Quantum Suicide

[noexpert]

Similar to the Schrodinger's Cat thought experiment, there is a thought experiment that makes implications about an infinite number of universes. It was originally published independently by Hans Moravec in 1987 and Bruno Marchal in 1988 and was further developed by Max Tegmark in 1998 (Wikipedia). Essentially the subject would be sitting with a gun aimed at his head (or really just any means of killing him). The gun would be rigged to a device that has a 50% chance of fireing it every 10 seconds. However every time that the gun is to fire, an alternet universe is created and in one the subject is killed, in the other he lives. The subject then could never die, he would simply cease to exist as a concious entity in the universe where he is killed and lives on in the other.

 

I personally do not believe in this idea, simply because it does not mesh with rational thought and is too complicated for me to fathom.

 

Should this mean in our universe we have people who have lived much longer (maybe infinitely) than people seem to live?

I really just wanted to hear any thoughts on the subject of this experiment as a whole. So any insight would be appreciated.

[CraigD]

The quantum suicide though experiment is closely related to the metaphysical concept of quantum immortality, so much so that many encyclopedic references, such as this wikipedia article, present them as aspects of a single concept arising from the Many Worlds Interpretation of quantum mechanics.

 

I personally do not believe in this idea, simply because it does not mesh with rational thought and is too complicated for me to fathom.

I think a key to understanding the idea of quantum suicide/immortality is first having a thorough understanding of what an interpretation of a scientific theory is, as distinct from what a scientific theory is.

 

A theory is a collection of formal statements – in the case of mathematical physic theories such as quantum mechanics, mathematical ones – explaining phenomena that can be tested with experiments designed by associating these statements with physically real experimental instruments and events.

 

Though more difficult and subtle to define, an interpretation of a theory is a sort of consensual story intended to guide students and contributing scientists in understanding, expanding, and in some cases, even overturning the theory. Interpretations make no experimentally testable predictions on their own, but, ideally, they suggest new directions to take in working with the theory to make new predictions, and hypotheses.

 

The MWI is an interpretation of quantum mechanics. Principally, it helps students make intuitive sense of what the formalism of quantum physics predicts, specifically it’s profoundly weird concept of decoherence – when the probabilistic reality exactly described by the theory “collapses” when measured, into certain outcomes, the “God playing dice with reality” that so offended theorist/philosophers like Einstein. It’s more intuitively satisfying to many people than the Copenhagen interpretation, which unsatisfying instructs the student to, in essence, not think about some of the more intuitively troubling implications of quantum mechanical theory.

 

In MWI terms, the quantum suicide/immortality concept – one might even call it a principle – simply states that, in some “multiversal world line”, the main character always “get lucky” and experiences a series of a few (in the quantum suicide version) or a gigantic number (in the “immortal” line of the quantum immortality version) collapsed probabilities so she or he survives (the 50% likely to fire gun in one case, any life-ending outcome in the other). In other terms, this is merely an expression of the simple statistical prediction that there is a diminishing small, but non-zero, probability that the subject of either scenario will survive. According to the MWI, this means that, in some universe-line, a person, or even every person in the world, experiences themselves to be so unfaultingly lucky that they cannot die. Obviously, we are not experiencing this universe-line.

 

One can invent more whimsical scenarios in the quantum suicide family – for example, a universe-line in which everytime the subject ventures outside, every bird in her or his vicinity craps on them. Fortunately, we aren’t experiencing this universe-line, either.

 

The quantum immortality idea is given a more dramatic treatment when the pseudo-scientific, mystical idea that human consciousness somehow spans the many universes, so that all, or perhaps just spiritually special people, experience a succession of deaths and reincarnations into successively more heavenly universes, or perhaps are able through an act of will to chose a universe of good outcomes, the “mundo bueno” (good world) of some new age magical traditions. Though I personally believe there is some value to these beliefs as morally instructive metaphors – expressively imagining a good world can encourage you and the people around you to realize it – there is not, to the best of my knowledge, and scientific evidence that these idea have an basis in objective reality.