Didn’t read the entire article carefully (sorry!), but I’m not sure why you state that the existence of the classical cat invalidates Schrödinger’s point that something is missing from the classical formulation of quantum mechanics. I think it’s pretty clear that, on the contrary, it bolsters his point. We either need an ontological posit of many worlds, or an operator of some kind which can invoke wave function collapse at higher scales (e.g. the Copenhagen approach, or Penrose’s gravity idea). The point is we need something, otherwise QM is incomplete, exactly as Schrödinger pointed out.
To elaborate some more: I always understood Schrödinger’s point to be in reply to the early day quantum theorists who thought that classical phenomena were purely emergent from quantum phenomena. The idea being that, given the wave function, you would predict that classical phenomena would emerge at large scales simply due to the fact that quantum effects, like uncertainty, would tend to probabilistically cancel out given high degrees of interactions, as found at the classical scale.
Schrödinger, in response, came up with the cat experiment to show that actually it is possible to construct a scenario where a large scale phenomenon (the life or death of a cat) was entirely dependent on a single quantum variable (the decay of an atom).
Thus, if the early emergentists were right, we should actually predict that Schrödinger’s cat would not behave classically. But of course the cat is either dead or alive, so it seems like pure emergentism is false. Schrödinger’s conclusion was that we need some extra ingredient to quantum mechanics to explain classical phenomena. It’s not just a matter of the quantum probabilistically cancelling out at large scales.
That’s how I always understood the motivation behind the thought experiment anyways. But please correct me if you feel that’s not the case.
The three sentences that remain in that paragraph are what's left after several edits. I was never happy with that bit. Going down the rabbit hole added too many words, and paring it down obviously left it confusing. The clause before the line you're complaining about is about Einstein's dislike for the randomness, and what I was trying to get at is that they were both hoping -- contra the Copenhagen Interpretation -- for an approach to QM based on realism. But there just isn't one.
Schrödinger published his paper in 1935 shortly after, and very much as a consequence, of the 1935 EPR paper Einstein was involved in. The two corresponded after the EPR paper, and that's when Einstein proposed the unstable keg of gunpowder as being in the state of both exploded and not. Schrödinger ran with that ball and came up with his cat.
For me, a fascinating fact here is that the Schrödinger's Cat thing comes from one paragraph in a 25-page paper. The cat and experiment are only mentioned in that paragraph, but the idea has become not just famous but a meme. The paper, for the most part, is about the mutually incompatible properties in QM -- uncertainty relationships between conjugate pairs -- which reflects the similar discussion in the EPR paper.
Jim Baggott is a favourite writer of mine, outside his scientific publications which I haven’t seen as my interest is in his popular science integration and history for the non-expert. Nice essay thanks.
Didn’t read the entire article carefully (sorry!), but I’m not sure why you state that the existence of the classical cat invalidates Schrödinger’s point that something is missing from the classical formulation of quantum mechanics. I think it’s pretty clear that, on the contrary, it bolsters his point. We either need an ontological posit of many worlds, or an operator of some kind which can invoke wave function collapse at higher scales (e.g. the Copenhagen approach, or Penrose’s gravity idea). The point is we need something, otherwise QM is incomplete, exactly as Schrödinger pointed out.
To elaborate some more: I always understood Schrödinger’s point to be in reply to the early day quantum theorists who thought that classical phenomena were purely emergent from quantum phenomena. The idea being that, given the wave function, you would predict that classical phenomena would emerge at large scales simply due to the fact that quantum effects, like uncertainty, would tend to probabilistically cancel out given high degrees of interactions, as found at the classical scale.
Schrödinger, in response, came up with the cat experiment to show that actually it is possible to construct a scenario where a large scale phenomenon (the life or death of a cat) was entirely dependent on a single quantum variable (the decay of an atom).
Thus, if the early emergentists were right, we should actually predict that Schrödinger’s cat would not behave classically. But of course the cat is either dead or alive, so it seems like pure emergentism is false. Schrödinger’s conclusion was that we need some extra ingredient to quantum mechanics to explain classical phenomena. It’s not just a matter of the quantum probabilistically cancelling out at large scales.
That’s how I always understood the motivation behind the thought experiment anyways. But please correct me if you feel that’s not the case.
The three sentences that remain in that paragraph are what's left after several edits. I was never happy with that bit. Going down the rabbit hole added too many words, and paring it down obviously left it confusing. The clause before the line you're complaining about is about Einstein's dislike for the randomness, and what I was trying to get at is that they were both hoping -- contra the Copenhagen Interpretation -- for an approach to QM based on realism. But there just isn't one.
Schrödinger published his paper in 1935 shortly after, and very much as a consequence, of the 1935 EPR paper Einstein was involved in. The two corresponded after the EPR paper, and that's when Einstein proposed the unstable keg of gunpowder as being in the state of both exploded and not. Schrödinger ran with that ball and came up with his cat.
For me, a fascinating fact here is that the Schrödinger's Cat thing comes from one paragraph in a 25-page paper. The cat and experiment are only mentioned in that paragraph, but the idea has become not just famous but a meme. The paper, for the most part, is about the mutually incompatible properties in QM -- uncertainty relationships between conjugate pairs -- which reflects the similar discussion in the EPR paper.
Jim Baggott is a favourite writer of mine, outside his scientific publications which I haven’t seen as my interest is in his popular science integration and history for the non-expert. Nice essay thanks.
Baggott is a favorite of mine, too. Glad you enjoyed the post!