Tuesday, March 8, 2011

Schrödinger's Cat Walked Into a Bar — And Didn't

The famous story of the boxed cat who is simultaneously dead and alive was first proposed as a thought experiment by Austrian physicist Erwin Schrödinger in 1935. The cat came to quasi-life as part of an argument between Schrödinger and Albert Einstein concerning elements of the Copenhagen interpretation of quantum mechanics.

No cats, of course, were actually injured in the making of this theory.

In his 1935 article, Schrödinger wrote:

"One can even set up quite ridiculous cases. A cat is penned up in a steel chamber, along with the following device (which must be secured against direct interference by the cat): in a Geiger counter, there is a tiny bit of radioactive substance, so small that perhaps in the course of the hour, one of the atoms decays, but also, with equal probability, perhaps none; if it happens, the counter tube discharges, and through a relay releases a hammer that shatters a small flask of hydrocyanic acid. If one has left this entire system to itself for an hour, one would say that the cat still lives if meanwhile no atom has decayed. 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."

“Ridiculous” is the tip-off. Schrödinger didn’t want us to take the cat — or the argument — seriously. But if you move from the realm of quantum mechanics to the realm of our macro reality, Schrödinger's Cat is far from ridiculous: it’s our everyday experience.

Imagine a call comes in from Cat Rescue HQ. That Schrödinger boy is at it again, locking yet another innocent kitty inside that infernal device. As you load up the van, what do you bring? Well, that depends on the state of the cat. So you bring some food and medicine, or a cat carrier — but just in case, you need to pack a pet-size body bag and some disposable gloves.

Operationally, you treat the cat as alive and dead up until the moment the sad (or happy) truth is revealed.

That’s risk management. You have to plan and prepare for a range of outcomes, treating each as in some sense real until the state collapses and time’s final verdict is rendered. It’s seldom wise to believe in a single deterministic future.

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