4 ms·

Does polarization (or polarization based filtering) of a photon qualify as an interaction based on time?

• pdonis 5y ago
  Polarization based filtering involves other objects besides the photon being present, so it is not quite the kind of thing we're discussing. We're discussing the possibility of a photon just by itself, with nothing else present, undergoing some kind of change. There is a small probability of this happening; it's small, but it's not zero. So the claim that the photon's worldline being null (i.e., having zero "length" in terms of the metric of spacetime) prevents it from undergoing any change whatever as it travels is not true.
  • zeusk 5y ago
    Ah, does doppler effect or relativistic stretching affect the photon wave packet? I was told, that's what causes red/blue shift but aren't photons immune to relativistic effects since they travel at v = c?
    • pdonis 5y ago
      > does doppler effect or relativistic stretching affect the photon wave packet? Yes. > aren't photons immune to relativistic effects since they travel at v = c? No. Lorentz transformations still affect photons; they just affect them by dilation (they change all of the components of the photon's wave vector by the same factor, without changing the direction the wave vector points) rather than by hyperbolic rotation.