Time Travel Roundup | Accurate Append

Time Travel Roundup

Writing for Live Science, Adam Mann suggests that the concept of time travel might be hardwired into our brains. Our tendency to conflate time and space in our linguistic structures is possible evidence of this “structural” tendency to believe that time is elastic or relative to space. Adam gives several examples using the work of Israeli linguist Guy Deutcher: the notion of “moving through time the way we move through three-dimensional space” and being “essentially incapable of talking about temporal matters without referencing spatial ones” and how the “around” in “I’ll meet you around lunchtime” are evidence that we think we can move through time as we move through space. Adam also notes that all cultures have “time slip” stories where people fall asleep, lose consciousness, sing a chant, or do other things that result in voluntary or involuntary time travel.  

Conventional wisdom on time travel these days is that we can “travel forward through time” but not backward because backward time travel results in paradoxes (more about that later). This “traveling forward through time” isn’t just a sarcastic joke meaning that we are always traveling forward through time. It seems pretty clear that we can also hack forward time travel by “jumping” forward, even in the most simple example of the “time slows down at the speed of light” narrative (which results in my travel “into the future” if I return to Earth after a few years and find that several decades have passed). 

There are other ways to accelerate/decelerate time, such as designing a controlled (but somehow supermassive) black hole in which time moves more slowly than in the space outside it. Stephen Hawking discussed this in 2010. Travelers near a black hole could travel at half the speed of time, as it were—”Round and round they’d go,” Hawking said (in the voice of Benedict Cumberbatch), “experiencing just half the time of everyone far away from the black hole.” 

But forward time travel seems rather uninspiring. If there’s no way to get back, and no way to get to the past to begin with, time travel is of limited utility. From a utilitarian standpoint, as a society or as individuals, we’d want to travel through time to fix things we are otherwise unable to correct or to learn things about the future, knowledge that is useless if there’s no way to return from the future to the present. Of course, all these things are paradoxical, and that’s exactly why they present the greatest utilitarian cases for time travel—because they overcome the “scarcity of the possible.” 

Quantum theorists see the possibility of non-paradoxical (or transparadoxical) time travel. That they see such a possibility isn’t surprising. The recent development and publicity of quantum computers’ ability to do calculations in minutes that might otherwise take thousands or tens of thousands of years understandably suggest optimism about overcoming temporal limits. 

One quantum-level approach to the paradoxes of traveling into the past is the (Igor) Novikov self-consistency principle, which “asserts that if an event exists that would give rise to a paradox, or to any ‘change’ to the past whatsoever, then the probability of that event is zero. Put another way, “contradictory causal loops cannot form, but that consistent ones can.” Another possible interpretation of the dynamics of such causal loops is that they create parallel universes like bubbles, competing against each other in a Darwin-esque fashion, until the most optimal (non-paradoxical) outcome wins. It would be the ultimate do-over.

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