Imagine this: you’re walking down the street when suddenly a car swerves toward you. In one reality, you die on impact. But in another, you narrowly escape. According to the wild theory of quantum immortality, your consciousness would simply slide into the universe where you survived—and you’d never even know you died elsewhere.
Mind. Blown.
This isn’t just some sci-fi concept dreamed up for a Netflix series. It’s actually based on legitimate quantum physics theories that have scientists and curious minds everywhere debating its possibility.
So, are you secretly immortal in your own subjective experience? Let’s dive into this reality-bending concept that might just change how you think about life—and death.
What Is Quantum Immortality? The Origins That Will Make Your Brain Hurt
The quantum immortality theory comes from something called the “many-worlds interpretation” (MWI) of quantum mechanics that American physicist Hugh Everett III proposed back in 1957. Don’t worry, we’re going to break this down into terms that won’t require a physics degree.
Basically, Everett suggested that the universe constantly splits into multiple realities where all possible outcomes of every situation happen somewhere. Think of it like this: every decision you make creates a fork in your timeline.
Let’s say you’re deciding whether to go shopping with friends. Before you choose, two potential realities exist: mall-you and stay-home-you. When you grab your keys and head out, your reality splits from the one where you decided to binge Netflix instead. Now imagine this happening for literally every decision anyone has ever made. That’s a LOT of parallel worlds.
Remember that famous thought experiment with Schrödinger’s cat? Where the cat in a box is both dead and alive until someone checks? That’s relevant here. According to standard quantum theory (the Copenhagen interpretation), when you open the box and find the cat dead, the “alive cat” possibility disappears. But according to MWI, both realities exist—you just experience one of them.
And this isn’t just philosophical mumbo-jumbo. Quantum mechanics shows that at the subatomic level, things get weird. Particles act as both particles and waves depending on whether they’re being observed (the “observer effect”). In the classic double-slit experiment, light particles behaved differently when scientists watched them versus when they didn’t. Seriously, reality changes when you look at it.
That’s the foundation that eventually led to the quantum immortality theory. And it gets even wilder.
How Quantum Immortality Works — In Theory (And Why You Might Be Unkillable)
Here’s where things get really interesting. Imagine playing a round of Russian roulette (don’t actually do this, please). You put one bullet in a revolver, spin the cylinder, press it to your head, and pull the trigger.
Conventional wisdom says you have a 1-in-6 chance of dying. But according to quantum immortality, you would only ever experience the outcomes where you survive. You literally cannot experience your own death because your consciousness would always transition to a reality where you lived.
This concept was formally introduced by physicist Euan Squires in 1986. The theory suggests your consciousness can hop between universes, always landing in one where you’re still alive. So even if you lose that deadly game in one universe, your consciousness just picks up in another universe where the gun jammed or you got lucky with an empty chamber.
Think about all those near-misses in your life—the car accident you narrowly avoided, that time you almost fell off a ladder, or the illness you recovered from when doctors were worried. According to quantum immortality, in other timelines, you actually did die in those moments. But your consciousness continued in this timeline, where you survived to read this article today.
Like particles that can exist in multiple places simultaneously, your consciousness might be doing the same thing. And since you can only observe your consciousness when you’re alive (because, well, dead people don’t observe things), you’ll always find yourself in a living state. That doesn’t mean you haven’t died countless times in alternate universes—it just means you’ll never experience those deaths firsthand.
The Problems With Living Forever (According To Physics)
In 1997, MIT physicist Max Tegmark published a paper testing these multiple-worlds ideas. He explored the concept of “quantum suicide”—essentially the flip side of quantum immortality—where a person could theoretically travel through dimensions to find a universe where they always survive ordinarily fatal events.
The quantum suicide experiment works like Schrödinger’s cat but with humans (again, please don’t try this at home). A test subject would face a “quantum gun” that fires based on quantum particle behavior. According to the theory, the subject would only ever experience the outcomes where they survive—essentially achieving immortality from their perspective.
Sounds pretty cool, right? Living forever in your own subjective experience?
Well, not so fast. Even Tegmark himself acknowledges the theory likely isn’t true, and there are some major issues with it.
For one thing, quantum immortality can’t account for physical aging and decay. How long can someone realistically avoid fatal accidents or illnesses until their body simply can’t function anymore?
Another problem is slow death. What happens when someone dies gradually over months or years, losing consciousness bit by bit? Where does a fragmenting consciousness go? Could it spread across multiple realities, essentially fracturing your sense of self?
As Tegmark himself put it: “After all, dying isn’t a binary thing where you’re either dead or alive—rather, there’s a whole continuum of states of progressively decreasing self-awareness….I suspect that when I get old, my brain cells will gradually give out (indeed, that’s already started happening…) so that I keep feeling self-aware, but less and less so, the final ‘death’ being quite anti-climactic, sort of like when an amoeba croaks.”
And finally, there’s the simple fact that we can’t prove it. Scientists currently can’t travel on a quantum level or “choose” alternate paths that would allow consciousness to continue, making it impossible to confirm or deny the theory.
For now, quantum immortality remains a fascinating thought experiment that makes us question the nature of consciousness, reality, and what it truly means to be alive—or whether versions of ourselves might be living completely different lives in realities we’ll never know.