl4co1l on February 13, 2017, 10:03:18 pm --- --- Quote from: John Heath on February 13, 2017, 03:57:11 pm ---I would add that waves leaving of the surface of the water outward become smaller and smaller through distance but photons do not as seen in the photoelectric effect. Green light will force an electron off metal but red light no matter how strong will not. The waves are quantified into energy packets of E=hv for reasons unknown. --- End quote --- Honestly: the photoelectric effect is far more complex (surface physics, yay!..) than its traditional origin story suggests. It's remarkable to me that any research on the subject could be eligible for a Nobel prize! Though to be fair, it's generally been said that Einstein was honored, not so much for that particular paper (On The Photoelectric Effect), but more generally, because, well, Einstein. Familiar examples are phototubes, with sensitivity curves seemingly much longer in wavelength than the materials used would suggest. (But, they use compounds, selected for wideband sensitivity, which might not obey the same rules as pure metals.) But also of note -- EVERYTHING is nonlinear, to some degree. Some crystals exhibit multi-photon mixing (essentially: upconversion due to a locally-quadratic field response). Such phenomena are uncommon, both because of material properties (only specialized crystals are chosen for applications), and because of small probabilities (the likelihood of two photons being in the same location, phase and polarization, is small; however, laser light is quite luminous and coherent, so the effect can be usefully applied). A more banal example: simply heating something, with any radiation source sufficiently intense. Induction heating achieves up-conversion from 60Hz (~coherent) to ~400THz ("white" noise -- oh, wait, white indeed!), and that's just in ordinary industrial steelmaking! :) In the extreme, space itself is nonlinear: the kugelblitz is a black hole, created from a sufficient density of pure light at a point. The mass of a black hole, summoned purely from energy! Of course, you need a truly astronomical amount of light, converging on an exact point, which might not be possible given optical limitations; but there's nothing prohibiting it on the lowest physical levels, that we know of. Tim --- End quote --- Your response makes you the qualified to do a photoelectric test as you have the understanding that the real world is not the elegant picture painted by arm chair physics. Why would you assume the minds of the men and women 100 years ago to be different. The test was done with care to control third variables. |
| aetherist:
--- Quote from: calexanian on February 07, 2017, 05:47:16 am ---I was taught, and I just did some google searching because its been so long, is that the actual radio wave propagation (In the common communication ranges) is purely electromagnetic and electrostatic based on Maxwells equations. They propagate independent of photons in a manner dictated by QED. The photons are just an emitted byproduct generated by the intrinsic energy of the signal itself. In other words an antenna is producing the EM field, but any photons that are being released are not the principal emission and nowhere near the frequency of the base band, or in other words the antenna does not emit electrons or photons as a primary mode, only fields. It emits no more photons than any other piece of metal with that amount of energy going on about it. Things get a bit more complicated as you go higher up in frequency though. Via QED more "Loss" of energy is expressed via photons until you have an infrared light source. Somebody please correct me. Like I said. It has been a very long time. --- End quote --- Wow - i just then read this -- i thort that this forum (& modern electricity & radio) was populated with idiots -- but calexanian is a breath of fresh air -- yes, radio waves are not photons -- radio waves are em radiation. And, re the OP.... ....................We know how an electron makes a photon in an LED. It jump from a higher orbital to a lower one emitting a photon. But in an antenna its occupying the same valance just with a different nucleus each hop. How is the energy transferred to a radio frequency photon?................. .... i reckon that electricity aint due to the movement of electrons -- neither in the Cu nor on the Cu. |
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