Time travel and the Harry Potter Paradox

Last Saturday, I had my 20-year school reunion. The class of 1997. 1997 is gone. But maybe if I stepped into a wormhole, I could come out the other end in 1997. With apologies to the Carpenters, it really is Yesterday Once More. And would I find my beuniformed self, sitting at my desk in my Alma Mater, learning about volumetric titrations and ablative absolutes?

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