mc.prey-第27部分

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　〃Because　of　what's　going　on　here。〃
　〃And　what　is　going　on　here？〃
　He　stopped　before　a　small　cubicle　on　the　other　side　of　the　room。　〃Julia　couldn't　tell　you；　because　it　was　classified。〃　He　touched　the　door　with　a　keycard。　I　said；　〃Classified？　Medical　imaging　is　classified？〃
　The　door　latch　clicked　open；　and　we　went　inside。　The　door　closed　behind　us。　I　saw　a　table；　two　chairs；　a　puter　monitor　and　a　keyboard。　Ricky　sat　down；　and　immediately　started　typing。　〃The　medical　imaging　project　was　just　an　afterthought；〃　he　said；　〃a　minor　mercial　application　of　the　technology　we　are　already　developing。〃
　〃Uh…huh。　Which　is？〃
　〃Military。〃
　〃Xymos　is　doing　military　work？〃
　〃Yes。　Under　contract。〃　He　paused。　〃Two　years　ago；　the　Department　of　Defense　realized　from　their　experience　in　Bosnia　that　there　was　enormous　value　to　robot　aircraft　that　could　fly　overhead　and　transmit　battlefield　images　in　real　time。　The　Pentagon　knew　that　there　would　be　more　and　more　sophisticated　uses　for　these　flying　cameras　in　future　wars。　You　could　use　them　to　spot　the　locations　of　enemy　troops；　even　when　they　were　hidden　in　jungle　or　in　buildings；　you　could　use　them　to　control　laser…guided　rocket　fire；　or　to　identify　the　location　of　friendly　troops；　and　so　on。　manders　on　the　ground　could　call　up　the　images　they　wanted；　in　the　spectra　they　wanted…visible；　infrared；　UV；　whatever。　Real…time　imaging　was　going　to　be　a　very　powerful　tool　in　future　warfare。〃
　〃Okay　。。。〃
　〃But　obviously；〃　Ricky　said；　〃these　robot　cameras　were　vulnerable。　You　could　shoot　them　down　like　pigeons。　The　Pentagon　wanted　a　camera　that　couldn't　be　shot　down。　They　imagined　something　very　small；　maybe　the　size　of　a　dragonfly…a　target　too　small　to　hit。　But　there　were　problems　with　power　supply；　with　small　control　surfaces；　and　with　resolution　using　such　a　small　lens。　They　needed　a　bigger　lens。〃
　I　nodded。　〃And　so　you　thought　of　a　swarm　of　nanoponents。〃
　〃That's　right。〃　Ricky　pointed　to　the　screen；　where　a　cluster　of　black　spots　wheeled　and　turned　in　the　air；　like　birds。　〃A　cloud　of　ponents　would　allow　you　to　make　a　camera　with　as　large　a　lens　as　you　wanted。　And　it　couldn't　be　shot　down　because　a　bullet　would　just　pass　through　the　cloud。　Furthermore；　you　could　disperse　the　cloud；　the　way　a　flock　of　birds　disperses　with　a　gunshot。　Then　the　camera　would　be　invisible　until　it　re…formed　again。　So　it　seemed　an　ideal　solution。　The　Pentagon　gave　us　three　years　of　DARPA　funding。〃
　〃And？〃
　〃We　set　out　to　make　the　camera。　It　was　of　course　immediately　obvious　that　we　had　a　problem　with　distributed　intelligence。〃
　I　was　familiar　with　the　problem。　The　nanoparticles　in　the　cloud　had　to　be　endowed　with　a　rudimentary　intelligence；　so　that　they　could　interact　with　each　other　to　form　a　flock　that　wheeled　in　the　air。　Such　coordinated　activity　might　look　pretty　intelligent；　but　it　occurred　even　when　the　individuals　making　up　the　flock　were　rather　stupid。　After　all；　birds　and　fish　could　do　it；　and　they　weren't　the　brightest　creatures　on　the　planet。
　Most　people　watching　a　flock　of　birds　or　a　school　of　fish　assumed　there　was　a　leader；　and　that　all　the　other　animals　followed　the　leader。　That　was　because　human　beings；　like　most　social　mammals；　had　group　leaders。
　But　birds　and　fish　had　no　leaders。　Their　groups　weren't　organized　that　way。　Careful　study　of　flocking　behavior…frame…by…frame　video　analysis…showed　that；　in　fact；　there　was　no　leader。　Birds　and　fish　responded　to　a　few　simple　stimuli　among　themselves；　and　the　result　was　coordinated　behavior。　But　nobody　was　controlling　it。　Nobody　was　leading　it。　Nobody　was　directing　it。
　Nor　were　individual　birds　genetically　programmed　for　flocking　behavior。　Flocking　was　not　hard…wired。　There　was　nothing　in　the　bird　brain　that　said；　〃When　thus…and…such　happens；　start　flocking。〃　On　the　contrary；　flocking　simply　emerged　within　the　group　as　a　result　of　much　simpler；　low…level　rules。　Rules　like；　〃Stay　close　to　the　birds　nearest　you；　but　don't　bump　into　them。〃　From　those　rules；　the　entire　group　flocked　in　smooth　coordination。　Because　flocking　arose　from　low…level　rules；　it　was　called　emergent　behavior。　The　technical　definition　of　emergent　behavior　was　behavior　that　occurred　in　a　group　but　was　not　programmed　into　any　member　of　the　group。　Emergent　behavior　could　occur　in　any　population；　including　a　puter　population。　Or　a　robot　population。　Or　a　nanoswarm。
　I　said　to　Ricky；　〃Your　problem　was　emergent　behavior　in　the　swarm？〃
　〃Exactly。〃
　〃It　was　unpredictable？〃
　〃To　put　it　mildly。〃
　In　recent　decades；　this　notion　of　emergent　group　behavior　had　caused　a　minor　revolution　in　puter　science。　What　that　meant　for　programmers　was　that　you　could　lay　down　rules　of　behavior　for　individual　agents；　but　not　for　the　agents　acting　together。　Individual　agents…whether　programming　modules；　or　processors；　or　as　in　this　case；　actual　micro…robots…could　be　programmed　to　cooperate　under　certain　circumstances；　and　to　pete　under　other　circumstances。　They　could　be　given　goals。　They　could　be　instructed　to　pursue　their　goals　with　single…minded　intensity；　or　to　be　available　to　help　other　agents。　But　the　result　of　these　interactions　could　not　be　programmed。　It　just　emerged；　with　often　surprising　outes。
　In　a　way　this　was　very　exciting。　For　the　first　time；　a　program　could　produce　results　that　absolutely　could　not　be　predicted　by　the　programmer。　These　programs　behaved　more　like　living　organisms　than　man…made　automatons。　That　excited　programmers…but　it　frustrated　them；　too。　Because　the　program's　emergent　behavior　was　erratic。　Sometimes　peting　agents　fought　to　a　standstill；　and　the　program　failed　to　acplish　anything。　Sometimes　agents　were　so　influenced　by　one　another　that　they　lost　track　of　their　goal；　and　did　something　else　instead。　In　that　sense　the　program　was　very　childlike…unpredictable　and　easily　distracted。　As　one　programmer　put　it；　〃Trying　to　program　distributed　intelligence　is　like　telling　a　five…year…old　kid　to　go　to　his　room　and　change　his　clothes。　He　may　do　that；　but　he　is　equally　likely　to　do　something　else　and　never　return。〃
　Because　these　programs　behaved　in　a　lifelike　way；　programmers　began　to　draw　analogies　to　the　behavior　of　real　organisms　in　the　real　world。　In　fact；　they　began　to　model　the　behavior　of　actual　organisms　as　a　way　to　get　some　control　over　program　outes。　So　you　had　programmers　studying　ant　swarming；　or　termite　mounding；　or　bee　dancing；　in　order　to　write　programs　to　control　airplane　landing　schedules；　or　package　routing；　or　language　translation。　These　programs　often　worked　beautifully；　but　they　could　still　go　awry；　particularly　if　circumstances　changed　drastically。　Then　they　would　lose　their　goals。　That　was　why　I　began；　five　years　ago；　to　model　predator…prey　relationships　as　a　way　to　keep　goals　fixed。　Because　hungry　predators　weren't　distracted。　Circumstances　might　force　them　to　improvise　their　methods；　and　they　might　try　many　times　before　they　succeeded…but　they　didn't　lose　track　of　their　goal。
　So　I　became　an　expert　in　predator…prey　relationships。　I　knew　about　packs　of　hyenas；　African　hunting　dogs；　stalking　lionesses；　and　attacking　columns　of　army　ants。　My　team　had　studied　the　literature　from　the　field　biologists；　and　we　had　generalized　those　findings　into　a　program　module　called　PREDPREY；　which　could　be　used　to　control　any　system　of　agents　and　make　its　behavior　purposeful。　To　make　the　program　seek　a　goal。
　Looking　at　Ricky's　screen；　the　coordinated　units　moving　smoothly　as　they　turned　through　the　air；　I　said；　〃You　used　PREDPREY　to　program　your　individual　units？〃
　〃Right。　We　used　those　rules。〃
　〃Well；　the　behavior　looks　pretty　good　to　me；〃　I　said；　watching　the　screen。　〃Why　is　there　a　problem？〃
　〃We're　not　sure。〃
　〃What　does　that　mean？〃
　〃It　means　we　know　there's　a　problem；　but　we're　not　sure　what's　causing　it。　Whether　the　problem　is　programming…or　something　else。〃
　〃Something　else？　Like　what？〃　I　frowned。　〃I　don't　get　it；　Ricky。　This　is　just　a　cluster　of　microbots。　You　can　make　it　do　what　you　want。　If　the　programming's　not　right；　you　adjust　it。　What　don't　I　understand？〃
　Ricky　looked　at　me　uneasily。　He　pushed　his　chair　away　from　the　table　and　stood。　〃Let　me　show　you　how　we　manufacture　these　agents；〃　he　said。　〃Then　you'll　understand　the　situat