Time does not pass for photons. So yes, that is exactly what GP is saying.

There's also a different thing that GP might be hinting at, which is that by convention we assume that the speed of light is the same in all directions, but there are other conventions we can use as long as the round-trip speed of light agrees with that which we've measured (and yes, we can only ever measure the round-trip speed of light, FYI). Another convention is that all the light we see takes zero time to get to us but the light we emit goes out at half the speed one would expect with the standard convention (known as the Einstein synchronization convention). So instead of "light we see from Alpha Centauri is 4 years old" or "we see Alpha Centauri as it was 4 years ago" we can say that we see it as it is right now, but this is not a very commonly used convention.

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jb1991 3 days ago | parent [-]

interesting, why would this be?

> we can only ever measure the round-trip speed of light, FYI

	▲	cryptonector 3 days ago \| parent [-]
		Because say you fire a photon from an emitter to some target and you want to know how much time elapsed for that flight, but how would you find out? The target will have to communicate to the observer (you in this case) when it received the photon, but that communication will require.. more photons, and a trip back to you. If you're colocated with the emitter then it's a round-trip, else you need a photon from the emitter and the target, as well as the one from the emitter to the target, and this amounts to a round-trip anyways. Therefore you can't measure the speed of light in any one direction. You can only measure the round-trip time of flight (e.g., if you have the detector at the emitter and use a mirror).