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While I was listening to my teacher present the basic idea's of Schrodinger's famous thought experiment, he said that because we can not SEE the cat, the cat exists in some sort of position in which it is both dead and alive.

I was wondering if "see" encompasses all the other senses? Surely if we can hear the cat meow, we can deduce that the cat is still alive. If we smell the cat, it must be alive. So shouldn't "see" be changed to "sense"?

my2cts
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Viradeus
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    Does this answer your question? What constitutes an observation/measurement in QM? – Metropolis May 22 '20 at 15:34
  • Does this answer your question? What is an observer in quantum mechanics? – John Rennie May 22 '20 at 15:49
  • I'd like to mention a relevant point regarding your question which is not so much relevant to the linked question: you mentioned that the cat is in a superposition before we see it. The point to remember is that a quantum system will always be in a superposition regardless of whether the measurement has been performed or not. The measurement will (potentially) change as to which superposition the state is in. But a state can always be shown to be in a non-trivial superposition both before and after a measurement. –  May 22 '20 at 16:31
  • All right guys thanks for all you help! – Viradeus May 22 '20 at 17:01
  • My position is that wave function collapse does not occur. A wave function describes an ensemble of systems. In the case of Schrodinger's cat this means that the wave function describes which fraction of an ensemble of cats that is dead and which is alive. No cat in this thought experiment is ever both dead and alive. See https://en.m.wikipedia.org/wiki/Ensemble_interpretation – my2cts May 22 '20 at 19:20

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You are correct, it is not required that you visually see the cat. Any form of observation would qualify for this thought experiment, whether you hear, feel, smell, or even taste the cat. The concept of an "observer" is somewhat nebulous in this thought experiment, but any type of ability to sense whether the cat is alive or dead would count.

Nuclear Hoagie
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I think your teacher is misconstruing Schrodinger's famous thought experiment. Griffith's Introduction to Quantum Mechanics section 12.4 has a very good discussion about the philosophy behind it.

Schrodinger originally posed it as an example as to why the concept of wave-function collapse from measurement is an absurd idea. Our intuition says, as it should, that a macroscopic living being such as a cat cannot possibly occupy an alive/dead superposition. Griffith's argues that the measurement doesn't occur when we open the box and observe the cat, but rather when the geiger counter is triggered by the decay, i.e. the microscopic measurement influences the macroscopic system.

As such, it doesn't matter whether or not we can see, hear, or smell the cat: we are not doing any measuring ourselves.

NJP
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