Overthinking Back to the future

And you thought I would let the date go blank, right? We arrive and go through that moment where the three "Back to the Future" films are set in the past. The distant thirty years from 85 to 2015 passed without flying cars or hoverboards, the Fax was defeated and we didn't have so many sequels to the film Jaws... if only they had bet on the Star Wars film franchises they would be much closer to the truth.

But I think everyone has read somewhere almost everything that can be said about the three films and their successes and failures, with one commendable exception: the time-space relationship of travel.

You know: at the beginning of film one Dr. Brown tells us that Delorean cannot travel in space, only in time, so traveling in Hill Valley of 1985 can only take you to other Hill Valleys of other years. But to go from Hill Valley 1985, to New York in, say, 1929, you would have to choose between: either going to New York and then traveling back in time, or traveling back in time and then traveling to New York. And with a Delorean carrying plutonium, it wouldn't be the easiest trip in the world. Not in 85, not in 55 and not in 29.

Well then. Within the mistakes and successes of the three films, the most staunch critics cling precisely to the fact that it would be impossible to travel in time without traveling in space. See, the Earth has two movements: rotation and translation. When traveling in time, from point A to the same point A, even one minute would be the difference between being on the beach one instant, and the next minute in the sea, as the Earth rotates at 1666 km/h (that is, in 24 hours it rotates its 40,000 km in circumference), which means that the Earth rotates at 462 m/s.

In one minute of our hypothetical trip to the future, its position would already be 27 km different from the point of origin. How to start your trip in Sé Square and a minute later be in Itaquera City. And this, thinking only about the rotation of the Earth, and ignoring the translation, the movement of the Earth around the Sun. In other words, if we travel long enough, we may not even be on Earth when we resurface. just floating in an empty space where the Earth has yet to arrive or has already passed. And this is ignoring the ballet that our solar system does in the Milky Way, our Galaxy.

But then, the film really got it wrong on this issue, right? Well... Maybe Dr. Brown was wrong, and the movie was right. If we ignore the part where the Solar System also rotates, and just stick with rotation and translation, then it could be.

It turns out that in film two we see a dazzled Dr. Brown with the coincidence that among so many possible days in the past, Biff Tannen returned precisely to the same year that Marty also returned in film one, and the good doctor comes to consider that that day of 1955 was perhaps a cosmic junction. Or maybe it was just the time machine searching for a year that Hill Valley was where it was, in space and time!

 

Now excuse me, this overthinking made me need a headache pill...

 

(this essay was inspired by the great book of Randall Monroe, What if...)