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What is quanta immortality theory?

Published in Quantum Physics Theory 4 mins read

The Quanta Immortality theory is a thought experiment that suggests a conscious observer would, from their own subjective perspective, always experience surviving, even in scenarios that should lead to death. This highly speculative concept is rooted in one of the interpretations of quantum mechanics, particularly the Many-Worlds Interpretation (MWI).

At its core, quantum immortality refers to the experience of surviving what is known as quantum suicide.

The Quantum Suicide Thought Experiment

The quantum suicide thought experiment was famously popularized by physicist Max Tegmark, building on earlier ideas. It serves as the primary illustration of quantum immortality and is set up as follows:

  • The Setup: A person stands in front of a gun (or other deadly device) that is rigged to a quantum event.
  • The Quantum Trigger: The gun's firing mechanism is controlled by the outcome of a subatomic particle's quantum state. For instance:
    • If a subatomic particle is detected as having an upward spin, the gun fires.
    • If the particle is detected as having a downward spin, the gun does not fire.
  • The Branches of Reality: According to the Many-Worlds Interpretation, when such a quantum measurement occurs, the universe "splits" or "branches" into multiple parallel realities.
    • In one branch, the particle has an upward spin, the gun fires, and the person dies.
    • In another branch, the particle has a downward spin, the gun does not fire, and the person survives.

Why the Observer "Survives"

The theory posits that from the perspective of the conscious observer, they would only ever experience the branches of reality where they survive. The branches where they die simply cease to be experienced by that particular conscious stream. Each time the experiment is run, even if the probability of survival is infinitesimally small, there will always be some branch where the observer continues to exist. Therefore, subjectively, the individual would feel as though they are endlessly surviving, perpetually finding themselves in the "lucky" branch where the gun misfired, or some other improbable event saved them.

Underlying Principles: The Many-Worlds Interpretation

Quantum immortality relies heavily on the Many-Worlds Interpretation (MWI), proposed by Hugh Everett III in 1957. Unlike other interpretations that suggest wave function collapse upon observation, MWI posits that every time a quantum measurement is made, all possible outcomes are realized in different, parallel universes.

Key Concept Description
Quantum Superposition A fundamental principle of quantum mechanics where a particle exists in all possible states simultaneously until it is observed or measured.
Many-Worlds Interpretation (MWI) A quantum mechanics interpretation stating that every quantum measurement or interaction causes the universe to split into multiple, non-interacting parallel universes, one for each possible outcome.
Observer's Experience In the context of quantum immortality, it implies that the conscious "self" only ever experiences the branches of reality where it continues to exist, leading to a subjective perception of unending survival.
Branching Reality The core mechanism of MWI, where universes continuously divide to accommodate all possible outcomes of quantum events, creating an ever-expanding multiverse.

Implications and Criticisms

While a fascinating philosophical thought experiment, quantum immortality is not a testable scientific theory in the traditional sense and is widely debated:

  • Not Scientifically Provable: There is no known way to empirically test or verify the existence of parallel universes or the subjective experience of infinite survival.
  • Reliance on MWI: The theory's validity is entirely dependent on the Many-Worlds Interpretation being the correct description of reality, which is one of several competing interpretations of quantum mechanics and is not universally accepted by physicists.
  • Philosophical vs. Practical: It does not suggest that the physical body can avoid death or decay, but rather that the consciousness or self would always perceive itself in a surviving branch. This does not prevent the grieving of others in branches where death occurs.
  • Definition of "Self": The theory raises profound questions about the nature of consciousness and what constitutes the "self" that continues to exist across these branching realities.

Quantum immortality remains a compelling idea for discussions on the nature of reality, consciousness, and the implications of quantum mechanics.