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Suppose the first mile that this photon covered was from A to B. This was 13.7 billion years ago. Say for the sake of argument, A to B used to be 1 mile, but by now has grown to 10 miles.

Now take a mile in the middle of the journey, say from L to M. Back when the photon passed through it, that was just a mile. By now though, it's 5 miles.

Now take the last mile that the photon travelled, Y to Z. The universe hasn't had time to expand since then, so that's still 1 mile.

Now if you think about the average mile that the photon has passed through, that average mile is going to be most like that L to M mile. By now that average mile has grown to 5 miles.

So, the photon originally covered 13.7 billion lightyears in distance. On average, those lightyears have now stretched out to 5 lightyears. So the distance the photon has covered has by now stretched out to 5 * 13.7, or 68.5 billion light-years.

That doesn't mean that the photon ever went went faster than light. Back in the day when it moved between those points, they were much closer together.
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"Everything is vague to a degree you do not realize till you have tried to make it precise." -- Bertrand Russell
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