Quantum Mechanical Cats

Questions of Probability and Philosophy

My initial post involves two people whose works I admire, and who I also follow here on Substack: Hans Schantz and William Briggs. I heartily recommend you consider following both of them for some stimulating, educational, and entertaining discussions.

Hanz Schantz (@Aetherczar):

William Briggs (@wmbriggs):

After reviewing Schantz' recent Substack posts on philosophy of Quantum Mechanics, I read Briggs’ most recent pre-Thanksgiving post and came across this paragraph:

You must understand, a coin toss has no probability of coming up heads. Only our uncertainty in the toss, that which is in our heads about it, has a probability. Nothing in the coin has a probability. This video and article explains why.

It reminded me of something that has always grated on me in Physics education, as well as in its application: Schroedinger's "Cat in the Box" Thought Experiment.

Recap of the experiment: A cat is placed in a closed box, into which the outside observer cannot see. Inside the box with the cat is a poison gas cartridge. The contents of the cartridge are released by a relay, which itself is controlled by the decay of a radioactive material. When the material decays past a preset activity, the relay closes, the gas is released, and the cat expires. We will assume a poison that acts instantly, so there is no intermediate state of "dying" which can be observed versus “alive” or "dead”, making this a two-state system.

The typical explanation of this thought experiment is that since we, the outside observer, cannot observe the events inside the box until we open it, the cat resides in an indeterminate state between alive or dead. It's probabilistic wave function has not yet collapsed to a single state, call it "1" for alive or "0" for dead. Its state is only known (or determined) when the observer opens the box and the wave function collapses to one or the other state, by observation, and only then do we discover whether the cat is alive or dead.

As with several thought experiments in Modern Physics and Quantum Mechanics, this interpretation has always struck me as being wrong in the strictest sense. The cat, independent of the observer, is either alive or dead within the box. It does not reside in some probabilistic state hovering between "alive" and "dead" just because it was placed inside a box with a poison capsule. The cat is in one of two known states at any time while the box is closed.

So what is the "unknown" here? The unknown is our *KNOWLEDGE* of what that state might be, not the *STATE OF THE CAT ITSELF* nor that state's claimed creation by observation. We, the observer, just don't know what the state is until we look inside the box. It is our knowledge of the cat that is deficient or incomplete. We do not "create" the state of the cat being alive or being dead by observing it — we get additional information about it by observing it. The cat was in one of those states before we opened the box. We are not the Demiurge making the cat alive or dead with our presence or will as the observer.

This confusion between "acting" and "seeing" has frustrated me throughout my physics career, especially since those two philosophical stances are at loggerheads with one another if you think about if for a moment or two. Fellow physicists often do not recognize this distinction, or even when recognizing it, choose to dismiss it as unimportant. Much like the observation of visible light photons or a very low-density electron stream in double slit experiments, the behaviors of various quantum mechanical systems are all rolled into "probabilities" or "probability densities" and then typically ignored in favor of grinding out mathematical results.

Do these probability-related constructs give you the correct answers to various quantum mechanical problems? They can. Unfortunately, they might also be hiding a good many "causes" for why the observed behavior takes place inside that probability envelope. Those causes may be deterministic as well as random in nature. But, because the assumption is that the behavior is intrinsically random and cannot be known without "uncertainty", the question of investigating potential causes is diminished or dismissed under the current philosophy that dominates Quantum Mechanics.

The greater issue is that the philosophy of current Quantum Mechanics is so very contrary to the basics of deterministic Classical Physics, which still applies in the world we perceive in everyday life, and which *MUST* still hold as we move toward the smaller dimensions (i.e., physical sizes) of the quantum world due to the Correspondence Principle. The competing philosophies here are "I make the event happen by my observing it" versus "I gain more complete understanding of the event by observing it." These two philosophies are *NOT* compatible.

Determinism cannot just vanish merely because of a claim that determinism doesn't exist at the quantum interaction level. It's these competing philosophies that are at odds here, as no doubt, Hans will expound upon in future posts. Both Schantz and Briggs point to other ways of looking at Nature that might be more correct in the long run.

All this is to say, I will continue to follow both Hans Schantz and William Briggs here on Substack, and I respectfully suggest that you should as well.