Hacker News Reader

Comment by rogerbraun | Hacker News Reader

What I find much more amazing is that the thought experiment of Schrödinger's cat is so often used to explain the implications of quantum mechanics, because it was meant as a way to show that all that superposition stuff clearly doesn't happen in normal life, so something has to be wrong / missing in quantum mechanics.

View on HN

The key fact that most people miss out on when explaining Schrodinger's cat is that the box is not simply "a box", say, a cardboard box or a plastic box or something. It's a magic box that completely isolates the cat from the entire rest of the universe. No neutrinos, no photons of any frequency, no quantum interaction of any kinds between the inside and the outside of the box, probably not even any gravity (though how important that is is currently unknown). The "cat in the box" is effectively in a separate universe until we open the box.

That point has to be hammered on, rather than neglected, because in reality it is completely true that no such box exists, and almost certainly no such box could exist, and it's very important when explaining this to people that it's a thought experiment, a metaphor, not something that actually happens in the macroscopic world.

Thank you. I've been trying to get this point across to people for decades. I think that the use of the word observe has been a real hindrance.

Please everyone, stop using the word 'observe' to describe what happens when the box is opened. It has been used by physicists to mean the same as 'measure' which really means something like 'touch'. The problem is that for all but a tiny fraction of the world's population 'observe' simply means 'see' and is something that can be done without 'touching' and without being seen oneself.

Um, the original formulation needed no magic box. The original formulation is also equivalent to setting up a gun that fires at a cat you're watching the whole time iff the next photon you send at a beam splitter is detected by one detector over the other.

In thought-experiment-land, it may be, with the right thought experiment.

In the real world it most emphatically is not equivalent. And also in the real world, a lot of people get very confused about this.

Reply on news.ycombinator.com