posted on Aug, 10 2021 @ 08:46 PM
a reply to: Steffer
You asked for a physicist's approach so you're going to get a physicist's answer: in the Bose-Einstein coherent state of a laser, all of those
photons are literally identical.
Then there's the question: "why are elementary particles identical in the first place, when all the big stuff we see is always slightly
distinguishable from one another?"
Turns out that's a pretty non-trivial thing: it's because every particle of a given type is really an excitation of some fundamental elementary
particle field, and there is only one of those per type in the Universe. (In truth, it's a little bit more complicated how the elementary fields map
to particles). Universe really is just those fields of the Standard Model which has all the 'stuff'.