• Question: What is the Schrodinger's cat thing? I think it has something to do with a box, and something to do with science? :)

    Asked by lisaloo to Claire, Kate, Matt, Rob, Sam on 24 Jun 2013.
    • Photo: Sam Geen

      Sam Geen answered on 24 Jun 2013:

      Schrodinger’s Cat is a thought experiment – it says that if you put a cat in a box, and put with the cat a machine that kills the cat if a certain particle has decayed radioactively, then quantum mechanics means that before you open the box to check on the cat it’s both alive and dead (don’t worry, this isn’t a real experiment, no cats were harmed!)

      It highlights how weird quantum mechanics is. Firstly, particles like electrons aren’t solid objects with a definite position, they’re fuzzy probability “waves” that could be in various places at one time. Secondly, they only become definite objects with a certain position when you measure them. But no-one is really sure what a “measurement” is in this case – what is it about the measurement that makes the probability wave “collapse” (i.e. go away) and the particle have a definite position? We still don’t know the answer to this.

    • Photo: Claire Lee

      Claire Lee answered on 24 Jun 2013:

      That’s right 🙂 Schrodinger’s cat is a bit of a story used to explain one interpretation of the quantum mechanics wave equation.

      Quantum mechanics is *weirdMATOMO_URL It’s really strange – it tells us that the way the universe works on a really small level is completely different to the way we’d expect it to work!

      The idea goes that you put a cat in a box, and with it you put a machine that basically has a 50% chance of killing the cat. You seal up the box, so that you can’t see what’s going on inside.

      Wait a few minutes.

      Now, normal logic would say that the cat is either dead OR alive, each with a 50% chance. When we open the box, we merely confirm which one it was, but the point is that according to everything we know about the universe from our normal everyday lives, the cat is either dead OR alive.

      Not so quantum mechanics! With quantum mechanics, the cat is both dead AND alive at the same time! The cat “exists” in both states at once. Only when we open the box and take a look, then the universe selects one of those (dead or alive) with a 50% probability.

      The difference is subtle – but important. Normal life says that something is in one particular state no matter what. Quantum mechanics says that something will be in *all possible states* until we observe it, and then it chooses just one.

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