Miners Mills


Musings on Logic, Analysis, Decision-Making, and Other Elements of Natural and Artificial Intelligence

Schrodinger’s Black Cat

Today is Friday the 13th, a day on which we celebrate the avoidance of walking under ladders, opening umbrellas indoors, and crossing paths with black cats.  And while doing any of these is certain to bring you bad luck, it’s a good time to remember a particular unlucky 80-year-old cat...

Back in the 1930s, an Austrian physicist named Erwin Schrodinger posited a thought experiment (which has become popularly known as "Schrodinger’s Cat") as a way to manifest quantum theory in more accessible form.  A very short version is that a living cat is placed in an opaque box, into which is dropped a device that has a 50/50 chance of releasing an instantly-acting deadly material.  Thus, when we open the box shortly after, there is a 50% chance we will find a living cat, and 50% chance of finding a dead cat.

But popular renditions of Schrodinger’s Cat often conflate two similar, but subtly very different, types of uncertainty around any probabilistic event:

a) the event has not yet occurred, and thus the outcome doesn’t yet exist (i.e. the result itself exists in a probabilistic state),

b) the event has occurred, however the outcome is not yet revealed (i.e. only our observation of the result exists in a probabilistic state).

To use a very simple example for each:

a) I’m about to flip a coin.  (i.e. the result has not yet occurred)

b) I just flipped a coin, but my hand covers it.  (i.e. the result has occurred, but is unknown to me)

As for the two slightly, but meaningfully, different versions of Schrodinger’s cat: in one, the opening of the box is what triggers the release of the (instantaneously-acting) material, and in the other, the material is released before we open the box.

Note how this implicates the 2 very different types of uncertainty during the unopened-box phase: in the former case, we’re in situation a, and in the latter, we’re in situation b.  And because I (like most people) still don’t really understand quantum theory, I’m still unclear on whether there is a majority belief among physicists which type of uncertainty governs quantum behavior...does a quantum particle actually exist in a particular state which is only revealed when observed, or does it literally exists in multiple states until observed?

So, as we consider the intersection of quantum theory and Friday the 13th, we can imagine that if Schrodinger’s cat crosses your path, there is a 50/50 chance it is a black cat.  But once you look at it, then it either is, or is not, a black cat.  And we should probably leave it to the quantum physicists to determine whether, if you never look at the cat, it is both black, and not black, and thus, you will both have, and not have, bad luck!


David Chariton