Michael Eriksson's Blog

A Swede in Germany

A few thoughts on and around the Back to the Future movies

with one comment

I am currently re-watching the “Back to the Future” movies. A few observations:

  1. 2015, the part of the future actually shown in the movies, is come and gone in real life—and looked nothing like the fictional depiction. 1985 was closer to the real-life 2015 than the fictional 2015 was, and the same might* even, conceivably, apply to 1955.

    *1955 definitely feels more familiar, even though I was born twenty years later; however, this is possibly explained by my exposure to other fiction set in a similar time, or through deviations between the real and fictional 1955s.

    This is paralleled by other sci-fi works, in that they are often quite bad at guessing what the future will bring, often simply taking the trends and technology of the author’s now and extrapolating them optimistically (or pessimistically…) into some point of the future.* These trends, however, will usually diminish, cease, or even revert over time, depending on the type of trend**. At the same time, this method will not be a good means to discover e.g. new technologies. For instance, the average sci-fi author (or citizen, in general) of the 1960s might be horribly disappointed by the current state of space travel—but equally positively surprised by the Internet. To boot, there can be obstacles of a more practical, legal, societal, whatnot, nature that are not taken into account. Consider e.g. the flying cars of pseudo-2015: Making a flying car was technologically (but not necessarily economically) feasible even in 1985, but consider the ramifications on traffic accidents, the new opportunities for criminals and terrorists, or the problems with keeping the noise down to a tolerable level. Even if we had affordable flying cars ready to roll out of the factory tomorrow, there would be years before regulations, infrastructure, and whatnot, caught up.

    *This should not necessarily be seen as a criticism: In some cases this could be the result of naivete or laziness; in others it might be a mere lack of clairvoyance or a deliberate attempt to critique the contemporary society. In the specific case of the “Back to the Future” franchise, the choices made were likely strongly motivated by humor and the wish to create a future that was easy for a movie-goer from 1985 to relate to.

    **For instance, microchips have continued to grow smaller while the stereotypical 1980s’ fashion is long gone.

    Another complication is obviously that some things naturally change slowly, as exemplified by the clock tower that was present in 1955, 1985, and 2015—and actually saw its beginnings in 1885: Buildings are occasionally replaced en masse, but more often they experience a gradual change that often even puts buildings from different centuries next to each other. The furniture of a home is usually bought at some point, and then only changes a little here-and-there over a few decades—and usually includes inherited objects of even greater age. The hair-style of many people in their eighties often come close to what it was in their twenties, leaving a wide mixture in overall society. Most people do not drive “this year’s” car model, usually keeping their old car for as long as it is feasible. Etc.

  2. Time truly does fly—even if the cars still do not. I actually had planned to write something on this topic in 2015, but never got around to it because time flew too fast… A more timely and possibly even more interesting example from my personal point of view is “Grease”: This movie plays in 1958, was released in 1978, was first seen by me in 1998 (a twentieth anniversary re-release), and now we have 2018… 1998 does not quite feel like yesterday, but if twenty years go past this fast, twentieth anniversaries are hardly worth the trouble. In contrast, in 1998, I still thought of 1978 as half-an-eternity back, seeing that it was way back when I was still three years old. (More generally, the older I have become, the shorter time intervals have appeared, something which well matches what I have heard from people who actually are old—not just older.)
  3. “Back to the Future” commits the possibly most common and largest single error in time-travel fiction: It assumes that when the time line changes, the people remain* the same while society, their respective position in society, whatnot changes. Of course, the people already born at the point when the time-line changes will remain in existence**, but very soon after the change, there will be virtually no overlap between the people born in the two time-lines: For a certain person to be born, it is not enough that the same two parents land in bed, we have to see basically that one single sperm fertilizing that one single egg. Even the most minuscule of changes will cause that to not happen. (Also cf. parts of some previous discussions.)

    *The treatment within the franchise could be seen as inconsistent, with the events of the first movie erasing people, and the events of the second and third leaving them in place. The hitch is that the first movie deals primarily with the specific event of Marty’s parents becoming or not becoming an item, which gives the difference a certain pseudo-justification. Unfortunately, it would not work that way in real life.

    **But will, obviously, experience a diverging set of events afterwards, potentially including a considerably earlier death, as was the case with Marty’s father in the second movie. An interesting play on this can found in the very promising TV series “Counterpart”, which depicts two alternate realities with a “Check-Point Charlie”-style crossing (and which is obviously strongly inspired by the old divided Berlin and the Cold War).

  4. The whole siblings-fading-from-a-photo thing is of course ridiculous, even if we assume that time travel is possible. By any reasonable rule-set* for time travel, it would be a binary either–or deal: Either the siblings are there or they are not. To boot, the same mechanism that would cause a sibling to fade from a photo would also cause a fade from memory under any reasonable rule-set. Marty would not be in the position to panic over the fate of his siblings for the simple reason that either he would not himself remember them or they would not disappear from the photo. For that matter, if the photo is altered then Marty would be altered too at the same time. Of course, since the eventual alteration is his own erasure, he would not worry about the photo irrespective of his memories—he would not only not remember, he would have ceased to exist. (As would the photo as a whole, not just the contents.)

    *By which I mean something that is logically consistent and at least somewhat plausible in other regards. A problem is, obviously, that we do not know what the real rules of time travel are. Also see an excursion at the end.

Excursion on time travel and paradox:
In my personal estimate, the three most likely resolutions to time travel and typical paradoxes are:

  1. Time travel is simply not possible and such paradoxes can, therefore, not arise.
  2. (The change in) causality would not take effect instantaneously along the time-line, instead traveling at the speed of 1 s/s (likely with some modifications for movements in space in accordance with the Lorentz transformations), preventing paradoxes through this delay. For instance, if someone goes back in time from 2018 to 1918 and kills his own grand-father, he will only be removed from 1918 after causality has reached the point of 2018 when he went back in time, leading to his grand-father being dead or surviving depending on where causality is. Eventually the grand-father is alive again, causing the grand-son to be born and allowing him to go back in time again, after which the grand-father is killed, and so on.

    This can to some degree be compared to a river where a small rivulet goes back from the main flow of the river at point A and re-enters the river at an earlier point B if the water level at point A is high enough, but where an the arrival of more water at point B causes the (possibly manual) diversion of even more water at an intervening point, implying that the water level at point A drops too low for water to flow back to point B, implying that the diversion ceases, etc. (A better example would use a river that actually changes course; however, I cannot come up with an immediate example that would not require twice the text to describe, and the preceding explanation is likely complicated enough.)

  3. The appearance of a time traveler in the past will still happen, even if his actions would have apparently prevented him from going back in time. This event simply stays happened and the apparent paradox is resolved by considering* the sum of the two time lines, one (using the example above) ending in 2018, one beginning in 1918, and their 100 years of overlap (but probably not simultaneous existence).

    *Theoretically: More practically speaking, this might be impossible to actually achieve, because of insufficient knowledge of the overlap. Possibly, the new timeline will just see a so-unlikely-as-to-be-virtual-impossible physical coincidence creating the time-traveler out of thin air.

    This can be compared to the same river with the alteration that the diversion does not cease again, when water levels drop.


Written by michaeleriksson

February 25, 2018 at 10:14 pm

One Response

Subscribe to comments with RSS.

  1. […] A similar trend is seen in “Counterpart” (mentioned as “very promising” in my recent post on “Back to the Future”): Two alter egos (or counterparts…) from different realities meet each other and eventually […]

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: