It’s a paradoxical question. My oldest child, a clever and passionate woman, answered it this way:
I’d want to find out how Joan of Arc knew what she did. Because if anyone looks like a time traveler in history, she does.
I’d love to see the Beatles in 1963, the Grateful Dead in 1968, and Star Wars in 1977 (again).
I’d want to hear Elizabeth’s rally to her troops just before the sinking of the Spanish Armada.
I think it would be fascinating to eavesdrop on Einstein explaining Schrödinger’s Cat after the academic elite missed the point.
But those are all selfish reasons to use a time machine. If I were to be a hero about it, I’d smother Stalin in his crib, figure out how to sabotage FoxNews before it got a toehold, bitch-slap St. Paul along the road to Damascus and tell him not to be such a misogynist, and creep into the Warsaw Ghetto on the last evening of the siege and assure them it was not all in vain.