Life on a closed timelike curve.

This is just symmetrical time reversal, which is just an identity. I mean, it couldn’t be any other way. That’s just how the equations work since they are all time-reversible.

To greatly, greatly simplify, this paper is just saying 2+1 = 3 is the same as 3 = 1+2¹.

1. Which is sort of a little joke, because in certain quantum systems it matters what order you add up the numbers as to the results you get. However, this isn’t one of them!