The cat

I found myself trying to explain to someone about the so-called Schrödinger’s Cat experiment. I am sure you will have heard of it, and it comes in many varieties, but basically is:

  • you take an opaque box, a live cat, some poisonous gas and a device that will release the gas at random. The chance of the gas being released is 50%, and if it is, the cat dies. You put it all in the box and close the lid.
  • After a time, you open the box

At this point, there is some discussion along these lines:

  • the cat will either be alive or dead. As it is in an opaque box and we cannot know, what state is in, we can say the chance of it being alive is 50%. We can say that the cat’s state is 50% alive and 50% dead.

OK, so, firstly, it’s a thought experiment. You could, I suppose, do it for real, but that would be pointless and cruel.

The conclusion does not really mean that the cat is 50% dead and 50% alive. It’s an idea to try to explain something in quantum mechanics. It’s to do with observation. It doesn’t matter what you think the cat is, you can only find out whether it really is alive by observing it in some way (eg lift the lid). In quantum mechanics, the act of observation can affect the object you are observing, but it only applies to very small objects, not cats. This is an analogy, so don’t add more to it than there is.

The person I was chatting with understood it to mean that the cat would literally be half dead and half alive, in some kind of transitional state. And this highlights a problem to do with analogies, and the rather deplorable lack of even general knowledge about science.

It goes with the argument “we don’t understand everything about science, so ghosts and parapsychology and human invisibility could easily exist”.

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