garden/photon.md

• "We are reminded of the process in which a molecule loses or gains a whole atom or a whole electron but never a fraction of one or the other" -- Gilbert Lewis in The Conservation of Photons.
  • "Einstein was led to the idea of light quanta which has proved so fertile"
  • "…two photons, as seen by a single observer, differ in direction of motion, in energy and in polarisation".
  • "If we were moving with rapid acceleration toward a wireless station, its photons would appear to possess increasing amounts of energy, and would pass over the whole spectral scale through the visible and into the ultraviolet"
  • "Even so fundamental a process as the flow of heat must involve two factors, the amount of energy and the number of photons transferred"
• From Wikipedia:

  • The name photon derives from the Greek word for light, φῶς (transliterated phôs).

  • Although Wolfers's and Lewis's theories were contradicted by many experiments and never accepted, the new name was adopted by most physicists very soon after Compton used it.

  • In physics, a photon is usually denoted by the symbol γ (the Greek letter gamma). This symbol for the photon probably derives from gamma rays,

  • (...) (this article is great)

  • Dirac's second-order perturbation theory can involve virtual photons, transient intermediate states of the electromagnetic field; the static electric and magnetic interactions are mediated by such virtual photons.