When I was a very young kid, maybe five, I found the book Stranger Than Science by Frank Edwards — a sort of compendium of Forteana, UFO tales and ghost stories.
There was one story in the book about two American women — schoolteachers, as I remember — who were visiting Versailles on vacation. As they walked around the grounds, they turned a corner and found themselves surrounded by people in late 17th century clothing who appeared to be having some sort of party. Assuming it was some sort of historical re-creation event, the women observed the whole spectacle for a while, amused…but when they turned another corner, they found the “actors” had simply disappeared.
Turned out, of course, that there had been no such “event” held that day…and furthermore, when the Americans talked to one of the resident historians, they discovered that what they’d seen corresponded with a very specific party held during the reign of Louis XIV, the Sun King.
I have no idea of the veracity of this story, but it often occurs to me when I think about the theory of the multiverse — the notion that there are an infinite number of parallel universes, new ones being formed every nanosecond, each one containing one possible “timeline” of probability. (I’m simplifying the hell out of this, of course, but you get the general idea.) In this multiverse, adjacent universes would be almost identical to one another; for example, a nearby universe to ours would be absolutely identical except that one molecule of one leaf on one tree on one planet halfway across the galaxy would be slightly different. Presumably, the further you got away from any given universe (along some dimension perpendicular to linear time, one would guess) the universes you passed through would be more and more different from the one you started from.
Because an infinite number of universes would display an infinite number of possible initial conditions, not only any but every possible universe one could imagine, and an infinite number of universes one couldn’t, would exist — including universes where, say, everything was identical to ours, except human civilization started a few centuries earlier, but played out identially otherwise. Such a universe would seem absolutely identical to ours, but if we visited it it would seem like we’d gone back in time. (Dates would be the same, because nobody’s counting precisely from the time human life formed or anything.)
If this sounds familiar, it’s because it’s the premise of the Michael Crichton novel Timeline, in which a group of medieval archaeologists have to travel back in time to feudal France, because otherwise it’d be a short and rather pointless book. Crichton pointed out, correctly, that most physicists who subscribe to the multiverse (or “many-worlds”) theory believe that other universes are impossible to reach from our own; that all of these universes are only permeable from one to another at the very smallest quantum levels of scale, where reality itself seems to break down entirely.
But here’s my question: if all of the “adjacent” universes are essentially identical to our own, how would you know if you’d walked out of one and into another, if everything was exactly the same except our one molecule on one leaf on one tree on one planet ten thousand light years away? How do you know it’s not happening all the time, a dozen or a hundred or a million times a day, you flitting from one reality to another, like walking back and forth across the border between one US state and another? What if we exist not in a single universe, but in a sort of cluster of probabilities, universes almost but not quite exactly the same?
And what if, one time out of a million or billion or trillion, you walked out of your own “home” universe into one that wasn’t identical enough as to be unnoticeable? One where, for example, it was still the 17th century, on a lazy summer day when Louis the Sun King was having a revelry in his country palace?
I’m not saying I believe this, or even necessarily think it’s possible. I see no reason why it couldn’t be possible, though the notion is a bit too tough for Occam’s razor to easily cut.
But what if the fundamental way reality works is much more complex than we think? And what if those teachers weren’t mad or lying?
What if they simply walked through a hole in one universe and spent a charming afternoon in another?