It doesn’t require time travel, any more then centuries ago travelers arriving in the New World before the official notice of thier departure did.
You’re conflating our ability to measure something with the thing itself.
Not if the clock moved backwards and therefore that would be the only way I believe these two could prove their theory....LOL I would believe it could happen on paper, but between prisms three feet apart, I have trouble comprehending.....I hope they did it, but I doubt they did. I too would like to look at the data and see if the experiment could be duplicated. And I am not a scientist....LOL But I am pretty good with math...LOL