In celebration of everyone’s favorite web-head, July is Spectacular Spider-Month at AiPT!. We have a series of amazing articles in store for the month. Movies, television, gaming, and of course comics will all be covered with great responsibility as we honor one of comics’ greatest heroes.
At this point, after near-universal critical and consumer praise (and an Oscar win) for Sony’s breakthrough animated feature revolving around alternate dimension versions of everyone’s favorite wall-crawler, one thing is undeniable — the Spider-Verse is here to stay.
But could there be alternate versions of *US* lurking out there, somewhere, in other universes, and if so, could we ever interact with them?
Back when Dan Slott originally introduced the idea of the Spider-Verse, in something called a [pulls glasses down nose to read notes] “comic book,” I wrote about the current state of thought on whether a multiverse might actually exist. While it only took four years for the funny pages to hit the silver screen, real physics doesn’t move so fast. Not a lot has changed on that front.
Calculations of the total mass and energy in the universe are still pretty much the same, indicating the universe is likely flat in shape and possibly infinite in extent. So that remains the best bet for a (sort of) multiverse — infinite extent means every possible physical combination happens, an infinite number of times. Wouldn’t be as easy to meet your analogue as turning on a machine, though, unless you’re going to invoke the even shakier concept of wormholes.
That’s what’s been called a “Type I” multiverse. A Type II multiverse is a consequence of some versions of inflationary cosmology, the idea that there was a short period of almost inconceivably rapid expansion immediately following the Big Bang. The quantum fluctuations that caused the Big Bang were random, meaning that they’d “stop” at different points in time. While we’ve settled down here, in our own cosmic neighborhood, other universes could be continually born far away, beyond the limits of our detection.
That might sound promising, but it’s actually one of the big problems with the multiverse. If there are potentially infinite other universes out there, with infinitely diverse sets of physical laws, it’s impossible to make testable predictions about what we might find. Any random guess would be right.
Stephen Hawking says hold the phone, from beyond the grave! In his final paper, written with Thomas Hertog and published posthumously last year, the famous physicist tweaked some beginning conditions to find a way that the multiverse would actually be finite, so there actually could be useful predictions made (though the pair didn’t suggest any particular experiments). Hawking simplified a lot to make the math work, and even invoked the bizarre holographic principle, so many argue the paper was a neat exercise, but it didn’t actually get us anywhere.
The Type III multiverse is the one we’re probably all most familiar with, as it even wound up in Avengers: Endgame with all the other quantum jibber-jabber. It’s the so-called “Everett interpretation” of quantum mechanics, named after physicist Hugh Everett III (coincidentally enough), which says all outcomes occur somewhere — when a thing happens here, everything else that could have happened instead kicks off a whole new universe, like an endless unfurling of What If? comics.
Earlier this decade, some cosmologists thought there might be evidence in the cosmic microwave background radiation (the “afterglow” of the Big Bang) for other universes “bumping into” ours, but later, better data falsified that claim. And besides, if the radioactive spider did bite Gwen instead of Peter, creating a new world, there’s really no imaginable way for her to travel between universes in a Type III multiverse. Even wormholes are out.
But now there’s yet another idea, with a concrete experiment set to happen soon. Strangely enough, neutrons created in particle beams take longer to decay than those just sitting around, and no one knows why. One thought is that some of those “normal” neutrons might be decaying into something else we can’t detect. In fact, one of the weird aspects of the weak nuclear force that governs neutron decay could be explained if all particles had a corresponding “mirror” particle, and it’s the creation of “mirror” neutrons that’s fouling up our counts.
So Leah Broussard of Tennessee’s Oak Ridge National Laboratory decided she’s going to blast billions of neutrons against a wall to see if any come out the other side. None should, so any that do would represent neutrons that turned into mirror neutrons, and then back again, revealing that there really is a “mirror universe” slightly askance from our own. But that’s more Dr. Strange than Spider-Verse, isn’t it?
In any case, whatever the outcome, we should all remember that a single experiment never proves anything. As with the previously mentioned microwave background data, and those faster-than-light neutrinos that weren’t, things can go wrong and data can be incomplete. When the existence of our otherworldly doppelgangers is on the line, we’d better double check to make sure.
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