Why do dopplegangers keep being born centuries after a divergence?

[Anthony]

My experience with time travel novels is that if you have an alternate reality where the dinosaurs didn't go extinct and all the people are dinosaur-people instead of human, you still are likely to have doppelgangers...

[tshiggins]

Originally Posted by Anthony

My experience with time travel novels is that if you have an alternate reality where the dinosaurs didn't go extinct and all the people are dinosaur-people instead of human, you still are likely to have doppelgangers...

It's a genre convention because that sort of thing gives the author the ability to tell an entertaining story in a comprehensible setting.

It needs no other explanation, although the techno-babble can be a lot of fun. :)

[AlexanderHowl]

Just because you have an infinity of possible timelines does not mean that every possible timeline exists. Timelines that do not maintain sufficient divergence seem to merge, creating reality quakes, which may explain why there are no functionally identical timelines (Echoes only appear to be functionally identical, we have no idea how they diverge in the Andromeda Galaxy). Without real significant divergence though, timelines probably cannot maintain separation.

As I mentioned previously, Earths that possess significantly divergent geography probably are unreachable from Centrum or Homeline unless they fortuitously possess a cavern or a mountain right where the automated conveyor exits. Imagine the surprise of Infinity if they discover a parallel because the conveyor just happens to appear in a cavern 6 kilometers below local sea level (for an Earth 0.1% larger than Homeline) or on the peak of a mountain 6 kilometer above local sea level (for an Earth 0.1% smaller than Homeline). Would Infinity be capable of exploiting the former? Would Infinity be willing to explore the latter?

[Michael Thayne]

In universe, I don't think anyone really understands this, anymore than they understand why the United States of Lizardia exists (to quote the book: "Nobody even pretends to explain any of this without talking about
'gods with a weird sense of humor.'" - IW149). But I think something like David Jonston's explanation has to be correct:

Originally Posted by David Johnston2

Myth parallels tell us that human thoughts affect the selection. Therefore differences that almost nobody would care about do not manifest as reachable parallels.

This is actually hinted at more directly in the source material. See the section on the "Williams-Khor Hypothesis" (IW21), which postulates that quanta are pin fact psychic constructs!

[malloyd]

Originally Posted by maximara

One thing people don't realize is there are different scales of Infinity. The set of whole even numbers is infinite but it is smaller then then the set of whole numbers which in turn smaller then the set of rational numbers and on it goes.

Actually all three of those infinite sets are the same size - you can establish a 1:1 correspondence in which every member of one of them is assigned to a unique member of the other. Probably anyway, there are apparently some people who will argue about whether or not two infinite sets are the same set if you rearrange the order of them, which is necessary for those proofs.

Yes this seems strange - mathematics that deals with infinity (or its inverse infinitesimals) gets slippery and counterintuitive quite quickly.

Of course there is no real evidence there are a genuinely infinite number of any sort of worlds out there.

[Fred Brackin]

Originally Posted by Anthony

My experience with time travel novels is that if you have an alternate reality where the dinosaurs didn't go extinct and all the people are dinosaur-people instead of human, you still are likely to have doppelgangers...

Specifically not the case for Lizardia. The remark is made that lizard-clones would be less weird.

[Tyneras]

My general hypothesis is this:

Similar (in some complicated non-intuitive way) timelines cluster. Excessively similar timelines merge, so all existing lines are different in some significant manner or are in danger of merging soon. Conversely, more divergent timelines are more distant and difficult to access. The current mix of accessible timelines means that the fundamental principles of timeline similarity are not understood well, even by Centrum.

Doppelgangers are the result of timelines being near each other and interfering with each other. Maybe Hitler didn't exist on Homeline until a Reich timeline got too close.

Where are the aliens?

The most common timeline involves earth being a sterile, lifeless ball. This is the same for all potentially inhabited planets. Cascading merging means that virtually all timelines have a single inhabited planet (which might be earth or might not) in an otherwise sterile universe.

This works because timeline merging can be partial and messy rather than total and perfect, which is where reality shards come from. Alien artifacts from aliens that never existed in this universe, but did visit a dead and sterile earth in their universe prior to merging and reality quakes, for example.

[AlexanderHowl]

The universe is likely not sterile though. The current thinking is that we are sharing the galaxy with tens of billions of life bearing planets. It is unknown how many of the have advanced technological life of our level or higher, but even one in one hundred thousand would mean hundreds of thousands of advanced technological sapient species sharing the galaxy with us. Of course, they would have an average separation of around 800 ly, so we could not detect them with our current technology.

[tanksoldier]

.The current thinking is that we are sharing the galaxy with tens of billions of life bearing planets.

...but the problem isn’t where life develops and a technological civilization develops from that... its WHEN.

Thousands of starfaring civilizations could have been born, existed and died out before mankind walked upright... and 5housands more may do the same after us.

The chances of a civilization anywhere close to ours existing at same time as ours is highly improbable.

[DataPacRat]

Originally Posted by AlexanderHowl

The universe is likely not sterile though. The current thinking is that we are sharing the galaxy with tens of billions of life bearing planets. It is unknown how many of the have advanced technological life of our level or higher, but even one in one hundred thousand would mean hundreds of thousands of advanced technological sapient species sharing the galaxy with us. Of course, they would have an average separation of around 800 ly, so we could not detect them with our current technology.

There's been a new paper released on this topic, "Dissolving the Fermi Paradox", readable at https://arxiv.org/abs/1806.02404 . The short, probably slightly-inaccurate version: Using some better math than has been previously applied, and taking into account the lack of any evidence of visitors, there's more than a 99% chance we're the only sophonts in our galaxy, and there's good odds we're the only ones in the universe.