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Surprisingly Modern Neandertals • National Medal of Technology QUARK SOUP CERN cooks up a new state of matter see page 16 APRIL 2000 $4.95 www.sciam.com QUANTUM Teleportation The Future of Travel? Or of Computing? Of Mice and Mensa Genetic formula for a smarter mouse Brown Dwarfs Stars that fizzled fill the galaxy Copyright 2000 Scientific American, Inc. C o April 2000 Volume 282 Number 4 n COVER STORY 50 t Quantum Teleportation e n Anton Zeilinger The “spookyaction ata distance” ofquantum t NDERS mechanicsmakespossible the science-fiction dream of s U A teleportation—a wayto make objectsdisappear from one HILIP S place and reappear atanother. Ithasalreadybeen NEL/P demonstrated with photons. Yetthe greatestapplication N A SPACE CH ofteleportation maybe in computing. 62 Building a Brainier Mouse Joe Z. Tsien To geneticallyengineer a smarter mouse, scientists assembled some ofthe molecular componentsof learning and memory. Understanding Clinical Trials 69 Monitoring Earth’s Vital Signs 92 Justin A. Zivin Michael D. King and David D. Herring The journeyfrom initial A new NASAsatel- medicalresearch to the lite—one ofa fleet bottle in your family’s called the Earth Ob- medicine cabinetis serving System— complex, time-consuming usesfive state-of- and expensive. Can the the-artsensorsto clinicaltrialprocess better diagnose the be refined? planet’shealth from the sky. The Discovery of Brown Dwarfs 76 GiborBasri Lessmassive than starsbutmore massive TRENDS IN PALEOANTHROPOLOGY 98 than planets, brown dwarfswere long as- Who Were the Neandertals? sumed to be rare. New skysurveys, howev- er, show that8in 0our galaxythe objectsmay Kate Wong, staffwriter be ascommon asstars. Controversiesrage over how much theywere like usbehaviorally The Aleutian Kayak 84 and biologically. George B. Dyson With contributionsby The Aleutsbuiltthese smallboatsfor hunterson the open ErikTrinkaus, Cidália ocean. The sophisticated design isstillnotentirelyunderstood. Duarte, João Zilhão, Francesco d’Errico andFred H. Smith. 3 Copyright 2000 Scientific American, Inc. s t April 2000 Volume 282 Number 4 n 46 e THE NATIONAL MEDAL OF TECHNOLOGY t A report on the winners of the nation’s highest award for innovation n o C RAY KURZWEIL ROBERT A. SWANSON ROBERT W. TAYLOR GLEN JACOB CULLER FROM THE EDITORS 8 BOOKS 114 Matt Ridley’sGenomeoffers a celebrity LETTERS TO THE EDITORS 10 tour of human DNA, according to Dean H. Hamer.With more from The Editors 50, 100 & 150 YEARS AGO 14 Recommend. PROFILE 36 WONDERS, by the Morrisons 117 The long-lost lions of Los Angeles. String theorist and physics star CONNECTIONS, by James Burke 118 Brian Greene. ANTI GRAVITY, by Steve Mirsky 120 TECHNOLOGY 42 END POINT 120 & BUSINESS NEWS & ANALYSIS 16 What the “Frankenfoods” deal means for biotech. CERN’s little piece of the big bang. 16 CYBER VIEW 44 How deadly viruses enter the U.S. 20 16 Who wants privacy? Refrigerating that leftover mammoth. 24 WORKING KNOWLEDGE 108 How soap and detergents work. Making plastic from feathers. 26 20 Profiting from idle computers. 27 THE AMATEUR SCIENTIST 110 by Shawn Carlson Virtual air-traffic control. 28 A furnace in a thermos. 24 By the Numbers 30 MATHEMATICAL 112 Women and the professions. RECREATIONS by Ian Stewart News Briefs 32 26 Bullish on mooo-thematics. Scientific American (ISSN 0036-8733),published monthly by Scientific American,Inc.,415 Madison Avenue,New York,N.Y.10017-1111. Copyright ©2000 by Scientific American,Inc.All rights reserved.No part of this issue may be reproduced by any mechanical,photo- About the Cover graphic or electronic process,or in the form of a phonographic recording,nor may it be stored in a retrieval system,transmitted or oth- erwise copied for public or private use without written permission of the publisher.Periodicals postage paid at New York,N.Y.,and at ad- Photocomposition ditional mailing offices.Canada Post International Publications Mail (Canadian Distribution) Sales Agreement No.242764.Canadian BN No.127387652RT;QST No.Q1015332537.Subscription rates:one year $34.97 (outside U.S.$49).Institutional price:one year $39.95 (out- by Chip Simons. side U.S.$50.95).Postmaster:Send address changes to Scientific American,Box 3187,Harlan,Iowa 51537.Reprints available:write Reprint Department,Scientific American,Inc.,415 Madison Avenue,New York,N.Y.10017-1111;(212) 451-8877;fax:(212) 355-0408 or send e-mail to [email protected] Subscription inquiries:U.S.and Canada (800) 333-1199;other (515) 247-7631.Printed in U.S.A. 4 Copyright 2000 Scientific American, Inc. EDITOR_JOHN RENNIE s r ® Quantum Bits o Established 1845 and Reliable Boats t EDITOR IN CHIEF:John Rennie i MANAGING EDITOR: Michelle Press d ASSISTANT MANAGING EDITOR: Ricki L. Rusting NEWSEDITOR: Philip M. Yam ASSOCIATEEDITORS: Timothy M. Beardsley, Gary Stix E ON-LINEEDITOR: Kristin Leutwyler Quantum teleportation and the Aleutian kayak, both forms of transporta- SENIOR WRITER: W. Wayt Gibbs tion described in this issue, could not be more different. The former is EDITORS: Mark Alpert, Carol Ezzell, Alden M. Hayashi, futuristic and derived from applications of quantum physics, about which Steve Mirsky, Madhusree Mukerjee, George Musser, e Sasha Nemecek, Sarah Simpson, Glenn Zorpette we are still learning. The latter is a historical curiosity based on prin- CONTRIBUTING EDITORS: Graham P. Collins, ciples of boat design centuries-old, many of which have been forgot- Marguerite Holloway, Paul Wallich h ten. Quantum teleportation can in theory move people and things from one place to another without taking them through intervening points, and it can do so at the ART DIRECTOR: Edward Bell t SENIOR ASSOCIATEART DIRECTOR: Jana Brenning speed of light. The kayak carried hunters through rough seas at a possible top speed ASSISTANT ART DIRECTORS: Johnny Johnson, of about 10 knots. Quantum teleportation involves ex- Heidi Noland, Mark Clemens m otic stuff called “entangled matter.” The kayak was PHOTOGRAPHYEDITOR: Bridget Gerety PRODUCTION EDITOR: Richard Hunt built of animal skin and wood. Which of these will be more important as a form of COPYCHIEF: Maria-Christina Keller o transportation? I think it’s obviously the kayak. COPYAND RESEARCH: Molly K. Frances, Daniel C. Schlenoff, Let me reemphasize the words as a form of transporta- Katherine A. Wong, Myles McDonnell, Rina Bander, r tion. The Aleutian kayak can fall back on its record: it Sherri A. Liberman F was a mainstay of the Aleuts’ Kayaks beat EDITORIALADMINISTRATOR: Rob Gaines livelihood for perhaps thou- ADMINISTRATION: Eli Balough teleporters for sands of years. It helped ASSOCIATEPUBLISHER, PRODUCTION: William Sherman them tame the forbidding transportation. MANUFACTURING MANAGER: Janet Cermak seaways around the Bering ADVERTISING PRODUCTION MANAGER: Carl Cherebin Strait. George B. Dyson’s fascinating article on these craft begins on page 84. PREPRESSAND QUALITYMANAGER: Silvia Di Placido PRINT PRODUCTION MANAGER: Georgina Franco Quantum teleportation, though ingenious, is still unproved for shipping anything PRODUCTION MANAGER: Christina Hippeli other than photons. In science fiction, teleportation is a great convenience for ad- ASSISTANT PROJECT MANAGER: Norma Jones vancing plots in either wonderful (see Star Trek) or horrible (see either movie version CUSTOM PUBLISHING MANAGER: Madelyn Keyes of The Fly) directions. Of course, those imaginary teleporters disassembled people’s ASSOCIATEPUBLISHER/VICEPRESIDENT, CIRCULATION: atoms, zapped them through the ether and reassembled them elsewhere. Measure- Lorraine Leib Terlecki ment uncertainties and the sheer overload of information required would make that CIRCULATION MANAGER: Katherine Robold feat impossible. Quantum teleporters do not disassemble anything, so their mishaps CIRCULATION PROMOTION MANAGER: Joanne Guralnick FULFILLMENT AND DISTRIBUTION MANAGER: Rosa Davis could never produce anything quite like poor fly-headed David Hedison. But at least for now, quantum teleportation works only one out of four times— SUBSCRIPTION [email protected] and that 25 percent probability applies distinctly to each particle in the subject’s U.S. and Canada (800) 333-1199, Outside North America (515) 247-7631 body. What comes out at the far end of a quantum teleporter therefore still might make even a genetically fused Jeff Goldblum blanch. Then there’s the philosophical GENERALMANAGER: Marie M. Beaumonte quandary of whether someone who steps into a quantum teleporter is really the MANAGER, ADVERTISING ACCOUNTING AND same person who steps out at the other end or just a duplicate, perfect down to the COORDINATION: Constance Holmes DIRECTOR, FINANCIALPLANNING: Christian Kaiser memories. (Somehow this never comes up in kayaking.) For all these reasons, quantum teleportation’s application to moving matter may DIRECTOR, ELECTRONICPUBLISHING: Martin O.K. Paul always be limited. On the other hand, as an extension of quantum computation, a radically different way of processing information, its potential may be unlimited. As DIRECTOR, ANCILLARYPRODUCTS: Diane McGarvey you’ll learn in Anton Zeilinger’s article beginning on page 50, it even offers a way for CHAIRMAN EMERITUS quantum computers to start processing information that they haven’t received yet. John J. Hanley CHAIRMAN Rolf Grisebach No messages have reached me yet about this, but I know my answer to them: PRESIDENT AND CHIEFEXECUTIVEOFFICER yes, we have redesigned some departments in the magazine. We hope the Joachim P. Rosler changes help you identify the articles interesting to you that much more easily and [email protected] generally enhance your reading enjoyment of Scientific American. VICEPRESIDENT Frances Newburg Scientific American, Inc. 415 Madison Avenue New York, NY 10017-1111 PHONE: (212) 754-0550 NER FAX: (212) 255-1976 NS [email protected] WEB SITE: www.sciam.com A LA C RI E 8 Scientific American April 2000 From the Editor Copyright 2000 Scientific American, Inc. s [email protected] r o LIVING LONGER to lose its feedback-control mechanism: early death resulting in the weeding out t In “Can Human Aging Be Postponed?” of deleterious genes. In a parallel (with a i Michael R. Rose suggests that we could twist) to the current problem of excessive postpone aging via natural selection by antibiotic use, which results in natural d delaying childbirth. This is already being selection of resistant bacterial strains, I followed by the current generation of foresee a reduction of the natural-selec- E Americans, albeit for other, more imme- tion mechanism as drugs take over the diate reasons. Marriage age has increased longevity job. We will become more and dramatically, and the smaller family size more dependent on drugs just to hold e is probably the result of starting child- our ground. In other words, be careful bearing later, rather than stopping earlier, about fooling Mother Nature. h as couples pursue careers that demand ROBERT P. HART longer educations and longer working East Hampton, Conn. t hours. It’s interesting that we are, as a re- sult of our affluence and technological DISSECTING THE MIND o sophistication, adopting the very strategy that will lead to longer life spans. Reading Antonio R. Damasio’s article FILMS t ERIC GOLDWASSER “How the Brain Creates the Mind” SLIM Yorktown Heights, N.Y. reminded me of something the comic SELF-AWARENESSemergeswithin whatAn- Emo Phillips once said: “I used to think tonio Damasio callsthe movie-in-the-brain. s We don’t need a genetic miracle to the brain was the most important organ prolong healthy life. For average people in the body, until I realized who was reports, are some that model the self and r not smoking, regular exercise, effective telling me that.” some that model the fact that the self is e stress management, lean weight and a LUKE E. SOISETH doing some representing of the world. heart-healthy diet can mean 20 to 25 St. Paul, Minn. But then he inserts a non sequitur: fur- t healthy years beyond the age of 60. ther elaboration of these lines of inquiry THOMAS PERLS Damasio supplies a bullish account of will lead to a resolution of all questions t Harvard Medical School how neuroscience is moving toward a of consciousness. e satisfactory account of consciousness, Yet it does not follow that the subjec- Rose sees no limit to the length of time and he falls straight into a well-known tive life of the mind could, in principle, L human life can be extended by turning trap: a failure to distinguish the “hard” be explained by an account that confines on antiaging genes or preparing drug problem of consciousness from other, itself to biological or computational mech- cocktails to combat aging. But I see a less troublesome issues. Damasio writes anisms. What, for example, could a com- problem. Any assistance provided by that neuroscience is identifying more plete map of the visual pathways ever tell new therapies can backfire on us over the and more places in the brain where par- us about the subjective redness of the long run. As we provide our own antiag- ticular kinds of representation are com- color red? The distinction between the ing remedies, natural selection will begin puted. Among those representations, he hard problems of consciousness and the lesser issues was invented recently to eliminate the kind of confusion injected THE_MAIL into the debate by contributors such as Damasio, who assert that the problem is not as difficult as everyone makes it out READERS HAD STRONG OPINIONS about our to be and then go on to attack the wrong December 1999 issue on “What Science Will Know in problem. 2050,” and none more forcefulthan the proteststhatthis RICHARD LOOSEMORE “End-of-the-Millennium SpecialIssue” came a year early. Canandaigua, N.Y. We sympathize with their pointofview, butin answer: It may be more mathematically rigorous and precise to Damasio replies: startthe 21stcenturyin 2001, butitisa meaninglesspre- cision given the caprices with which calendars have As stated in my article, I propose a means been modified over the years. Moreover, when people re- to generate, in biological terms, the sub- fer to periodslike “the 20th century” or “the nextmillen- jective feeling that accompanies our image- nium,” our understanding isthattheyare typicallylessconcerned with the precise making. Loosemore does not have to accept demarcationsthan with the overallhistoricalcharacter and significance. my proposal, but the aim of my effort is Assuch, “the 20th century” isa labelakin to “the Renaissance” or“the Victorian era.” clear: to understand not just how, say, the The bottom line isthatifmostofthe world thinksthata new millennium hasbegun, color red is mapped but also how we have a then for allpracticalpurposes, ithas. Additionalreader commentsconcerning articlesin subjective perspective of redness. I am neither the December issue are featured. bullishly claiming that we know all nor that 10 Scientific American April 2000 Letters to the Editors Copyright 2000 Scientific American, Inc. s we will know all, although I am convinced OTHER EDITIONS OF r we will know a lot more. I do claim, however, SCIENTIFIC AMERICAN that the assumed hardest part of the hard o problem—subjectivity—may not be so hard Sandra Ourusoff PUBLISHER after all. [email protected] Spektrum der Wissenschaft t Verlagsgesellschaft mbH NEWYORKADVERTISINGOFFICES Vangerowstrasse 20 i ROBOTREFLECTIONS 415MADISONAVENUE, NEWYORK, NY10017 69115 Heidelberg, GERMANY 212-451-8523 fax 212-754-1138 tel: +49-6221-50460 d Denise Anderman [email protected] Regarding Hans Moravec’s robot ASSOCIATEPUBLISHER dreams [“Rise of the Robots”], I’ve [email protected] E been a science-fiction writer for more phPaertsehra Mm@. Hscaiarsmh.acmom Pour la Science than 40 years, and I like to create robot Randy James Éditions Belin characters. Most are miners on airless [email protected] 8, rue Férou e Wanda R. Knox 75006 Paris, FRANCE moons or builders and land-shapers on [email protected] tel: +33-1-55-42-84-00 new worlds. Some are self-aware, and Carl Redling LE SCIENZE h [email protected] sometimes they malfunction, go crazy Le Scienze t and behave in evil ways. A few are hu- Laura SalantM AMRAKREKTEITNIGNGDIRECTOR Pi2az0z1a2 d1e Mllai lRanepou, bITbAliLcaY, 8 man-shaped and tend to pose around ad- [email protected] tel: +39-2-29001753 miring themselves. None of them takes Diane Sdchscuhbueb [email protected] [email protected] o out the garbage. I would hope that 50 Susan Spirakis RESEARCHMANAGER [email protected] years from now we would find some- Nancy Mongelli PROMOTIONDESIGNMANAGER t thing better to do with garbage—convert [email protected] Investigacion y Ciencia Prensa Científica, S.A. it into fuel, for instance—than have a ro- DETROIT Muntaner, 339 pral. 1.a bot lug it to the curb. Although Moravec Edward A. Bartley 08021 Barcelona, SPAIN MIDWESTMANAGER s admits that all attempts by roboticists to 248-353-4411 fax 248-353-4360 tel: +34-93-4143344 [email protected] [email protected] create a human level of intelligence in r CHICAGO machines have failed, he still envisions Rocha & Zoeller MEDIASALES e within 50 years a species of superintelli- 333 N. Michigan Ave., Suite 227 Majallat Al-Oloom gent robots that leaves the human spe- Chicago, IL 60601 Kuwait Foundation for 312-782-8855 fax 312-782-8857 t cies with nothing to do but putter around. [email protected] the Advancement of Sciences [email protected] P.O. Box 20856 t (This quaint vision harks back 70-odd LOSANGELES Safat 13069, KUWAIT years, where it flourished for a while in Lisa K. Carden tel: +965-2428186 WESTCOASTMANAGER e Hugo Gernsback’s magazines of “scien- 310-234-2699 fax 310-234-2670 [email protected] tifiction.”) If I thought that kind of slug- L like existence was in store for my grand- SADNebFRraA NSCilIvSeCrO Swiat Nauki children in their middle age, I would tru- SANFRANCISCOMANAGER Proszynski i Ska S.A. 415-403-9030 fax 415-403-9033 ul. Garazowa 7 ly despair. [email protected] 02-651 Warszawa, POLAND PHYLLIS GOTLIEB DALLAS tel: +48-022-607-76-40 THEGRIFFITHGROUP [email protected] Toronto, Canada 972-931-9001 fax 972-931-9074 [email protected] CANADA Moravec concludes that by 2050 ro- FENNCOMPANY, INC. Nikkei Science, Inc. 905-833-6200 fax 905-833-2116 bots will outperform their human cre- [email protected] 1-9-5 Otemachi, Chiyoda-ku Tokyo 100-8066, JAPAN ators “in every conceivable way, intellec- RoEyU ERdOwPaErds tel: +813-5255-2821 tual or physical.” One can only hope that INTERNATIONALADVERTISINGDIRECTOR Julie Swaysland the robots will outperform us in the Thavies Inn House, 3/4, Holborn Circus moral and ethical arena as well—it is London EC1N 2HA, England +44 207 842-4343 fax +44 207 583-6221 Svit Nauky frightening to contemplate from whom [email protected] [email protected] Lviv State Medical University the robots may learn their ethical stan- 69 Pekarska Street FRANCE dards. Once we have become, in effect, Christine Paillet 290010, Lviv, UKRAINE AMECOM tel: +380-322-755856 their pets, let’s hope the scenario is more 115, rue St. Dominique [email protected] like Isaac Asimov’s I, Robotthan Termina- 75007 Paris, France +331 45 56 92 42 fax +331 45 56 93 20 ELLHNIKH EKDOSH tor 2: Judgment Day. GERMANY Scientific American Hellas SA JEFFRY A. SPAIN MAarmen W Scinugpeirnt sGbeürngt h9er 35–37 Sp. Mercouri St. Cincinnati, Ohio D-61348 Bad Homburg, Germany Gr 116 34 Athens GREECE +49-6172-66-5930 fax +49-6172-66-5931 tel: +301-72-94-354 MIDDLEEASTANDINDIA [email protected] Lettersto the editorsshould be sentbye- PETERSMITHMEDIA&MARKETING mailto [email protected] or bypostto Sci- +44 140 484-1321 fax +44 140 484-1320 JAPAN entific American, 415 Madison Ave., New NIKKEIINTERNATIONALLTD. Ke Xue +813-5259-2690 fax +813-5259-2679 York, NY 10017. Letters may be edited for Institute of Scientific and KOREA Technical Information of China length and clarity. Because ofthe consider- BISCOM, INC. P.O. Box 2104 +822 739-7840 fax +822 732-3662 able volume ofmailreceived, we cannotan- Chongqing, Sichuan swer allcorrespondence. HUTTOHNONMGEDKIOANLGIMITED PEOPLE’S REPUBLIC OF CHINA +852 2528 9135 fax +852 2528 9281 tel: +86-236-3863170 12 Scientific American April 2000 Letters to the Editors Copyright 2000 Scientific American, Inc. Einstein, o nals, the fireman and engineer being en- tirely protected. Its appearance is most g grotesque, looking not unlike a gigantic the H-Bomb and Whale Harpoons French poodle dog.” A OLD HARPOONED WHALE— “A whale has been found with a harpoon in its body s which, by its markings, showed that it APRIL1950 facts as to the temperature of the ocean at must have been hurled at the whale at r HYDROGEN BOMB: A WARNING— “We have great depths. The data obtained up to the least thirty-six years ago.” a to think how we can save humanity from present time shows that at a depth of 180 APRIL1850 this ultimate disaster. And we must break meters the temperature of the water re- e the habit, which seems to have taken mains nearly invariable at all seasons. NEW WHALE HARPOON—“Capt. Robert hold of this nation, of considering every Nearly all the deep water of the Indian Brown, of New London, Conn., has in- Y weapon as just another piece of machin- Ocean is below 1.7˚C, but in the North vented a most important improvement ery and a fair means to win our struggle Atlantic and the greater part of the Pacific for shooting and capturing whales. It is with the U.S.S.R. —Hans A. Bethe” the temperature is higher. As the depths well known that some whales of the Pa- 0 of the sea constitute an obscure region cific cannot be approached with the har- GRAVITYEQUATION— “The skeptic will say: where the solar rays cannot penetrate, it poon in a boat, and at best the harpoon- 5 ‘It may well be true that this system of follows that vegetable life must be absent ing and lancing of whales is a very dan- equations is reasonable from a logical upon 93 per cent of the bottom.” gerous and difficult business. The idea of 1 standpoint. But this does not prove that it firing the harpoon out of a gun has been SOFT ARMOR— corresponds to nature.’ You are right, dear “The armored train has often advanced, but Capt. Brown’s har- skeptic. Experience alone can decide on played an important part in the South poon, with the line attached, can be fired & truth. Yet we have achieved something if African war. One memorable incident as accurately as a musket ball. The inven- we have succeeded in formulating a mean- was the attack on the armored train at tion may be termed, ‘Whaling made suc- ingful and precise equation. The deriva- Chieveley in which Winston Churchill cessful and easy by a Yankee Captain.’” tion, from the questions, of conclusions was captured. As is well known, railway 0 AGE OF STEAM— which can be confronted with experience iron and boiler plates are the usual pro- “It is said that according will require painstaking efforts and proba- tection, but the locomotive shown in our to the late census of England, the num- 0 bly new mathematical methods. —Albert engraving was made safe in an unique ber of horses in that country has been Einstein” manner. Rope mantlets were used for the found to have diminished from 1,000,000 1 protection of the engine on the Colenso to 200,000 within the last two years—in ATOMIC SPY— “The celebrated case of line. The work was done by sailors, and it other words, the Railroad have dispensed Klaus Fuchs, atomic spy, came to a swift has been found that the rope protection with the use of 800,000 horses, and these , end last month. Fuchs, a German Com- is a most admirable one. It is probable animals, as well as oxen, are now scarcely 0 munist who went to England in 1933 that the engine is run entirely by bell sig- used for transportation.” and was head of theoretical physics at 5 the British atomic energy research center at Harwell, pleaded guilty to having transmitted atomic secrets to agents of the U.S.S.R. Fuchs received the maxi- mum sentence of 14 years in prison. A strange feature of the case was that the U.S.S.R. repudiated Fuchs’ confession.” APRIL1900 ANTARCTIC PIONEER— “The steamer ‘South- ern Cross,’ with C. E. Borchgrevink, a Norwegian, and the survivors of the South Polar expedition, fitted out in 1898 by British publisher Sir George Newnes, has arrived at Wellington, New Zealand. Herr Borchgrevink reports that the mag- netic pole has been located.” [Editors’ note: Carsten E. Borchgrevink led the first ex- pedition to winter over on the Antarctic mainland.] N dSrUeNssLeEdSSth eS EGAe—og“rSaipr hiJcoahl nS ecMtiuornr aoyf tahde- NEW APPLICATION for softarmor: a locomotive for the South African war, 1900. NTIFIC AMERICA British Association on some interesting M SCIE O FR 14 Scientific American April 2000 50, 100 and 150 Years Ago Copyright 2000 Scientific American, Inc. s PHYSICS_ELEMENTARY PARTICLES i Fireballs of Free Quarks s y CERN appearsto have spotted the long-soughtquark-gluon plasma—lastseen during the big bang l ot every scientific discovery aN is heralded by a clear cry of “Eureka!” A case in point is n the study of an exotic state of matter known as a quark-gluon plasma (QGP), in which hundreds of ordinary Aprotons and neutrons melt together and form a fiery soup of free-roaming quarks and gluons. The universe consisted of such a quark stew 10 microseconds after the big bang, about 15 billion years ago. & Seven experiments have been gathering data for the past six years at CERN, the Eu- ropean laboratory for particle physics near Geneva. Although the accumulated evi- dence is not as direct and clear-cut as had sbeen hoped for when the program began, scientists conducting the experiments felt sufficiently confident to make their Febru- w ary 10 announcement. “We now have compelling evidence that a new state of matter has been created,” said CERN theo- e rist Ulrich Heinz. And that state, he con- MORE THAN 1,600 PARTICLES tinued, “features many of the characteris- Ntics” predicted for a quark-gluon plasma. sprayoutfrom a single collision of Most modern high-energy particle phys- two lead nuclei, carrying evidence of ics experiments smash together the small- a quark-gluon plasma. est convenient particles—electrons or protons—because the simpler the protag- onists, the cleaner the data. The CERN ex- periments, in contrast, use relative behe- moths: lead nuclei composed of 208 pro- but comes in three varieties called colors. At lower energies, most of these particles tons and neutrons. These nuclei are hurled Confinement requires that quarks group will be new hadrons, particles made up of at almost the speed of light at a thin foil, together in sets of three whose colors confined quarks and antiquarks. At suffi- also made of lead. On occasion, one of the blend to make “white” or in pairs of quark ciently high energy densities, however, projectiles strikes a target nucleus, produc- and antiquark whose colors similarly can- the newly generated particles are so tight- ing a spray of thousands of particles that cel out. Separating the component quarks ly packed together that confinement travel on to the experimental detectors. of a particle takes a large amount of ener- stops being relevant; each quark has nu- From these particles, physicists try to deter- gy, and instead of exposing their bare color merous companions within a femtome- mine whether the collision momentarily charges to the world, the energy generates ter. Instead of being a hot swarmof nu- created a seething fireball of debris, hot new quarks and antiquarks, which pair up merous hadrons colliding together and and dense enough to set quarks loose. with any potential lone quarks to keep reacting, the fireball becomes one large Quarks, glued together by particles aptly their colors balanced. This pairing process cloud of quarks and gluons. The tremen- named gluons, are the basic constituents kicks in when a quark gets farther than dous energy and pressure of the quark- of matter, making up the familiar protons about a femtometer (10–15meter)from its gluon plasma causes it to explode out- and neutrons as well as more exotic crea- companions—the approximate size of par- ward. The temperature and density fall tures seen only in cosmic rays and particle ticles such as protons and neutrons. and soon become too low to sustain the accelerators. Ordinarily, quarks are locked In the CERN experiments, when the plasma state. The quarksthen rapidly pair N away inside their parent particles by a two lead nuclei collide, the interactions off again, forming colorless hadrons. The CER phenomenon called confinement. Indi- between their component protons and fireball, now composed of hadrons, con- OVAL vidual quarks carry a kind of charge that is neutrons generate a swarm of new parti- tinues expanding and cooling, and ulti- ND somewhat analogous to electric charge cles out of the available collision energy. mately the hadrons fly on to the detectors. DRES SA N A 16 Scientific American April 2000 News & Analysis Copyright 2000 Scientific American, Inc. s Physicists have been eager to create the pairs are produced essentially as easily as plete and consistent dynamical theory i QGP in part because it provides clues pairs of ups and downs are. The CERN ex- that described the collisions, such indi- about the origin of the universe. The periments saw several features of enhanced rectness might be less of a concern. But s process of the quark fireball cooling to strangeness. When conditions were ripe such a theory does not exist: theorists must y form hadrons (and later to form atoms) for a plasma, overall strangeness was two resort to various approximation schemes mimics what happened during the big times higher, and a particle called omega, and computer models, incorporating l bang. Our understanding of the uni- containing three strange quarks, occurred guesses about which processes are most a verse’s expansion has been tested by ex- 15 times more often. Such extra enhance- significant to try to re-create the observed periment back to the third minute, when ment of “multistrange” particles is charac- data. Indeed, some theorists will now be n ordinary atomic nuclei formed; with the teristic of a plasma. playing devil’s advocate, doing their quark-gluon plasma, “we have extended Whereas strangeness is enhanced in a darnedest to concoct a model involving A our knowledge back to 10 mi- only hadron collisions that croseconds after the big can explain all the CERN data. bang,” says Reinhard Stock of A way to shortcut such ef- the University of Frankfurt, forts is to obtain untainted & who led one of the CERN ex- evidence directly from the periments. The explosive plasma—by studying parti- pressure at that time was cles that do not interact s comparable, he remarks, to strongly with quarks and glu- w the weight of “150 solar- ons and so can escape from masses acting on an area the the QGP while it is still a plas- size of a fingernail.” (Apoca- ma. They would carry direct e lyptists take note: the pre- signals of the extant condi- N sumed creation of the QGP tions. For example, the forma- did not create a mini–black tion of a QGP should greatly hole or other Earth-destroy- increase the number of pho- ing phenomenon, as some tons emitted. Alas, CERN’s press reports suggested it STEW OF QUARKS (colored balls) issetfree from protonsand photon data are inconclusive, might last year.) neutrons(grayballs) when two nuclei collide. almost swamped by the large CERN researchers cite sev- background of photons that eral lines of evidence that strongly indi- QGP, certain charm particles, containing are explicable without a QGP. “There are cate they created the quark-gluon plas- the next heavier variety of quark, are sup- intriguing indications of direct photons, ma. First are the relative numbers of pressed, as predicted in 1986. Attention fo- but they are marginal,” Heinz says. various hadrons, which indicate the tem- cuses on the J/psi meson, which consists of Such direct evidence will have to wait perature and energy density that must a charm quark and a charm antiquark. for the Relativistic Heavy Ion Collider, or have prevailed when they formed. The Charm quarks are so massive that these RHIC (pronounced “rick”), at Brookhaven result is consistent with the levels theo- charm-anticharm pairs can be produced National Laboratory in Upton, N.Y., which retically required to produce a plasma. only during the initial extremely high en- will start examining head-on collisions of Theenergy density is about seven times ergy proton-neutron collisions and not two beams of gold ions in the summer [see that of ordinary nuclear matter,and the during the subsequent fireball. How many “ALittle Big Bang,” by Madhusree Muker- fireball is expanding at 55 percent of the of the pairs remain together to be detect- jee, SCIENTIFIC AMERICAN, March 1999]. The speed of light when the hadrons “freeze ed as J/psi mesons depends on whether usablecollision energies will be 10 times out” of it. they had to endure a QGP: a hot, seething those of CERN’s program, which ought to The next observed effect is enhance- plasma separates a charm quark from its produce a QGP with a higher temperature ment of strangeness, which refers to a partner charm antiquark, so they end up and longer lifetime, allowing much clearer type of quark. Altogether there are six dif- detected as a different species of hadron. direct observations. RHIC’s plasma should ferent species, or “flavors,” of quark, go- The observed pattern of J/psi suppression be well above the transition point be- ing by the whimsical names of up, down, in the CERN experiments “rules out tween a QGP and ordinary hadronic mat- strange, charm, bottom and top. The the available conventional [explanations] ter, allowing numerous more advanced lion’s share of ordinary matter is com- based on confined matter,” asserts Louis studies of the plasma’s properties, not posed of the lightweight up and down Kluberg of the Laboratory of High Energy merely an uncertain demonstration that quarks: two ups and one down quark Nuclear Physics in Palaiseau, France. it exists at all. make a proton; one up and two downs, a All this evidence comes down on the In 2005, CERN’s Large Hadron Collider neutron. Strange particles, produced in side of a quark-gluon plasma. Why, then, will come on-line and slam ions at 30 particle physics experiments, contain at in the words of Heinz, is this evidence times the energy level of RHIC.“We have laenaSdstt r daoonnwgee ns tsqr, aumnagrakek siq nuagar ert kh heomera a vmnietoirq reuth adariknffi. cuuplst “dbneoeountb etc”nr eoatuhtegadht ? tao qpuroavrke- gbleuyoonn dp rleaasmsoan ahbales nTHhoaewd rh osingcrh aCetroc hlelnieddeer grt ihaerese o snfu eRrefHadcIeCed, ”at onH d“e ctihonmez Lpsaalreygtsee. of Frankfurt tpaobr eupdnridoctadenudtc eitnh. aItnht e tth QheeGy Pes,ah wrolyhu el1dre9 b8ee0n seu rtnghuye slouervaieslltlyss dpirroTedhcute, c peirdno vwbolhelvmeinn igtsh tedh epattle atcshtmieo aen vc hiodafen npgceaesr tibisc ailcneks- theW piitcht urerep.o”rting by Uw—eG Rraeihcahmert P o. fC Soplleinks- WEBER University are so high that strange quark-antiquark to ordinary hadrons. If there were a com- trum der Wissenschaftin Geneva. NG NI N HE 18 Scientific American April 2000 News & Analysis Copyright 2000 Scientific American, Inc. s EPIDEMIOLOGY_EMERGING DISEASES i Outbreak Not Contained s y l WestNile virustriggersa reevaluation ofpublichealth surveillance a n he appearance of West Nile succumbing as well. In two weeks Debo- experts, the initial misidentification re- T virus in New York City last sum- rah S. Asnis, chief of infectious disease at mains worrisome. As Reisen points out, A mer caught the U.S. by surprise. the Flushing Hospital Medical Center in diagnostic labs can only look for what That this virus—which is known Queens, saw eight patients suffering simi- they know. If they don’t have West Nile in Africa, Asia and, increasingly, in parts lar neurological complaints. After the reagents on hand, they won’t find the & of Europe—could find its way to Ameri- third case, and despite some differences virus, just its relatives. “In California we can shores and perform its deadly work in their symptoms, Asnis alerted the New have had only one flavivirus that we were for many months before being identified York City Department of Health. The looking for, so if West Nile had come in has shaken up the medical five years ago, we would have s community. It has revealed missed it until we had an iso- w several major gaps in the pub- late of the virus as well,” Reisen lic health infrastructure that comments. may become ever more impor- This is true even though Cal- e tant in this era of globalization ifornia, unlike New York State, N and emerging diseases. has an extensive, $70-million- Because it is mosquito-borne, a-year mosquito surveillance West Nile has reinforced the and control system. The in- need for mosquito surveil- sects are trapped every year so lance—something that is only that their populations can be sporadically practiced around assessed and tested for viruses. the country and something Surveillance has allowed Cali- that could perhaps help doc- fornia to document the ap- tors identify other agents caus- pearance of three new species ing the many mysterious cases of mosquito in the past 15 of encephalitis that occur every years. In addition, 200 flocks year. And because it killed birds of 10 sentinel chickens are sta- before it killed seven people, tioned throughout the state. the virus made dramatically Every few weeks during the clear that the cultural divide summer they are tested for vi- between the animal-health ral activity. and the public-health commu- In 1990 sentinel chickens in nities is a dangerous one. “It Florida detected St. Louis en- was a tremendous wake-up call cephalitis before it infected for the United States in gener- people. “Six weeks before the al,” says William K. Reisen of human cases, we knew we had the Center for Vector-Borne a big problem,” recalls Jon- Disease Research at the Univer- athan F. Day of the Florida sity of California at Davis. Medical Entomology Labora- No one is certain when, or tory. After warning people to how, West Nile arrived in New take precautions and spraying York. The virus—one of 10 in a with insecticides, the state family called flaviviruses, which documented 226 cases and 11 includes St. Louis encephali- AVIAN AUTOPSY: Closer attention to crow deathsmighthave deaths. “It is very difficult to tis—could have come via a better prepared publichealth officialsfor the outbreaklastyear. say how big the problem bird, a mosquito that had sur- would have been if we hadn’t vived an intercontinental flight or an in- health department, in turn, contacted the known,” Day says. “But without our ac- fected traveler. It is clear, however, that state and the Centers for Disease Control tions I think it would have been in the West Nile started felling crows in New and Prevention (CDC), and the hunt for thousands.” (Day says surveillance in his York’s Queens County in June and had the pathogen was on. It was first identi- county costs about $35,000 annually.) moved into the Bronx by July, where it fied as St. Louis encephalitis, which has a New York City, home to perhaps about cteomntbienru, ebdir dtos akti ltlh cer oBwrosn axn Zdo toh.en, in Sep- swimithil aWr ecstli Nniiclea li np trhoefi llaeb .and cross-reacts 4ve0i lslapnecciee isn o pf lamceo,s eqvueinto t, hhoausg nho s osmuceh o sfu itrs- D AP Photo By the middle of August, people were Understandable as it is to many health neighbors—Suffolk County, Nassau Coun- B CHIL O B 20 Scientific American April 2000 News & Analysis Copyright 2000 Scientific American, Inc.

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