Chaos and Harmony: Perspectives on Scientific Revolutions of the Twentieth Century - Softcover

Thuan, Trinh Xuan

Softcover

ISBN 10: 1932031979 ISBN 13: 9781932031973

Publisher: Templeton Press, 2006

Synopsis

Extraordinary advances in science in the twentieth century profoundly changed the way we perceive the world. New discoveries restored mystery to the universe, revealing a system of symmetry and chaos.

In this book, world-renowned astrophysicist Trinh Xuan Thuan reignites the excitement of these discoveries while considering their philosophical and theological implications. He describes the process through which constraining and sterile determinism was challenged, transformed, and swept aside by contingency, which took a prominent place in fields as diverse as cosmology, astrophysics, geology, biology, and genetics. He traces the view of reality as dependent not only on natural laws, but also on a series of historical and contingent events.

Originally published in France where it became a bestseller, this is the first paperback English-language edition.

About this title

About the Author

Trinh Xuan Thuan has been a professor of astronomy at the University of Virginia since 1976. He currently teaches a course in astronomy for non-scientists. His primary research involves studying very young dwarf galaxies in the local universe; he recently co-authored a study that identifies what is possibly the youngest known galaxy within this universe. He has written many articles on galaxy formation and evolution, and he is the author of several books for the general public.

Excerpt. © Reprinted by permission. All rights reserved.

Chaos and Harmony

Perspectives on Scientific Revolutions of the Twentieth CenturyBy Trinh Xuan Thuan

Templeton Foundation Press

Copyright © 2006 Trinh Xuan Thuan
All right reserved.
ISBN: 9781932031973

Chapter One

Truth and Beauty

A MAN AND A WOMAN

It is a beautiful spring day in Paris. At a sidewalk café, a man is enjoying aglass of beer while reading a newspaper. At the next table, a woman is sippingcoffee while watching passersby. They haven't noticed each other yet.Suddenly, the man turns his head and his gaze meets the woman's. At thatinstant, a remarkable series of events is set in motion. The golden light ofthe sun reflects off the woman's slender body and penetrates the man's eyes.Traveling at a speed of 300,000 kilometers per second, 10,000 billion particlesof light (called photons) rush in through his pupils. First they traversean oval-shaped body called the lens, then a transparent and gelatinous substance,before they strike the retina.

THE DANCE IN THE RETINA

In the retina, more than 100 million rod- and cone-shaped cells go to work.Covering the retina like darts bristling out of a dartboard, some of theserods receive large amounts of light from the bright areas of the woman'sbody, such as her moist lips highlighted by vivid red lipstick. Others receiveless light, because it comes from more subdued parts of the woman, such asher discreetly made-up cheeks. While rods are sensitive to very dim light,cones require brighter light. Both rods and cones contain light-sensitivepigments that respond differently to different levels of light coming fromthe woman's body. All rods have the same type of pigment. Cones, however,come in three types, each containing a different visual pigment. One typeabsorbs best in the blue, another in the green-yellow, and the third in theorange-red. Visual pigment molecules are each composed of 20 carbonatoms, 28 hydrogen atoms, and 1 oxygen atom. They respond to light byengaging in a kind of strange ballet. When at rest, in the absence of light,each such molecule is attached to a protein and is all crumpled up. But assoon as light strikes it (the light reflected by the woman hits 30 million billionmolecules in the man's eye every second), the molecule in the retinaseparates from the protein and straightens out. After a while, it crumplesback up until the next photon arrives.

NEURONS SPRING INTO ACTION

All these events took less than 1/1,000 of a second since the moment the man'sgaze met the woman's. But the man is still not "conscious" of the woman'spresence, because the information carried by the particles of light has yet toreach his brain. The frenetic dance of the molecules in his retina must fireup neurons, first in his eyes and then in his brain. Molecules on the surfaceof neurons also change shape, blocking the flow of sodium ions (particleswith a positive electrical charge) in the surrounding liquid, which triggersan electrical current propagating from neuron to neuron, from the eye allthe way to the brain. In the cerebral cortex, each neuron processes theinformation transmitted by thousands of neurons before relaying it in turnto thousands of other neurons farther up the chain. A great many of thehundreds of billions of neurons in the man's brain, interconnected in anincredibly complex network, participate in relaying the information. Theflow of potassium and sodium stops depending on whether or not it isblocked by neurons. Electrical currents race furiously through neural networks,exciting swarms of neurons relaying signals that go on to excite yetmore neurons. Current crackles everywhere. After a few thousandths of asecond, an image is reconstructed in the man's brain: He finally sees thewoman. He notices her short blond hair, her deep blue eyes, her dark browndress molding her body, her slightly tilted head with a pensive look.

    The woman turns her head, meets the man's eyes, gives him a faint smile,and offers a cheerful "Hello." Instantly, a multitude of air molecules start jigglingabout. The vibrations transmit the sound of the woman's vocal cordsto the man's ears. Only two meters separate them, and the sound arrives in1/150 of a second. The drum (a 1-millimeter-thick membrane) in each of theman's ears begins to vibrate. The vibrations are transmitted to the liquid inthe cochlea, a structure shaped like a snail's shell. That is where sounds aredecoded. A thin membrane starts oscillating in synchronism with the vibratingliquid. This membrane contains an array of fibers of various thicknesses,much like the strings of a harp. The harp resonates in unison with thewoman's sensuous voice and reconstructs the relatively high pitch of the syllable"hel-" and the deeper one of the syllable "-lo." Eventually, the soundsare passed on to the auditory nerve, which conveys the information to thecerebral cortex. And the man finally hears the word "hello."

    All theses processes are quite well understood. Neurobiology unveilsmore and more secrets of the brain each passing day. What remains a completemystery is what causes the lightning-quick thought that crosses theman's mind: "She is so beautiful!"

NATURE IS BEAUTIFUL

What is beauty? Not only do we have no clue about how our brain apprehendsbeauty, but we are even less able to describe it in precise terms. It iseven more of a challenge to speak of beauty in the context of science, whichis exactly what I am going to attempt to do. The popular wisdom is that scientificwork is a purely rational pursuit from which any emotion is banned.Physics is widely perceived as a precise and exact science in which there is noplace for aesthetic contemplations. Aesthetic judgments are supposedlyirrelevant in science; all that is left are cold and impersonal facts. The truthis that scientists are no less sensitive to Nature's beauty than artists. My frequentvisits to various observatories have never dulled the intense andalways renewed pleasure I experience when I find myself in sites of exceptionalbeauty, far removed from the lights of civilization. I am in absoluteawe every time I see the majestic and arid splendor of the Arizona desert,where the Kitt Peak Observatory is located, or the desolation of the moonscape,stripped of any vegetation, on the summit of Mauna Kea, an extinctvolcano in Hawaii where huge telescopes have popped up like mushrooms.My heart always starts racing when the spiral arms of a galaxy billions oflight-years away take shape on a monitor screen hooked up to a telescope.

    If Nature is so beautiful, why should the theories that describe it not beso too? Why should scientists be less prone than poets to letting themselvesbe guided by aesthetic considerations in addition to rational arguments?Some of the greatest scientists have answered the question unequivocally.The French mathematician Henri Poincaré (1854-1912), for one, stated:"Scientists do not study Nature for utilitarian reasons. They do it becausethey find it pleasurable; and they find it pleasurable because Nature is beautiful.If Nature were not beautiful, it would not be worth studying, and lifewould not be worth living." Poincaré even offered a definition of beauty towhich I will return later on: "I speak of an inner beauty that stems from theharmonious order of the parts, which pure intelligence has the ability tograsp." A cri de coeur expanded upon later on by Werner Heisenberg(1901-1976), one of the fathers of quantum mechanics: "If Nature leads usto mathematical forms of great beauty and simplicity?by 'forms' I meancoherent systems of hypotheses, axioms, and the like?which nobody hadforeseen before, we cannot help but think that they must be real, that theyreveal a true side of Nature.... You must have experienced it too: Thealmost frightening simplicity and totality of the interconnections whichNature displays before us and for which we were not at all prepared." AlbertEinstein (1879-1955) himself wrote at the end of his first paper on generalrelativity: "Anyone who understands the present theory could not miss itsmagic." "Harmonious order," "simplicity," "coherence," "magic": These areall words defining "beauty" in science, a concept which I will now try to furtherarticulate.

THE THINGS OF LIFE AND THE RELATIVITY OF BEAUTY

The beauty a physicist speaks of is quite different from what a musicianexperiences when listening to a sonata by Mozart or a fugue by Bach. Nor isit the same as what an art lover reacts to when admiring the dancers ofDegas, the apples of Cézanne, or the water lilies of Monet. It is not even thesame as what our earlier character was feeling upon noticing the beautifulwoman sitting at the next table. Feminine beauty obeys criteria that arenotoriously dependent on cultural, psychological, or even biological contexts.The plump bodies of the women painted by Rubens or Renoir are nolonger considered the paradigm of beauty. In the 1960s, Twiggy's skinny figurewas considered attractive. The beauty of oriental women is differentfrom that of their Western counterparts, even though massive advertisingcampaigns for cosmetic products have spread Western standards throughoutthe world, which has led to such absurd practices as some Asian womenhaving the shape of their eyelids rounded. There are fashionable trendseven in the world of art. Van Gogh died in poverty, unable to sell his canvases.Half a century later, people trip over one another buying his paintingsat astronomical prices. Aesthetic perceptions change from one culture toanother. The style of a painting of Mount Fuji by Hokusai has little in commonwith Cézanne's rendition of the Sainte-Victoire mountain. The timelessmagnificence of the Taj Mahal in India is quite different from the splendorof the cathedral of Chartres. It would be downright presumptuous foranyone to define what constitutes beauty. Like love and hatred, we recognizeit when it takes over our soul, no matter how difficult it may be to describethe experience in words.

    Beauty is in the eye of the beholder. It is a cliché, perhaps, but so true. Itcan spring up around any street corner and find its way into ordinary objectsin our everyday lives, provided we are receptive. A simple flower, a tree thatonly yesterday was completely unremarkable because we were preoccupiedwith other issues, suddenly evokes an overwhelming aesthetic sense. As theGerman philosopher Arthur Schopenhauer (1788-1860) put it so eloquently,at such times we consider "neither the place, nor the time, nor thewhy, nor the purpose of things, but quite simply and purely their essence";we do so because we then allow "neither abstract thought nor any principleof reasoning to clutter our conscience; instead, we turn all the power of ourmind toward intuition." Schopenhauer went on to argue: "When we arecompletely engrossed by it and our conscience is filled by a natural object,be it a landscape, a tree, a rock, a building, or anything else; ... the momentwe forget our own individuality, our own will, and we remain as pure subject,as a clear mirror of the object, in such a way that everything happens asthough the object existed in and of itself without anyone being able to perceiveit, when it is impossible to distinguish between the object and intuitionitself, when they both merge into a single entity, a single conscience completelyfilled and dominated by a unique and intuitive vision; in short, whenwe sever all ties with will: that is when what we grasp is no longer any particularthing in its individuality but, rather, the idea, the eternal form."

    If there is no objective criterion for beauty in human creation, should weexpect to discover one in scientific work? Is there a way to forge an aestheticsystem in science to judge Nature's beauty and her organization? Perhapsthe answer is yes, for unlike the relative beauty of women and things, theappeal of a physical theory is universal. It can be appreciated by any scientist,regardless of ethnic origin or cultural heritage. A Vietnamese physicistcan extol the virtues of general relativity with as much passion as any of hisFrench or American colleagues.

    In spite of Schopenhauer's exhortations to disregard reason and let intuitionbe our guide in grasping beauty, I will in fact attempt the hazardousfeat of trying to define the concept of beauty in a physical theory. I willrefrain from offering a precise definition, which would be doomed to failure.I shall, instead, simply list and illustrate the characteristics a scientifictheory must exhibit in order to be beautiful.

BEAUTY IN SCIENCE

To begin with, the word beautiful does not refer to the purely plastic beautyof equations carefully laid down on a piece of paper, even though I confessthat even that sight elicits in me a certain sense of abstract beauty, similar towhat I feel when I look at a page filled with characters lovingly drawn by aChinese calligrapher. The poet and painter Henri Michaux made expert useof the plastic beauty of Chinese characters in his ink drawings. Nor is beautythe same thing as what physicists and mathematicians talk about when theyuse the word elegance. A mathematical proof or a result in physics are "elegant"when they are derived with a minimum number of steps. A theory canbe beautiful without the benefit of elegant solutions. By any measure, thetheory of general relativity is one the most beautiful intellectual constructsever produced by the human mind. Yet, in most cases, its solutions hardlyqualify as elegant. The mathematical derivations are extremely complicated.That does not prevent it from being perhaps the most beautiful theory everdevised. A theory is beautiful when it has an air of inevitability. It is the samefeeling some people experience when listening to a fugue by Bach. Not asingle note could be changed without upsetting the overall harmony. Thesame can be said of the Mona Lisa by Leonardo da Vinci. Not a single strokeof the brush could be altered without destroying the perfection of the painting.So it is for a theory. The moment Einstein accepted the physical principlesat the basis of his theory of gravitation, he no longer had any choice:General relativity was inevitable. As he himself wrote: "The main appeal ofthe theory lies in the fact that it is self-contained. Should any of its conclusionsbe invalidated, the entire theory would have to be rejected. It is impossibleto modify it without jeopardizing the entire structure" The inevitabilityof a beautiful theory is so overwhelming that when it bursts onto the scene,physicists often wonder how they could have missed it before.

    The second quality of a beautiful theory is its simplicity. We are not talkinghere about the simplicity of the equations themselves, as measured forinstance by the number of symbols they contain, but rather of the simplicityof the underlying ideas. As an example, Isaac Newton (1642-1727) neededonly three equations?one for each dimension of space?while general relativityrequires a total of fourteen. Yet the latter is more beautiful because itrests on simpler fundamental concepts, which we will discuss later on. Theheliocentric universe of Copernicus (1473-1543), in which planets move inan orderly fashion along elliptical orbits around the Sun, is simpler than thegeocentric model of Ptolemy (ca. 90?ca. 168), where Earth occupies a centralplace and the planets describe circles whose centers themselves describeother circles. A theory that is simple uses a minimum number of hypotheses.It does not carry excess baggage. It satisfies the postulate of simplicity statedby William of Occam (ca. 1285-1349): "What is not necessary is useless."

CONFORMITY WITH THE WHOLE

The final quality?the most important one, in my opinion?is to conformwith Nature's intricacies. It must allow beauty and truth to merge into one.Indeed, a physical theory has no reason for existing unless it reveals newconnections in Nature that can be verified by observations or laboratoryexperiments, unless it lays bare before our eyes "the almost frightening simplicityand totality of the interconnections of Nature," as Heisenberg put itso well. A theory that cannot be verified experimentally belongs not in therealm of science but of metaphysics. Intellectual speculations remain sterileas long as they are not rooted in the forms of Nature. Heisenberg definedbeauty as it was perceived in antiquity as "conformity of the parts betweenthemselves and with the whole." Relativity theory is beautiful because it managedto connect and unite fundamental physical concepts that until thenhad remained completely distinct?time, space, matter, and motion. Mattercurves space, and the curvature of space dictates how motion proceeds. TheMoon follows an elliptical trajectory around the Earth because Earth's masscauses the space around it to curve. In turn, motion determines the behaviorof space-time. An elementary particle traveling at nearly the speed oflight sees its time stretch out and its space shrink. The slowing down of timeis not a utopian fountain of youth: Particles hurtling around accelerators,such as the one at CERN in Geneva, Switzerland, have been shown to indeedlive longer than when they are at rest. And detailed observations havedemonstrated that the path of starlight bends when it grazes the sun exactlyas if space were curved in its vicinity.

    The beauty of a theory is all the more compelling when it reveals a hostof new and unexpected connections as researchers explore its deeper implications.General relativity meets this criterion to the utmost degree. Its richnessnever ceases to amaze us. Einstein himself was stunned when he realizedthat his equations implied an expanding universe. Just as a stone tossedin the air cannot remain frozen in place, the universe cannot be static: Itmust either expand or contract. Back in 1915, every astronomical observationsuggested that the universe was static. That prompted Einstein to modifyhis equations so as to conform with the then-prevailing view. He wouldlater regret this action and call it "the greatest blunder of my life" when theAmerican astronomer Edwin Hubble (1889-1953) discovered in 1929 thatthe universe is in fact expanding. Einstein had failed to place enough trustin the beauty and truth of his own equations. General relativity has kept ondelivering wonderful treasures ever since. It is the pillar on which the bigbang theory rests. It has enabled cosmologists to go back in time anddescribe how the universe evolved out of a huge primordial explosion thatalso gave birth to space-time. It has allowed us to conceive of regions ofspace where gravity is so powerful and space so strongly curved that not evenlight can escape?these regions have been dubbed "black holes." It also tellsus that massive galaxies can curve space so as to bend the light emitted bydistant objects, creating cosmic mirages. Astronomers refer to these galaxiesas "gravitational lenses," because they bend and focus light much as the lensin our eye does.

    Inevitable, simple, congruent with the whole: Those are the hallmarks ofa beautiful theory. It is, in fact, this aesthetic yearning for congruity with thewhole that has spurred on physicists of the last two centuries to search for aTheory of Everything that could encompass all physical phenomena in theuniverse and unify the four fundamental forces of nature.

    Before embarking on a search for the holy grail in physics?the Theory ofEverything?with beauty as our guide, we must first become acquainted withthe power of contingency. Beauty can lead to truth only if we learn to distinguishwhat is fundamental from what is fortuitous. Beauty alone cannot be areliable guide in constructing a theory if we fail to take into account theintervention of chance. Nature is governed both by fundamental laws and byaccidental events without deep significance. The history of the formation ofthe solar system is a perfect example to illustrate how random events canshape Nature. Accordingly, we are about to travel back 4.6 billion years to witnesslive the birth of the solar system. What happened then is of crucialimportance not only because it eventually culminated in our own existencebut also because it can teach us to distinguish necessity from contingency.

Continues...

Excerpted from Chaos and Harmonyby Trinh Xuan Thuan Copyright © 2006 by Trinh Xuan Thuan. Excerpted by permission.
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Edition details

• Publisher: Templeton Press
• Publication date: 2006
• Language: English
• ISBN 10: 1932031979
• ISBN 13: 9781932031973
• Binding: Paperback
• Edition number: 1
• Number of pages: 384