Quantum suicide is a thought experiment in quantum mechanics that was independently proposed by Hans Moravec in 1987 and Bruno Marshal in 1988. In 1998 it was expanded by Max Tegmark. This thought experiment, being a modification of Schrödinger's cat thought experiment, clearly shows the difference between two interpretations of quantum mechanics: the Copenhagenian interpretation and Everett's Bagatoswite interpretation. In fact, the experiment is an experiment with Schrödinger's cat from the point of view of the cat.
In the proposed experiment, a gun is directed at a participant, which fires or does not fire, depending on the decay of any radioactive atom. The probability that as a result of the experiment the gun will fire and the participant will die is 50%. If the Copenhagen interpretation is correct, then the gun will finally fire and the competitor will die. If Everett's Bagatoswitt interpretation is correct, then as a result of each experiment carried out, the universe splits into two universes, in one of which the participant remains alive and in the other dies. In worlds where a participant dies, he ceases to exist. On the contrary, from the point of view of the participant survived, the experiment will continue without causing the participant to disappear. This is because, in any branch, the participant is able to observe the result of the experiment only in the world in which he survives. And if Bagatosvitov's interpretation is correct, then the participant may notice that he will never die during the experiment.
Unfortunately, the participant will never be able to talk about these results, because from the point of view of an outside observer, the probability of the result of the experiment will be the same in both the Bogatosvitov and Copenhagen interpretations.
One of the varieties of this thought experiment is called "quantum immortality." This paradoxical experiment assumes that if the Bagatoswitan interpretation of quantum mechanics is correct, then the observer may never cease to exist at all.