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If each isolated photon interferes with itself as a wave, and the unbound photons' wave equations for position extend the entire universe (with decreasing amplitude), would faint interference patterns still show up at the extreme ends of the detector (e.g. 20ly away from center), and would they show up faster than light?

Ex: The slits are on Earth and detector is perpendicularly bisecting mars, extending 20ly in each direction. Would I see a faint interference pattern if I'm standing at one end 20ly away from center, and would it appear at t=3.03 minutes (1 way trip time form Earth to Mars) or 20ly later from my perspective.

Or in other words...does an unbound particle's position amplitude extend outside its own light cone, and would that part of its wave equation still show up interference in a double slit experiment. And could that be used to send a signal somehow ftl?

J Kusin
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  • please see this answer trying to explain the double slit experiment one photon at a time https://physics.stackexchange.com/questions/506916/in-a-double-slit-experiment-does-each-and-every-photon-leave-a-dot-on-the-scree/506921#506921 – anna v Jul 10 '20 at 14:56
  • ty. So if a single photon dot appears toward an edge of the detector screen, does that mean it took longer to appear there because the path is longer (than a dot appearing near the middle)? @annav – J Kusin Jul 10 '20 at 15:52
  • yes ,but the classical electromagnetic wave emerges from a confluence of a large number of photons, as the last slide shows. – anna v Jul 10 '20 at 16:01
  • ty, for taking the time to explain it all. – J Kusin Jul 10 '20 at 16:42
  • Despite the experimental design, it takes at least 13 billion years to see the results. – David White Jul 10 '20 at 18:43
  • Its worth looking at the delayed-choice quantum eraser. It describes effects you are talking about, can be done on a human scale, and it can be constructed with a long arm so that light-cones actually come into play. – Cort Ammon Jul 10 '20 at 21:30

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You could think of the photon wave function as 2 distinct processes: 1) let's take an excited atom with its excited electron, this electron disturbs the EM field but these forces do not involve an exchange of energy (they are said to be caused by virtual photons also known as force carriers). These forces in theory extend a great distance uniformly and effect the electrons in many atoms. Now take an another electron resting in its atom, based on the laws of probability (i.e.QM) let us say they "agree" to exchange the energy. So now process 2 begins and this is what we typically refer to as the "photon wave function". This function is the one Maxwell describes (sinisoidal, straight line, wavelength etc) but its existence is based on probability.

The photon wave function changes dynamically with the environment, for example let's say a star (10 light years away) emits a photon toward an atom on the earth ... just before it arrives a water wave forms, or a mirror is placed at the location, now the photon gets reflected ... maybe back to the star or any place else.

The EM field is everywhere and is transmitting the forces of all the universes' electrons (and protons) simultaneously, the EM field is also capable of transmitting energy ... this is the photon.

PhysicsDave
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According to Special Relativity's definition of a light cone, a particle's position cannot be outside it. Therefore no detector will ever detect it there.

It may help to recall that a detector actually registers the position of the localized particle upon the collapse of the wave function. The wave function is at heart a possibility amplitude (where, famously, $probability = possibility ^2$) and is zero outside the light cone, among other places. Hence there is zero chance that it can collapse there.

Guy Inchbald
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