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.
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.