Applying Occam's razor to fictional time travel

[prog]

In the last few years I have settled on what I can't help but feel is the inarguably most elegant way to resolve time travel when used as a plot device, particularly in regards to in-story concerns over "temporal paradoxes". These ideas synthesize descriptions seen in works like Greg Benford's Timescape and the film Primer, which, as I think their

Comments

[cortezopossum]

One problem I have in the whole 'traveling back in time splits the universe into two' idea is that in order to split the entire universe you need to somehow gain the mass-energy for that entire universe

[prog]

My whole thing rests on the assumption that you get your universe-splitting for free by dint of the many-worlds hypothesis being true. In that case, a time-traveler's emergence into their own timeline's past is just another quantum event that results in a world-fork, such as surely as putting a cat in Schroedinger's box does.

If many-worlds isn't true, than yeah, my method is way too expensive to pull off as written. :)

[cortezopossum]

Another possibility that kind of works in both cases is if you have a whole bunch of 'universe time lines' all tightly woven and bundled together kind of like a rope, again with individual threads splitting and merging at various points. Along comes a time traveler and changes a significant event -- from then the entire rope splits with one group being the 'new timeline' and the remainder being the 'unchanged timeline'. Again for symmetry stake it's possible for these large bundles to merge however they may not merge at all -- you could have a slow 'unraveling' of timelines as you progress which would represent an increase in the entropy of the multiverse.

[synchcola]

Sorry, I'm a random person from internet

[gemini6ice]

This seems to be the theory that Doctor Who uses.

[mmcirvin]

Sometimes. But they're really very loose and inconsistent about it.

An element that they emphasize in the new series, though it was arguably present to some degree in the old one, is that some things about history are OK to change and some aren't, and attempts to mess with the latter category cause poorly-defined cataclysms, ranging from flying monsters eating the universe to history collapsing into a surreal mess in which everything happens at the same time and the calendar date never changes.

The difference between the two kinds of event is only Time Lords understand shut up.

[gemini6ice]

You're right. I haven't come across things about history that he's explicitly changed yet. It seems that most adventures of the week are already how things turned out in the timeline we're in, so he's just fulfilling prophecy, in a way.

[gemini6ice]

If you version A and you version B both arrive at the Sahara at the same precise time, do you fork the timeline into four paths: one where neither arrive, one where A arrives, one where B arrives, and one where both arrive?

[prog]

I'm not sure what you're asking exactly. Two parallel iterations of the same traveler making the same trip at the same time will result in two new universe-forks at the point they emerge into their own timelines' respective Sahara deserts. They cannot interfere with one another, being in wholly separate universe-branches to begin with, if that's what you're wondering about...

[gemini6ice]

However, the second iteration's "respective Sahara desert" won't be separate *until* the first iteration emerges in the Sahara

[rikchik]

Does this connect with the "glancing blow" idea? That's where if you throw a ball that goes through a time-like wormhole and hits itself so it doesn't go in in the first place, the universe finds the solution where it hits itself just enough to change its trajectory to hit itself just enough. I kind of like it though how exactly it would work is not obvious.

[wrog]

I cannot pick up a textbook to discover that, say, World War II never happened, nor will my memories get overwritten to match reality however you intended monkey around with it. The world objectively remains exactly as you left it. Soon enough we must reluctantly come to accept you as dead, and life goes on for the rest of us.
The underlying assumption here is that the you, as observer of the "original" timeline, continue to exist with your original memories/experiences of the world around you intact. It's possible to imagine sensible (*) rewriting regimes in which, if the timeline gets rewritten, you're just gone, just as if you were flash-incinerated by a nuclear bomb; barring metaphysical life-after-death wankery, there's no you there to ever know the difference.

One of the key points of the Schroedinger's Cat scenario that everybody seems to miss is that the box is never actually opened. If at any point you ever open the box, all that means is that the boundary conditions were not what we thought they were (**), the solutions