In quantum suicide, one would have the possibility of being immortal. This thought experiment is a delicate and complicated one – it breaks down when associated with the Copenhagen interpretation of quantum physics, but it proves the Many Worlds interpretation of quantum physics in a rather violent way.
Before we jump into the quantum suicide thought experiment, let’s familiarise ourselves with the two popular interpretations of quantum mechanics.
Here are some quintessential basics of the Copenhagen interpretation.
- Observer will disrupt superposition.
- The wave function of a superposition in a non-isolated system will collapse (decoherence).
- A particle exists in all of its possible states until observed.
Many worlds interpretation
And the basics of the many worlds interpretation are as follows.
- The universe splits into two to accommodate all possible outcomes (states) of an object or situation.
- The observer no longer influences the outcome of quantum situations.
An example would be a scientist observing a subject. Lets say the subject could either be a wave, or a particle. When an observation is made by the scientist, he will observe either a wave or a particle. According to the many worlds interpretation, the universe , in a sense, copies itself to accommodate both possibilities. In one universe, he observes a particle. In the other, he observes a wave.
The thought experiment
- Let’s assume that there is a gun. It is modded and rigged so that it fires according to the spin of some quark. If the quark has a spin up, the gun fires. If the quark has spin down, the gun will not fire even when the trigger is pulled.
- A criminal uses this gun and holds it to his victims head. Since there is a 50/50 possibility of the quark having an up or down spin, according to the Many Worlds theory, the universe will split into two parallels to accommodate these possibilities.
- The criminal pulls the trigger. The gun either fires or it doesn’t . The prisoner dies, or he doesn’t.
- We can infer that each time the trigger is pulled and the universe splits into two. The man will either live or die
- According to this inference, we can conclude that there will be an infinite continuum of universes where the victim never dies and survives each trigger pull, where the spin of the quark is down. Therefore the victim is immortalise.
Another way of looking at this experiment is that you can also imagine being Schrödinger’s cat, instead of being the observer.
This is the thought experiment- very fascinating to ponder. There will be timelines where the criminal is innocent as the gun was never shot (due to the quark’s spin being down ). And timelines where the victim dies and the criminal is guilty as charged.