The Science Behind Stranger Things ‘Upside Down’

The Stranger Things series, which has attracted the attention of many people in recent days, after the release of the fourth season on the Netflix platform, is full of interesting references. Among them are quotes from the works of Stephen King, Spielberg, and even the Cave of the Dragon. But the references are deeper and more complex when you dive straight into the content of the series.

In the first season, for example, character physics professor Hugh Everett mentioned the “many worlds hypothesis,” which was proposed in 1957, and which was the first to put on paper the idea of ​​”parallel universes,” something that today permeates many of studies. Anyone who’s watched the series knows that Stranger Things’ “Upside Down” is a parallel universe unto itself. But let’s talk a little more about the theory proposed by Everett.

The American physicist, at first, developed his theory based on his concern about a feature of quantum physics. The hypothesis that kept Everett awake at night was that if we are particles, we are not really ourselves, but a cloud. In the same way that the clouds that we see in the sky are made of water, the “cloud” in this case will be formed from several versions of our personality.

The problem with all this is that when someone visits us, that person will not see this cloud full of our clones, but only one of the infinite versions of our individuality. All the others, at this moment, will cease to exist. It may sound crazy, and it probably is, but that’s how quantum physics works.

When we think, for example, of the electron, it is actually a “cloud of possibilities”. Observing an electron, we theoretically have a 20% chance of finding the electron in one part of the “cloud”, 99.7% of finding it in another part, and 5.14% in a third…never 100%, never 0%. But all these possibilities, even if they seem strange, are real. It is as if they correspond, individually, to a different electron. In other words, the same electron can be in several places at the same time.

When you find an electron in a point in the cloud where the chance of it appearing was 5.14%, other infinite points in the cloud cease to exist. In theory, it is as if an infinite number of electrons have left the universe so that the cloud of probability leaves only one particle in reality. In other words, the electron was omnipresent in many parts of the cloud, but when it finds it at a certain point, all the other parts automatically disappear.

And in Everett’s theory, each of those electrons that no longer exists goes to a different parallel world. For him, finding an electron in one point of the cloud does not simply make all the other points evaporate. In fact, for a physicist, what happens is that electrons split into infinite copies, scattered across an infinite number of parallel universes.

Everett’s idea isn’t exactly crazy, though it might seem. The theory predicts that there is not just one universe, but an enormous amount of “multiverses”. Supposedly, in one of these universes you were never born, while in another the Earth probably doesn’t exist, and in the third you’re probably Barcelona’s No. 10 and you’re on the cusp of winning the Ballon d’Or. But the big question is, can we connect to these other universes? Practically speaking, the answer is of course no, but things are a bit more complicated.

According to the physics we have today, other universes can exist as long as they do not overlap our dimensions. Theodore Kaluza, an early 20th century physicist, hypothesized that if our universe had four dimensions of space (as opposed to the three we already have), gravity could work based on the equations of electromagnetism.

But to save Klosa’s idea, physicist Oscar Klein came up with another idea, which later led to the story of the ant in a straw, which you may have heard. But in case you haven’t heard of it before, we explain: Think of a giant straw, bigger than a football field, for example, now, I think, an ant was put inside by someone. From an ant’s point of view, the straw is all it knows, and as much as you spin around and spin inside it, you’ll hardly be able to get out of it. However, to an outsider, from afar, the straw seems to be just a very thin one-dimensional line. An ocean through which an ant can walk its whole life, to those who see it from afar, does not seem to exist.

From this idea, known as the “concept of coiled dimensions”, another story often told by physics teachers emerged: the story of “Flea Walkers and Tightrope”, which is even used as the title of one of the episodes of the Stranger series of things. The tightrope walker in this story is us, who can’t help but walk forward or backward on the rope, which is an analogy to the only dimension of space we have.

The rope, in turn, is the straw proposed by Klein, through which the fleas can move freely, bypassing all other dimensions of space. These days, a number of physicists are divided over string theory, which arises from the mixing of all these concepts together. Those who believe strongly in it say that our world has nine dimensions – six of which are “wrapped” and three, which we can experience, are “stretched”.

In the end, this is all just a theory, as the characters of the series are careful to remember at some points in the plot. The same physicists who believe in these concepts say that in order to “break through” a coiled dimension, it will be necessary to exert a colossal force, which we have not yet been able to produce.

Edward Witten, of the Institute for Advanced Study in Princeton, is one of the most respected names when it comes to discussing the multidimensional world. And for him, the multiverse is made up of several different universes, each with at least 10 dimensions.

These ten dimensions are, for Witten, “encapsulated” by the eleventh dimension, which serves as a platform for all other dimensions to float. Practically speaking, this eleventh dimension will touch all others, and perhaps that is why the main character of the series “Stranger Things” is rightly called “Eleven”.