Superman nos hace pensar

Recordáis la estúpida escena de superman en la que su novia ha muerto y decide hacer girar la Tierra al revés para que el tiempo vuelva atrás y así rescatarla? Eso no tenía pies ni cabeza, para empezar intenta girar la Tierra ¿volando? para eso mejor agárrala! Y además, en todo caso crearía un desastre monumental con terremotos, maremotos y vete tú a saber, no simplemente hacer q vuelva atrás el tiempo pacíficamente. Pues bien, si habíais pensado eso, como yo, sois unos malpensados y hay una explicación mucho más satisfactoria. Visto en What if de XKCD:

In the first Superman movie, Superman flies around Earth so fast that it begins turning in the opposite direction. This somehow turns back time [... ] How much energy would someone flying around the Earth have to exert in order to reverse the Earth's rotation?

—Aidan Blake

Someone recently blew my mind by telling me I’d been misinterpreting that scene all my life. I like their take on it way better:

Superman wasn't exerting a force on the Earth. He was just flying fast enough to go back in time. (Faster than light, I guess? Comic book physics.) The Earth changed direction because we were watching time run backward as he traveled. It didn't actually have anything to do with the direction he was flying.

Now that I see it, it makes a lot more sense. I mean, as much sense as a red-cape-and-outside-underwear time traveler can make.

A discussion of the reversal of the Earth’s spin—and what that even means—will have to wait for another article.