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January 10, 2008

Is consciousness a by-product of room-temperature superconductivity?

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If so, it kind of makes us seem a bit less important in the greater scheme of things.

And generally — at least over the past 10,000 or so years — movement in that direction seems to be consistent with a more realistic view of things.

Yesterday, as I was reading Kenneth Chang's superb New York Times Science section story about the celebration last month of the fiftieth anniversary of the publication of "Theory of Superconductivity," a landmark paper which appeared in Physical Review in December 1957, I got to reflecting on the halting progress of high-temperature superconductivity studies in the decades since.

And then I got to thinking about how it is that after all these years and myriad conflicting theories, we seem no closer to a theory of consciousness today than we were fifty years ago.

Well, the way I see it, if you're getting nowhere in two different avenues, that's no reason not to see what happens when you combine them.

Wasn't it the noted physicist Billy Preston who wrote, "Nothin' from nothin' leaves nothin'?"

Addition by subtraction — that's where it's at.

Here's the Times article.

    When Superconductivity Became Clear (to Some)

    Superconductivity, the flow of electricity without resistance, was once as confounding to physicists as it is to everyone else.

    For almost 50 years, the heavyweights of physics brooded over the puzzle. Then, 50 years ago last month, the answer appeared in the journal Physical Review. It was titled, simply, “Theory of Superconductivity.”

    “It’s certainly one of the greatest achievements in physics in the second half of the 20th century,” said Malcolm R. Beasley, a professor of applied physics at Stanford.

    Superconductivity was discovered in 1911 by a Dutch physicist, Heike Kamerlingh Onnes. He observed that when mercury was cooled to below minus-452 degrees Fahrenheit, about 7 degrees above absolute zero, electrical resistance suddenly disappeared, and mercury was a superconductor.

    For physicists, that was astounding, almost like happening upon a real-world perpetual motion machine. Indeed, an electrical current running around a ring of mercury at 7 degrees above absolute zero would, in principle, run forever.

    If the phenomenon defied intuition, it also defied explanation.

    After wrapping up special and general relativity, Albert Einstein tried, and failed, to devise a theory of superconductivity. Werner Heisenberg, the physicist who came up with the Heisenberg uncertainty principle, struggled with the problem, as did other pioneers of quantum mechanics like Niels Bohr and Wolfgang Pauli. Felix Bloch, another thwarted theorist, jokingly concluded: Every theory of superconductivity can be disproved.

    This long list of failure was unknown to Leon N. Cooper. In 1955 he had just received his Ph.D. and was working in a different area of theoretical physics at the Institute for Advanced Study in Princeton when he met John Bardeen, a physicist who had already won fame for the invention of the transistor.

    Bardeen, who had left his transistor research at Bell Labs for the University of Illinois, wanted to recruit Dr. Cooper for his latest grand research endeavor: solving superconductivity.

    “I talked to John for a while,” Dr. Cooper recalled at a conference in October, “and he said, ‘You know, it’s a very interesting problem.’ I said, ‘I don’t know much about it.’ He said, ‘I’ll teach you.’

    “He omitted to mention,” Dr. Cooper said, “that practically every famous physicist of the 20th century had worked on the problem and failed.”

    Bardeen himself had already made two unsuccessful assaults. Dr. Cooper said the omission was fortunate, because “I might have hesitated.”

    Dr. Cooper arrived at the University of Illinois in September 1955. In less than two years, he, Bardeen and J. Robert Schrieffer, a graduate student, solved the intractable puzzle. Their answer is now known as B.C.S. theory after the initials of their last names.

    Bardeen died in 1991, but Dr. Cooper and Dr. Schrieffer returned to the University of Illinois in October to commemorate the publication of their superconductivity paper.

    Their Herculean achievement was honored with the 1972 Nobel Prize in physics, and it deeply influenced theorists who were putting together theories explaining the to and fro of fundamental particles. The theory has also been applied in subjects as far flung as the dynamics of neutron stars.

    B.C.S. theory, however, never achieved recognition in popular culture like relativity and quantum mechanics. That may be understandable given the theory’s complexities, applying quantum mechanics to the collective behavior of millions and millions of electrons. “They were very, very difficult calculations,” Dr. Cooper recalled. “They were superdifficult.”

    Even for physicists, the 1957 paper was a difficult one to read.

    On the first day of the October conference, Vinay Ambegaokar of Cornell held up a small notebook from 1958. The notebook, Dr. Ambegaokar said, “shows I read it, but I did not understand it.” He said that he continued to prefer approaches “with less constant intellectual effort.” (Soviet physicists had come up with a so-called phenomenological theory — equations that described the behavior of superconductors but did not explain what created that behavior.)

    Electrical resistance arises because the electrons that carry current bounce off the nuclei of the atoms, like balls in a diminutive pinball machine. The nuclei recoil and vibrate, sapping energy from the electrons.

    In a superconductor, electrons seem more like ghosts than particles, passing the nuclei as if they were not there.

    Clues to the nature of superconductivity began to accumulate when Walther Meissner and Robert Ochsenfeld, two German physicists, measured the magnetic field inside a superconductor and discovered, to everyone’s surprise, that it was exactly, precisely zero. Further, any magnetic field that was present in a material would disappear as it was cooled into a superconductor.

    This phenomenon, known as the Meissner Effect, was the first sign that superconductors were more than just the perfect conductors envisioned in the early theories.

    Then there were signs of a large energy gap between the lowest energy, superconducting state and the next possible, higher-energy configuration. That kept the electrons trapped in the superconducting state.

    Finally, experiments showed that the temperature at which an electrical resistance disappeared varied when heavier or lighter versions of an atom were substituted; the weight of atoms play a negligible role in the electrical resistance of ordinary conductors.

    Bardeen believed that if he could understand the energy gap, he would understand superconductivity.

    In 1955, David Pines — Dr. Schrieffer’s predecessor in the Bardeen group — came up with the first breakthrough.

    Negatively charged electrons generally repulse each other, but Dr. Pines showed that vibrations in the lattice of nuclei could generate a minuscule attraction.

    When an electron passes near a positively charged atomic nucleus, the opposite electric charge slightly pulls the nucleus toward the electron. The electron flits away, leaving behind a positively charged wake, and that, in turn, attracts other electrons.

    Dr. Pines’s result showed why the weight of the atoms mattered — heavier atoms accelerate more slowly.

    The next two key breakthroughs came via mass transit.

    In December 1956, Dr. Cooper was on a 17-hour train ride to New York City. He had spent his first months applying his theoretical bag of tricks on the equations. “I did it and I did it and I did it, and I got absolutely nowhere,” he said. “I wasn’t feeling that clever any more.”

    On the train, Dr. Cooper discarded his failed calculations. “I just thought and thought, ‘I know this is a difficult problem, but it seems so simple,’” he said. Physicists think of electrons in a normal conductor as piling on top of one another in a “Fermi sea,” named after Enrico Fermi, who was still formulating the theory at the University of Chicago.

    Dr. Cooper realized that it was only the electrons near the top of the Fermi sea that were crucial. “You introduce a small effect,” he said, “and somehow you get a superconductor.”

    As he worked on the problem for the next few months, Dr. Cooper realized that these electrons not only attracted others as Dr. Pines had shown, but also grouped themselves into pairs. It now seemed that superconductivity depended on these pairs, subsequently named Cooper pairs.

    Contrary to simple expectations, the two electrons did not revolve closely around each other but were far apart, with many other electrons in between. The multitude of overlapping pairs made the calculations a morass.

    A year after Dr. Cooper’s trip, Dr. Schrieffer headed to New York for a scientific conference. (At the same time, Bardeen headed to Stockholm to collect his first Nobel Prize, for the transistor.) Dr. Schrieffer had been looking at statistical approaches to solve the tangle of Cooper pairs. On the subway, he wrote down the answer, which turned out to be fairly simple in form.

    The Cooper pairs essentially coalesced into one large clump that moved together, and the energy gap prevented the scattering of any one pair. Dr. Schrieffer gives the analogy of a line of ice skaters, arm in arm. “If one skater hits a bump,” he said, the skater is “supported by all the other skaters moving along with it.”

    Back in Illinois, he showed what he had written to Dr. Cooper and then Bardeen. Bardeen was convinced.

    Charles P. Slichter, a professor of physics at Illinois then and now and who had conducted many of the experiments teasing out the clues to superconductivity, remembered Bardeen’s stopping him in the hallway one day.

    “John wasn’t a great talker,” Dr. Slichter said. “I could see he had something he wanted to say, and we sort of stood there. It seemed like we stood there for five minutes.”

    Dr. Slichter was tempted to say something, “but I knew I shouldn’t, because if I did, I would shut him up. So he spoke to me finally. ‘Well, Charlie, I think we’ve solved superconductivity.’

    “And wow, it is the most exciting moment in science I’ve ever experienced,” Dr. Slichter said.

    In February 1957, the three submitted a paper, essentially outlining their ideas, to Physical Review. Their longer, more complete paper did not appear in print until December that year.

    A new puzzle appeared in 1986 with the discovery of so-called high-temperature superconductors. These superconductors work at higher, though still very low, temperatures.

    No theory has emerged as convincing; one session at the Illinois conference was a mass interrogation of the competing theorists.

    The theorists agreed that high-temperature superconductors were different, that the attractive force did not come from the vibrations of nuclei. Rather, they said, the attraction somehow arose from the flipping of the atoms’ tiny magnetic poles. Beyond that, they did not agree.

    Other types of superconductors, and more theories, could well follow.

    As Dr. Beasley of Stanford said in the closing talk of the conference: “We have no idea of the limits of superconductivity in the universe. If 85 percent of the universe is dark matter, I hope 5 percent of it is superconducting.”

....................

What triggered my thought connecting superconductivity to consciousness was the final sentence of the legend of the figure up top (by Jonathan Corum, it accompanied the Times article), to wit, "With no resistance, the current may persist for years."

Huh.

Let's see... what else is measured in years?

Hey, I know: a human life.

Instead of calorie restriction and the like, maybe longevity researchers should instead focus on promoting the conditions which allow the "miracle" (in quotes because both miracles and magic usually turn out to result from superior technology... but I digress) of consciousness to flourish for decades at body temperature before choosing another venue.

Here's a link to "... 4,652 free online papers on consciousness...."

That ought to keep you occupied for the rest of the day.

Knock yourself out.

January 10, 2008 at 10:01 AM | Permalink


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Comments

The problem with most longevity research is that they forget "time" is largely a human construct. The universe does not use "time" as we humans do, so longevity is not really an issue. The quantum brain researchers need to first figure out how quantum mechanics actually works, and accords with relativity, before postulating that quantum microtubules in the brain are the cause of consciousness.

Posted by: Quantum Man | Jan 12, 2008 8:52:41 AM

No one "invented" the transistor any more than anyone invented air. The characteristic operation of a three-part semiconductor combination was DISCOVERED by the great William Shockley in the 1950s. Even Shockley initially could work out how it worked. I've never heard of the guy you mention in your article.

Posted by: Paul | Jan 10, 2008 6:47:17 PM

PBS Nova had an excellent show this week on the History of Cold, and discussed superconductivity. Fairly interesting.

Posted by: Elux Troxl | Jan 10, 2008 11:56:00 AM

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