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Time for Speculation

There's no time for this.

by
Charlie Martin

Bio

October 31, 2013 - 5:00 pm
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Salvador-Dali-Soft-Construction-with-Boiled-Beans-Premonition-of-Civil-War-1936

Time travel is a favorite trope of science fiction going back to at least A Connecticut Yankee in King Arthur’s Court and The Time Machine. It took until the mid-40s for someone to come up with the grandfather paradox, which has been pretty well beaten to death in the years since. (How many times has Star Trek alone used it?)

So I started thinking about time and time travel, primarily to see if I could find a theory that would result in new ideas for a time-travel story. While story ideas were not forthcoming, I did come up with a reasonably interesting idea.

Since Einstein and Minkowski, we’ve become used to thinking of time as the fourth dimension. In normal life, we think about locations basically in terms of three numbers: x, y, z, latitude, longitude, and elevation, Fifth and Broadway on the 14th floor, whatever. But if we want to meet someone at Fifth and broadway on the 14th floor, we have to also tell them what time we’re going to meet, say 1:00 PM. Einstein’s general relativity showed that we have to think about time in general as a fourth dimension for everything, not just dates with the brunette you met on the subway, so we always need x,y,z,t.

Now, imagine we could step back from the universe and look at the whole thing, all at once. Then what we think of as our history becomes a path through the whole four-dimensional universe: Fourth and Broadway on the street at 12:54 PM, Fifth and Broadway on the street at 12:56, in the elevator at 12:58, at the new friends office at 1:00 PM. Physicists call this a world line.

Now, you can also imagine that small changes lead to slightly different world lines: the elevator makes a few extra stops and you’re a minute late, or you took a taxi and you’re a few minutes early but you took a different path. Since we’ve stepped back, with Godlike omniscience we see not only everything that is actually on your world line, but every possible world line — so both of those along with all possible other choices are part of the whole picture, along with every other possible arrangement of the pieces: you took the subway, you walked, a taxi brought you down Broadway from uptown (to the sound of honking and shouting, I think Broadway is one way the other direction). In fact, our omniscient view even includes arrangements that aren’t possible, like the one where you simply levitated, or just disappeared one instant and re-appeared the next, teleporting where you wanted to go.

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All Comments   (10)
All Comments   (10)
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Great stuff! Thanks for the links. Maybe I haven't been hallucinating after all.
1 year ago
1 year ago Link To Comment
My own theory about "time" is, something like Barbour's. Material existance, as we know it is only "now." The future is just potential energy and probabilities. As the succession of "nows" proceeds, the probabilities converge and result in an instant of existance, where both matter and energy coexist in delicate balance. Once the moment is past, you are left with just cold, dead matter (I prefer the term ashes). "The future is but dreams, and the past is but ashes."

If you could stand back from this and watch it as a bystander, it would be something analagous to a fuse that is continuously being formed from future probabilities and potential energies. The distant future "nows" are quite indistinct, while the near future nows take a more definite form, until they reach what we perceive as the present, the spark, so to speak of that burning fuse. And when it's done, just ashes.

This gets a lot deeper if you talk about corporal and spiritual existance, and the possibility that our spiritual existance exists outside the progression of nows, and is, if you will, timeless.
1 year ago
1 year ago Link To Comment
The problem with the Grandfather Paradox is that it's all theoretical. Until (and unless) we can do time travel, we won't know how this works out... so all we can do is concoct lovely theories.

In the end, there are no paradoxes in nature, only in the way we describe nature. Usually a "paradox" is our way of saying "it seems like it should work out like THIS, but somehow we don't think that makes sense"... which usually means that our ideas of what makes sense need revision.

Remember the Twins Paradox? Special Relativity predicted time dilation, meaning that if one identical twin left home and traveled close to the speed of light, then returned, he'd be younger than his twin, because time would have slowed down for him. Today this isn't considered a paradox at all; we've adjusted our standards of what makes sense and how things work. But at the time, it was called a paradox... because everyone knows that twins are the same age, and that never changes!

There are a few theories out there for time travel that would not violate causality. (See "Thrice Upon A Time" by James P. Hogan, for example.) Maybe one of them is the way our universe actually works. Maybe not. Maybe one day we'll know. Or maybe we'll stick with Larry Niven's hypothesis, which is that time travel creates paradoxes, and thus the universe self-corrects into a state in which time travel is never invented by anybody. (Admittedly, that sounds a lot like the self-justification that used to predict that the "sound barrier" would never be broken.)
1 year ago
1 year ago Link To Comment
As to the Grandfather Paradox - I've often wondered about this - I see a third possibility here...that the universe won't prevent you or self-correct, but will just go ahead and allow you to delete yourself from the timeline. Why not? It resolves the Paradox, doesn't it?
1 year ago
1 year ago Link To Comment
What about all the things you did before then? What if *you* had a child?
1 year ago
1 year ago Link To Comment
That's the old parable of the Drowning Man, who shouts out at the universe, "But I exist!" "The universe replies, "yes, but that does not instill in me a sense of obligation," and so the man drowns.

Why would an entire timeline care if you self-deleted, up to and including your own descendents?
1 year ago
1 year ago Link To Comment
Headline: Physicist Says Cause, Effect Unrelated

If general relativity is correct (and there's as of yet no reason to think otherwise), then space and time are co-related, time is linear, and the grandfather paradox is valid.

Elegant equations are nice. Even interesting. But they aren't worth a can of beans unless they're predictive. And if time is not linear, predictive is an impossible hurdle to clear.
1 year ago
1 year ago Link To Comment
Well, no. First of all, Barbour isn't getting rid of cause and effect; cause and effect is what we observe as a result of what the most probable transitions are between "instantaneous states". My theory of time travel would mean finding a way to make improbable transitions.

As to the other part, well, there's this problem: right now GR and quantum theory are incompatible. The Wheeler-DeWitt equation and what follows it offers a way that makes them compatible, but loses time in the process. Both GR and quantum theory are marvelously predictive. Now what?
1 year ago
1 year ago Link To Comment
Fourth and Broadway on the street at 12:54 PM, Fifth and Broadway on the street at 12:56, in the elevator at 12:58, at the new friends office at 1:00 PM.

That means you left the diner on Great Jones at noon. And it's 1928.
You're lookin' swell Dali, I can tell, Dali
Your'e still glowin' you're still crowin' you're still goin' strong
1 year ago
1 year ago Link To Comment
At 4th and Drucker he turns left, at Drucker and 4th he turns right, he crosses MacArthur Park and walks into a great sandstone building. (smack)
1 year ago
1 year ago Link To Comment
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