Science Behind the Fiction: Netflix's Russian Doll plays with the reality of Quantum Immortality

What if the decisions you made weren't permanent? What if no matter how badly you messed up, you could try again? Or rather, what if you were forced to try again? These are the questions Russian Doll, a new Netflix series created by Leslye Headland, Natasha Lyonne, and Amy Poehler, asks ... over and over again.

The series opens on Nadia's (Lyonne) birthday party. She's turning 36, and she's not particularly psyched about it. Her mother died at 35, and Nadia sees that as a cursed birthday. She's not wrong. See, Nadia dies today, over and over again. But no matter what happens, no matter what decisions she makes, no matter the manner in which she dies, she always comes back to life no more than 24 hours before.

It's difficult to think about Russian Doll without also thinking about Groundhog Day, or, more recently, Edge of Tomorrow and Happy Death Day. This isn't the first time we've seen time loops used as a plot narrative. But Russian Doll isn't content to just accept the repetitions as par for the course; it subtly nods toward a potentially real-world explanation.

*Spoiler Alert: There are spoilers for Russian Doll below*

Unlike Bill Murray's character in Groundhog Day, Nadia doesn't experience a perfect recreation with each loop. Instead, she starts to notice minor changes: missing objects, people in different places and doing different things. It's as if her reality is shifting with each iteration. No one else seems to realize anything has changed, which is our first hint toward what might really be going on. The point is reinforced in the fifth episode, when Nadia asks, "What if they keep going?" They being the other versions of herself, her friends, and her family.

The implication is, Nadia is experiencing a death loop followed by beginning again, but it's an illusion. In reality, every time she dies she's actually dying, just not in this reality.

These experiences, while fantastical, are rooted in an established scientific thought experiment known as Quantum Death, or Quantum Immortality.

In order to discuss Quantum Immortality, we must first discuss Quantum Mechanics, an inherently fuzzy endeavor. Richard Feynman once said, "I think I can safely say that nobody understands quantum theory," but we're going to try anyway. Let's start with the double slit experiment.

QUANTUM FUZZINESS

Let's say you put up a wall, and in that wall is a slit, behind which is another wall. Then you pick up a Nerf gun and start shooting darts at the wall. When your magazine is empty and you look at the back wall, you'd expect to see a pattern of darts, mostly resembling a straight line, directly behind the slit. And you'd be right.

You repeat the experiment, only this time there are two slits. By firing the darts at the wall, you'd expect to see a pattern of two lines when you're finished. But if you do this experiment with electrons instead of darts, that isn't what happens. Instead, you see a series of many lines, where the darts (electrons) interacted with one another, bouncing off and canceling out.

By introducing a second opening, you've opened the possibility of a wave probability. In short, instead of the darts being forced into one eventuality, you've allowed for any and all possible conclusions. If this all sounds unrealistic, you're not alone in that thought.

What's more, if you observe the path of the darts or electrons by placing a measuring device near one of the openings, they no longer behave as a probability. The wave function collapses and you see what was originally expected, a pattern of two lines at the far end of the openings.

This suggests that, at the quantum level, reality behaves as a set of probabilities. Anything that can happen, will happen, at least until the event is observed. This is the primary concept behind Erwin Schrödinger's famous thought experiment.

While Quantum Mechanics has survived rigorous experimentation, the interpretation of the data has been the subject of much debate. Several hypotheses have arisen from the data. The Copenhagen interpretation is one such conclusion and suggests that measurement, or subjective experience, forces the wave function of quantum behavior to collapse, forcing only one reality to exist. Meanwhile, the Many Worlds Interpretation suggests that all possible outcomes exist within their own contained realities; the cat, which is both dead and alive before observation, continues to be both dead and alive afterward, in distinct realities.

HOW I LEARNED TO STOP WORRYING AND LIVE FOREVER

The Many Worlds Hypothesis was first suggested by Hugh Everett III. His paper The Theory of the Universal Wave Function laid the groundwork for his ideas. According to Everett's colleague Keith Lynch, "Everett firmly believed that his many-worlds theory guaranteed him immortality: His consciousness, he argued, is bound at each branching to follow whatever path does not lead to death — and so on ad infinitum." Sadly, Everett died of a heart attack at age 51, at least in this reality.

His thought experiment, based loosely on the same ideas that govern Schrödinger's Cat, takes the observer inside the box. The probability of survival is the same: 50 percent. But the observer, now inside the box, can only experience one outcome, the one in which they survive. By repeating the scenario indefinitely, we find that the experimenter always lives, while the probability of living continually decreases.

The ultimate conclusion is, so long as there is a non-zero probability of living, the observer (you) will survive.

Taking this idea to its extreme, when considering increases in medical technology and ideas suggested by futurists, the probability that you will live an incredibly long time may be non-zero; therefore, according to Everett, you may never personally experience your own death. Instead, you might experience a sequence of close calls that never come to fruition while in other planes of existence your loved ones bury infinite versions of you. Likewise, those you've lost may continue to exist in other planes of existence to which you are not privy. There's some comfort there, perhaps.

Maybe Everett is laughing all the way to eternity somewhere along the quantum wave function. Who knows? If Quantum Immortality is to be believed, it suggests that all of us might live forever, though our experience of that immortality might be incredibly lonely as we watch our loved ones fall away into their own increasingly unlikely probabilities.

Still, the world suggested by Russian Doll is an enviable one. It's a world in which your mistakes can be corrected, a world in which the severest consequences are not permanent and a do-over is always on the other side of a car crash. The payment is high, but so is the payoff.

In any event, for now, we should all strive to actualize the most ideal of our potential eventualities. Because maybe we'll live forever, but maybe not.

Russian Doll is available now on Netflix.