Intelligent Design in the Physics Classroom?
A dangerous enemy has infiltrated our science classrooms and is infecting our students’ minds. The enemy is a profoundly unscientific theory masquerading as legitimate science. Its presence in the science classroom blurs the distinction between real science and arbitrary dogma and “makes students stupid” by leaving them less able to distinguish reasonable ideas from unreasonable ones – a skill that is surely one of the main goals of teaching science in the first place.
You probably suspect the enemy I'm talking about is Intelligent Design (ID). Yes, ID has infiltrated some science classrooms. Yes, ID is specifically designed to blur the distinction between real science and religious dogma. And yes, the phrase “makes students stupid” is straight out of Pennsylvania Judge John Jones' recent finding that “ID is not science” and shouldn't be taught in the biology classroom. But, in part because of Jones’ excellent analysis, I don't think ID is a terribly significant danger. It is too transparently unscientific, too widely recognized for what it really is: a thinly-veiled attempt to inject religious creationism into the science classroom.
The enemy I'm worried about is something else – something just as unscientific as ID, but more dangerous because it is not widely recognized as such: the Copenhagen interpretation of quantum mechanics.
The Copenhagen interpretation, so named because of the Danish roots of its main author Niels Bohr, grew out of the paradoxical nature of sub-atomic particles revealed by experiments in the 1920s: electrons sometimes acted like particles but sometimes like waves. This is a paradox because particles are, by definition, localized entities that follow definite trajectories while waves are not confined to any particular path or region of space. How could the same thing be both confined and not confined, both a particle and a wave? Paradox indeed!
Luckily, the two conflicting aspects never appear simultaneously. The experimental situations in which the particle and wave properties manifest themselves are, in a sense, mutually exclusive. The famous Heisenberg Uncertainty Principle codifies this separation: any experiment which reveals the precise particle character of an electron will necessarily obscure the wave character completely, and vice versa.
If one wants to achieve a coherent physical understanding of the nature of the electron, however, this is not very satisfying. Bohr's approach was not so much to resolve the paradox as to embrace it. Naming his philosophy “complementarity,” he posited that the electron’s wave and particle natures were mutually incompatible – yet still jointly exhaustive – perspectives. A complete theoretical description of the electron would have to include both wave and particle aspects; yet, like the experimental situations in which they are revealed, the very concepts of “wave” and “particle” could not be applied simultaneously. According to the Copenhagen view, physicists can never really understand the surprising experimental results or the real nature of the electron. We must simply embrace the paradox and quit looking for a coherent physical picture.
This is clearly all rather weird and philosophical, at least compared to what scientists normally consider scientific. One might think, therefore, that Bohr’s ideas could have had little or no impact on the actual scientific theory of quantum mechanics. This, however, is definitely not the case. Bohr’s ideas were tremendously influential in the development of the theory, and continue to be taught – in all the textbooks and in the overwhelming majority of classrooms – as an essential, ineliminable part of the formal textbook theory.
Indeed, Bohr’s paradox-embracing philosophy has an exact counterpart in the theory’s mathematics. It describes electrons as waves that obey Schrödinger’s wave equation. So far so good. But this part of the dynamics only applies when nobody is looking. When somebody looks (i.e., when a “measurement” of the electron is made) it suddenly (one is tempted to say, magically) becomes a particle – a process governed, not by Schrödinger's equation, but by a different, incompatible bit of mathematics. According to the Copenhagen theory, the fundamental laws of nature governing electrons are thus deeply dependent on the human-centered concept of “measurement.”
Bohr's colleague Pascual Jordan expressed the implications of the Copenhagen theory this way: “We compel [the electron] to assume a definite position; previously it was, in general, neither here nor there; it had not yet made its decision for a definite position. …we ourselves produce the results of measurement.”
Heisenberg explains that “we can no longer speak of the behavior of the particle independently of the process of observation. As a final consequence, the natural laws formulated mathematically in quantum theory no longer deal with the elementary particles themselves but with our knowledge of them. Nor is it any longer possible to ask whether or not these particles exist in space and time objectively.” He concludes that “science no longer confronts nature as an objective observer, but sees itself as an actor in this interplay between man and nature.”
Bohr advocates complete surrender: “There is no quantum world... It is wrong to think that the task of physics is to find out how Nature is. Physics concerns what we can say about Nature.”
I think that on some level, most physicists recognize the irrational and unscientific character of these sorts of statements – but also that they are reasonable extrapolations from the Copenhagen theory. This is probably why physicists have developed a kind of pragmatic, anti-philosophical attitude, and why they deliberately suppress discussion of the more philosophical aspects of the Copenhagen quantum theory. This attitude is best expressed in the popular slogan “Shut up and calculate,” often wielded against students wishing to steer discussion toward these interesting (if disturbing) implications.
But if the textbook theory really has these crazy implications, isn’t it rather pathetic to just ignore and suppress them while maintaining allegiance to the fundamental ideas at their root? Unscientific views should be openly identified, challenged, and rejected – even if they have, somehow, become scientific orthodoxy. Why haven't physicists been willing to critically analyze (and then reject) the Copenhagen philosophy?
Part of the reason is that they apparently think there is no better alternative. As Murray Gell-Mann once said, “Niels Bohr brainwashed a whole generation of physicists into believing that the problem [of interpreting quantum theory] was solved fifty years ago.” The orthodox dogma is that the Copenhagen approach is the only way to deal with the paradoxes. Physicists were allegedly forced – by incontrovertible experimental data – to accept Bohr’s interpretation. This is the premise behind physicists’ pathetic and evasive strategies for dealing with the Copenhagen theory and its implications.
But, in fact, this premise is a complete fabrication. The Copenhagen philosophy is not the only possible conceptual framework for quantum theory. There exists a completely normal, scientific, common-sensical alternative – a theory that agrees with all of the experiments but avoids completely the unscientific philosophical baggage and subjectivist implications of the Copenhagen approach. This alternative theory gives no special dynamical role to “measurement,” in no way implies that the world doesn't exist until somebody looks at it, and completely undermines the case for mind-over-matter anti-realism, channeling, the magical healing power of crystals, and all the other nonsense (as expressed, for example, in the bizarre recent movie What the Bleep do We Know?) that draws its lifeblood from the Copenhagen philosophy. In short, it has none of the subjectivist-epistemological “human implications” which Kuttner and Rosenblum urged us, in the previous issue of this journal, to explore with our students.
This alternative theory was first proposed in the 1920s by Louis de Broglie, who (tragically) abandoned his ideas in the face of tremendous peer pressure from the likes of Bohr and Heisenberg. De Broglie's theory was then independently rediscovered in 1952 by David Bohm, and clarified and elaborated in the 60's and 70's by John Bell.
How does this alternative theory resolve the basic wave-particle paradox which spawned such bizarre contortions in the Copenhagen approach? The solution is almost embarrassingly simple. Bell explains: “While the founding fathers agonized over the question
‘particle’ or ‘wave’
de Broglie in 1925 proposed the obvious answer
‘ particle’ and ‘wave.’”
And that's that. The paradox is resolved: there are two entities, a wave and a particle. The motion of the particle is affected by the wave according to a simple dynamical equation, and the resulting particle trajectories are completely consistent with what is observed in experiments. It is hard not to agree with Bell's judgment that “this idea seems to me so natural and simple, to resolve the wave-particle dilemma in such a clear and ordinary way, that it is a great mystery to me that it was so generally ignored.”
And it continues to be ignored. The theory is rarely mentioned in textbooks – or, when mentioned, usually dismissed as flawed, impossible, or inconsistent, all as part of a bogus proof that the Copenhagen view must be accepted. But the theory exists. It is possible; it is consistent; it is real. And there is no defensible reason that it should not be more widely known – i.e., more widely included in the quantum physics curriculum.
This may seem like a rather technical issue that physicists should straighten out for themselves, an issue that those outside of physics shouldn't or needn't worry about. But the wider academic community – and, indeed, society at large – has a legitimate interest and stake in this issue, just as it has a legitimate interest and stake in the debate over Intelligent Design. Like ID, Copenhagen quantum mechanics “makes students stupid.” Like ID, it probably has no place in college science classrooms. If it is nevertheless to be given such a place, shouldn't the obviously more rational alternative theory of de Broglie and Bohm also be taught – “not as the only way, but as an antidote to the prevailing complacency? To show that vagueness, subjectivity, and indeterminism are not forced on us by experimental facts, but by deliberate theoretical choice?”
This is a question physicists should have asked long ago. Given their stubborn refusal to do so, perhaps it is time for their colleagues and administrators – and any willing Pennsylvania judges – to provide the necessary wake-up call. Because, if you ask me, our physics students deserve a more intelligently designed curriculum.
“Bohm’s Alternative to Quantum Mechanics” by David Albert: Scientific American, May 1994
“Bohmian Mechanics” by Sheldon Goldstein: http://plato.stanford.edu/entries/qm-bohm (and many references therein)
Quantum Mechanics: Historical Contingency and the Copenhagen Hegemony by James Cushing: University of Chicago Press, 1994
“A Suggested Interpretation of the Quantum Theory in terms of ‘Hidden’ Variables” by David Bohm, Physical Review 85, 166 (1952)
Speakable and Unspeakable in Quantum Mechanics by J. S. Bell: Second Edition, Cambridge University Press, 2004
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