Re: If a quantity isn't real then what is being represented?

AMH <amh2.71828@gmail.com> writes:

Can you elaborate on the question? Sounds like you are asking about whether=
complex quantities are physical.

  Complex numbers can appear in a very natural way.

  When a beam of coherent light of a certain frequency is split
  (with a half-silvered mirror) and then reunited after each part
  has travelled the same length (and was redirected using mirrors),
  the interference is constructive, which can be observed.

  Introducing a glass platelet of thickness d/2 into one of the two
  beams will lead to the observation of a destructive interference,
  which is interpreted by saying that the wave of that beam has been
  multiplied with (-1) by the platelet. Interference with the other
  beam which was not multiplied then leads to destructive interference.

  When two platelets of thickness d/2 are introduced into the same
  beam, the wave of that beam is being multiplied by (-1) twice.
  (-1)*(-1) gives (+1). Multiplication with (+1) is the same as no
  multiplication at all, so the interference is constructive again.

  A platelet of thickness d thus corresponds to a multiplication
  with (+1); a platelet of thickness d/2 corresponds to a
  multiplication with (-1), and (-1)*(-1)=(+1).

  A platelet of thickness d/2 has the same effect as two platelets
  of thickness d/4. So what do platelets of thickness d/4 multiply
  the wave with?