Duda Jarek Posted January 24 Author Share Posted January 24 5 hours ago, exchemist said: No, that is wrong for this situation, because it is a bound system and therefore quantised. I pointed out to you earlier that electrons in atoms do not radiate and fall into the nucleus. But excited atoms radiate abundant energy - getting to the lowest energy: ground state? So why shouldn't unaligned spin radiate abundant kinetic energy - getting to the lowest energy: aligned spin? ... especially that this is exactly what they observe in Stern-Gerlach ... and EM says that oscillating dipoles should radiate energy. 5 hours ago, exchemist said: Forget brehmsstralung. It's irrelevant. That is for free, i.e. unbound, particles. Indeed, and in Stern-Gerlach we have free unbounded objects - having magnetic dipole, in external magnetic field - as also e.g. electrons in synchrotron radiating energy as EM waves. 4 hours ago, swansont said: Yes, this is what I asked you about. How did you arrive at this conclusion? I want your reasoning, not just a repetition of the statement. Magnetic dipole in external magnetic field gets torque - Larmor precession ... rotating dipole creates varying EM fields - like antenna radiating energy as EM waves, of power given by the used formula. 4 hours ago, swansont said: But other effects are not classical (the deviation of the beam), so why should the alignment be classical? The discrete deviation is an indication that you do not have randomly-aligned spins that come into alignment over some period of time. Larmor precession comes from torque - works in all scales: from electron to macroscopic magnets. For non-polarized beam, the original direction of magnetic dipole is random, the final in Stern-Gerlach is aligned in parallel or anti-parallel way - exactly as we would expect for a classical magnet in external magnetic field. Link to comment Share on other sites More sharing options...
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