Is this really all there is? No really, think about it: is our universe a unique and infinite phenomenon, or are there other realities where Germany won the Second World War, the Vandals didn’t sack Rome in 455 or the Chicago Cubs have a shelf full of World Series wins? It’s kind of a heady thought, right? The parallel universe concept has inspired all kinds of authors and filmmakers for sure — but the theory has some pretty big-name physicist fans as well, because the math in our current science kind of points to it.
Here are a few facts and figures about alternate realities that are sure to make you the talk of your next party — provided it takes place in a science lab.
10. It’s Not Just Sci-fi Nonsense
Sure, everyone from Captain Kirk to Buffy the Vampire Slayer’s had some sort of alternate-reality deal going on at some point, but the fact is that there just might be something to the whole parallel-universe thing. We’re going to keep it simple and start with a cosmologist named Alan Guth, who came up with the concept of “cosmic inflation,” which is the notion that for a tiny slice of time after the Big Bang, the universe’s expansion was exponential, which is to say not only fast, but holy-crap fast. Relax, you’re not going to get tested on this.
In the 1980s, Russian physicists Alexander Vilenkin and Andrei Linde built on Alan Guth’s inflation theory to come up with a multiverse concept, where inflation creates bubble universes. The way it breaks down is this: you know that big ball of boom that your TV screen shows every time a documentary mentions the Big Bang? Well, instead of that single explosion, imagine something more like a growing fractal of little expanding universes, and you’ve got it.
9. It Kind Of Is Sci-fi Nonsense
No sci-fi writer worth his or her salt can stay away from a good alternate-reality story, and if you’ve watched a lot of Star Trek, Sliders or any number of other sci-fi shows, you know all about it. There’s just something super cool about a tale set in a world that’s a carbon copy of ours, but with some sort of major twist. Put it this way: which is better, jumping the subway turnstile because you forgot your pass, or jumping the subway turnstile while being chased by Imperial Roman hoverbots? Didn’t even have to think about it, did you? That right there is why alternate-reality fiction is so popular.
8. It’s Also Fantasy Nonsense
Okay, you might not think of fantasy when someone mentions alternate realities, but there’s lots going on there, too. Hugely famous example: when Peter, Susan, Edmund and Lucy enter C. S. Lewis’s Narnia via a chance shot through a closet, they emerge into an alternate world where they’re so much more than mundane schoolkids. Slightly more cult: The Chronicles of Thomas Covenant is a sprawling series about a bitter-assed writer with leprosy who flips into a heroic figure in an alternate fantasy land. The conceit is pretty standard: total real-world zero transcends to become the savior of an alternate world, with or without dragons. If this sounds familiar, it’s because you pretty much daydreamed the same thing every math class in high school.
7. It’s Not Always What It Seems
There’s a lot of stuff on TV that takes place on a planet that has developed in a sort of weirdly close parallel to the Earth, but where something changed at a certain point, so that their version of Nazi Germany won their version of World War II, or their analogue to the Roman Empire never fell. The original Star Trek was all over this stuff, but it doesn’t count as a parallel universe so much as much as parallel evolution. Basically, if you get shot through a portal to another universe, you climb through a closet and end up in Narnia, or you phase-shift into another realm, that’s alternate-reality goodness. If you fly to another world that just happens to exist as a 21st-century Aztec empire, that’s just convergent evolution.
6. The Multiverse Idea Is Really Old
The multiple-universe concept is heavily plumbed by sci-fi and fantasy writers for sure, but the truth is that the idea goes back past Alan Guth, past C. S. Lewis and back a couple of millennia. Hindu cosmology incorporates the idea that our universe is just one in an endless cycle of universes. Carl Sagan himself said that “the Hindu religion is the only one of the world’s great faiths dedicated to the idea that the Cosmos itself undergoes an immense, indeed an infinite, number of births and deaths.”
5. Another Day, Another Multiverse Theory
Multiple universes, multiple theories. Some of them are pretty familiar by now, like the bubble multiverse imagined by Linde and Valenkin. Then, there’s the concept that every move you make spins off another in a series of branching universes, where you… wait; this is easier with an example. Say you flip a quarter. The universe branches into two realities: one where the coin comes up heads and one where it lands tails. Now imagine that happening for every decision you make. Pretty soon, you have an epic tree of branching parallel universes.
One of the strangest theories tosses a slew of new dimensions into the mix. No, really; we’re not going to go too hard into this, but M-theory (which, if you must know, is the theory that unifies five superstring theories. Again, you won’t be tested on this) calls for a universe of 11 dimensions. And things just get weirder from there.
Oh yeah, then there’s the one where we live in a black hole, and there might be universes in other black holes. No joke: there’s a huge number of philosophies grappling with this stuff.
4. We May Have Already Collided With Another Universe
There’s some pretty cool recent news that just might point towards proof that other universes actually exist. Dr. Ranga-Ram Chary of the California Institute of Technology seems to have found cosmic “bruises” left over from our universe bumping against another one a few hundred thousand years after the Big Bang. We don’t even know how to crunch the numbers behind Dr. Chary’s work, but the image of two expanding bubble universes bouncing off each other is weak-knees-level cool.
3. The Other Universes Are Likely Almost All Totally Lifeless
Okay, the math here gets pretty hairy, especially since there are so many theories to choose from. But the big idea is that not all of these other universes will have the same basic physics as ours. Many bright minds agree that a whole lot of unusual stuff happened to make our universe juuust right for life, so the idea that most of the other universes will be inhabited is basically just crazy talk. In fact, some say that without a very specific set of physical laws (make gravity a teensy bit stronger or weaker, for instance), you don’t even get stars. So for life, the chances are slim, to say the least. But with an infinite number of other bubble universes out there, you never really know.
2. The Whole Thing Sounds A Bit Crazy
In his book The Hidden Reality, American string theorist Brian Greene talks about nine different types of multiverse with names like Quilted, Brane, Landscape, Holographic and Ultimate. Each of these types runs on a distinct physics model. Well, except for Ultimate, which pretty much includes every model possible.
Nutso-sounding names aside, this is pretty compelling stuff. “Brane” is short for membrane, and the notion is that our run-of-the-mill universe exists on a brane, which might be moving through endless dimensions along with other branes, which are parallel universes — unless there are only five dimensions, that is. Seriously, once you cross the line into stuff this theoretical, it’s models within models all the way down.
1. This Might Really Be All There Is
Nobody likes to rain on everybody’s parade, but until there’s some hard proof, all this is just guesswork, and maybe just a touch of wishful thinking. But hey, you can’t blame us for wanting this to be true. After all, who wouldn’t love the thought that there’s another version of their own bad self somewhere who grew up to be skipper of a celestial gunship instead of a cube dweller?