Does Anyone Understand Quantum Mechanics?

This is the second in a series of informal posts to be used as background for the Atlanta Science Tavern discussion Quantum Physics and Human Consciousness.

Richard Feynman, Los
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Richard Feynman, one of the great physicists of the 20th century, offered this somewhat discouraging claim in his book, The Character of Physical Law, "I think I can safely say that no one understands quantum mechanics."  Given that Feynman was not only a technical but also an intuitive master of the subject - the likes of which will seldom be seen again, I might add - it would be pointless for me to try to contradict him.  But I think it is reasonable to suggest that this oft-quoted statement might benefit from some clarification.

Certainly, as a practical endeavor, many, many thousands of scientists and engineers around the world today understand quantum mechanics.  They use it routinely in their work, whether designing computer circuits or predicting the outcome of the collisions of the protons that hurtle toward each other at near light speed at the intersections of the beam lines of the Large Hadron Collider outside of Geneva, Switzerland.  Indeed, the related theory of Quantum Electrodynamics, of which Feynman was a pioneer, is, hands down, the most successful physical theory ever devised as far as the precision of its predictions is concerned.  It would be hard to beat.

Compact Muon Solenoid at
the LHC at CERN

Yet it comes as a surprise to lay people, who find themselves beguiled by the mystery of quantum physics, to learn only a fraction of physicists are troubled, at least professionally, with the philosophical questions that it raises.  The dictum. "shut up and calculate!" holds sway in laboratories and universities, with the meaning of the theory being no more and no less than its thoroughly demonstrated correctness and utility.

And this is where, to a certain extent, they part company with Feynman, whose discouraging words might more accurately - and perhaps more hopefully - be expressed as, "no one understands yet what quantum mechanics means."  The fact of the matter is that, after almost nine decades of earnest striving, there is no agreed upon interpretation of what quantum physics says about the very nature of the world it so successfully models.  Some have more currency than others, but none has proven so superior that it has vanquished its competitors.

In my opinion it is our failure to formulate a convincing interpretation that fuels the controversy that surrounds the question of quantum physics and consciousness which has motivated the discussion at hand.  The absence of a conclusive answer to the stubborn question of meaning has been an invitation for all contending interpretations of quantum mechanics, of whatever stripe, to enter the fray.

That said, I do think that the central concepts of quantum physics are in fact understandable by "ordinary" people, that is if they are willing to let go of preconceptions and to imagine themselves, instead, as inquisitive travelers to an unexplored country.  This will be the topic of the next post in this series.


Does Anyone Understand Quantum Mechanics? by Marc Merlin is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License.
Based on a work at thoughtsarise.blogspot.com.

Why We Fight - For Science

A couple of nights ago, on the edge of the meadow at Piedmont Park, over a convivial dinner that included an appropriate amount of beer and wine, the conversation turned to science - more precisely to how to promote interest in science to the public at large. What, in conventional circles, would have been an unusual dinner-time topic, was an unexceptional one with this group, since we were members of the Atlanta Science Tavern, and we are given to talk about science every chance we get.

Enamored with science. but, somewhat blinded by our adoration, we are sometimes puzzled that others don't share our enthusiasm for the object of our affection. So, when we get together, we often wonder, "how can we encourage our friends to better support and appreciate science?"

A common answer to this question begins with a recitation of the connections between important developments in the history of science and the benefits that have accrued to modern society as a result: the double helix of DNA and cancer-fighting medical diagnosis; quantum physics and high-performance computer chips; genetic engineering and increases in agricultural productivity; Maxwell's theory of electromagnetic waves and near-instantaneous global communications; Newton's orbital mechanics and hurricane tracking. The list goes on and on. It is extraordinarily convincing.

[So as not to whitewash the matter, I readily acknowledge that science has been implicated in its share of failures and catastrophes. On balance, I believe that science comes out ahead in the cost-benefit tally, but some, notably Theodore Kaczynski - better known as the Unabomber - have constructed serious arguments to the contrary. Should, for example, the most dire predictions for global warming be borne out, Ted may well be proven right for his skepticism about technology being an unequivocal force for good, although he should never be excused for the psychotic tactics he used in trying to disrupt its advance.]

Although this kind of utilitarian argument for science is persuasive, I find it, in some respects, disingenuous and, in others, incomplete. It is less than forthright in that it fosters a misconception about why people undertake scientific careers. No doubt there are those who do so motivated primarily by their interest in benefiting mankind, but, in my experience, scientists are, more often than not, driven by an unabashedly self-centered desire to better understand the world in which they live. Public service, although a welcome side effect, is not preeminent among their personal goals. In addition, although arguing for science based on its practical applications may be the strongest hand we have to play in general, the fact of the matter is that many significant fields of scientific research have no chance of bearing technological fruit.



On the morning of the day of the informal Science Tavern dinner the New York Times had published a front-page article announcing the successful reconstruction of a skeleton nicknamed Ardi, the fossil remains of 4.4 million-year-old hominid, and a member of a likely bipedal species which may turn out to be a direct ancestor of our own. To say the least, it would be quite a stretch to come up with a justification for supporting such a masterwork in paleoanthropology based on its potential contribution to our practical technological progress.



I am no stranger, personally, to the rather quixotic pursuits that are part and parcel of basic research. As a graduate student in the late 1970s I worked with a group at the Fermi National Accelerator Laboratory (Fermilab) studying neutrino interactions. Neutrinos are subatomic particles notorious for having little or nothing to do with the real world. Cruising at near the speed of light, they would hardly notice planets placed in their path; the Greta Garbo of elementary particles, after all is said and done, they want to be alone. Consequently, they are seldom considered to be of much practical use, although a once-secret patent was issued for the far-fetched scheme of employing neutrinos to communicate with deep-ocean submarines. Why would anyone pay to study them?

Likewise, what is true about neutrino research in particular is true about the enterprise of elementary particle physics more generally; outside the realm of speculative science-fiction, it is hard to imagine how the knowledge revealed in the course of these investigations into the fundamental structure of matter could lead to anything of practical value. But the value, practical or not, of such basic research is a question we cannot avoid. CERN's Large Hadron Collider (LHC), a Europe-based successor to the accelerator at Fermilab, and the most ambitious instrument yet devised to advance our understanding of the submicroscopic workings of the universe, is scheduled to begin full-fledged operation within a year, at a cost of almost $6 billion. How do we begin to justify such an extravagant expense, given that there is no reasonable prospect of deriving practical benefits from the results that the experiments that will be performed there will produce?

A very similar question had been posed to post-war American researchers, during an era when that country, which had placed a high-stakes wager on the success of the Manhattan Project and had won, was eager to fund the research efforts of the generation of scientists who had participated in the development of the atomic bomb. Robert R. Wilson was not only one of the best of that wartime cohort of physicists, he was also a sculptor, an architect, and the driving force behind the development and construction of Fermilab, as well as its director for a number years, including the brief period that I worked there.

In 1969 Wilson was called before a joint congressional committee on atomic energy to give an accounting as to why the public should continue funding the building of his giant proton accelerator, which, when completed, would measure almost 4 miles in circumference and cost over $250 million, at a time, it should be recalled, when $250 million was a significant line-item in the federal budget.

It was the height of the cold war, and any relationship to military purposes could have been offered by Wilson as an explanation and would have been accepted on the spot. But Wilson, who had been deeply affected by the regret he felt for his work on the atomic bomb and had distanced himself from the defense establishment as a result, did not take this easy way out. Instead, declining to use "national security" as a justification, he said this of his Fermilab project:

It has only to do with the respect with which we regard one another, the dignity of men, our love of culture. It has to do with: Are we good painters, good sculptors, great poets? I mean all the things we really venerate in our country and are patriotic about. It has nothing to do directly with defending our country except to make it worth defending.

Promoting public appreciation of science in this way is much more challenging than appealing to concrete interests based on the expectations of advances, for example, in nutrition or healthcare or transportation or power production or consumer electronics or, in Wilson's case, national defense. But the fact of the matter is that it is the only honest way to argue for public support for many areas of basic research, and often more accurately reflects the motives of those engaged in scientific endeavors. In addition, it serves to reframe the debate about what genuinely constitutes the public interest and expands the conventional definition beyond concrete practical concerns. Ultimately the triumph of our civilization is not only the elevation of our comfort and our security, but also of our culture.