Tuesday, February 24, 2009

Evolution and Anti-Magical Thinking

A friend of mine, Mick Stone, is about to take his Anti-Magic Show on the road. Now, Mick's show, billed as "the magic show for magic haters", works quite well for magic lovers, too.

After attending one of Mick's performances last fall, I found my fascination for stage magic revived. How delightful it was - for a brief time - to suspend disbelief and imagine that things happen in the world that defy explanation.

Suspension of disbelief and willingness to rely on supernatural explanations, a fun way to spend the evening with friends, turns out, though, to be a very bad way to go about doing science.

Magic had largely been banished from contemporary scientific discussions until 1989 and the attempt to insert of the doctrine of Intelligent Design (ID) into the biology curriculum in this country. The defining contention of ID is that there exist features of living organisms that are so complex that they can not be explained as the result of the processes of undirected evolution by natural selection. According to ID, these extraordinary biological artifacts are deemed to be irreducibly complex and are, therefore, evidence of the hand of a transcendent designer, the ticking proof of a supernatural watchmaker.

For most scientists - and many supporters of science - the controversy stoked by ID is a political one, and, for them, ID is not much more than a stalking horse for so-called creation science and its determined program to return teaching of the creation myths of Genesis to high school biology classes. Although I believe this to be the case, I accept that there are proponents of Intelligent Design, whose agenda is not religious and whose intentions are sincere. These people, many of whom subscribe to the broad outlines of Darwinian evolution, are at a loss to see how it alone could account for certain biological phenomena. Instead, they turn to magic for their scientific salvation.

Unfortunately for ID and these earnest seekers, the three premier examples of irreducible complexity, championed by ID advocate Michael Behe - the cascade of reactions that causes blood to coagulate, the elaborate structure of the eye, and the 40-part molecular engine that propels bacteria - have failed to remain inexplicable as advertised.

Much of the ID argument concerning the physical impossibility of the origin of the blood clotting pathway assumes that the multiplicity of chemical factors involved in coagulation had to come into existence all at once, an, admittedly, astronomically improbable event. Yet, not only does natural selection allow the mutations responsible for these clotting factors to accumulate over an extended period of time - a much more likely course of events - it also appears, contrary to ID assertions, that not all these clotting factors are essential for clotting to occur in all species. This is not to say that the evolutionary development of this complex process is completely understood, but a thorough understanding of it would seem to be reasonable possibility without having to invoke a magical helper.

Claims that the structure of the eye are too complex to be explained as a result of a natural processes stem from Darwin's admission that its evolution presented difficulties to his own theory. But much has been added to our understanding of the origins of the anatomical features of the eye in the last 150 years, enough so, that how its gross components originated is no longer a mystery. Behe contends that the lineage of the molecular mechanism of the eye's photo-receptor still defies explanation. This is an area of active research. It looks likely, though, that, supernatural intervention will not be needed to account for the origins of vision, either.

The problem of the evolution of the flagellum, the whip-like propeller and intricate motor that allows bacteria to swim about, was long-considered the poster child of the Intelligent Design movement. When ID came on the scene, the flagellum was presented as its foremost example of irreducible complexity. At the time, its evolutionary origins were, at best, vague. This is no longer the case. In the last half dozen years evidence has mounted that the flagellum - whose evolutionary construction ID insisted could only have been accomplished through supernatural meddling - had gotten its start as a sort of molecular syringe used to inject toxins into other cells.

So much, then, for the ID claims of that such things are forever beyond our ability to explain as the results of long-term physical processes driven by natural selection. No magic is required. The poster child of Intelligent Design has become the prototypical example of why ID is, on its face, scientifically untenable.

To underscore this point, let's consider my reaction to Mick's magic show, again. I admit to being amazed and baffled by his tricks. Honestly, I can't even begin to say how he does what he does. Yet, be that as it may, it never occurs to me that my inability to give an account of how Mick creates his illusions restricts anyone else from figuring them out.

This is the the essential fallacy of Intelligent Design. Its adherents assert that the contemporary failure to produce a naturalistic explanation for the origin of a particular complex biological feature means categorically that no one will ever be able to do so. The limitations of our understanding and capabilities here and now, somehow become those of all investigators for all time to come.

The fact of the matter is that some problems in science, in general, and in evolutionary biology, in particular, are formidable. Ironically, it is the very activity of dogged scientific inquiry that has led us to pose many of these difficult questions. When, then, it must be asked, has the cause of science ever been advanced by insisting that hard-to-understand phenomena have to have a supernatural explanation? At best, such claims have been quickly discredited - as with the supposed irreducible complexity of the bacterial flagellum - at worst, such recourse to the supernatural has discouraged research and foreclosed avenues of investigation.

So let's hear it for magic - of the Mick Stone variety. But let's repudiate the defeatist reliance on magical thinking advanced by doctrines such as Intelligent Design. It only serves to undermine our bold efforts to confront and solve the mysteries of the scientific world and it demeans us as the intellectually restless and ingenious species that we are.

Monday, February 16, 2009

Through a Universe Darkly

"An inordinate fondness for beetles." This is how the eminent evolutionary biologist, J. B. S. Haldane, is reported to have replied when asked by theologians to speculate, based on the character of the biological world, what may have motivated the Creator when he undertook its initial design.

No doubt, they had hoped for a more inspirational answer.

Yet Haldane, a pioneer in mathematical genetics, was absolutely right. He had done the arithmetic, so to speak. At that time over 350,000 species of beetles had been identified, comprising half of all the known insect species. What better insight, then, could one divine concerning divine intention? From all appearances, God played favorites in the animal kingdom, and beetles were at the top of His list.

It's not hard to imagine that a latter-day Haldane, steeped in astrophysics instead of natural history, might be confronted with an analogous theological challenge. What does the character of the physical universe that we inhabit reveal about the mind of the Creator who set things in motion some 14 billion years ago? What insights can we derive about Him from our determined investigations of his His creation?

"An inordinate fondness for dark energy," would be a fitting response.

Following Haldane's lead, let's do the math. According to analysis of the results from the Wilkinson Microwave Anisotropy Probe (WMAP), a satellite launched in 2001 to measure the cosmic background radiation - the electromagnetic afterglow of the primordial Big Bang - to unprecedented precision, our universe consists of 74 percent dark energy, 22 percent cold dark matter and 3.6 percent interstellar gas, leaving a paltry 0.4 percent to the atoms which make up not only nebulae and stars but also the flotsam and jetsam, our home planet for example, that orbit around them.

Among these constituents, dark energy is the new kid on the astrophysical block, proposed in 1998 to account for the discovery that the universe is expanding at an ever-increasing rate. Currently no one quite knows what dark energy is. It could be the physical manifestation of the long-suppressed cosmological constant from Einstein's first formulation of his theory of general relativity. Or, it might represent an entirely new type of matter, a background field of particles that permeates the so-called vacuum of space. Whatever dark energy is, its existence is required to make sense of the large scale structure of the universe as indicated by increasingly accurate measurements from experiments such as WMAP.

As with dark energy, dark matter is a name given to a form of matter whose composition has not yet been determined. In spite of this, astronomers are convinced that it exists, because, without it, the observed motion of galaxies within galactic clusters would be impossible to explain. Such galaxies maintain long-term stable configurations, yet the mass of these gravitationally bound systems, as estimated by adding up that of their readily observable constituents such as stars, is not sufficient to keep them from flying apart. Something must be missing, and the missing something that solves this problem has come to be called dark matter. Although the detailed properties of dark matter remain a mystery, confidence in its existence continues to increase, supported, in part, by recent observations of the colliding galaxies that form the Bullet Cluster.

The most remarkable thing to be said about unremarkable intergalactic gas, which consists of a lone hydrogen atom spaced every cubic meter or so, is that there is so much of it, at least relative to the amount of matter that we find in our immediate neighborhood.

Finally we come in our astrophysical inventory to the category of galactic atoms, weighing in at about one-half of one percent of the entire mass of the universe. A significant fraction of these are hydrogen nuclei, engaged in - or acting as bystanders to - the phenomenon of thermonuclear fusion that powers the stars. Hardly meriting arithmetic mention are the the other naturally-occurring chemical elements, the ones that make up everything from planets to plutoids, from people to petunias. Although "rain drops on roses and whiskers on kittens" are, arguably, a few of our favorites things, they and their kind of material stuff appear not to have meant much to the Creator in His grand design, at least as far as the allocation of mass and energy was concerned.

Returning now to the theological question that opened this discussion, as in Haldane's time, most theologians - indeed, most believers - today look for inspiration in the prospect of a creator God. Yet attempts at an objective reading of creation as the unfolding of a divine plan leaves one contemplating more a slap-dash muddle than a carefully drafted blueprint. To the extent the Creator had humans in mind in the beginning, He chose bizarrely inefficient means to go about creating them. It would seem that an omnipotent being could have done without adding so much dark energy and so many kinds of beetles to the cosmological mix. As far as science can tell, our species is an unintended consequence of the undirected physical processes that gave rise, first to space and time and matter, and, much later, to life on earth.

There is, though, some consolation to be had. God, if he exists, possesses not only an inordinate fondness for beetles and for dark energy, but also an inordinate fondness for puzzles and for wonder. This revelation may be cold comfort for many theologians, but it is a source of unending delight for scientists.

Creative Commons License
Through a Universe Darkly by Marc Merlin is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 United States License.
Based on a work at thoughtsarise.blogspot.com.

Thursday, February 12, 2009

The Physics of Unwelcome Surprises

"Who ordered that?" This was the flustered response of physicist Isidor Isaac Rabi when he was told that a new elementary particle, one that would eventually be named the muon, had just been observed.

The year was 1936, and the world of 20th century physics, rocked by three decades of disorienting discoveries, was in need of a breather, a bit of time to take stock, to consolidate the mind-bending theories that had been cobbled together at an unprecedented pace.

This roller coaster ride of surprises was set in motion in 1900 with Max Planck's quantum hypothesis. It turned out, to Planck's despair, that the the elegant mathematical models of the physical world, painstakingly developed over the preceding three centuries, failed abjectly when scrutinized at extreme microscopic levels. Graceful, continuously-varying classical arcs gave way to jagged, stair-stepped quantum diagrams when atoms were the object of investigation. It was as though a mischief-maker had stolen into the Louvre one night and had replaced Leonardo's "Mona Lisa" with Braque's "Woman with a Guitar". Planck, crestfallen, soldiered on.

Only five years later Albert Einstein, exploiting Planck's conjecture about the particle nature of light to solve, virtually en passant, the problem of the photoelectric effect, proposed his theory of special relativity, demolishing the heretofore unquestioned notion that measurements of space and time were absolute. Astonishingly, distances shortened and clocks ticked more slowly as observers moved relative to one another - the closer their difference in speed to the unassailable speed of light, the more dramatic the distortion. Ever the iconoclast, Einstein forged ahead with his assault on Newton's theory of gravitation while the rest of the world was still reeling from his recent revelations.

Ironically, the troubled time after the Great War and the early years of the decade of the roaring twenties provided physicists an opportunity to recover their bearings. The early quantum musings of Planck and Einstein, followed soon by those of Niels Bohr, found rigorous mathematical expression with the so-called matrix mechanics of Werner Heisenberg and in Erwin Schrödinger's eponymous wave equation. The structure of the hydrogen atom could now be calculated to impressive precision. A tentative understanding of the universe - at least one consisting of protons, electrons and photons (quanta of light) - appeared to be within reach.

Forging ahead, in 1928, Paul Dirac advanced a formulation of quantum mechanics, which explicitly took into account Einstein's special relativity, and, in doing so, predicted the existence of antimatter. According to Dirac, every elementary particle possessed a negative-image twin of sorts. For the neutral photon, this turned out to be the photon itself. But, for the electron and the proton, Dirac's equations demanded the existence of, yet-unobserved, particles of identical mass and opposite charge. Dirac was serenely confident in the implications of his mathematically elegant theory. Other physicists, though, awaiting experimental confirmation, were skeptical. Four years later, the discovery of the positron, the electron's antimatter doppelgänger laid their doubts to rest.

At about the time of the positron's debut, the existence of another, apparently fundamental, particle was being established. The neutron, a sister particle to the proton - a little heavier but possessing no electrical charge - was, in many ways, a welcome addition to the particle family. Its discovery led to the understanding that the atomic nucleus was composed of an unimaginably compact knot of protons and neutrons, bound together by a hypothetical "strong" force.

The behavior of the electrons orbiting this nuclear droplet, in accordance with now established quantum theory, explained the chemical activity of the elements, while the numbers of protons and neutrons within their nuclei accounted for their atomic weights. At long last an explanation for the organization and the particulars of the periodic table of elements, devised by Dmitri Mendeleev in 1867, had been provided, and with it came the first comprehensive understanding of ordinary matter in the history of the world.

But, to everyone's surprise, the neutron itself proved to be anything but ordinary. Unlike the other elementary particles, neutrons were not immortal. Within an atomic nucleus their lifetimes varied widely, but left to fend for themselves they survived, on average, a little less than 15 minutes, decaying spontaneously into a proton and electron.

To make matters worse, when the momenta of the proton and the electron resulting from the neutron's decay were tallied, it turned out that energy accounts did not balance. Either the supposedly inviolable law of the conservation of energy had to be jettisoned, or a new particle had to be called into existence, one that fled the neutron's self-destruction unobserved, stealing away with the unaccounted for missing energy. This placeholder, promissory note of a particle, conjured into being by Wolfgang Pauli and christened the neutrino by Enrico Fermi escaped detection for another quarter century, owing to the fact that it felt the push and pull of only the aptly-named "weak" interaction. In the meantime, the hypothesis of the neutrino, a ghost of a particle bullet, allowed physics to dodge another, much more potentially damaging, one.

By the mid-1930s a family portrait of elementary particles looked like it was coming into focus. There were the "adults", the neutron and the proton: the heavy-set neutral momma and positive poppa particles, bound in enduring strong-force matrimony, comfortably ensconced in their nuclear home. Then there were the "kids": the bantam-weight, negatively-charged electron, a mercurial and rambunctious boy-child, hovering close by when mindful of his father's tugs, but venturing beyond the atomic neighborhood when overly stimulated, and the neutrino, an alienated and asthenic teenage daughter, resembling her brother in outline, but drained entirely of charge and heft, a Garbo manqué, withdrawn and in perpetual flight.

Of course, there was Planck's voluble particle of light, around from the beginning, less a full-fledged blood relation than a domesticated sprite, a restless go-between, bounding from electrical lap to electrical lap. There were rumors circulating, though, that the photon had relatives of her own, answerable to the commands of the strong force and weak force, the way she obeyed the beck and call of electricity and magnetism. Physicists were on the lookout for them.

That's about the time that, to Rabi's feigned consternation, the muon showed up, unsummoned. At first it appeared that it might be the strong-force cousin of the photon forecast by Hideki Yukawa only a year before. That turned out not to be the case. Instead, the muon was the harbinger of a wave of particle discoveries to come.

By the time the "unwelcome" muon arrived on the scene, the enterprise of physics had been transformed in a fundamental way by the philosophical buffeting of the preceding 30 years. Grudgingly, physicists had come to appreciate that the universe was such a strange and marvelous place, that their understanding of it was, in a profound way, destined to be forever provisional, and that any charter for their investigations required that they not only seek answers to long-standing questions, but also be prepared to wrestle with unexpected - even confounding - surprises.

This intellectual no man's land, bounded on one side by time-tested facts and theories and on the other by ever-restless skepticism and doubt, was both a precarious and a wondrous territory. Nevertheless, it was, and remains, the quintessential realm of all scientific discovery.