Previous IFODs have discussed how crazy and strange quantum mechanics is.  A thought experiment designed by Edwin Schrödinger illustrates the disconnect between what we observe in the macro-material world and what goes on at the sub-microscopic quantum level.  The thought experiment is designed to show the bizarreness of the concept of “superposition” which provides that sub-atomic particles exist in multiple locations until observed. His thought experiment is referred to as “Schrödinger’s Cat.”  Here it is:

A living cat is placed into a steel chamber, along with a device containing a vial of cyanide gas. In the chamber there is a very small amount of a radioactive substance. If even a single atom of the substance decays during the test period, a relay mechanism will trip a hammer, which will, in turn, break the vial and kill the cat. The observer cannot know whether or not an atom of the substance has decayed, and consequently, cannot know whether the vial has been broken, the cyanide released, and the cat killed. Since we cannot know (because the steel chamber is closed), the cat is both dead and alive according to quantum law, in a superposition of states. It is only when we break open the box and learn the condition of the cat that the superposition is lost, and the cat becomes one or the other (dead or alive). Schrödinger eloquently described the situation: “The psi-function of the entire system would express this by having in it the living and dead cat (pardon the expression) mixed or smeared out in equal parts.”

Scientists know that superposition actually occurs at the subatomic level because there are experiments in which a single particle is demonstrated to be in multiple locations simultaneously (and of course, the math says that must be the case as well). What that fact implies about the nature of reality on the observable level (cats, for example, as opposed to electrons) is one of the stickiest areas of quantum physics. Einstein hated quantum mechanics and spent much of his career trying to disprove the bases of quantum mechanics (even though some of his theories were really the start of quantum mechanics).  Schrödinger did not wish to promote the idea of dead-and-alive cats as a serious possibility. The thought experiment serves to illustrate the bizarreness of quantum mechanics and the mathematics necessary to describe quantum states.

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