Is There Life After Death? Science Has A Mind-Bending Prediction

Everything we know about consciousness suggests that it is intrinsically tied to our physical brains. If, for instance, your visual cortex is damaged to the point it no longer works, you will cease to experience conscious vision (though other areas of the brain can, remarkably react to visual stimuli). Likewise, many individuals with traumatic brain injury find that their ability to recognize faces is affected. Our understanding of consciousness, then, is that it needs a brain in order to function, much like software needs hardware on which to run.

So, the idea of us somehow outlasting death — the point at which our brains cease to work — seems prima facie absurd. How could it be possible that if a certain area of our brain is damaged, we lose certain abilities, but that if the entire brain stops working we're still able to have entire conscious experiences? By establishing how our subjective experience of life changes when our brains are affected, science has seemingly answered the question of whether there's life after death with a resounding "no."

But when you get into the realm of quantum mechanics things start to get very counterintuitive. We're far from proving that there is indeed life after death, but a startling thought experiment suggests that there exists something akin to this most unlikely scenario.

Consciousness is what's known as an emergent property, meaning that it arises entirely unexpectedly from the collaborative functioning of a system, in this case, our brains. Put simply, if you were to simply study the physical makeup of a brain under a microscope, nothing about it would tell you that it produces the phenomenon of subjective experience, or consciousness. This has led to the labelling of what's known as the "hard problem of consciousness," which essentially refers to the mystery surrounding why the particular physical arrangement of our own brains produces conscious experience, while the physical arrangement of, say, a rock doesn't.

You might think this obvious, and indeed, not every expert agrees that there is such a thing as the hard problem of consciousness. But many experts do agree that such a problem exists and one of the most prominent is Thomas Nagel, whose 1974 paper "What Is It Like to Be a Bat?" elucidates the issue most clearly. In the paper, Nagel writes that an organism has conscious mental states if "there is something that it is like to be that organism — something it is like for the organism." This, says Nagel, is "the most difficult" aspect with which any physical explanation of the mind must contend. Why is it "like something" to be us and not a rock?

One thing that isn't hard to comprehend, however, is that if consciousness describes what it's like to have a subjective experience, then death is the exact opposite — a complete absence of subjective experience. There is nothing that it is "like" to be dead. Therein lies the contradictory nature of even positing the idea of "life after death." One way around this, however, comes from theoretical physics, namely quantum theory and specifically a thought experiment called "quantum suicide."

In order to understand how there might be life after death from a quantum perspective, a basic understanding of quantum theory — which is concerned with the way things work at the level of atoms and subatomic particles — is required, in particular wave functions. A wave function is a description of the quantum behavior of a given particle. In much simpler terms, a wave function is an equation that describes where we might be able to observe a certain particle at a certain time. In quantum theory, before a particle is observed, it exists in a superposition of multiple states, but once it is observed the wave function collapses to a single, definable point.

This view of quantum physics is known as the Copenhagen interpretation, and is still the most widely-accepted explanation for why a particle might behave in multiple different ways. But there is another view that has been gaining more and more traction of late: the many worlds interpretation. American physicist Hugh Everett is credited with originating this theory, but Erwin Schrödinger — the man responsible for the famous Schrödinger's cat paradox — entertained a similar idea half a decade prior to Everett. 

Both, however, were concerned with negating the idea of wave function collapse, and offered their versions of the many worlds interpretation as an alternative to the Copenhagen interpretation. This theory posits that, instead of a wave being forced to collapse to a single point when it is observed, there are actually multiple universes for every possible outcome. Schrödinger maintained that those universes pre-exist the observed outcome while Everett argued that the universe actually splits into multiple timelines at the moment of observation. Regardless of whether you prefer Schrödinger or Everett's version of the theory, it's this many worlds interpretation that allows for the possibility of life beyond death.

Quantum suicide or quantum immortality takes the many worlds interpretation of quantum mechanics and tries to follow it to a theoretical conclusion. It is a thought experiment that posits that we are, essentially, already immortal due to the fact that we will only ever experience consciousness in the universes in which we remain alive.

The thought experiment imagines a person playing Russian roulette. If a revolver has one bullet in a six-chamber cylinder, then we can imagine in quantum theoretical terms its wave function as existing in a superposition of six possible outcomes — five in which the person survives and one in which they die. Using the Copenhagen interpretation, this superposition collapses into one outcome as soon as the trigger is pulled. But according to the many worlds interpretation, there will be six universes created by this experiment: five where the human survives and one where they die. The immortality element comes into play by virtue of the fact that consciousness and death are incompatible. You cannot experience what it's like to be dead, therefore your consciousness will always jump to the timeline in which you survived, basically making you immortal.

This neatly gets around the whole "consciousness is tied to the brain" problem of life after death in that there's always a conscious brain available in at least one universe. In this sense, quantum immortality is more like the experience of life after a close brush with death, as the actual conscious experience would, theoretically, always be one of surviving a close call rather than dying and regaining consciousness. Either way, it's a theoretical form of immortality, though it entails a heck of a lot of universes in which death actually does occur.