Forum:Alternate timelines vs. parallel worlds

In the thread Alternative timeline individuals, the issue came up of whether alternate timelines and parallel universes are distinct things in the Whoniverse.

The article Alternate timeline starts with:


 * An alternate timeline is a reality which is different from a parallel universe in that historical events have been altered by a time traveller or other temporal phenomena. These alterations can be prevented from having ever come to pass, although memories of them are usually retained.

Meanwhile, Parallel universe starts with:


 * A parallel universe was a reality created when historical events diverged from the main timeline. Unlike alternate timelines, these occurred naturally. Travel to parallel universes became impossible after the Last Great Time War.

I brought up the fact that there are "other realms that aren't alternate timelines, but also aren't part of the main Whoniverse" as a minor side argument against tossing individuals from non-canonical stories into an "alternative timeline individuals" category.

CzechOut pointed out that the only evidence for any such distinction is some vague comment by Sarah Jane in one SJA episode.

There are definitely other places where a distinction has been made in-universe. Sometimes it's just as simple as the Doctor saying "It's not an alternate timeline, or a parallel universe, or…", implying they're two different things; sometimes it actually explains some difference. And maybe in general there's more of a sense of "wrongness" when the Doctor talks about alternate timelines than when he talks about parallel universes.

But I sincerely doubt there's anything like the clear, solid distinction that we're making on this wiki. And there are probably a lot of contradictions. On top of that, these aren't the only two terms that are ever distinguished; there are also alternate histories, strands of the multiverse, and so on, which are all similar and related ideas but with different connotations. And that's not even counting things like the bottle universe from Interference, the bubble universe from The Doctor's Wife, E-space, the universes before and after this one, the universe next door, etc., all of which sometimes serve similar narrative purposes.

Even though we have in-universe evidence that the Doctor can clearly distinguish them all, if he never gives us enough information to make that distinction, we shouldn't be trying to make one up on our own. --70.36.140.19 08:24, September 18, 2011 (UTC)


 * By the way, I believe the distinction between "alternate" and "parallel" in SF/AH fiction in general comes from Poul Anderson (or at least Niven credits him with it). In his tradition, an alternate world is a parallel world where there is a clear single point of divergence. But I don't think that's relevant to the Whoniverse. (Or, rather, it's probably true in some sources, but not others.) --70.36.140.19 08:36, September 18, 2011 (UTC)

The definition that you gave about a clear single point of divergence is basically correct, at least if you go by the majority of science fiction. I'm not sure if they've ever defined in Doctor Who, but a parallel universe would be what the Doctor encountered in Inferno and Rise of the Cybermen, while an alternate timeline would be what he encountered in Turn Left and The Big Bang. Even though with all the time travel in Doctor Who, each episode would probably take place in a slightly alternate timeline, there are still some alternate timelines that are more radically different from the "main" one. Basically, if somebody travels back in time and changes something, then it's an alternate timeline, but if somebody travels through the void to another universe than it's a parallel universe. E-space, the bubble universe, and the universes before and after this one are not parallel universes, but just different universes. The non canon stuff isn't anywhere in the multiverse. Its the same reason that we really know that Shapiro isn't Q in diguise.Icecreamdif 18:24, September 18, 2011 (UTC)

What we can gather about alternate timelines, at least from the episodes and novels that are springing to mind, is that they aren't normally created by time travel into the past, but can be; they're usually caused by a single POD; they're usually unstable; they at least sometimes requires a great deal of energy to sustain; they "feels wrong" to the Doctor and often to the TARDIS; and they can be—and usually should be, and usually are, by the end of the story—"collapsed" by either undoing the POD itself or by introducing some change that counteracts it. In some cases, collapsing it tragically means that billions or quadrillions of sentient beings will never have existed, but usually this apparently isn't a concern for some reason. There clearly is some distinction between alternate timeline and parallel universes, and the Doctor can tell them apart from in-universe, but he never tells us how.

It's actually pretty easy to tell the difference from out-of-universe: An alternate timeline is something the Doctor is trying to collapse, while a parallel universe is something he's trying to get out of. The question is, do we actually have a good in-universe distinction that we can use on this wiki? I don't think we do.

The single-POD distinction used by the AH community does work, at least reasonably well, but there are plenty of exceptions—the cracks caused many separate points of divergence in The Big Bang, and so did the Council of Eight in Sometime Never…, for just two examples. Also, why is Just War explicitly not an alternate timeline, when it was caused by the Doctor accidentally changing history, and collapsed when he and his companions countered that change? For that matter, do we actually know that there were multiple PODs in Inferno and Pete's World? More importantly, I don't know of any in-universe or behind-the-scenes source that corroborates this distinction.

The POD-caused-by-a-time-traveler vs. POD-caused-naturally distinction that the wiki currently uses is much less common in AH/SF in general, no better supported in-universe, and no more workable—again, the divergences in The Big Bang were caused by cracks in the skin of the universe, and those in Sometime Never… were caused by the Council sitting in their Vortex Palace.

Even separating multiverse-y things like alternate timelines and parallel universes from big-universe-y things like E-space and the universe next door isn't always easy. For example, before the new series, the Void was always the space between the separate universes (e.g., The Taking of Planet 5, and a string of NAs), while in the new series, it's usually the space between parallel universes in the multiverse (Army of Ghosts)—although even that isn't always consistent; often travel between parallel universes is described in terms of breaking through the walls between them, rather than traveling through the Void between them. On top of that, the multiverse/parallel worlds/etc. thing isn't always kept separate from the second dimension of time.

If we don't have an in-universe-supportable distinction, I don't think we should try to invent one. We should have a single article describing all of the "multiverse-y" things, which states only what we know about each (possibly including an out-of-universe section describing stuff like the fact that the Doctor is always trying to collapse alternate timelines but not parallel worlds), and doesn't try to categorize any stories, especially not ones where the Doctor didn't explicitly tell us which one they were.

But I have no idea how to reorganize the existing pages to do that. --70.36.140.19 00:15, September 19, 2011 (UTC)