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I recently read an article about "Delayed-choice entanglement swapping". Here is an excerpt from the article:

Delayed-choice entanglement swapping consists of the following steps. (I use the same names for the fictional experimenters as in the paper for convenience, but note that they represent acts of measurement, not literal people.)

  1. Two independent sources (labeled I and II) produce pairs photons such that their polarization states are entangled. One photon from I goes to Alice, while one photon from II is sent to Bob. The second photon from each source goes to Victor. (I'm not sure why the third party is named "Victor".)

  2. Alice and Bob independently perform polarization measurements; no communication passes between them during the experiment—they set the orientation of their polarization filters without knowing what the other is doing.

  3. At some time after Alice and Bob perform their measurements, Victor makes a choice (the "delayed choice" in the name). He either allows his two photons from I and II to travel on without doing anything, or he combines them so that their polarization states are entangled. A final measurement determines the polarization state of those two photons.

The results of all four measurements are then compared. If Victor did not entangle his two photons, the photons received by Alice and Bob are uncorrelated with each other: the outcome of their measurements are consistent with random chance. (This is the "entanglement swapping" portion of the name.) If Victor entangled the photons, then Alice and Bob's photons have correlated polarizations—even though they were not part of the same system and never interacted.

Question: Does the passage of time (from our perspective) really matter? Each photon itself is traveling at the speed of light, which I believe should make time have very little, if any, affect on it. I would think that measuring a photon at X time and Y time from our perspective would be the same exact time from the photons perspective. Therefore, wouldn't it make sense that "modifying" a photon at Y time would have an affect on a measurement taken at X time? After all, it would seem as if we are looking at the same exact photon...

   0   <-- same time from the photons perspective
  / \
 X   Y <-- different times from our perspective
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