So, I have a strange career. I know it because people come up to me, like colleagues, and say, "Chris, you have a strange career."
Ja se bavim čudnim poslom. Znam to zato što mi ljudi, kolege na primer, prilaze i kažu: "Krise, baviš se čudnim poslom."
(Laughter)
(Smeh)
And I can see their point, because I started my career as a theoretical nuclear physicist. And I was thinking about quarks and gluons and heavy ion collisions, and I was only 14 years old -- No, no, I wasn't 14 years old. But after that, I actually had my own lab in the Computational Neuroscience department, and I wasn't doing any neuroscience. Later, I would work on evolutionary genetics, and I would work on systems biology.
Razumem šta hoće da kažu, jer sam počeo karijeru kao teoretičar nuklearne fizike. Razmišljao sam o kvarkovima i gluonima i sudarima teških jona, a imao sam samo 14 godina. Ne, nisam imao 14 godina. Ali posle toga sam zapravo imao svoju laboratoriju na departmanu za računarske neuronauke a uopšte se nisam bavio neuronaukama. Kasnije sam se bavio evolucionom genetikom, a potom biologijom sistema.
But I'm going to tell you about something else today. I'm going to tell you about how I learned something about life. And I was actually a rocket scientist. I wasn't really a rocket scientist, but I was working at the Jet Propulsion Laboratory in sunny California, where it's warm; whereas now I am in the mid-West, and it's cold. But it was an exciting experience. One day, a NASA manager comes into my office, sits down and says, "Can you please tell us, how do we look for life outside Earth?" And that came as a surprise to me, because I was actually hired to work on quantum computation. Yet, I had a very good answer. I said, "I have no idea."
Ali danas ću vam govoriti o nečemu drugom. Govoriću vam o tome kako sam naučio nešto o životu. A bio sam raketni naučnik. Nisam baš bio raketni naučnik, ali sam radio u Laboratoriji za razvijanje mlaznog pogona u sunčanoj Kaliforniji, gde je toplo; dok sada radim na srednjem Zapadu, i hladno mi je. Ali bilo je to jedno uzbudljivo iskustvo. Jednog dana službenik NASA-e je ušao u moju kancelariju, seo i rekao: "Možete li, molim vas, da nam kažete kako da tražimo život van Zemlje?" To me je iznenadilo jer sam bio zaposlen tamo kako bih radio na kvantnom računarstvu. Ipak, imao sam veoma dobar odgovor na njegovo pitanje. Rekao sam: "Nemam pojma."
(Laughter)
On mi je rekao: "Znakovi života,
And he told me, "Biosignatures, we need to look for a biosignature." And I said, "What is that?" And he said, "It's any measurable phenomenon that allows us to indicate the presence of life." And I said, "Really? Because isn't that easy? I mean, we have life. Can't you apply a definition, for example, a Supreme Court-like definition of life?"
treba da tragamo za znakovima života." Ja sam pitao: "Šta je to?" A on je rekao: "To su merljive pojave koje nam ukazuju na prisustvo života." Zapitao sam: "Stvarno? Jer, znate, nije li to lako? Mislim, mi imamo život. Zar ne možete da primenite definiciju, definiciju kakvu bi dao Vrhovni Sud, na primer?"
And then I thought about it a little bit, and I said, "Well, is it really that easy? Because, yes, if you see something like this, then all right, fine, I'm going to call it life -- no doubt about it. But here's something." And he goes, "Right, that's life too. I know that." Except, if you think that life is also defined by things that die, you're not in luck with this thing, because that's actually a very strange organism. It grows up into the adult stage like that and then goes through a Benjamin Button phase, and actually goes backwards and backwards until it's like a little embryo again, and then actually grows back up, and back down and back up -- sort of yo-yo -- and it never dies. So it's actually life, but it's actually not as we thought life would be. And then you see something like that. And he was like, "My God, what kind of a life form is that?" Anyone know? It's actually not life, it's a crystal.
Razmišljao sam malo o tome i rekao: "Da li je zaista toliko lako? Jer, da, kada vidite ovako nešto, onda je u redu, to jeste život, nema sumnje u to. Ali evo nečega." On će na to: "Da, u redu, i to je život, znam to." Ali, ako mislite da se život definiše kao nešto što na kraju umire onda s ovim nećete imati sreće, jer je ovo jedan vrlo čudan organizam. On postaje odrasla jedinka, a onda prolazi kroz fazu "Bendžamin Baton" zapravo, vraća se unazad dok ponovo ne postane mali embrion, a onda poraste ponovo, pa se vrati unazad, pa ponovo raste - kao jo-jo, i nikad ne umire. Tako da, to jeste život, ali nije baš onakav kakvim ga zamišljamo. A onda vidite nešto kao što je ovo. On je upitao: "Bože, kakav je pa ovo oblik života?" Zna li neko? Ovo zapravo nije živo, to je kristal.
So once you start looking and looking at smaller and smaller things -- so this particular person wrote a whole article and said, "Hey, these are bacteria." Except, if you look a little bit closer, you see, in fact, that this thing is way too small to be anything like that. So he was convinced, but, in fact, most people aren't. And then, of course, NASA also had a big announcement, and President Clinton gave a press conference, about this amazing discovery of life in a Martian meteorite. Except that nowadays, it's heavily disputed. If you take the lesson of all these pictures, then you realize, well, actually, maybe it's not that easy. Maybe I do need a definition of life in order to make that kind of distinction.
Dakle, jednom kada počnete da gledate i gledate u sve manje i manje stvari... Tako je ova osoba napisala čitav članak, rekavši: "Hej, ovo su bakterije." Ali, kada pogledate malo bolje, videćete, u stvari, da je ovo suviše malo da bi bilo tako nešto. Dakle, on je bio uveren, ali, zapravo, većina ljudi nije bila. A onda, naravno NASA je objavila, i predsednik Klinton je imao konferenciju za štampu vezanu za ovo neverovatno otkriće života na marsovskom meteoritu. Ipak, danas, ovo otkriće je predmet rasprave. Ako izvučete pouku iz svih ovih slika, shvatićete da ovo zapravo možda i nije tako lako. Možda nam i treba neka definicija života kako bismo napravili razliku.
So can life be defined? Well how would you go about it? Well of course, you'd go to Encyclopedia Britannica and open at L. No, of course you don't do that; you put it somewhere in Google. And then you might get something.
Pa može li život da se definiše? Kako biste vi to uradili? Naravno, uzeli biste Enciklopediju Britaniku i otvorili na slovo L. Ne, naravno, ne biste uradili to, već biste izguglali. Tada biste možda dobili nešto.
(Laughter)
A ako od toga što dobijete,
And what you might get -- and anything that actually refers to things that we are used to, you throw away. And then you might come up with something like this. And it says something complicated with lots and lots of concepts. Who on Earth would write something as convoluted and complex and inane? Oh, it's actually a really, really, important set of concepts. So I'm highlighting just a few words and saying definitions like that rely on things that are not based on amino acids or leaves or anything that we are used to, but in fact on processes only. And if you take a look at that, this was actually in a book that I wrote that deals with artificial life. And that explains why that NASA manager was actually in my office to begin with. Because the idea was that, with concepts like that, maybe we can actually manufacture a form of life.
sve što govori o stvarima na koje smo navikli odbacite, dobićete nešto ovako. Ovo vam govori nešto komplikovano i sadrži puno različitih koncepata. Ko bi na ovom svetu napisao nešto ovako nategnuto i kompleksno i blesavo? No, to je zapravo veoma, veoma važan skup koncepata. Istaći ću samo nekoliko reči, a davanje takvih definicija oslanja se na stvari koje nisu zasnovane na aminokiselinama ili listovima ili na bilo šta na šta smo navikli, nego isključivo na procese. Ako bacite pogled na to videćete da je to iz moje knjige koja se bavi veštačkim životom. To objašnjava šta je taj službenik NASA-e uopšte radio u mojoj kancelariji. Zamisao je bila da sa takvim konceptima možda i možemo da napravimo oblik života.
And so if you go and ask yourself, "What on Earth is artificial life?", let me give you a whirlwind tour of how all this stuff came about. And it started out quite a while ago, when someone wrote one of the first successful computer viruses. And for those of you who aren't old enough, you have no idea how this infection was working -- namely, through these floppy disks. But the interesting thing about these computer virus infections was that, if you look at the rate at which the infection worked, they show this spiky behavior that you're used to from a flu virus. And it is in fact due to this arms race between hackers and operating system designers that things go back and forth. And the result is kind of a tree of life of these viruses, a phylogeny that looks very much like the type of life that we're used to, at least on the viral level.
A ako se pitate: "Šta je, zaboga, veštački život? pustite me da vam na brzinu pokažem kako je do svega ovoga došlo. Počelo je prilično davno kada je neko napisao jedan od prvih uspešnih komjuterskih virusa. Za one koji nisu dovoljno stari, nemate pojma kako je ova infekcija funkcionisala, naime, preko disketa. Ono što je zanimljivo kod ovih kompjuterskih virusnih infekcija je to da, ako pogledate nivoe aktivnosti ovih infekcija, dobićete ovaj talasasti prikaz kakav smo navikli da vidimo kod virusa gripa. Ovo je rezultat "nadmetanja u naoružanju" između hakera i dizajnera operativnih sistema, zato sve ide ovako napred-nazad. Rezultat je neka vrsta porodičnog stabla ovih virusa prikaz razvoja koji prilično podseća na prikaze razvoja živog sveta na koje smo navikli, barem na nivou virusa.
So is that life? Not as far as I'm concerned. Why? Because these things don't evolve by themselves. In fact, they have hackers writing them. But the idea was taken very quickly a little bit further, when a scientist working at the Santa Fe Institute decided, "Why don't we try to package these little viruses in artificial worlds inside of the computer and let them evolve?" And this was Steen Rasmussen. And he designed this system, but it really didn't work, because his viruses were constantly destroying each other. But there was another scientist who had been watching this, an ecologist. And he went home and says, "I know how to fix this." And he wrote the Tierra system, and, in my book, is in fact one of the first truly artificial living systems -- except for the fact that these programs didn't really grow in complexity.
Je li to, dakle, život? Ne, ako mene pitate. Zašto? Zato što ove stvari ne evoluiraju same od sebe. Postoje hakeri koji ih pišu. Ipak, ideja je vrlo brzo uznapredovala kada je jedan naučnik koji je radio u Naučnom institutu rekao: "Zašto ne probamo da spakujemo ove male viruse u veštačke svetove unutar kompjutera i pustimo ih da evoluiraju?" Taj čovek je bio Stin Rasmusen. On je dizajnirao ovaj sistem, ali on zapravo nije radio, jer su njegovi virusi stalno uništavali jedni druge. Sve ovo je posmatrao drugi naučnik, ekolog. Otišavši kući jednog dana, rekao je: "Znam kako da rešim ovo." Rezultat je bio "Tierra" sistem, i u svojoj knjizi sam rekao da je to jedan od prvih zaista veštačkih "živih" sistema - samo što ti programi nisu zaista postajali složeniji.
So having seen this work, worked a little bit on this, this is where I came in. And I decided to create a system that has all the properties that are necessary to see, in fact, the evolution of complexity, more and more complex problems constantly evolving. And of course, since I really don't know how to write code, I had help in this. I had two undergraduate students at California Institute of Technology that worked with me. That's Charles Ofria on the left, Titus Brown on the right. They are now, actually, respectable professors at Michigan State University, but I can assure you, back in the day, we were not a respectable team. And I'm really happy that no photo survives of the three of us anywhere close together.
Videvši ovaj rad i poradivši malo na tome, uključio sam se u celu stvar. Rešio sam da napravim sistem koji sadrži sve potrebne osobine koje dovode do evolucije složenosti, sve složenije i složenije probleme koji konstantno evoluiraju. Naravno, pošto ja zaista ne umem da sastavim kod, imao sam pomoć. Imao sam dvojicu studenata sa Kalifornijskog Instituta za Tehnologiju koji su radili za mene. Sa leve strane je Čarls Ofria, sa desne Tajtus Braun. Oni su danas ugledni profesori na Državnom univerzitetu u Mičigenu, ali, uverevam vas, u to vreme, mi nismo bili ugledan tim. Drago mi je što nijedna fotografija nas trojice zajedno nije sačuvana.
But what is this system like? Well I can't really go into the details, but what you see here is some of the entrails. But what I wanted to focus on is this type of population structure. There's about 10,000 programs sitting here. And all different strains are colored in different colors. And as you see here, there are groups that are growing on top of each other, because they are spreading. Any time there is a program that's better at surviving in this world, due to whatever mutation it has acquired, it is going to spread over the others and drive the others to extinction.
Ali kakav je ovaj sistem? Ne mogu baš da detaljišem, ali ovde možete da vidite neke od elemenata. Ono na šta sam hteo da se fokusiram je šema strukture populacije. Ovde se nalazi oko 10.000 programa. Različite vrste su obojene različitim bojama. Kao što vidite, grupe njih rastu jedna preko druge, šire se. Kad god se pojavi program koji bolje preživljava u ovom svetu, koja god mutacija da se pojavila kod njega, raširiće se preko ostalih i dovesti ih do istrebljenja.
So I'm going to show you a movie where you're going to see that kind of dynamic. And these kinds of experiments are started with programs that we wrote ourselves. We write our own stuff, replicate it, and are very proud of ourselves. And we put them in, and what you see immediately is that there are waves and waves of innovation. By the way, this is highly accelerated, so it's like a 1000 generations a second. But immediately, the system goes like, "What kind of dumb piece of code was this? This can be improved upon in so many ways, so quickly." So you see waves of new types taking over the other types. And this type of activity goes on for quite a while, until the main easy things have been acquired by these programs. And then, you see sort of like a stasis coming on where the system essentially waits for a new type of innovation, like this one, which is going to spread over all the other innovations that were before and is erasing the genes that it had before, until a new type of higher level of complexity has been achieved. And this process goes on and on and on.
Pokazaću vam film u kome se vidi ta vrsta dinamike. Ovakvi eksperimenti su počeli sa programima koje smo mi sami napisali. Pisali smo sopstvene programe, umnožavali ih, i veoma smo ponosni na sebe. Stavili smo ih unutra i, kao što se odmah vidi, javljaju se talasi i talasi inovacije. Usput, ovo je vrlo ubrzano, nekih hiljadu generacija u sekundi. Ali vrlo brzo, sistem kaže: "Kakva je sad ovo glupost od koda? Ovo se može unaprediti na toliko načina i to veoma brzo." Tako da vidite talase novih tipova kako preovladavaju nad drugim tipovima. Ovakva aktivnost traje prilično dugo, sve dok svi programi ne razviju one glavne lake funkcije. Onda vidite nešto kao stagnaciju u toku koje sistem čeka neku novu inovaciju, kao što je ova, koja će se proširiti i nadvladati druge inovacije koje su tu bile ranije, obrisati gene koji su bili tu ranije sve dok se novi, složeniji, tip ne pojavi. Ovaj proces traje i traje i traje.
So what we see here is a system that lives in very much the way we're used to how life goes. But what the NASA people had asked me really was, "Do these guys have a biosignature? Can we measure this type of life? Because if we can, maybe we have a chance of actually discovering life somewhere else without being biased by things like amino acids." So I said, "Well, perhaps we should construct a biosignature based on life as a universal process. In fact, it should perhaps make use of the concepts that I developed just in order to sort of capture what a simple living system might be."
Dakle, ono što vidimo ovde jeste sistem koji funkcioniše na prilično sličan način na koji smo navikli da život funkcioniše. Ipak, ono što su me ljudi iz NASA-e zapravo pitali bilo je: "Da li ova "stvorenja" daju znake života? Možemo li da "izmerimo" ovaj oblik života? Jer, ako možemo, možda imamo šansu da zapravo otkrijemo život negde drugde i da pritom ne budemo ograničeni stvarima kakve su aminokiseline." Ja sam rekao: "Pa, možda mogu da konstruišem prikaz znakova života zasnovan na životu kao univerzalnom procesu. Zapravo, taj prikaz može da koristi koncepte koje sam razvio samo kako bih zabeležio
And the thing I came up with -- I have to first give you an introduction about the idea, and maybe that would be a meaning detector, rather than a life detector. And the way we would do that -- I would like to find out how I can distinguish text that was written by a million monkeys, as opposed to text that is in our books. And I would like to do it in such a way that I don't actually have to be able to read the language, because I'm sure I won't be able to. As long as I know that there's some sort of alphabet. So here would be a frequency plot of how often you find each of the 26 letters of the alphabet in a text written by random monkeys. And obviously, each of these letters comes off about roughly equally frequent.
šta bi jednostavan živi sistem mogao da predstavlja." Ono što mi je palo na pamet, da napravim uvod u ideju, bi zapravo bio neki detektor značenja, pre nego detektor života. Način na koji bismo to postigli -- recimo, želim da saznam kako da razlikujem tekst koji je napisalo milion majmuna, od teksta koji je u knjigama. I želeo bih to da uradim na takav način da uopšte i ne moram da znam da čitam na tom jeziku, pošto sam siguran da neću znati. Uvek mora da postoji neka vrsta alfabeta. Dakle ovo je nivo učestalosti, tj. koliko često se javlja svako od 26 slova alfabeta u tekstu koji su napisali neki majmuni. Očigledno, svako od ovih slova javlja se otprilike podjednako često.
But if you now look at the same distribution in English texts, it looks like that. And I'm telling you, this is very robust across English texts. And if I look at French texts, it looks a little bit different, or Italian or German. They all have their own type of frequency distribution, but it's robust. It doesn't matter whether it writes about politics or about science. It doesn't matter whether it's a poem or whether it's a mathematical text. It's a robust signature, and it's very stable. As long as our books are written in English -- because people are rewriting them and recopying them -- it's going to be there.
Ali ako pogledate distribuciju slova u tekstovima na engleskom, nivo učestalosti je ovakav. Kažem vam, ovaj nivo učestalosti u tekstovima na engleskom je vrlo stalan. Ako bi pogledali tekstove na francuskom, bilo bi malo drugačije, kao i u tekstovima na italijanskom ili nemačkom. U svakom su slova drugačije distribuirana, ali nivo učestalosti je stalan. Nije bitno da li tekst govori o politici ili o nauci, da li je u pitanju poezija ili tekst o matematici, ova slika je vrlo robusna i stabilna. Dok god pišemo knjige na engleskom, a ljudi ih stalno iznova pišu i umnožavaju, takva slika će biti prisutna.
So that inspired me to think about, well, what if I try to use this idea in order, not to detect random texts from texts with meaning, but rather detect the fact that there is meaning in the biomolecules that make up life. But first I have to ask: what are these building blocks, like the alphabet, elements that I showed you? Well it turns out, we have many different alternatives for such a set of building blocks. We could use amino acids, we could use nucleic acids, carboxylic acids, fatty acids. In fact, chemistry's extremely rich, and our body uses a lot of them.
To me je inspirisalo da razmislim o sledećem - dakle, šta ako pokušam da primenim ovu ideju, ne da bih razlučio nasumične tekstove od onih koji imaju značenje, već da bih otkrio da li postoji značenje u biomolekulima koji sačinjavaju život. Prvo moram da se zapitam: šta su uopšte ove kockice, ovaj alfabet, ovi elementi koje sam vam pokazao? Ispostavilo se da ima više različitih zamena za ovaj set kockica. To mogu biti aminokiseline, nukleinske kiseline, karboksilne kiseline, masne kiseline. Zapravo, hemija je izuzetno bogata, i naše telo koristi mnogo hemikalija.
So that we actually, to test this idea, first took a look at amino acids and some other carboxylic acids. And here's the result. Here is, in fact, what you get if you, for example, look at the distribution of amino acids on a comet or in interstellar space or, in fact, in a laboratory, where you made very sure that in your primordial soup, there is no living stuff in there. What you find is mostly glycine and then alanine and there's some trace elements of the other ones. That is also very robust -- what you find in systems like Earth where there are amino acids, but there is no life.
Dakle, kako bismo testirali ovu ideju morali smo prvo da ispitamo aminokiseline i neke druge karboksilne kiseline. I evo rezultata. Evo, ovo se dobija kada, na primer, ispitate distribuciju aminokiselina na nekoj kometi ili u međuzvezdanom prostoru ili u laboratoriji za koju ste sigurni da u njoj nema ničeg živog. Ono što ćete naći su uglavnom glicin i alanin a ostalih kiselina ima u tragovima. Ova slika je takođe vrlo konstantna - ovo je ono što bismo našli u sistemima nalik Zemlji u kojima ima aminokiselina,
But suppose you take some dirt and dig through it and then put it into these spectrometers, because there's bacteria all over the place; or you take water anywhere on Earth, because it's teaming with life, and you make the same analysis; the spectrum looks completely different. Of course, there is still glycine and alanine, but in fact, there are these heavy elements, these heavy amino acids, that are being produced because they are valuable to the organism. And some other ones that are not used in the set of 20, they will not appear at all in any type of concentration. So this also turns out to be extremely robust. It doesn't matter what kind of sediment you're using to grind up, whether it's bacteria or any other plants or animals. Anywhere there's life, you're going to have this distribution, as opposed to that distribution. And it is detectable not just in amino acids.
ali nema života. Ali šta ako bismo uzeli malo zemlje i kopali malo po njoj i onda je stavili u ovaj spektrometar? Pošto ima bakterija na sve strane. Isti rezultat bi bio i sa vodom uzetom bilo gde na Zemlji, kada bi se sprovela ista analiza, jer je i ona prepuna života; spektar bi izgledao potpuno drugačije. Naravno, glicin i alanin bi još uvek bili tu, ali bilo bi i teških elemenata, teških aminokiselina, koje se proizvode zato što su od značaja za život organizma. Neke druge koje ne spadaju u dvadeset esencijalnih, se uopšte ne bi pojavile ni u kojoj koncentraciji. Dakle, i ova slika je konstantna. Nije bitno koji sediment je u pitanju, da li su u pitanju bakterije ili neke biljke ili životinje. Gde god ima života imaćete ovakvu distribuciju, a ne ovakvu. Ove razlike možemo očitati ne samo kada su aminokiseline u pitanju.
Now you could ask: Well, what about these Avidians? The Avidians being the denizens of this computer world where they are perfectly happy replicating and growing in complexity. So this is the distribution that you get if, in fact, there is no life. They have about 28 of these instructions. And if you have a system where they're being replaced one by the other, it's like the monkeys writing on a typewriter. Each of these instructions appears with roughly the equal frequency. But if you now take a set of replicating guys like in the video that you saw, it looks like this. So there are some instructions that are extremely valuable to these organisms, and their frequency is going to be high. And there's actually some instructions that you only use once, if ever. So they are either poisonous or really should be used at less of a level than random. In this case, the frequency is lower. And so now we can see, is that really a robust signature? I can tell you indeed it is, because this type of spectrum, just like what you've seen in books, and just like what you've seen in amino acids, it doesn't really matter how you change the environment, it's very robust, it's going to reflect the environment.
Sada se možda pitate: dakle šta sa ovim "Avidijancima"? "Avidijanci" su stanovnici kompjuterskog sveta u kome su savršeno srećni što se umnožavaju i postaju sve složeniji. Dakle, ovo je prikaz distribucije koji dobijamo u slučaju da života nema. Oni imaju 28 ovakvih instrukcija, i ukoliko imamo sistem u kome se one javljaju jedna za drugom, sistem nema značenja - kao majmuni sa kucaćim mašinama. Svaka od instrukcija se pojavljuje otprilike podjednako često. Ali ako uzmemo skup ovih stvorenja koja se množe kao na snimku koji ste videli, prikaz distribucije izgleda ovako. Dakle, postoje neke instrukcije koje su izuzetno važne za ove "organizme", i one će se javljati učestalije. A ima i onih instrukcija koje se koriste samo jednom, ili nikad. One su, dakle, ili otrovne, ili ih treba koristiti ređe nego što bi se pojavljivale kada bi sve bilo nasumično. Nivo učestalosti ovih instrukcija je niži. Sada možemo da vidimo da li zaista postoji neka šema. Mogu vam reći da postoji, jer smo ovakav spektar videli na primeru sa knjigama, kao i na primeru sa aminokiselinama, i ne menja se kada promenite okruženje, veoma je postojan; i oslikava okruženje.
So I'm going to show you now a little experiment that we did. And I have to explain to you, the top of this graph shows you that frequency distribution that I talked about. Here, that's the lifeless environment where each instruction occurs at an equal frequency. And below there, I show, in fact, the mutation rate in the environment. And I'm starting this at a mutation rate that is so high that even if you would drop a replicating program that would otherwise happily grow up to fill the entire world, if you drop it in, it gets mutated to death immediately. So there is no life possible at that type of mutation rate. But then I'm going to slowly turn down the heat, so to speak, and then there's this viability threshold where now it would be possible for a replicator to actually live. And indeed, we're going to be dropping these guys into that soup all the time.
Pokazaću vam jedan mali eksperiment koji smo napravili. Moram da objasnim - na vrhu ovog grafikona prikazana je učestalost distribucije elemenata o kojoj sam pričao. Ovde imamo okolinu bez života gde se svaka od instrukcija ponavlja podjednako često. A ispod je prikazan nivo promene učestalosti instrukcija u okolini. Počeću eksperiment sa nivoom promene dovoljno visokim da, čak i ako bismo ubacili program koji se umnožava i koji bi inače rado porastao i ispunio čitav svet, on bi u ovom slučaju "umro" na licu mesta. Dakle, život je nemoguć kada je nivo mutacije ovakav. Ali ako polako smanjim temperaturu, da tako kažem, dolazim do praga održivosti u životu na kome bi bilo moguće da program koji se umnožava preživi. Dakle, ubacivaćemo ova stvorenja u ovu čorbu sve vreme.
So let's see what that looks like. So first, nothing, nothing, nothing. Too hot, too hot. Now the viability threshold is reached, and the frequency distribution has dramatically changed and, in fact, stabilizes. And now what I did there is, I was being nasty, I just turned up the heat again and again. And of course, it reaches the viability threshold. And I'm just showing this to you again because it's so nice. You hit the viability threshold. The distribution changes to "alive!" And then, once you hit the threshold where the mutation rate is so high that you cannot self-reproduce, you cannot copy the information forward to your offspring without making so many mistakes that your ability to replicate vanishes. And then, that signature is lost.
Pogledajmo kako to sve izgleda. U početku: ništa, ništa, ništa. Vrelo, vrelo. Sada je prag održivosti dostignut, a učestalost distribucije značajno izmenjena, tj. stabilizovana. A sada šta sam uradio? Pa, bio sam nevaljao, povećao sam temperaturu ponovo. I naravno, dostigli smo prag održivosti. Pokazujem vam ovo ponovo jer je mnogo lepo. Dostigli smo prag održivosti. Prikaz distribucije instrukcija se promeni u: "Živo!" A onda, ako ponovo dođemo do tačke na kojoj je nivo mutacije toliko visok da se programi ne mogu samoumnožiti, informacije se ne mogu preneti na potomstvo bez pravljenja toliko grešaka da sama sposobnost umnožavanja nestaje. Taj znak života je time izgubljen.
What do we learn from that? Well, I think we learn a number of things from that. One of them is, if we are able to think about life in abstract terms -- and we're not talking about things like plants, and we're not talking about amino acids, and we're not talking about bacteria, but we think in terms of processes -- then we could start to think about life not as something that is so special to Earth, but that, in fact, could exist anywhere. Because it really only has to do with these concepts of information, of storing information within physical substrates -- anything: bits, nucleic acids, anything that's an alphabet -- and make sure that there's some process so that this information can be stored for much longer than you would expect -- the time scales for the deterioration of information. And if you can do that, then you have life.
Šta možemo zaključiti iz toga? Pa, mnogo toga. Između ostalog, zaključićemo da, ako smo u stanju da zamislimo život u apstraktnom smislu, ne kao biljke, aminokiseline ili bakterije, već kao skup procesa, možemo početi da gledamo na život ne kao na nešto isključivo svojstveno Zemlji, već kao nešto što bi moglo postojati bilo gde. Zato što život ima veze, pre svega, sa konceptima vezanim za informacije, za skladištenje informacija u okviru fizičkog konteksta - bitova, nukleinskih kiselina bilo šta što predstavlja sistem znakova - obavezno je i postojanje nekog procesa koji omogućava da informacije budu skladištene mnogo duže nego što biste očekivali da mogu odoleti vremenu. Ako omogućimo tako nešto,
So the first thing that we learn is that it is possible to define life in terms of processes alone, without referring at all to the type of things that we hold dear, as far as the type of life on Earth is. And that, in a sense, removes us again, like all of our scientific discoveries, or many of them -- it's this continuous dethroning of man -- of how we think we're special because we're alive. Well, we can make life; we can make life in the computer. Granted, it's limited, but we have learned what it takes in order to actually construct it. And once we have that, then it is not such a difficult task anymore to say, if we understand the fundamental processes that do not refer to any particular substrate, then we can go out and try other worlds, figure out what kind of chemical alphabets might there be, figure enough about the normal chemistry, the geochemistry of the planet, so that we know what this distribution would look like in the absence of life, and then look for large deviations from this -- this thing sticking out, which says, "This chemical really shouldn't be there." Now we don't know that there's life then, but we could say, "Well at least I'm going to have to take a look very precisely at this chemical and see where it comes from." And that might be our chance of actually discovering life when we cannot visibly see it.
dobili smo život. Dakle, prvo što smo zaključili jeste da je život moguće definisati i samo kao skup procesa, bez ikakvog oslanjanja na stvari na koje smo naviknuti kada je u pitanju zemaljski život. To nas na neki način udaljava, kao i sva naša velika naučna otkrića ili bar većina njih - postepeno nas skida sa trona naših ubeđenja kako smo posebni jer smo živi. Dakle, možemo da napravimo život. Barem na kompjuteru. Naravno, to je ograničen život, ali smo tako naučili šta nam sve treba da bismo ga konstruisali. Jednom kad to budemo savladali više neće biti tako teško zamisliti da, pošto razumemo fundamentalne procese koji se ne odnose ni na jedan određeni kontekst, možemo otići odavde i ispitati druge svetove, otkriti kakvi bi hemijski alfabeti tamo mogli da postoje, saznati nešto o njihovom hemijskom sastavu, odnosno geohemiji te planete, kako bismo znali kako nivoi distribucije izgledaju u odsustvu života, tada bismo mogli tragati za odstupanjima od toga - ukoliko naiđemo na nešto što se izdvaja, recimo: "Ovoj hemikaliji ovde nije mesto." Nećemo tada biti sigurni da tu ima života, ali moći ćemo da kažemo: "Ispitaću ovu hemikaliju vrlo pažljivo da vidim odakle potiče." To može biti naša šansa da otkrijemo život i kada život ne bude bio očigledan.
And so that's really the only take-home message that I have for you. Life can be less mysterious than we make it out to be when we try to think about how it would be on other planets. And if we remove the mystery of life, then I think it is a little bit easier for us to think about how we live, and how perhaps we're not as special as we always think we are. And I'm going to leave you with that.
Dakle, to je jedina poruka koju želim da ponesete odavde. Život postaje manje misteriozan nego što nam se čini kada pokušamo da ga zamislimo na drugim planetama. Ako uklonimo veo misterije sa naše predstave o životu, postaće nam lakše da razmišljamo o tome kako mi živimo, i shvatićemo da možda nismo toliko posebni kao što smo oduvek mislili. Mislite o tome.
And thank you very much.
I hvala vam puno.
(Applause)
(Aplauz)