As a particle physicist, I study the elementary particles and how they interact on the most fundamental level. For most of my research career, I've been using accelerators, such as the electron accelerator at Stanford University, just up the road, to study things on the smallest scale. But more recently, I've been turning my attention to the universe on the largest scale. Because, as I'll explain to you, the questions on the smallest and the largest scale are actually very connected. So I'm going to tell you about our twenty-first-century view of the universe, what it's made of and what the big questions in the physical sciences are -- at least some of the big questions.
Kao fizičar čestica, ja proučavam elementarne čestice i kako one međusobno reaguju na najosnovnijem nivou. Veći deo svoje istraživačke karijere koristim akceleratore, kao što je akcelerator elektrona na Univerzitetu Stanford, ovde blizu, kako bi proučavala stvari na najmanjoj skali. Ali od nedavno, počela sam da se bavim univerzumom na najvećoj skali. Pošto su, kako ću vam objasniti, pitanja na najmanjoj i najvećoj skali zapravo veoma povezana. Znači pričaću vam o našem viđenju univerzuma u 21. veku, od čega se sastoji i koja su velika pitanja fizičkih nauka -- barem neka od velikih pitanja.
So, recently, we have realized that the ordinary matter in the universe -- and by ordinary matter, I mean you, me, the planets, the stars, the galaxies -- the ordinary matter makes up only a few percent of the content of the universe. Almost a quarter, or approximately a quarter of the matter in the universe, is stuff that's invisible. By invisible, I mean it doesn't absorb in the electromagnetic spectrum. It doesn't emit in the electromagnetic spectrum. It doesn't reflect. It doesn't interact with the electromagnetic spectrum, which is what we use to detect things. It doesn't interact at all. So how do we know it's there? We know it's there by its gravitational effects. In fact, this dark matter dominates the gravitational effects in the universe on a large scale, and I'll be telling you about the evidence for that.
Nedavno smo shvatili da obična materija u univerzumu -- i kada kažem obična materija mislim na vas, OK, mene, planete, zvezde, galaksije -- obična materija koja čini samo nekoliko procenata sastava univerzuma. Skoro četvrtina, ili otprilike četvrtina materije u univerzumu, je ono što je nevidljivo. Kada kažem nevidljivo mislim da ne apsorbuje elektromagnetni spektar. Ne emituje u elektromagnetni spektar. Ne reflektuje. Nema interakciju sa elektromagnetnim spektrom, koga koristimo za detekciju stvari. Uopšte nema interakcije. Pa kako onda znamo da je tu? Znamo da je tu zbog njegovog gravitacionog dejstva. Zapravo, ova tamna materija dominira gravitacionim efektima u univerzumu na velikoj skali, i govoriću vam o dokazima za to.
What about the rest of the pie? The rest of the pie is a very mysterious substance called dark energy. More about that later, OK. So for now, let's turn to the evidence for dark matter. In these galaxies, especially in a spiral galaxy like this, most of the mass of the stars is concentrated in the middle of the galaxy. This huge mass of all these stars keeps stars in circular orbits in the galaxy. So we have these stars going around in circles like this. As you can imagine, even if you know physics, this should be intuitive, OK -- that stars that are closer to the mass in the middle will be rotating at a higher speed than those that are further out here, OK.
A šta je sa ostatkom kruga? Ostatak kruga je veoma misteriozna supstanca nazvana tamna energija. Više o tome kasnije, OK. Za sada, hajde da se okrenemo dokazima za tamnu materiju. U ovim galaksijama, posebno u spiralnoj galaksiji poput ove, većina mase zvezda je koncentrisana u sredini galaksije. Ova ogromna masa svih ovih zvezda drži zvezde u kružnim orbitama u galaksiji. Znači imamo ove zvezde koje kruže ovako. Kao što pretpostavljate, čak iako znate fiziku --ovo treba da je intuitivno, OK -- da će se zvezde koje su bliže masi u sredini rotirati većom brzinom od onih koje su udaljenije, OK.
So what you would expect is that if you measured the orbital speed of the stars, that they should be slower on the edges than on the inside. In other words, if we measured speed as a function of distance -- this is the only time I'm going to show a graph, OK -- we would expect that it goes down as the distance increases from the center of the galaxy. When those measurements are made, instead what we find is that the speed is basically constant, as a function of distance. If it's constant, that means that the stars out here are feeling the gravitational effects of matter that we do not see. In fact, this galaxy and every other galaxy appears to be embedded in a cloud of this invisible dark matter. And this cloud of matter is much more spherical than the galaxy themselves, and it extends over a much wider range than the galaxy. So we see the galaxy and fixate on that, but it's actually a cloud of dark matter that's dominating the structure and the dynamics of this galaxy.
Ono što biste očekivali jeste da ako biste merili orbitalnu brzinu zvezda, one bi trebalo da budu sporije na ivicama nego unutra. Drugim rečima, ako bi merili brzinu kao funkciju rastojanja -- ovo je jedini put da ću prikazati grafikon, OK-- očekivali bismo da se ona smanjuje kako se rastojanje povećava od centra galaksije. Kada se ta merenja izvrše, umesto toga nalazimo da je brzina u suštini konstantna, kao funkcija rastojanja. Ako je konstantna, to znači da zvezde tamo osećaju gravitaciono dejstvo materije koje mi ne vidimo. Zapravo, ova galaksija i svaka druga galaksija su izgleda ubačene u oblak ove nevidljive tamne materije. A ovaj oblak materije je mnogo više sferičan nego same galaksije, i prostire se preko veće oblasti od galaksije. Znači vidimo galaksiju i to fiksiramo, ali to je zapravo oblak tamne materije koji dominira strukturom i dinamikom ove galaksije.
Galaxies themselves are not strewn randomly in space; they tend to cluster. And this is an example of a very, actually, famous cluster, the Coma cluster. And there are thousands of galaxies in this cluster. They're the white, fuzzy, elliptical things here. So these galaxy clusters -- we take a snapshot now, we take a snapshot in a decade, it'll look identical. But these galaxies are actually moving at extremely high speeds. They're moving around in this gravitational potential well of this cluster, OK. So all of these galaxies are moving. We can measure the speeds of these galaxies, their orbital velocities, and figure out how much mass is in this cluster.
Same galaksije nisu nasumično razbacane po prostoru; one imaju tendenciju da se grupišu. I ovo je primer veoma, zapravo, čuvene grupe: Coma grupe. A postoje hiljade galaksija u ovoj grupi. One su ove bele, mutne, eliptične stvari ovde. Znači ove galaksije se grupišu - sada ih slikamo, i ako ih slikamo za deset godina -- izgledaće isto. Ali ove galaksije se zapravo kreću veoma visokim brzinama. One se kreću okolo u ovoj gravitacionoj potencijalnoj jami ove grupe, OK. Znači sve ove galaksije se kreću. Možemo meriti brzine ovih galaksija, njihovu orbitalnu brzinu, i izračunati koliko mase postoji u ovoj grupi.
And again, what we find is that there is much more mass there than can be accounted for by the galaxies that we see. Or if we look in other parts of the electromagnetic spectrum, we see that there's a lot of gas in this cluster, as well. But that cannot account for the mass either. In fact, there appears to be about ten times as much mass here in the form of this invisible or dark matter as there is in the ordinary matter, OK. It would be nice if we could see this dark matter a little bit more directly. I'm just putting this big, blue blob on there, OK, to try to remind you that it's there. Can we see it more visually? Yes, we can.
I ponovo, vidimo da postoji mnogo više mase tu nego što se može pripisati galaksijama koje vidimo. Ili ako posmatramo druge delove elektromagnetnog spektra, vidimo da postoji dosta gasa u ovoj grupi takođe. Ali ni to ne može objasniti masu. Zapravo, izgleda da postoji oko deset puta više mase ovde u obliku ove nevidljive ili tamne materije nego što postoji obične materije, OK. Bilo bi lakše kada bismo mogli da direktnije vidimo ovu tamnu materiju. Staviću ovu veliku, plavu mrlju ovde, OK, da bih vas podsetila da je tu. Da li je možemo jasnije videti? Da, možemo.
And so let me lead you through how we can do this. So here's an observer: it could be an eye; it could be a telescope. And suppose there's a galaxy out here in the universe. How do we see that galaxy? A ray of light leaves the galaxy and travels through the universe for perhaps billions of years before it enters the telescope or your eye. Now, how do we deduce where the galaxy is? Well, we deduce it by the direction that the ray is traveling as it enters our eye, right? We say, the ray of light came this way; the galaxy must be there, OK. Now, suppose I put in the middle a cluster of galaxies -- and don't forget the dark matter, OK. Now, if we consider a different ray of light, one going off like this, we now need to take into account what Einstein predicted when he developed general relativity. And that was that the gravitational field, due to mass, will deflect not only the trajectory of particles, but will deflect light itself.
Sada ću vam objasniti na koji način to možemo učiniti. Ovo je posmatrač. to može biti oko; može biti teleskop. I pretpostavimo da postoji galaksija tamo u univerzumu. Kako vidimo tu galaksiju? Zrak svetlosti napušta galaksiju i putuje kroz univerzum možda milijardama godina pre nego što dospe u teleskop ili vaše oko. Sada, kako zaključujemo gde je ta galaksija? Pa, zaključujemo prema smeru u kome putuje zrak dok ulazi u naše oko, uredu? Kažemo, zrak svetlosti je došao odavde; galaksija mora da je tamo, OK. Sada, pretpostavimo da između stavim grupu galaksija -- i ne zaboravite na tamnu materiju, OK. Sada, ako uzmemo u obzir drugi zrak svetlosti, koji ide ovako, sada moramo uzeti u obzir Ajnštanova predviđanja iz teorije opšte relativnost. A to je da gravitaciono polje, zbog mase, skreće ne samo putanju čestica, već skreće i samu svetlost.
So this light ray will not continue in a straight line, but would rather bend and could end up going into our eye. Where will this observer see the galaxy? You can respond. Up, right? We extrapolate backwards and say the galaxy is up here. Is there any other ray of light that could make into the observer's eye from that galaxy? Yes, great. I see people going down like this. So a ray of light could go down, be bent up into the observer's eye, and the observer sees a ray of light here.
Znači ovaj zrak svetlosti neće nastaviti da ide pravolinijski, već će se saviti i na kraju bi mogao da završi u vašem oku. Gde će posmatrač videti galaksiju? Možete odgovoriti. Gore, jel' tako? Ekstrapoliramo unazad i kažemo da je galaksija tamo gore. Da li postoji neki drugi zrak svetlosti koji bi mogao da stigne do oka posmatrača iz te galaksije? Da, super. Vidim ljude koji ovako pokazuju. Znači zrak svetlosti bi mogao da ide na dole, da se savije u oko posmatrača, i posmatrač vidi zrak svetlosti ovde.
Now, take into account the fact that we live in a three-dimensional universe, OK, a three-dimensional space. Are there any other rays of light that could make it into the eye? Yes! The rays would lie on a -- I'd like to see -- yeah, on a cone. So there's a whole ray of light -- rays of light on a cone -- that will all be bent by that cluster and make it into the observer's eye. If there is a cone of light coming into my eye, what do I see? A circle, a ring. It's called an Einstein ring. Einstein predicted that, OK. Now, it will only be a perfect ring if the source, the deflector and the eyeball, in this case, are all in a perfectly straight line. If they're slightly skewed, we'll see a different image.
Sada, uzmimo u obzir činjenicu da živimo u trodimenzionalnom univerzumu, OK, u trodimenzionalnom prostoru. Da li ima još zraka svetlosti koji mogu da dospeju u oko? Da! Zraci bi ležali na --volela bih da vidim --da, na kupi. Znači postoje zraci svetlosti -- zraci svetlosti na kupi -- koji će svi biti savijeni tom grupom i dospeti u oko posmatrača. Ako postoji kupa svetlosti koja dolazi do mog oka, šta ja vidim? Krug, prsten. To se naziva Ajnštajnovim prstenom -- Ajnštan je to predvideo, OK. Sada, to će biti savršeni prsten ako su izvor, prepreka, i oko, u ovom slučaju, u savršenoj pravoj liniji. Ako su malo ukrivo, videćemo drugačiju sliku.
Now, you can do an experiment tonight over the reception, OK, to figure out what that image will look like. Because it turns out that there is a kind of lens that we can devise, that has the right shape to produce this kind of effect. We call this gravitational lensing. And so, this is your instrument, OK. (Laughter). But ignore the top part. It's the base that I want you to concentrate, OK. So, actually, at home, whenever we break a wineglass, I save the bottom, take it over to the machine shop. We shave it off, and I have a little gravitational lens, OK. So it's got the right shape to produce the lensing. And so the next thing you need to do in your experiment is grab a napkin. I grabbed a piece of graph paper -- I'm a physicist. (Laughter) So, a napkin. Draw a little model galaxy in the middle. And now put the lens over the galaxy, and what you'll find is that you'll see a ring, an Einstein ring. Now, move the base off to the side, and the ring will split up into arcs, OK. And you can put it on top of any image. On the graph paper, you can see how all the lines on the graph paper have been distorted. And again, this is a kind of an accurate model of what happens with the gravitational lensing.
Sada, možete probati eksperiment večeras na prijemu, OK, da zaključite kako će ta slika izgledati. Jer se ispostavlja da postoji sočivo koje možemo napraviti, koje je odgovarajućeg oblika da stvori tu vrstu efekta. Ovo nazivamo gravitacionim sočivom. I tako, ovo je vaš instrument, OK. (Smeh). Ali zanemarite gornji deo. Želim da se koncentrišete na osnovu, OK. Zapravo, kod kuće, kada god slomimo vinsku čašu, Sačuvam dno, odnesem je do mašinske radionice. Skinemo gornji deo i imamo malo gravitaciono sočivo, OK. Znači to je pravi oblik za pravljenje sočiva. I sledeća stvar koju želim da uradite u vašem eksperimentu, jeste da uzmete salvetu. Ja sam uzela parče milimetarske hartije. Ja sam ipak fizičar. (Smeh) Znač, salvetu. Nacrtajte mali model galaksije u sredini. I onda stavite sočivo preko galaksije, i videćete da ste dobili prsten, Ajnštajnov prsten. A sada pomerite osnovu na stranu, i prsten će se podeliti na lukove, OK. I možete ga staviti preko bilo koje slike. Na milimetarskoj hartiji možete videti kako su sve linije na milimetarskoj hartiji izobličene. I ponovo, ovo je neka vrsta preciznog modela onoga što se dešava sa gravitacionim sočivom.
OK, so the question is: do we see this in the sky? Do we see arcs in the sky when we look at, say, a cluster of galaxies? And the answer is yes. And so, here's an image from the Hubble Space Telescope. Many of the images you are seeing are earlier from the Hubble Space Telescope. Well, first of all, for the golden shape galaxies -- those are the galaxies in the cluster. They're the ones that are embedded in that sea of dark matter that are causing the bending of the light to cause these optical illusions, or mirages, practically, of the background galaxies. So the streaks that you see, all these streaks, are actually distorted images of galaxies that are much further away.
OK, znači pitanje je: da li vidimo ovo na nebu? Da li vidimo lukove na nebu kada gledamo, na primer, grupu galaksija? I odgovor je: da. I tako, ovo je slika od svemirskog teleskopa Hubble. I mnoge od slika koje gledate su ranije dobijene sa svemirskog teleskopa Hubble. Kao prvo, za galaksije zlatnog oblika -- to su galaksije u grupi. To su one ugrađene u more tamne materije koje izazivaju savijanje svetlosti da bi izazvale optičke iluzije, fatamorgane, praktično, galaksija u pozadini. Znači crte koje vidite, sve ove crte, su zapravo iskrivljene slike galaksija koje su mnogo više udaljene.
So what we can do, then, is based on how much distortion we see in those images, we can calculate how much mass there must be in this cluster. And it's an enormous amount of mass. And also, you can tell by eye, by looking at this, that these arcs are not centered on individual galaxies. They are centered on some more spread out structure, and that is the dark matter in which the cluster is embedded, OK. So this is the closest you can get to kind of seeing at least the effects of the dark matter with your naked eye.
Ono što možemo je da, onda, na osnovu stepena iskrivljenja koje vidimo na tim slikama, izračunamo koliko mase mora da postoji u ovoj grupi. A to je ogromna količina mase. I takođe, možete videti golim okom, dok ovo posmatrate, da ovi lukovi nisu centrirani u pojedinačnim galaksijama; oni su centrirani u nekoj raširenijoj strukturi. A to je tamna materija u kojoj je ugrađena grupa, OK. Znači to je najbliže što možemo doći da vidimo barem efekte tamne materije golim okom.
OK, so, a quick review then, to see that you're following. So the evidence that we have that a quarter of the universe is dark matter -- this gravitationally attracting stuff -- is that galaxies, the speed with which stars orbiting galaxies is much too large; it must be embedded in dark matter. The speed with which galaxies within clusters are orbiting is much too large; it must be embedded in dark matter. And we see these gravitational lensing effects, these distortions that say that, again, clusters are embedded in dark matter.
OK, kratak pregled, da vidim da li pratite. Znači dokazi koje imamo da četvrtinu univerzuma čini tamna materija -- ono što privlači putem gravitacije -- jeste da galaksije, brzine kojim zvezde orbitiraju oko galaksija jesu prevelike; mora da bude ugrađena u tamnu materiju. Brzina kojom galaksije u okviru grupa orbitiraju je prevelika; mora da je ugrađena u tamnu materiju. I vidimo ove efekte gravitacionog sočiva, ova izobličenja koja ponovo ukazuju da su grupe ugrađene u tamnu materiju.
OK. So now, let's turn to dark energy. So to understand the evidence for dark energy, we need to discuss something that Stephen Hawking referred to in the previous session. And that is the fact that space itself is expanding. So if we imagine a section of our infinite universe -- and so I've put down four spiral galaxies, OK -- and imagine that you put down a set of tape measures, so every line on here corresponds to a tape measure, horizontal or vertical, for measuring where things are. If you could do this, what you would find that with each passing day, each passing year, each passing billions of years, OK, the distance between galaxies is getting greater. And it's not because galaxies are moving away from each other through space. They're not necessarily moving through space. They're moving away from each other because space itself is getting bigger, OK. That's what the expansion of the universe or space means. So they're moving further apart.
OK. Hajde sada da se bavimo tamnom energijom. Da bi razumeli dokaze za tamnu energiju, potrebno je razmotriti nešto što je Stephen Hawking spomenuo u prethodnoj sesiji. A to je činjenica da se sam prostor širi. Znači ako zamislimo deo našeg beskonačnog univerzuma, OK, pa sam ovde stavila četiri spiralne galaksije, OK. I zamislimo da stavite nekoliko metara za merenje, tako da se svaka linija ovde poklapa sa metrom za merenje -- horizontalno ili vertikalno -- za merenje gde se šta nalazi. Ako biste to mogli da uradite, videli biste svakim danom, svakom godinom, svakom milijardom godina, OK, da se rastojanje između galaksija povećava. A to nije zato šte se galaksije međusobno udaljuju kroz svemir; nije baš da se kreću kroz svemir. One se međusobno udaljavaju jer se sam svemir povećava, OK. To znači širenje univerzuma ili prostora. Znači one se udaljavaju.
Now, what Stephen Hawking mentioned, as well, is that after the Big Bang, space expanded at a very rapid rate. But because gravitationally attracting matter is embedded in this space, it tends to slow down the expansion of the space, OK. So the expansion slows down with time. So, in the last century, OK, people debated about whether this expansion of space would continue forever; whether it would slow down, you know, will be slowing down, but continue forever; slow down and stop, asymptotically stop; or slow down, stop, and then reverse, so it starts to contract again. So a little over a decade ago, two groups of physicists and astronomers set out to measure the rate at which the expansion of space was slowing down, OK. By how much less is it expanding today, compared to, say, a couple of billion years ago?
Sada, ono što je Stephen Hawking pomenuo, takođe, jeste da se nakon Velikog praska, prostor širio veoma velikom brzinom. Ali pošto je materija koja ima gravitaciono privlačenje ugrađena u ovaj prostor, ona ima tendenciju da usporava širenje prostora, OK. Znači širenje se usporava s vremenom. Znači, u prošlom veku, ljudi su raspravljali o tome da li će se ovo širenje prostora nastaviti zauvek, da li će se usporiti, znate, da li će se usporavati, ali nastavljati zauvek. Usporiti i stati, asimptotski stati, ili usporiti, zaustaviti, a onda, obratno ponovo početi da se skuplja. Pre nešto više od jedne decenije, dve grupe fizičara i astronoma su počeli da mere stopu po kojoj se širenje prostora usporava, OK. Za koliko manje se širi danas, u poređenju sa, na primer, pre par milijardi godina?
The startling answer to this question, OK, from these experiments, was that space is expanding at a faster rate today than it was a few billion years ago, OK. So the expansion of space is actually speeding up. This was a completely surprising result. There is no persuasive theoretical argument for why this should happen, OK. No one was predicting ahead of time this is what's going to be found. It was the opposite of what was expected. So we need something to be able to explain that. Now it turns out, in the mathematics, you can put it in as a term that's an energy, but it's a completely different type of energy from anything we've ever seen before. We call it dark energy, and it has this effect of causing space to expand. But we don't have a good motivation for putting it in there at this point, OK. So it's really unexplained as to why we need to put it in.
Zapanjujući odgovor na ovo pitanje, iz ovih eksperimenata, jeste da se prostor širi brže danas, nego pre nekoliko milijardu godina, OK. Znači širenje prostora se zapravo ubrzava. Ovo je bio potpuno iznenađujući rezultat. Ne postoji ubedljiv teorijski argument zašto se ovo događa, OK. Niko nije unapred predvideo da će se to utvrditi. Očekivalo se upravo suprotno. Zato nam je potrebno nešto što će moći to da objasni. Sada ispada, u matematici, možete to nazvati vrstom energije. Ali to je potpuno drugačija vrsta energije od bilo čega što smo do sada videli. Mi to nazivamo tamnom energijom, i ima dejstvo da izazove da se prostor širi. Ali nemamo dobar razlog da to uvedemo u ovom trenutku, OK. Znači potpuno je neobjašnjeno zašto moramo da to unesemo.
Now, so at this point, then, what I want to really emphasize to you, is that, first of all, dark matter and dark energy are completely different things, OK. There are really two mysteries out there as to what makes up most of the universe, and they have very different effects. Dark matter, because it gravitationally attracts, it tends to encourage the growth of structure, OK. So clusters of galaxies will tend to form, because of all this gravitational attraction. Dark energy, on the other hand, is putting more and more space between the galaxies, makes it, the gravitational attraction between them decrease, and so it impedes the growth of structure. So by looking at things like clusters of galaxies, and how they -- their number density, how many there are as a function of time -- we can learn about how dark matter and dark energy compete against each other in structure forming.
Sada, u ovom trenutku, onda, ono što želim da vam naglasim, jeste da su kao prvo, tamna materija i tamna energija potpuno različite stvari, OK. Postoje stvarno dve misterije o tome šta čini veći deo univerzuma, i one imaju veoma različita dejstva. Tamna materija, pošto gravitaciono privlači, ima tendenciju da ohrabruje rast strukture, OK. Tako da će grupe galaksija imati tendenciju da se formiraju, zbog ovog gravitacionog privlačenja. Tamna energija, s druge strane, stvara sve više i više prostora između galaksija. Čini da se - gravitaciona privlačnost među njima - smanjuje, i tako ometa rast strukture. I tako posmatrajući stvari poput grupa galaksija, i kako one -- njihov broj gustine, koliko ih ima kao funkcija vremena -- učimo o tome kako se tamna materija i tamna energija međusobno takmiče u formiranju strukture.
In terms of dark matter, I said that we don't have any, you know, really persuasive argument for dark energy. Do we have anything for dark matter? And the answer is yes. We have well-motivated candidates for the dark matter. Now, what do I mean by well motivated? I mean that we have mathematically consistent theories that were actually introduced to explain a completely different phenomenon, OK, things that I haven't even talked about, that each predict the existence of a very weakly interacting, new particle.
Što se tiče tamne materije, rekla sam da nemamo, znate, stvarno ubedljiv argument za tamnu energiju. Da li imamo nešto za tamnu materiju? I odogovor je: da. Imamo dobro motivisane kandidate za tamnu materiju. Šta znači dobro motivisane? Mislim da imamo matematički konzistentne teorije koje su zapravo uvedene da objasne potpuno različite fenomene, OK, stvari o kojima nisam čak ni govorila, koje previđaju postojanje veoma slabo reagujuće nove čestice.
So, this is exactly what you want in physics: where a prediction comes out of a mathematically consistent theory that was actually developed for something else. But we don't know if either of those are actually the dark matter candidate, OK. One or both, who knows? Or it could be something completely different. Now, we look for these dark matter particles because, after all, they are here in the room, OK, and they didn't come in the door. They just pass through anything. They can come through the building, through the Earth -- they're so non-interacting.
Zapravo ovo je baš ono što želite u fizici: kada previđanje potekne iz matematički konzistentne teorije koja je zapravo razvijena za nešto drugo. Ali mi ne znamo da li je ijedna od ovih stvarno kandidat za tamnu materiju, OK. Jedna, ili obe, ko zna? Ili je možda nešto potpuno drugačije. Sada tražimo ove čestice tamne materije jer ipak, one su ovde u sobi, OK, a nisu ušle kroz vrata. One jednostavno prolaze kroz bilo šta. One mogu proći kroz zgradu, kroz zemlju; one nemaju interakciju.
So one way to look for them is to build detectors that are extremely sensitive to a dark matter particle coming through and bumping it. So a crystal that will ring if that happens. So one of my colleagues up the road and his collaborators have built such a detector. And they've put it deep down in an iron mine in Minnesota, OK, deep under the ground, and in fact, in the last couple of days announced the most sensitive results so far. They haven't seen anything, OK, but it puts limits on what the mass and the interaction strength of these dark matter particles are. There's going to be a satellite telescope launched later this year and it will look towards the middle of the galaxy, to see if we can see dark matter particles annihilating and producing gamma rays that could be detected with this. The Large Hadron Collider, a particle physics accelerator, that we'll be turning on later this year. It is possible that dark matter particles might be produced at the Large Hadron Collider.
Znači jedan način da ih posmatramo jeste da izgradimo detektore koji su izuzetno osetljivi na tamne čestice koje prolaze kroz i sudaraju se s njima. Znači kristal koji će zvoniti ako se to dogodi. Pa su jedan moj kolega ovde niz ulicu i njegovi saradnici sagradili takav detektor. I postavili ga duboko u rudniku gvožđa u Minesoti, OK? -- duboko pod zemljom -- i zapravo, u poslednjih nekoliko dana su objavili najosetljivije rezultate do sada. Ništa nisu videli, OK, ali to postavlja granice onoga što su masa i snaga interakcija ovih čestica tamne materije. Biće lansiran satelitski teleskop kasnije ove godine. I biće uperen ka središtu galaksije, tako da možemo da vidimo čestice tamne materije kako uništavaju i proizvode gama zrake koji bi mogli da se ovim detektuju. Veliki hadronski sudarač, akcelerator čestica, koji će biti uključen kasnije ove godine. Moguće je da će nastati čestice tamne materije u Velikom hadronskom sudaraču.
Now, because they are so non-interactive, they will actually escape the detector, so their signature will be missing energy, OK. Now, unfortunately, there is a lot of new physics whose signature could be missing energy, so it will be hard to tell the difference. And finally, for future endeavors, there are telescopes being designed specifically to address the questions of dark matter and dark energy -- ground-based telescopes, and there are three space-based telescopes that are in competition right now to be launched to investigate dark matter and dark energy. So in terms of the big questions: what is dark matter? What is dark energy? The big questions facing physics. And I'm sure you have lots of questions, which I very much look forward to addressing over the next 72 hours, while I'm here. Thank you. (Applause)
Sada, pošto su toliko neinteraktivne, one će zapravo pobeći detektoru, pa će njihov otisak biti energija koja nedostaje, OK. Nažalost, ima mnogo nove fizike čiji bi otisak takođe mogao biti energija koja nedostaje, pa će biti teško napraviti razliku. I na kraju, za buduće napore, prave se teleskopi konkretno da se bave pitanjima tamne materije i tamne energije: teleskopi koji će biti na zemlji. I postoji tri teleskopa baziranih u svemiru koji su sada u konkurenciji da se lansiraju kako bi ispitivali tamnu materiju i tamnu energiju. Znači što se tiče velikih pitanja: Šta je tamna materija? Šta je tamna energija? Velika pitanja sa kojima je suočena fizika. I sigurna sam da vi imate puno pitanja. Na koja ću rado odgovoriti tokom sledećih 72 sata dok sam ovde, OK. Hvala. (Aplauz)