Would Someone Please Kill the Cat

I was reading something earlier today in which someone made yet another inaccurate use of the Schrödinger’s Cat analogy.

The cat. The damned cat. Why does everyone fixate on the cat?

Schrödinger did a terrible thing when he imagined that scenario – he made it seem like the question he was positing could be framed in macro-world terms. And a whole lot of people have since latched on to it and think that they have an understanding of quantum physics as a result.

The cat is a lie. Even more so then the cake, but that’s another issue entirely.

What Schrödinger was trying to communicate was a much more complex and confusing notion by way of the cat, and the cat just doesn’t do it justice. We all know (er, well, anybody who might be interested in reading this at any rate) the story of the cat. You put it in a box with a vial of poison and a trigger that can be tripped by sensing subatomic activity. There’s a 50/50 chance that the activity will occur, and thus the cat can die without warning.

However, as per Schrödinger, if you haven’t observed the subatomic activity (or the consequences of it) then it hasn’t actually occurred. Thus, until you open the box the cat is neither alive nor dead – it’s in an unspecified state because it has not been observed. The moment that the box is opened, observation takes place and the state of the cat becomes fixed. It’s either going to be alive or dead.

The analogy is nonsense, and that’s pretty much what Schrödinger intended it to be. He was presenting an allegory that was supposed to illustrate how absurd the then-new notions of quantum mechanics were, and in effect was trying to undermine them. Unfortunately (for him, though fortunately for us) he instead invented a popular physics-Koan. For scientists, the whole point of the cat is to illustrate how wonky the sub-atomic regions of reality really are.

It’s a thought experiment, but it’s as close to a metaphysical experience as you’re going to get from physics unless you devote a decade or two to its study. The cat actually made sense to a great many people, even though the understanding was fundamentally misguided. The notion that the cat could be both alive and dead was actually comprehensible to many people who didn’t have a lengthy education in physics (and to whom the details of quantum mechanics would cause exploding-head-syndrome). “Yes,” they said, “I get it. The cat is neither alive nor dead until I observe it!” But they take it literally.

That’s not how it works.

If you actually performed the experiment as described, then the cat would live or die regardless of observation. Probabilities always collapse into a singular outcome… well, unless you subscribe to the Many Worlds notion – in that case the each possible result will generate an entirely new copy of the universe – and while I’m not about to dismiss the possibility of that entirely, it seems improbable given the energy requirement of duplicating the entirety of space-time whenever anyone makes a decision about what they’re going to have for dinner.

What makes quantum physics so disturbing is that it suggests that nothing is real until it is “observed”, yet plenty of stuff became “real” long before there was a sentient creature available to make observations. So while quantum probability may be subject to change as a consequence of observation, it does not change the fact that probabilities will collapse into a result state regardless of observation.

What that means is that for most things, the likelihood that a quantum event will result in the observed outcome of a particular particle in a particular place is so near to 100% as to be not worth arguing. An atom of iron in a red blood cell in your body is going to exist there upon observation because it *must* exist there regardless of probability. Hunt long enough and you might find a missing molecule where you’d otherwise expect to find one, but it’s pretty damn unlikely.

However, while the probability of that occurring may be 99.9999% it doesn’t actually guarantee that the particular confluence of sub-atomic particles that *should* be found at a given location will actually be there. Until we look for it, or until it *needs* to be there in order for some subsequent reaction to take place.

But now we’re entering an arena of near metaphysical science that has no clear ground on which laymen can stand – the venue occupied by super-string theory, many worlds theory, and so forth.

Frankly, it’s not that I understand any of it, it’s just that I’m really tired of hearing about that damn cat.

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