Every time I talk or write about Schrodinger's cat, I feel quite uncomfortable. I like cats very much, and the idea of killing one with poisonous gas in the sake of science, is not something I like to think about. Yet, a version of Schrodinger’s thought experiment that I came across lately, have made me feel even more uncomfortable. It is called, “Quantum suicide”.
The quantum suicide thought experiment is similar to Schrodinger’s cat thought experiment, except that it tries to look at things from the cat’s perspective, while accepting the many worlds interpretation. This means that unfortunately, in order to explain it to you, I have to ask you to put yourself in the place of the poor cat.
WARNING: The following is just thought experiment, so don’t get any ideas. No matter what you feel about your life right now, it is still wonderful and you are wonderful
I really had to put this warning on… okay… let’s continue…
Imagine you have a laser gun. It shoots a deadly laser beam. If this beam will hit you, you will surely die. Now imagine you set the laser gun to shoot its death ray through a device that deflects the laser beam randomly in two dimensions, based on Heisenberg's uncertainty principle. If you shoot the gun many times at a concrete wall, you will see an interference pattern formed on the wall. Now imagine you are standing against that wall and the gun is operated. You expect nothing but certain death, yet the rays keep missing you. Eventually the shooting stops, and as you step away and look at the wall, you feel like Jules in “Pulp fiction” - The interference pattern on the wall has the shape of your shadow in its middle, which makes all the sense in the world, except that you are alive.
According to the many worlds interpretation of quantum physics, every time a quantum measurement is made, the universe splits into several versions, one for each possible result of the measurement. If the measurement can have fatal consequences for you, but only for some of its possible results, then obviously you will only live to experience the versions of the universe in which you remained alive. Repeat this experiment many times, and you will end up looking at the imprint of your shadow at the center of a laser beam hit points on the wall.
Now let’s try to stretch this idea a little further: What if in any life and death situation, there is always a chance to remain alive? If so, then if the many worlds interpretation is true, then we are all immortal! Well before we begin to celebrate our immortality, let's pause and think about it: Is this kind of immortality a good thing at all? Because what it means is that our descend towards death will simply take an infinite time. Except for very rare cases such as when our body is blasted into elementary particles by a death ray, dying is a very graduate process. So parallel words based quantum survival may be in most cases a terrible kind of torture ( think of Madlenne and Helen in “Death becomes her”, rather than about Jules in “Pulp fiction” ).
However, some scientists suggest that it is exactly this fact that death is a gradual process, that makes quantum immortality into something very unrealistic. The split into several realities in the many worlds interpretation refers to the possibilities of the same instantaneous event, not to those which are created through a gradual process. In fact, this loss of coherence between quantum possibilities over time, probably renders the whole idea of quantum suicide as scientifically flawed.
Quantum physics is one of the most successful scientific theories in history. However, its non intuitive nature provokes many philosophical interpretations which are sometimes too far fetched, especially when it comes to concepts like life and consciousness. The problem with these concepts is that we don’t have a good definition of them as it is, so adding complex scientific theories into the mix, usually ends up with more confusion than clarity. On the other hand, who says that this is a bad thing?