October 20, 2013

IT'S JUST PHYSICS IN FANCY DRESS:

Has David Birnbaum solved the mystery of existence? (Oliver Burkeman, 10/18/20,The Guardian)

In the summer of 2012, a number of philosophers at British and American universities received a bulky, unmarked package in the post. It contained a 560-page book, written in English but with the Latin title Summa Metaphysica, by an amateur whose name they didn't recognise: David Birnbaum. It isn't unusual for philosophy departments to get mail from cranks, convinced they have solved the riddle of existence, but they usually send stapled print-outs, or handwritten letters; Summa Metaphysica stood out "for its size and its glossiness", says Tim Crane, a professor of philosophy at Cambridge. The book was professionally typeset. It even included endorsements from Claude Lévi-Strauss, the legendary French anthropologist, who described it as "remarkable and profound", and from the Princeton physicist John Wheeler, who once collaborated with Einstein. It would later transpire that 40,000 copies were in circulation, a print run any academic philosopher might kill for. The book claimed to have sliced through countless fundamental problems in philosophy, physics and theology, and there on the spine, where the publisher's name appears, was one deeply reassuring word: "Harvard".

Then the story grew stranger. In May this year, the US-based Chronicle of Higher Education reported that prominent scholars - scientists, philosophers and theologians - had been persuaded to attend an expenses-paid "international academic conference" at Bard College, a respected institution in upstate New York, devoted to Birnbaum's work. "We are especially pleased to announce that David Birnbaum will be present during discussion," the invitations glowingly explained. They hinted that his work might point the way toward a reconciliation of science and religion.

But the event itself, on Bard's leafy campus beside the Hudson river, proved disorienting. It was "definitely, absolutely the strangest conference I ever attended", the astrophysicist Marcelo Gleiser told the Chronicle. Tammy Nyden, an expert on Spinoza, the great rationalist of 17th-century philosophy, "felt hesitant about the invitation to begin with", the Chronicle reported, "but because it was taking place at a venerable institution like Bard, she decided to go". On the one hand, Birnbaum's work had attracted plenty of credible endorsements: a typical blurb for Summa Metaphysica, attributed to a mathematician at Warwick University named Hugo van den Berg, described it as "unparalleled and magisterial". On the other, nothing about Birnbaum's approach was conventional. Conference-goers were surprised to find him handing out Summa Metaphysica T-shirts; it subsequently emerged that he had provided thousands of dollars of his own money to fund the gathering. Nyden recalled feeling uneasy: "Here's someone with a lot of money," she thought, "and they're buying a lot of legitimacy." [...]

To grasp why a successful New York jeweller, with little philosophical or scientific expertise, might want to probe such questions, it is illuminating to consider Birnbaum's early life. He had been haunted by these grand mysteries, he told me, since the age of 11, when he attended an Orthodox Jewish school, or yeshiva, in Queens. It was the early 1960s and many of his classmates were the children of Holocaust survivors, or other Jewish émigrés from Nazi Europe: humanity's capacity for great evil loomed large in recent memory. Yet the yeshiva boys were urged daily to put their faith in a just and merciful God. The contradiction that weighed on the young Birnbaum was the ancient theological puzzle known as the "problem of evil": how could God be just and merciful, yet allow something like the Holocaust to happen? The secular side of the curriculum proved equally dissatisfying. If everything began with the Big Bang - a term coined just a few years previously, in the 1940s - then what caused the Big Bang? If evolution explained how living things changed, why did life start to begin with? Why was there anything?

"So, pretty soon, it becomes clear to me that I'm not going to get answers," Birnbaum said. "Everybody's smart. Everybody means well. But we never quite get there." Through college, and on to an MBA at Harvard Business School, the questions never stopped nagging. "There must be an answer," he remembered thinking, "but how is it possible that so many brilliant people, over thousands of years, have missed it?" That was when he began to suspect the answer might have remained hidden not because it was too complicated, but because it was too simple: "I decided it must be hiding in plain sight."

The answer, after years of fruitless reflection, dawned unexpectedly. Birnbaum was in Barbardos on holiday in 1982, sunbathing on a beach and turning matters over in his mind. "I'm good on the beach," he explained. "My brain is working a little better... And then" - he snapped his fingers - "it was clear to me." The answer was: potential.

This part takes a little explaining.

Birnbaum considers his specialism to be metaphysics, that hard-to-define corner of philosophy that deals with the most basic questions of what there is. It's the territory into which you cross when you reach the limits of what biology, chemistry or physics can tell you. Metaphysical explanations aren't supposed to be substitutes for scientific ones, though; they just claim to be even more fundamental. And what could be more fundamental than potential? What must have existed, before everything else, but the potential for all those things that later came into existence? If you believe in God, the potential for God must have been there first. And prior to the Big Bang, there must have been the potential for the Big Bang.

Rising from the Barbadian sand, Birnbaum saw the world in a new light: everything and everyone around him was an expression of cosmic potential, working itself out. Why? Because that's what potential does. Birnbaum calls this process "extraordinariation". It is explained in depth in the hundreds of pages of Summa Metaphysica, but the core idea is concise enough to fit on a T-shirt. The universe itself is potential, actualising itself.

You may be raising your eyebrows at this. But Birnbaum's perspective isn't without precedent. Since Aristotle, some thinkers have been drawn to the notion that the world must be heading somewhere - that there is some kind of force in the universe, pushing things forward. These teleological arguments are deeply unfashionable nowadays, but there's nothing inherently unscientific about them. In his controversial 2012 book Mind And Cosmos, the US philosopher Thomas Nagel argues that teleology might be the only way to account for the still unsolved mystery of why consciousness exists. Still, as Birnbaum explained his theory, I must have looked underwhelmed, because he leaned forward in his chair to emphasise his point. "It works!" he said. "It's powerful! And with all due respect to Harvard, Oxford, etcetera... it's more powerful than anything you got!"

From Timothy Ferris' The Whole Shebang: A State-of-the-Universe(s) Report (1997). (Timothy Ferris)

Heisenberg discovered quantum indeterminacy while working under Bohr, who was quick to appreciate its implications. Bohr was a wide-reaching thinker Heisenberg regarded him as "primarily a philosopher, not a physicist"-and it was due chiefly to his influence that the world soon came to regard quantum weirdness as a significant philosophical problem. [19] Although many capable theorists are like composers who play only the piano, Bohr and Einstein were both universalist thinkers, akin to those composers who can play every instrument in the orchestra. The world knows Einstein; perhaps we may take a moment to meet Bohr.

He was one of the physical physicists, blessed with a lifelong appetite for fresh air and exercise. He saw life as a whole and was immune to the scholarly delusion that brain power is superior to muscle power. Heisenberg tells a story that illustrates Bohr's integrated view of thought, action, and mystical philosophy: "Once, when on a lonely road I threw a stone at a distant telegraph post, and contrary to all expectations the stone hit, he said, ´To aim at -such-a-distant-object and-hit it-is-of course impossible . But if one has the impudence to throw in that direction without aiming, and in addition to imagine something so absurd as that one might hit it, yes, then perhaps it can happen. The idea that something perhaps could happen can be stronger than practice and will.'" [20] Bohr's younger brother Harald was a soccer star-a member of the Danish team that won a silver medal in the 1908 London Olympics-and Niels might have matched him athletically had he not been so preoccupied. Playing goalie against a German club, he busied himself tracing equations with his index finger on the goalpost, nearly letting an errant ball roll slowly into the goal. Like Einstein, Bohr was a sailor, but while Einstein liked to trace broad reaches on lakes, Bohr preferred blue water. (The greatest tragedy of his life came when his eldest son, Christian, was swept to his death from the deck of Bohr's cutter, the Cbita, in a summer storm in 1934. Only the restraining grip of friends on deck prevented Bohr from leaping into the sea after him.) Bohr viewed ignorance as an integral part of the learning process and regarded confusion and paradox as signposts on the road of inquiry. He complained on his deathbed that the philosophers too often "have not that instinct that it is important to learn something, and that we must be prepared to learn." [21]

Blunt and tenacious to a fault, Bohr was too serious to be pompous and too honest to be facile. If his way of speaking was often confusing, that was because he was himself frankly confused and liked to think out loud, and held that one should, as he put it, "never express yourself more clearly than you think." [22] (When Carl Friedrich von Weizsacker wrote in his diary on meeting Bohr, "I have seen a physicist for the first time. He suffers as he thinks," he meant that Bohr suffered out loud. [23]) His habit of being both frank and frankly uncertain could get Bohr in trouble. Winston Churchill, having been urged by Bohr to reveal nuclear secrets to the Soviets since they were bound to learn them anyway, responded in an outraged note to his science adviser, Lord Cherwell, who had arranged the meeting, "It seems to me Bohr ought to be confined or at any rate made to see that he is very near the edge of mortal crimes .... I did not like the man when you showed him to me, with his hair all over his head, at Downing Street .... I do not like it at all:" [24] Bohr fared little better-with -the -American secretary of state, Dean Acheson, with whom he met in the spring of 1950 to discuss a planned open letter to the United Nations. "The meeting began at, say, two o'clock, Bohr doing all the talking. At about two thirty Acheson spoke to Bohr about as follows. Professor Bohr, there are three things I must tell you at this time. First, whether I like it or not, I shall have to leave you at three for my next appointment. Secondly, I am deeply interested in your ideas. Thirdly, up till now I have not understood one word you have said." [25]

Bohr's explications of the Copenhagen outlook can sound as oracular as if he had uttered them from atop a tripod while chewing laurel leaves, but he was earnestly trying to bring as much clarity to quantum weirdness as he could, and his position is not all that difficult to understand. Briefly put, it is that since, owing to quantum indeterminacy, neither we nor any other observers anywhere in the universe can know everything about a given microscopic particle or system, it is pointless to speculate about whether the missing information "exists." Physics is not the pursuit of imaginary ideals, and physicists need not waste time speculating about quantities (such as whether a photon is "really" particle or wave) that are known to be unascertainable: "It is wrong to think that the task of physics is to find out how nature is," Bohr wrote. "Physics concerns what we can say about nature .... Our task is not to penetrate into the essence of things, the meaning of which we don't know anyway, but rather to develop concepts which allow us to talk in a productive way about phenomena in nature." [26] The Copenhagen interpretation asserts, to paraphrase John Wheeler (who was paraphrasing Bohr), that no elementary phenomenon is a phenomenon until it is an observed phenomenon.

To clarify this ontology, Bohr spoke of what he called complementarity. The wavelike or particlelike potential states of an undisturbed photon (or its polarization states, or the hard/soft and sweet/sour states of the particles in our schematic experiment) complement each other, like the black and white sides of the yin-yang diagram that Bohr incorporated into his family coat of arms. Bohr saw complementarity as a kind of chiaroscuro, an essential embracing by nature of opposites and contradictions that had been revealed to us by Heisenberg indeterminacy but that has wider implications. The more closely one looks at one side of the issue (e.g., studies the photon as a wave), the more paradoxical the other side (but it's a particle!) becomes.

Every interpretation of quantum weirdness amounts to sweeping the weirdness under one or another carpet, and a magic carpet at that. The magic carpet of the Copenhagen interpretation is the act of observation. It is by making an observation-a measurement-that one "collapses the wave function," thus resolving the superposed system into one or the other of its states. But what, exactly, is an observation? From this question have sprung the most enduring thought experiments to have probed the dark realms of quantum weirdness.

The best known of them is "Schrödinger's cat." It consists of a system with two potential states, A and B. This could be a piece of radium with a 50 percent chance of decaying within one hour, or a sweet/sour box into which is introduced a single particle that has a 50 percent chance of emerging from the sweet output window -any probabilistic quantum setup. The important point is that, according to Bohr, the system has no definite state-neither decayed nor undecayed, neither sweet nor sour-until it is observed. Instead it exists in a superposed state, one fully designated by the probabilities of its wave function. The radium or other quantum object is set up to trigger one of two devices located inside an opaque box that also contains a cat. If the system goes one way (if, say, the radium atom decays) it opens a canister of cyanide gas inside a sealed box, killing the cat. If it goes the other way (no decay), the cat survives. We set up the apparatus, then wait one hour before opening the box. Question: Right before we open the box, is the cat dead or alive? The Copenhagen interpretation answers that until we open the box and observe it, the cat is neither dead nor alive but exists in a superposed state of dead/alive. This seems implausible, and that is the point of the thought experiment: Schrodinger's cat critiques the Copenhagen interpretation by reducing it to absurdity. Its object is to deny the plausibility of a bifurcated, quantum-classical universe by demonstrating that such segregation yields nonsensical results. (Minimalists comfortable with a bifiircated physics can and do shrug it off. Stephen Hawking, paraphrasing Hermann Goering, says, "When I hear of Schrödinger's cat, I reach for my gun." [27])

The issue can be illuminated by considering our frame of reference. Suppose that the cat experiment is conducted in a locked laboratory, at night, with only one scientist keeping watch. At the end of the hour, he opens the box and sees . . . what? Until the scientist picks up the phone and announces the result, or runs into the street shouting "Eureka!" we don't know the outcome. [28] The wave function was collapsed in that scientist's frame of reference, but not in ours. That this is problematical is not terribly surprising: In science as in art, the choice of frame counts for a lot. (G. K. Chesterton: "Art is limitation; the essence of every picture is the frame." [29]) It amounts to saying that the Copenhagians are vague when it comes to defining just what, exactly, is meant by "measuring" or "observing" a phenomenon or "collapsing the wave function"-all of which mean the same vague thing.

Another thought experiment, more subtle than the cat but no less telling, was composed in 1935 by Einstein and two of his young associates at the Institute for Advanced Study in Princeton, Boris Podolsky and Nathan Rosen. It is known as the EinsteinPodolsky-Rosen ("EPR") "paradox," and works rather like our beam-sputter experiment. We start with a particle that decays into two other particles, X and Y, that must have a total spin equal to zero. So if one particle has a spin of + 1, the spin of the other must be -1. We let the particles fly far apart-this is the now-familiar amplification part of the experiment-and when they are separated by, say, one light-year, a physicist measures one of them, particle X, and finds that its spin is -1. He then knows that particle Y, a light-year away, must have a spin of + 1, as can be verified by a second physicist, off yonder where particle Y is. That would be perfectly sensible for a macroscopic system-if, say, the particles were replaced by a pair of one-ton gyroscopes that had been spinning in opposite directions all the way out. But according to the Copenhagen interpretation, remember, the particles were in neither spin state until their spin was observed. It seemed to Einstein-and has seemed to like-minded thinkers since-that if in fact a particle's spin is indeterminate, then the only way for Y to "know" that X had suddenly resolved itself into a spin -1 state would be if some sort of signal propagated instantaneously across a light-year of space, bringing the news from X to Y. And that, of course, would violate both special relativity and common sense. Einstein called it "spooky action at a distance." "No reasonable definition of reality could be expected to permit this," wrote Einstein, Podolsky, and Rosen. [30]

Much of the subsequent discussion of the Copenhagen interpretation-and such critiques of it as Schrödinger's dead-and-alive cat and the EPR "paradox"-has been infected with confusion. It helps in dispelling the mists to keep in mind that Bohr did not exactly maintain that a quantum system has no state prior to its being observed. Rather, he said that its state, prior to observation, cannot in principle be determined, and that attempts to define it are therefore meaningless. Bohr was an agnostic on the issue of what might be going on in nature beneath the threshold of its theoretical observability. Einstein used to poke fun at the Copenhagen interpretation by asking colleagues whether they really believed that the moon existed only when they looked at it. Bohr's answer was not that the moon does not exist when unobserved, but that we cannot know whether it, or some thoroughly unobserved moon of a remote and uninhabited planet, exists, until it is observed. His position sports a certain tough-minded bluntness: It confronts quantum weirdness and refuses to blink. But in doing so, it amounts, in the words of David Z. Albert, a physicist who holds a chair in philosophy at Columbia University, to a "radical undermining . . . of the very idea of an objective physical reality" [31]-which, I would add, has long been regarded as the whole point of science. [32] So it is understandable that at least a few philosophically minded scientists kept searching for a more accommodating way to draw quantum weirdness into the embrace of macroscopic logic.

Of course, the reaction to Mr. Birnbaum's entirely derivative idea is a demonstration of Bohr,'s dictum: "Anyone not shocked by quantum mechanics has not understood it."  How much difference is there between collapsing the wave and realizing potentialities.





Posted by at October 20, 2013 7:38 AM
  

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