Understanding Schrödinger's Cat: A Non-Physicist's Perspective

[Dmitry67]

This who thread is a good example of how much harm the Copenhagen Interpretation had done. I remember myself struggling with questions like 'did wavefunctions collapse before the first human was born etc'

 

[DrChinese]

This who thread is a good example of how much harm the Copenhagen Interpretation had done.

That might be a little harsh.

You can always shut up and calculate.

 

[eaglelake]

True but that measuring device is also in superposition: one state where it observed an effect, and one where it did not. The system that includes the cat AND the measuring device does not collapse into one or the other states until that system is observed. It is like a Russian Doll.

Almost true! In fact all parts of the experiment, including the cat, the measuring device, and the measured result, are non-separable and must be considered as a whole. We shouldn't speak of the cat and the measuring device as separate and independent objects [1]. The measured results depend on the entire experimental arrangement.

All we know is that half the time the cat is found alive and half the time the cat is found dead. We never observe the superposition state, or an evolving wave state, or the collapse of anything. In fact, we no nothing about any cat that is alive, or dead, or drinking a bud lite, for that matter, while waiting for someone to open the box!

Further, we no nothing about the measuring device before it is triggered. When that happens, the experiment yields a single result - alive or dead. Repeating the experiment many times yields the probability distribution of the two possible results. The experiment tells us nothing about the separate behavior of the cat or the measuring device. If we insist on discussing the cat, or the measuring device, independently, then we only generate confusion, contradictions, weirdness, etc.. This forum attests to that!

As an example: If the device is "collapsing", then surely, we should be able to see it happen. And, what is it collapsing from? We don't see that either. In my opinion, such a discussion is not only unnecessary, but further contributes to the confusion.

I do not mean to sound pompous about this. I struggle with this along with everyone else, but I try to accept quantum mechanics at face value, without trying to 'explain' it. (I don't even know what 'explain' means in this context!)
Best wishes.

[1] Neils Bohr. See Wheeler, J. A. and Wojciech, W. H (eds):
Quantum Theory and Measurement. Princeton University Press, Princeton, New Jersey, (1983) pp. 3-7

 

[eaglelake]

This statement shows the problems we have with language and QM. I am not saying it is wrong as written but at the same time: the cat is definitely NOT in ONE particular state. It can be considered as being in NO states OR TWO states. You pick it.

You are correct. We speak a classical language which becomes a terrible barrier when we try to discuss quantum events. But, here, I am trying to emphasize that we continually introduce concepts which have no basis in quantum theory or in the experiment. It is now commonplace in quantum mechanics to discuss unobservable entities as if they were, to the contrary, real. In this case, we discuss the behavior of Schrödinger's cat before opening the box, even though there is no way to verify it.

We all want to believe that Schrödinger's cat, prior to observation, is like any other cat in a box, which we have all seen many times. But the cats we observe are classical cats who exist somewhere at every instant, just like all other classical objects. Schrödinger's cat, on the other hand is a quantum object which has an existence only at the instant of observation. That is the only time we see the cat! We cannot see the cat, even in principle, prior to measurement. Wheeler [1] goes so far as to call the measurement event "an act of creation" to emphasize that there is no experiment without an experimental result [2]. Hence, there is no Schrödinger's cat until we open the box!

Yet, we insist on discussing the behavior of the cat prior to measurement without any evidence that there is actually a cat in the box. The original EPR experiment [3] assumes that quantum particles do exist prior to measurement. And the predicted results are erroneous! This tells us that we should not be talking about Schrödinger's cat before opening the box.

So, I think this is more than just a language problem.
Best wishes.

[1] John Archibald Wheeler, “Law Without Law” in John Archibald Wheeler and Wojciech Hubert Zurek, eds., Quantum Theory and Measurement (Princeton University Press, Princeton, New Jersey,1983),
pp. 182-213
[2] Niels Bohr in John Archibald Wheeler and Wojciech Hubert Zurek, eds., Quantum Theory and Measurement (Princeton University Press, Princeton, New Jersey,1983), pp. 3-7
[3] A. Einstein, B. Podolsky, and N. Rosen, Phys. Rev. 47, 777 (1935)
or simply Google in "EPR"