The idea of a parallel or alternate universe is central to Fringe. There’s plenty of weird stuff on the show, but a major element is the conflict between an alternate universe and our own, and inability of these universes to coexist.

Parallel and alternate universes are a popular element in science fiction, and the reason is obvious: a world that’s like ours (but isn’t ours) is rife with possibilities. It’s a writer’s dream and provides all manner of delicious opportunities for characters meeting their doppelgängers, examining outcomes based on different choices or events, and even the occasional “bizarro” episode.

Let’s start by saying that multiverse theory is complex. There are several different theories, none of them proven, and they all approach the idea of “alternate” or “parallel” universes in a slightly different manner. But let’s start simple.

What Is The Multiverse?

Simply put, multiverse theory centers around the idea that the universe we know and inhabit may not be the only one. In fact, it may be one of many. Though on the surface it sounds like something of a far-out notion, the theory has been deemed plausible and is gaining traction in the scientific community.

Problem is, that’s really difficult to prove. Not impossible, given, for example, the ability to maybe observe the gravitational effects of another universe on our own with satellites like LISA. There’s also the idea that if the inflationary theory (which we’ll get to in a second) is correct, there may be observable hot spots and cold spots in the universe thanks to what theoretical physicist and string theorist Brian Greene calls “tiny quantum jitters.”

Brian Greene and Multiverse Theory

Ignoring the significant problem of provability, the idea of the multiverse in broad strokes is theoretically sound. In a TED Talk on the subject, Greene explains string theory, how it plays into multiverse theory, the almost inconceivably small amount of dark energy required to push forward our rapidly expanding universe and the attempt to reconcile that number with the laws of physics.

To put it (possibly too) simply, string theory is founded upon the idea that there are vibrating strings of energy that are fundamental and which produce different particles based on their vibrations. “In string theory, vibration determines everything,” Greene says.

But the key element of string theory here is that for it to work, we have to allow for the idea of extra dimensions — that is, dimensions beyond height, width and depth.

Putting that on hold, Greene brings up the Big Bang and explains an enhanced version of the theory behind the Big Bang.

“It’s called inflationary cosmology, which identified a particular kind of fuel that would naturally generate an outward rush of space. The fuel is based on something called a quantum field, but the only detail that matters for us is that this fuel proves to be so efficient that it’s virtually impossible to use it all up, which means in the inflationary theory, the Big Bang giving rise to our universe is likely not a one-time event. Instead the fuel not only generated our Big Bang, but it would also generate countless other Big Bangs, each giving rise to its own separate universe with our universe becoming but one bubble in a grand cosmic bubble bath of universes.”

Greene goes on to explain how, exactly, this matters in terms of multiverse and string theory by saying that the extra dimensions of string theory dictate the shapes of universes in a theoretical multiverse.

“And now, when we meld this with string theory, here’s the picture we’re led to. Each of these universes has extra dimensions. The extra dimensions take on a wide variety of different shapes. The different shapes yield different physical features. And we find ourselves in one universe instead of another simply because it’s only in our universe that the physical features, like the amount of dark energy, are right for our form of life to take hold. And this is the compelling but highly controversial picture of the wider cosmos that cutting-edge observation and theory have now led us to seriously consider.”

Fringe and the Multiverse

So where is Fringe in the larger scheme of multiverse theory?

Let’s talk what we know about the alternate universe in Fringe and discuss them in terms of a few multiverse theories that come from Brian Greene’s 2011 book The Hidden Reality: Parallel Universes and the Deep Laws of the Cosmos.

First, the alternate universe in Fringe is like our own, but also not like our own. It has many of the same people, but some are dead in the other universe while their counterparts are still alive in this one and vice versa. Not only that, but it seems as though Manhattan is mostly the same in both places, with a few notable differences: big airships, a non-oxidized Statue of Liberty and the Twin Towers.

Theoretically, this universe could exist in the quilted multiverse theory which says, to simplify things immensely, that every possible permutation of reality that physically can exist does exist. Under this theory, the alternate universe with Fauxlivia and Walternate must exist simply because it is physically possible.

Related to the quilted multiverse theory is the theory of the ultimate multiverse, which removes the physical boundaries that constrain the quilted multiverse. In the ultimate multiverse, as long as it is logically possible, it is so. As with the quilted multiverse theory, the alternate universe in Fringe has to exist because it is not only possible given what we know about physical reality but also because it is mathematically possible.

Another possible explanation for the alternate universe in Fringe lies in the many-worlds interpretation of quantum mechanics (also called the quantum multiverse). Put forth in 1957 by Hugh Everett III, the many worlds interpretation centers around the idea that an event with more than one outcome gives way to divergent parallel universes. For example, if you flip a coin, there’s a created opportunity for two universes (at least, but that’s another discussion): one in which the coin is heads and another in which it is tails. If that’s the case, then there are a lot of parallel universes with a lot of Fauxlivias and a lot of Walternates, all of whom are playing out different versions of their lives based on choices, events and pure happenstance.

The second thing we understand about the alternate universe in Fringe is that it’s not hundreds or thousands of lightyears away, but pretty much right on top of our universe.

This tidbit, it would seem, relates more closely to the brane multiverse theory, which proposes that alternate universes don’t exist vast distances away from our own, but coexist with ours, even though we can’t interact with them. Again, to oversimplify a great deal, the idea is that open strings (back to string theory!) cannot escape the brane in which they exist, but that a loop-shaped string can. As Aleksei Klimkin says in an explanation of the brane multiverse theory:

“All the force-carrier particles except of the graviton are represented by open strings (that is why we are not able to see the other branes, since photons aren’t allowed to move from one brane to another), whereas gravitons are closed ones as determined by the value of their spin. Spin of the particles carrying non-gravitational forces is equal to 1 and only graviton is considered to have spin 2 and be represented by a loop-shaped string, thus it could escape brane’s grip and fly off the Universe. As you might guess this is one of the proposed explanations to the question of why the force of gravity is so weak in comparison with other forces. As we see, its carrier particles just can escape our Universe.”

The purpose of examining Fringe through the lens of multiverse theory isn’t to prove or disprove the show’s science or even to decide which theory, exactly, Fringe might subscribe to. Instead, we’re here to take a look at the ideas and concepts in the show and to think about them in terms of real-world science and theory. And, as far as multiverse theory is concerned, Fringe sets up some deeply compelling questions — the hallmark of any great work of science fiction.