Wednesday, 29 October 2014

Time Travel: CanCon 2014

This is a summary of the “Can We Time Travel?” panel from CanCon 2014. I learned about the Canadian Content Literary Convention last year, and previously blogged about that experience. I still plan to do some blogging on this year’s panels, but life is as crazy as ever. Particularly with me releasing 2,000 words every week in my “Choose Your Own Adventure” serial. (Feel free to check it out. Just saying.)

That said, priorities. Time travel has been my thing since Grade School! (It’s even a feature in my serial - where you can vote to influence my writing! Just saying.) So, if time travel is your thing too, or you simply want some perspectives on it, read on.


Panel Room, CanCon

TIME TRAVEL


The panel “Can We Time Travel? 10 Different Answers” occurred at 1pm on Saturday, Oct 4. (Or did it? Time is relative... no, ok, it did. As we understand it.) Professor Peter Watson (of the University of Ottawa) presented for about 45 minutes regarding that question. His first answer: Probably not. He started by running down the reasons why not - it’s forbidden by increase of entropy. By relativity. By logic. By cosmic censorship (according to Hawking). Alternatively, it’s possible in theory, but impractical as regards energy required. Or perhaps it’s irrelevant, because time is an illusion. For the rest of the session, he broke each of those arguments down, as follows.


Pictured: Not Now
The BIGGEST problem: Why is there a “NOW”? Our mental model of time (a linear model) sees time as a sequence of events. But in physics, time is a parameter, there is no ‘now’. Further to that, what tells us the direction of time? We like to think of “order moving towards disorder” (2nd law of thermodynamics) - is this why we think we can only go forward in time? Yet a refrigerator DECREASES entropy... as long as you plug it in (energy source needed). Peter Watson showed some videos to challenge our usual way of thinking (one of them from the show “Red Dwarf”).

What about paradox preventing time travel? First, why is it “the Grandfather Paradox” when you’re much more likely to know who your mother is than your grandfather? (Sexism? An aversion to killing your mother?) There’s also the “Where are they” paradox, in that we should now see time travellers back from the future, if they’re going to exist. Well, the ‘Many Worlds Theory’ takes care of such issues... while simultaneously being the most untestable and uneconomical theory ever. (Uneconomical because of the exponential explosion off of every action. Related to the notion of parallel Earths.)


THE MATHEMATICS



Pictured: Not quite what I mean
What about time as a fourth dimension? This is a vague concept. However, “light cones” allow us to map worldlines in a geometrical way. Picture yourself standing somewhere. You cannot exceed the speed of light, so even after a second has elapsed, we can still pinpoint your movement on a plane within a circle, the radius of which is the maximum distance you could reach. Now continue this process using time as the fourth dimension, and we get a cone, the tip of which is your starting position. All your possible futures exist within this cone. Now, can we time travel? Can we arrange for these world lines to be closed, or to intersect back on themselves?

Having turned a vague question into something specific, Einstein said NO. Conversely, Godel invented a universe where time travel is not only possible but compulsory - but it’s not our universe (it has a centre). We DO know that gravity can twist the light cone... and if you’re close to a black hole, all your possible futures involve falling into it. (“Event horizon”: The place where no events happen. Because to an external observer, there is no time.) So a Tipler Cylinder, which is infinitely massive and rotating fast CAN achieve a world line wrapping back on itself - but there’s a technical problem here. It would be made of matter a trillion times denser than an atomic nucleus. Also, more critically, the math breaks down if it becomes a finite cylinder.


Also possible: Bake Time. We clear?

So perhaps we can construct wormholes, bending space to get around the issue of massive infinities. First problem, it would allow for instantaneous communication across space (bad because... I’m not sure. Sound barrier?). Second problem, it requires negative energy to construct one. Thus probably cannot be done in practice. Perhaps then, time simply flows, using the analogy of a river, rather than existing as a separate dimension. In reality though, that isn’t useful beyond an analogy, because “rate of change” (or flow) is per unit time... so then is time “the amount of time that passes you in a given time frame”? (One second per second?)

At around this point, it was pointed out that if free will doesn’t exist, time travel is certainly possible, but it’s not very interesting. (Destiny becomes unchangeable.) Reference here to “Slaughterhouse-Five”, a SciFi novel with a war message (or vice versa), when Billy Pilgrim becomes unstuck in time. Of note, the aliens tell Billy that free will is a very human concept. There was also mention of the idea that dreams release us from linear time (and some stories do mental time travel), but then is time just an illusion? (Lunchtime doubly so?)

Well, if illusion is involved, we’re certainly not aware of the alternative. Much like asking a fish what their opinion is about water. Put another way, is a freeway ordered in time? As you move along it, events (locations) will occur at particular times - and we could return to earlier events - but this is merely mixing up spatial position with our speed. Moreover if time IS an illusion, how can we measure it to such fantastic accuracy? Why do we even care about it?

Peter’s conclusion to “Can We Time Travel?”: I wish I knew.


DISCUSSION


Peter Watson (who, by the way, teaches a course about this) then took questions for the last 10 minutes or so. I asked about the problem of an Anchor Point (which appears in my own stories). Given how we’re constantly in motion (on Earth’s axis, around the sun, etc), how can you pinpoint location along with time? Peter basically agreed that 99.9% of the time you should travel to empty space, and he’s not sure how Doctor Who manages it. (Makes me wonder if a machine itself needs to act as an anchor point, or if it can be mobile.)

Another teacher (Richard Taylor, at Merivale) asked about gravitational conventions. Zero is the baseline, so negative gravity CAN occur close to a planet, how does that affect calculations? Peter countered that it’s technically negative curvature, not negative energy. At least, that was the bit I understood. Those were the main questions I remembered. There was also a mention of “Meta Time”, the idea that big time jumps may be possible (over centuries) while little jumps are not (over years or hours), and perhaps that’s the reason we don’t see future time travellers.


The image makes sense if you know my serial.
Someone also asked Peter what he might recommend in terms of Time Travel fiction. In addition to “Slaughterhouse 5”, he had previously mentioned “All You Zombies” (by Robert A. Heinlan) and “River of Time” (by Jorma Kaukonen). Peter finished with a slide of a number of literary options, so a few more: “The Time Machine” (HG Wells), “Times Arrow” (Marin Amis), "Einstein’s Dreams" (Alan Lightman). There were also Non-Fiction books for the subject, which includes “Time Machines” by Paul J. Nahim - a book I read back in University when writing my own stories. (Apparently J. Ouellette has also written about the Physics of the Buffyverse.) With respect to movies, Peter said one of the best is “Sliding Doors”, and one of the worst is “Hot Tub Time Machine”.

To close off this post, it would seem that the one place we CAN “time travel” is in works of fiction. (Like my serial. Just saying.) It’s so dreamy. Oh, fantasy free me. ... Okay, at the least, I hope you don’t feel like the time you took going through this post was time wasted. If you have other thoughts, mention them below!

2 comments:

  1. Let's do the time warp again!

    It was an interesting panel. A few interesting ideas to use for figuring out how time travel works in a story if you don't know already. The negative gravity/negative curvature could easily explain at least one of Star Trek's methods (the slingshot at warp speed method). It's the energy needed and the destination pinpointing that gets ignored, and that might be something to explore.

    It's a matter of changing the flow of time away from 1 second per second. :)

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    1. Students at our school were performing it, it was somewhere in my conscious mind.
      I suppose given all I know, what I most took away was the reading/viewing recommendations (that I may never have time for...) and the fact that there is a course about this stuff, which is seriously cool. Good point about the Star Trek thing too. Everything comes down to time and energy, doesn't it?

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