Monday, November 27, 2006

Quantum Miracles

When I used my blog to ask for help explaining why my friend the EE was misusing science, I expected to hear from the usual crop of well-read laymen, and over educated computer scientists. I did, and for the most part, their comments were clear and helpful, and greatly appreciated. What I did not expect, however, was a guest post from one of the preeminent mathematical physicists in the country. It arrived yesterday out of the clear blue sky and is published below: (Note: My discussion of the straw and salt midrash will continue later today)

A guest post by Dr. Barry Simon

This is a follow-up on DovBear's post ( on quantum mechanics and the non-decomposition of dead bodies. I am not an Ivy-trained EE I'm afraid. But I am an Ivy-trained physicist (Harvard BA 1966; Princeton PhD 1970). Oh, and for Jesse's benefit, I have a connection with a technical school - for the past 20+ years I have been the IBM Professor of Mathematics and Theoretical Physics at Caltech. Not that it is relevant to my expertise (but it does explain my decision to write this), I am an observant Jew (RWMO or LWCh).

I have studied non-relativistic quantum mechanics for 40 years. If you want to check my bonafides you can look at or Of course, I can't easily prove that I am not someone pretending to be Barry Simon (this is the Internet after all).

Anyhow, DovBear's friend makes two claims: first that according to quantum mechanics, your conscious mind can change the physical world and second that the probabilities that are inherent in quantum mechanics can somehow explain miracles. Quantum Mechanics is often non-intuitive given our everyday experience - some thing that has been called Quantum Weirdness. But the friend's claims are so far from correct that I can only call them Quantum Madness.

Let's deal with the consciousness claim first. This is connected with one of the places where, to some, quantum mechanics is less that entirely satisfying. Quantum mechanics is arguably, the most successful scientific theory ever. It describes what can only be called potential probabilities - explaining what the outcomes of experiments and experience are not as absolutes but as probabilities.

Of course, once we make a measurement or observation that potential probability becomes a definite outcome. The conundrum comes when one asks when does the potential become absolute. In the case of the double split experiment where a single electron is sent towards a screen with two slits and hits an array of Geiger counters, quantum mechanics says there is an array of probabilities. If you do the experiment many times, the QM predictions are spot on. But what if you do it once? When does the potential array of probabilities turn into a specific counter clicking? When the counter is hit? (Lest you immediately say "of course", shouldn't the counter also be described by quantum mechanics?). When the computer that records the outcome gets the data? Or when you actually look at outcomes (or in the form asked by Wigner - if my friend looks at it first, does it happen when he looks or when I find out from him!).

The answer according to conventional quantum mechanics is that quantum mechanics doesn't tell us! It only talks about observable phenomena. If it has no observable consequence when the change over takes place then I have no way of testing what happens. Many physicists take the attitude that since it has no observable consequence, this is not an issue we need to worry about but others, especially those with a philosophical bent, speculate about it. This has led to many famous "paradoxes" - Schrodinger's cat, EPR, Wigner's friend, etc. Some attempted resolutions, especially Wigner's, focus on the idea that it only happens once "someone" consciously makes the observation. It is these speculations that DovBear's firend grabs onto in his claim that quantum mechanics says that your mind can change outcomes.

But this is a misreading of Wigner. Someone can look at the outcomes of a repeated double split experiment - using his will to force as many of the outcomes as possible to come through the top split. But you know what - in spite of that, QM accurately describes the outcomes without his will changing the result. According to Wigner, consciousness does not affect the outcome but rather causes the outcome to happen.

The idea that QM "explains free will" or worse, allows conscious production of miracles is one that will be rejected as ludicrous by 99.99% of physicists (I almost said, by all but I've been around too long not to know that there are always a few very well trained crackpots out there).

Second is the idea that somehow, because QM allows weird behavior with non-zero probability that it allows for the suspension of the usual laws of the universe. To take a vivid example, imagine someone who manufactures a basketball with a baseball inside. He blows up the basketball and gives it to you to test. You do some xrays and determine there is a baseball inside. You leave the balls aside and come back the next day and find an intact basketball with a baseball outside and none inside. You declare: "this is a miracle because it isn't allowed by the laws of physics." Your friend says: "Oh no, quantum theory allows it - the baseball tunneled through the basketball." (Of course, the only sane explanation is that someone destroyed and threw away the original basketball, took out the baseball and put down a new and different basketball but I digress).

It is correct that QM says there is a non-zero probability that the baseball will tunnel out so it is no longer "impossible". But that probability is 1 divided by 1 followed by too many zeros to count (possibly a googolplex ( So for all practical purposes, it is still impossible.

QM has some amazing consequences but explaining the impossible by appealing to incredibly low probabilities is not one of them.

I am writing because I am so saddened by the misuse of science, and quantum theory in particular, by some in the frum world. Our tradition has intellectual giants like Rambam, Meiri, the Gra who would have brooked no nonsense of this sort. Our religion is strong enough to be justified without calling on the miraculous and nature is too beautiful to be misused for narishkeit. I cannot resist ending with a thought of the Rashba that I have used elsewhere and which was in a letter he wrote to a neighboring community where someone claimed to be Moshiach: "Yisrael the inheritors of truth, descendants of Ya'akov the Man of Truth, zera emes, would prefer to suffer continued exile and its horrors rather than accept something without critically and thoroughly analyzing it, step after step, to separate out anything of doubtful validity...even when it appears to be miraculous and absolute!"

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