Philosophy in physics: returning to measurement

It has often been said, and certainly not without justification, that the man of science is a poor philosopher. Why then should it not be the right thing for the physicist to let the philosopher do the philosophizing? Such might indeed be the right thing to do at a time when the physicist believes he has at his disposal a rigid system of fundamental concepts and fundamental laws which are so well established that waves of doubt can’t reach them; but it cannot be right at a time when the very foundations of physics itself have become problematic as they are now. At a time like the present, when experience forces us to seek a newer and more solid foundation, the physicist cannot simply surrender to the philosopher the critical contemplation of theoretical foundations; for he himself knows best and feels more surely where the shoe pinches. In looking for a new foundation, he must try to make clear in his own mind just how far the concepts which he uses are justified, and are necessities.


A knowledge of the historical and philosophical background gives a kind of independence from prejudices of his generation from which most scientists are suffering.  This independence created by philosophical insight is–in my opinion–the mark of distinction between a mere artisan or specialist and a real seeker after truth.

Albert Einstein

The above-linked Physics Today article gives a fascinating portrait of a philosophically-informed scientist.  Even at the time, one notes some defensiveness about spending time thinking about the meaning of one’s theories instead of doing what many in physics would call “real work”.  Most physicists probably didn’t read all of Kant’s works as teenagers; it will surprise no one to learn that Einstein was exceptional in many ways.  Nevertheless, Professor Howard shows that a solid historical and philosophical background was much more expected and cultivated in physicists a hundred years ago than it is now.

Today, physicists and biologists feel qualified to mouth off on philosophical and religious questions like never before, and yet the exposure of most of them to philosophy–it’s classics, methodology, and current trends–has dwindled to next to nothing.  How did this happen?  One reason is probably the shift in the center of scientific activity from Europe (Germany, in particular) to America.  We do things differently here.  We don’t worry about what our theories mean; we just want to know how to calculate with them.  Cultural expectations no doubt play a role here.  In Germany a century ago, educated people were expected to have opinions on Hegel and Schopenhauer.  American science is also organized, to a much greater degree than European science was in Einstein’s day, around big projects, each of which mobilizes hundreds of researchers.  This way of doing things is better for addressing certain questions than others.

The other big change–which Einstein lived through and was not at all comfortable with–is the rise of quantum mechanics, whose bizarreness we’ve all learned to live with by not thinking about it.  There’s a definite prejudice among American physicists that only losers worry about what quantum mechanics means, all that “Schroedinger’s cat” stuff.  The discomfort is understandable, since all the major interpretive schemes involve weirdness and extravagances of their own:  a wavefunction collapse that at least seems very different from its ordinary Schroedinger-equation evolution, a multitude of parallel universes splitting off from each other, nonlocal hidden variables for which we have no other evidence.  Rather than seeing this as an exciting challenge, we’ve largely punted the whole issue to the philosophers, who presumably have nothing better to do.

It’s a shame, because the interpretation of quantum mechanics is important, really important.  You should all care about it.  Here’s physicist and First Things contributor Stephen Barr arguing that quantum mechanics disproves materialism.  Barr reviews the measurement problem:  quantum mechanics naturally leads to superpositions of states, but our knowledge is always of definite states.  Barr accepts the Copenhagen interpretation–when we make measurements on microscopic systems, the state vector “jumps” to a definite state with probabilities given by the Born rule–and he accepts the view of Wigner and a few others that “we observe” necessarily means a conscious observer.  In this version of the Copenhagen interpretation, minds somehow transcend the usual laws of nature.  The alternative is to accept the Everett (“Many Worlds”), which is downright crazy.

Read it and see what you think.  I personally think that the materialist isn’t in quite so bad a position as Barr makes out, even in the Copenhagen world.  After all, there are a lot of differences between subatomic particles and human beings besides consciousness.  It could be something else that triggers wavefunction collapse/state vector reduction.  One possibility, advocated by Roger Penrose and others, is gravity.  According to the (totally untested so far) “one graviton” rule, it’s things that are massive enough to put a dent in spacetime that can’t remain in indeterminate states.  There’s also complexity–humans have many more internal degrees of freedom.  This is basically how decoherence explains the lack of macroscopic entanglement effects (although it doesn’t, I believe, solve the measurement problem itself).  There are intriguing toy models (for example by Grigorenko and by Pearle–I went to a colloquium by Philip Pearle as an undergraduate and was very excited by it) of nonlinear modifications to the Schroedinger equation leading to wavefunction collapse, a sign that the problem shouldn’t be entirely left to the philosophers.

Coincidentally, I found this on the Wall Street Journal at about the same time:

‘Vain is the word of that philosopher which does not heal any suffering of man.” By the lights of this maxim, taken from the fourth-century B.C. Greek philosopher Epicurus, contemporary philosophy looks awfully vain. Upon opening the field’s most prestigious journal, one finds little that looks capable of healing and much that promises the opposite: an article titled “On the Supposed Inconceivability of Absent Qualia Functional Duplicates”; another that defends the “applicability of Bayesian confirmation theory to the Everett interpretation of quantum mechanics.” Epicurus, by contrast, taught his followers how to eliminate anxiety and irrational desires in order to lead a life of happiness.

I disagree.  The Everett interpretation is the most serious challenge to our sense of personal identity coming from the physical sciences today.  It’s truth or falseness is indeed a source of anxiety for me.  The viability of this Many Worlds idea hangs on its ability or inability to explain the Born rule for identifying wavefunction amplitudes with probabilities.  I think there’s a good argument that it doesn’t and can’t correctly make this identification–which gives me a reason other than philosophical repugnance for rejecting this multiplicity or worlds and multiplicity of mes–but the arguments that it can all hinge on the meaning given to probabilities.  In other words, that paper the author quotes is important, or at least it could be.

One of these days, I’d like to do a series of posts on quantum mechanics and its interpretation.  That might be pushing my readers’ indulgence a bit too far, though.

32 thoughts on “Philosophy in physics: returning to measurement

    • I remember pointedly asking Bonald for it six months ago.

      QM is where all the atheists are at these days. Everything about it, we’re told, disproves God. This is important stuff and reactionaries need a counter to it. A counter it, preferably, put out by a sympathetic and intelligent SME.

      • Really, they’ve migrated to quantum physics? And here I thought evolutionary biology was where all the atheist action was at. I wrote a whole blasted essay about it. They have a big advantage always getting to choose the field of battle.

  1. No, you should definitely do some posts on the interpretation of QM. Those of us who are not interested can just skip over them.

    Re the difference between the educated man of today versus his counterpart of a century ago, I was permanently humbled and ashamed when I read in Schroedinger’s autobiography about how when he was 16 years old, and after the end of hostilities in WWI, which had imposed a halt of several years on his studies, he wandered back on foot across the countryside to his university from the field, only to find it almost completely deserted. He scrounged some food and waited several weeks for the academic community to recollect itself. While he waited, he passed the time sitting in the blessed sunshine on the roof of one of the colleges and reading through the works of Plato. Again. In Greek.

  2. I found your post and Barr’s article fascinating. I’m a humanities professor who has always wanted to understand science better (and frankly wishes that he had been forced as an undergraduate to undergo a more rigorous introduction to science). Recently on a math colleague’s recommendation I’ve been working with a text by Commenetz on calculus and have made some progress. It takes a conceptual and somewhat philosophical approach but also includes proofs at every step. Could you recommend an introduction to physics that perhaps takes a similar approach? This is also a long way of saying please go ahead and post the more challenging article you have in mind.

    • Hello Professor Smith,

      My favorite physics books for the general public are “QED: the strange theory of light and matter” by Richard Feynman and “The Emperor’s New Mind” by Roger Penrose. (The former’s “Lectures on Physics” are rewarding for the very committed reader.) Both of those focus on topics in modern physics. I think there could be a fascinating book for the public covering classical phenomena (hydrodynamics, electromagnetism, stuff like that) that are closer to the level of day-to-day experience. Maybe it even exists, but I don’t know about it. If I get tenure, maybe someday I’ll write it.

  3. Hi Bonald,

    I second Kristor’s comment that you should do a series of posts on quantum mechanics. For one, I would personally find it very interesting, and for two, I am surrounded by smug tin-pot atheists who think that science has disproved God.

    Also, I wanted to thank you for your writings: I was introduced to traditionalism through your original Throne and Altar site (which I discovered by a googling accident). I read your essay on Monarchy the day I discovered your site, and it all but persuaded me on the spot.

    (Speaking of posts that you that you’d like to get around doing, did you ever do the series of posts on neofeudalism that was promised at the following link?

  4. Count me among those who would like to read such posts . . . I am thoroughly ignorant of quantum mechanics and would like to know more.

    I wish that there were more article’s like Barr’s — it is intelligible by the “uninitiated” without being condescending. It is hard to find well written explanatory articles about math, science, or philosophy that speak toward a broad, educated audience outside the field. We have become a society of insular experts.

    Also, I do not see what is so alarming about the “many worlds” theory. I have wondered about it, though not from knowing any discussion of it in physics — and certainly not to defend materialism. Rather, I wonder if our thinking that our world is “the world” is similar to our thinking that our present is “the present.” I call the latter temporal chauvinism. For our “now” is not God’s now any more than the moment when Heloise and Abelard first discovered their great love or some occasion in the thirty-fourth century of the Christian era. For God is beyond time, and thus past and future are causal directions in cosmic history relative to a given “present” moment on that timeline. Maybe, the same holds for multiple worlds. God surely knows every possible world, of which ours is one. But is it “the one” or simply one for us? Perhaps the structure of modal logic actually reveals something about reality — wherein the principle of plenitude may hold.

    Moreover, wouldn’t the many worlds theory itself discredit materialism? For if certain features/elements/entities show up in many worlds, and if there is an identity among them, then what is that very identity? If a particular baseball exists in so many different worlds, what explains the correspondence? Any decent answer will eventually have to resort to the non-material — form, an assembly of certain qualities (again, form), a relationship of the parts to the whole (formal structure yet again), and so on. Of course, we need not many worlds to see the same argument against materialism (thinking about atoms will suffice), but I find it queer that materialists would latch onto such an obvious refutation of their world view as a defense for that view.

    • Hi Joseph,

      The idea that my consciousness might bifurcate is one that I find troubling. Either all the bonald-states with nonzero amplitude are one person or they’re separate people. Either way, I would have to weaken my concept of unity and self-identity to either
      A) something that could simultaneously hold two incompatible conscious states
      B) something nontransitive, since in which (bonald after measuring result a) = (bonald before measurement) and (bonald after measuring result b) = (bonald before measurement), but (bonald after measuring a) =/= (bonald after measuring b)
      I find both alternatives distasteful.

      • There’s a far deeper problem with MWI. If everything that can happen does happen in one world or another, it can make no sense to wonder why one thing happens, rather than another. But this eliminates the data upon which science – formal or not – operates. I.e., it eliminates science, including QM.

        By definition, one can do physics on the natural history of just one world – the world in which the physicist finds that he exists. MWI is not therefore strictly speaking a hypothesis in physics. Which is fortunate. It would be odd if physics were to show that physics is impossible per se.

      • I think this is another way of saying my main objection to MWI: it doesn’t really establish the connection between wavefunction amplitudes and probabilities. On the other hand, there are a lot of smart people who think it can and does, so it would really need a full post to back up my claim.

      • I’ve actually thought about this problem a bit, so here’s a suggestion: perhaps not one universe is created per state, but several for each, and the number of universes for each state scaling to the amplitude for that state, with an equal probability of entering any one universe, but the number of universes skewing the balance. This assumes that there is some quantum for probability, but to my knowledge this does not exist. Without the quantum, I’m not sure if it would still work though (how much is 34% of infinity?). And of course, I have no idea why on Earth this would actually happen, only that it might explain the results of QM.

  5. Bonald,
    Is the question of justification of universal wave function (UW) no longer interesting to the physical community?

    I had recently interacted with Prof Barr regarding the postulate of UW but he rather casually likened the extrapolation to the extrapolation of assuming a uniform set of physical laws on earth and mars.

    But I do not think this comparison valid. The QM was originally formulated for interaction of a small physical system with a macroscopic measuring apparatus.
    There is no reason to assume an automatic extrapolation to the whole universe. The question of wavefunction is linked with that of measurement and what kind of measurement makes sense with th wave function of the entire universe?

    • Hi vishmehr24,

      I find it interesting, but I have higher-than-normal sympathy for out-of-the-mainstream work in this field. Barr is certainly right that a single state vector is *the* correct way to treat multiparticle systems according to quantum mechanics as we know it. He would correctly point to the case of indistinguishable particles–especially indistinguishable fermions–where if you try giving each particle an independent state vector and don’t (anti)symmetrize, you get definitely wrong answers. And these fermionic effects have macro effects on macro objects–white dwarf stars, to take the most dramatic example. If you want to screw with quantum mechanics (and I’m all for trying), you’ve got to do it in such a way as to not mess up QM’s proven successes.

      • Bonald,
        Are there experimental results from White Dwarfs?

        Also, a wave function for a white dwarf is still qualitatively different from the wave function for the Universe.

        My basic point is that the very concept of the wave function requires its collapse and thus an external measurement device or consciousness.

        So, what could be this device for the universal wave function?. How do we define the measurement process and the collapse?.

        Prof Barr suggested that the consciousnesses of persons in the universe be treated as external to the physical universe even though the bodies of the persons are within
        the universe and are part of the universal wave function.
        This could work, I suppose, but then I asked what credence he is willing to put on the results obtained by quantum cosmology such as Hawkings’ work. But I don’t have his answer to that

      • There’s a lot of evidence for the Pauli exclusion principle (the main consequence of requiring antisymmetrized fermion wavefunctions): the periodic table and the properties of metals, for instance. I gave white dwarfs only as the most extremely macroscopic case, but even for those objects we have a lot of data: masses, radii, and g-mode frequencies, to name three.

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  7. Hi bonald, I’m a frequent reader of this wonderful website and like a previous poster would like to mention how much I appreciate and value that series of articles you did on Throne and Altar. Though my religion is Islam they enhanced my development and set me more securely in that path. “Truth has been made clear from error. Whoever rejects false worship and believes in Allah has grasped the most trustworthy handhold that never breaks.” I believe this verse to refer to all monotheists and indeed I think there is some brotherhood or at least overlap between them all.

    Its quite vexing to deal with atheists who have a shaky grasp of science themselves and seem to insist that Quantum Mechanics or String Theory effectively disproves God. While I don’t think anyone can be convinced who is not already receptive (after all, I’m sure many here had “awakenings” from hardcore liberalism plus maybe one or two traditional values or an upbrinding which led to initial questioning) I think it would help people to gain a workable grasp of a subject that is probably the defining one of our age.

      • It is off topic but your gracious reply reminds me of these Sufi couplets by al-Shebli:

        Whatever house Thou tak’st for thine
        No lamp is needed there to shine.
        Upon the day that men shall bring
        Their proofs before the Judge and King,
        Our proof shall be, in that dread place,
        The longed-for beauty of Thy face.

    • Hello Luqman,

      Thank you very much for introducing yourself.

      It’s actually very surprising to me that anybody does say that quantum mechanics, string theory, or anything of the sort disproves God’s existence. They simply have nothing to do with the arguments for or against.

  8. bonald,

    What are your thoughts on Wolfgang Smith’s attempt to interpret quantum mechanics (and modern physics more generally) from a Thomistic perspective? He explores this at some length in his books The Quantum Enigma and The Wisdom of Ancient Cosmology. I found his works very interesting as a fellow physicist, although I think he is much less compelling when he makes (empirical) criticisms of evolutionary theory. His opposition to materialism and reductionism is one of the most forceful I have seen, even from other scientifically-inclined Thomists.

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  10. I realize I am late to this conversation. A few speculations:

    1) The Schrödinger equation may not point to multiple physical worlds at all, instead it is a peak into what the Greeks called the Noetic Cosmos(Mind of God/Platonic Forms). The function of the Nous is to describe the infinite, the one, God – resulting in an infinite number of forms. In my mind, Multiple World Theory does not apply to the physical emanation, rather it points to the necessary existence of the nous, this world of forms: the mind of God.

    2) If the observer causes the collapse of wave function into a definite event, it suggests a brain/mind duality whereupon the brain functions as an antenna for consciousnesses through which consciousness as metaphysical entity experiences the physical resulting in the individualized mind. Collapsed wave function resulting in physical events are merely artifacts of our hardware.

    • This is more or less the way I have parsed it, except for this:

      Collapsed wave function resulting in physical events are merely artifacts of our hardware.

      So far as I can tell, this leaves the work of the conscious mind superfluous: the material hardware does the collapsing that realizes the material hardware. The mind is then epiphenomenal. It makes more sense to me to think of the psyche as being the catalyst of the collapse, thus determining the state of the brain (and by extension of the world in general) that follows upon that decision. But the psyche is not itself material, or actual; the feeling of being a conscious mind is “what it is like” to be catalyzing a material collapse.

      Granted, the conscious mind apprehends the actual past – i.e., the already having been collapsed world – as the datum of its collapse. And in so doing it pays particular attention to the immediately past state of the brain (although there is no reason in principle it could not likewise directly apprehend past events far away in time or space). But it apprehends also as datum the mind of God (who is neither only past, nor only future, but always, and always present), and it is from his storehouse of formal possibilities for the world that a novel instance of collapse procures such novelty of configuration as it introduces to history. And until it has completed its assembly of data from the actual past and from God into a new synthesis, an instant of collapse – of becoming one thing, rather than another – is not actual, but rather incipiently actual. Until its synthetic collapse is complete, it does not actually exist, to have any causal effects; for its nature and character are not yet fully specified, until at last its career of becoming is complete and it has become what it is, rather than all the other things it might have become. Once an instance of becoming has settled fully into being, then the relevant brain state that reflects and signifies that decision comes into being with the same step.

      Brain states that reflect a given mental event, then, are not material states of affairs until and after, and by virtue of, the completion of an immaterial mental procedure of decision about the way the collapse shall have occurred.

  11. I agree with this. It had not intended the second point to imply that the mind as epiphenomenal. It was primarily speculation.

    I struggle coming to a conclusion as to whether the brain itself is the physical emanation of the archetype of individualized consciousness; or a receiver of sorts who’s sophistication accounts for the varying degrees of mentation present between and within species.

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  13. This is a wonderful article, Bonald, but the two misused apostrophes—both in it’s when you meant its—were so jarring that they made me physically uncomfortable.

    Proper punctuation is something that our late, lamented friend Lawrence Auster was a stickler for, and with good reason. I won’t go into the arguments; you know them already. But I do have a suggestion: whenever you write it’s, stop for a moment and expand it to its full form, it is. You’ll know instantly whether or not you’ve used the right spelling.

    (Some people find the possessive rule of thumb more useful (yours not “your’s”; ours not “our’s”; etc.).)

    I mean this in a spirit of friendship and helpfulness. You have many useful and interesting things to say. I just don’t want anyone to be put off from what you write by something like misused apostrophes.


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