Nobody likes to make a mistake. And I made a whopping one. And figuring out what I did wrong led to a discovery that completely changes the way we think about the Earth and Moon.
Nitko ne voli činiti pogreške. A ja sam napravila ogromnu. Moja je pogreška dovela do otkrića koje u potpunosti mijenja način na koji razmišljamo o Zemlji i Mjesecu.
I'm a planetary scientist, and my favorite thing to do is smash planets together.
Planetarna sam znanstvenica i više od svega volim sudarati planete.
(Laughter)
(Smijeh)
In my lab, I can shoot at rocks using cannons like this one.
U laboratoriju mogu pucati u stijene iz topova kao što je ovaj.
(Cannon shot)
(Pucanj topa)
(Laughter)
(Smijeh)
In my experiments, I can generate the extreme conditions during planet formation. And with computer models, I can collide whole planets together to make them grow, or I can destroy them.
Eksperimentima mogu stvoriti ekstremne uvjete za vrijeme formacije planeta. A zahvaljujući računalnim modelima, mogu međusobno sudarati čitave planete da narastu ili da ih uništim.
(Laughter)
(Smijeh)
I want to understand how to make the Earth and the Moon and why the Earth is so different from other planets.
Želim shvatiti kako stvoriti Zemlju i Mjesec i zašto se Zemlja toliko razlikuje od drugih planeta.
The leading idea for the origin of the Earth and Moon is called the "giant impact theory." The theory states that a Mars-sized body struck the young Earth, and the Moon formed from the debris disk around the planet. The theory can explain so many things about the Moon, but it has a huge flaw: it predicts that the Moon is mostly made from the Mars-sized planet, that the Earth and the Moon are made from different materials. But that's not what we see. The Earth and the Moon are actually like identical twins. The genetic code of planets is written in the isotopes of the elements. The Earth and Moon have identical isotopes. That means that the Earth and Moon are made from the same materials.
Prevladavajuća teorija o nastanku Zemlje i Mjeseca naziva se "teorija velikog udara". Teorija tvrdi da je tijelo veličine Marsa udarilo u mladu Zemlju, a Mjesec je nastao iz prstena krhotina koji je okružio planet. Ova teorija može objasniti toliko toga o Mjesecu ali ima jedan veliki nedostatak: po njoj je Mjesec većim dijelom nastao od planeta veličine Marsa, po njoj su Zemlja i Mjesec građeni od različitih materijala. Ali dokazi pokazuju suprotno. Zemlja i Mjesec zapravo su poput identičnih blizanaca. Genetski kôd planeta zapisan je u izotopima elemenata. Zemlja i Mjesec imaju identične izotope. Dakle, Zemlja i Mjesec građeni su od istih materijala.
It's really strange that the Earth and the Moon are twins. All of the planets are made from different materials, so they all have different isotopes, they all have their own genetic code. No other planetary bodies have the same genetic relationship. Only the Earth and Moon are twins.
Prilično je čudno da su Zemlja i Mjesec blizanci. Svi su planeti građeni od različitih materijala, stoga imaju različite izotope, svaki ima svoj vlastiti genetski kôd. Niti jedno drugo nebesko tijelo nema ovakvu genetsku poveznicu. Samo su Zemlja i Mjesec blizanci.
When I started working on the origin of the Moon, there were scientists that wanted to reject the whole idea of the giant impact. They didn't see any way for this theory to explain the special relationship between the Earth and the Moon. We were all trying to think of new ideas. The problem was, there weren't any better ideas. All of the other ideas had even bigger flaws. So we were trying to rescue the giant impact theory.
Kad sam počela raditi na postanku Mjeseca, bilo je znanstvenika koji su htjeli potpuno odbaciti ideju o velikom udaru. Nisu vidjeli kako ovom teorijom objasniti posebnu vezu Zemlje i Mjeseca. Svi smo pokušavali smisliti nova rješenja. Problem je bio što nije bilo boljih rješenja. Sva su druga rješenja imala još veće nedostatke. Stoga smo pokušali spasiti teoriju velikog udara.
A young scientist in my group suggested that we try changing the spin of the giant impact. Maybe making the Earth spin faster could mix more material and explain the Moon. The Mars-sized impactor had been chosen because it could make the Moon and make the length of Earth's day. People really liked that part of the model. But what if something else determined the length of Earth's day? Then there would be many more possible giant impacts that could make the Moon. I was curious about what could happen, so I tried simulating faster-spinning giant impacts, and I found that it is possible to make a disk out of the same mixture of materials as the planet. We were pretty excited. Maybe this was the way to explain the Moon.
Mladi znanstvenik u mojoj grupi predložio je da pokušamo promijeniti rotaciju velikog udara. Kad bi se Zemlja vrtjela brže, možda bi se pomiješalo više materijala i objasnilo Mjesec. Tijelo veličine Marsa odabrano je jer objašnjava i Mjesec i duljinu Zemljinog dana. Ljudima se doista sviđao taj dio modela. Ali što kada bi nešto drugo određivalo duljinu Zemljinog dana? Otvorila bi se mogućnost drugačijih velikih udara kojima bi nastao Mjesec. Zanimalo me što bi se dogodilo pa sam pokušala simulirati velike udare brže rotacije i otkrila da je moguće da prsten nastane od iste mješavine materijala kao i planet. Bili smo prilično uzbuđeni. Možda je to način da objasnimo Mjesec.
The problem is, we also found that that's just not very likely. Most of the time, the disk is different from the planet, and it looked like making our Moon this way would be an astronomical coincidence, and it was just hard for everyone to accept the idea that the Moon's special connection to Earth was an accident. The giant impact theory was still in trouble, and we were still trying to figure out how to make the Moon.
No također smo otkrili i da je vjerojatnost za to vrlo mala. Prsten se u većini slučajeva razlikuje od planeta i činilo se da bi pokušaj da na ovaj način izgradimo Mjesec bio tek astronomska slučajnost, a svima je bilo teško prihvatiti ideju da je Mjesečeva posebna povezanost sa Zemljom samo slučajnost. Teorija velikog udara i dalje je bila u problemima, a mi smo i dalje pokušavali otkriti kako napraviti Mjesec.
Then came the day when I realized my mistake. My student and I were looking at the data from these fast-spinning giant impacts. On that day, we weren't actually thinking about the Moon, we were looking at the planet. The planet gets super-hot and partially vaporized from the energy of the impact. But the data didn't look like a planet. It looked really strange. The planet was weirdly connected to the disk. I got that super-excited feeling when something really wrong might be something really interesting.
Zatim je došao dan kada sam shvatila gdje sam pogriješila. Moj učenik i ja pregledavali smo podatke tih velikih udara brze rotacije. Toga dana nismo razmišljali o Mjesecu, gledali smo planet. Planet se ekstremno zagrije i dijelom pretvori u plin od energije udara. Ali podaci nisu davali sliku planeta. Izgledalo je čudno. Planet i prsten bili su spojeni na čudan način. Obuzeo me onaj intenzivan osjećaj uzbuđenja, kad znate da bi nešto potpuno krivo moglo biti nešto jako zanimljivo.
In all of my calculations, I had assumed there was a planet with a separate disk around it. Calculating what was in the disk as how we tested whether an impact could make the Moon. But it didn't look that simple anymore. We were making the mistake of thinking that a planet was always going to look like a planet. On that day, I knew that a giant impact was making something completely new.
U svim sam izračunima pretpostavila postojanje planeta s odvojenim prstenom koji ga okružuje. Izračunima sastava prstena testirali smo mogućnost da udarcem nastane Mjesec. Ali više nije bilo tako jednostavno. Naša je pogreška bila što smo mislili da će planet uvijek izgledati kao planet. Toga dana, znala sam da je velikim udarom nastalo nešto potpuno novo.
I've had eureka moments. This was not one of them.
Doživjela sam prije aha trenutke. Ovo nije bio jedan od njih.
(Laughter)
(Smijeh)
I really didn't know what was going on. I had this strange, new object in front of me and the challenge to try and figure it out. What do you do when faced with the unknown? How do you even start?
Doista nisam shvaćala što se događa. Gledala sam u to čudno novo tijelo i pokušavala ga shvatiti. Što učiniti kad ste suočeni s nepoznatim? Odakle uopće početi?
We questioned everything: What is a planet? When is a planet no longer a planet anymore? We played with new ideas. We had to get rid of our old way of thinking, and by playing, I could throw away all of the data, all of the rules of the real world, and free my mind to explore. And by making a mental space where I could try out outrageous ideas and then bring them back into the real world to test them, I could learn. And by playing, we learned so much. I combined my lab experiments with computer models and discovered that after most giant impacts, the Earth is so hot, there's no surface. There's just a deep layer of gas that gets denser and denser with depth. The Earth would have been like Jupiter. There's nothing to stand on. And that was just part of the problem. I wanted to understand the whole problem. I couldn't let go of the challenge to figure out what was really going on in giant impacts. It took almost two years of throwing away old ideas and building new ones that we understood the data and knew what it meant for the Moon.
Preispitivali smo sve: Što je planet? U kojem trenutku planet više nije planet? Igrali smo se novim idejama. Morali smo odbaciti stari način razmišljanja, a igrajući se, mogla sam odbaciti sve podatke, sva pravila stvarnog svijeta i osloboditi um da istražuje. Izgradivši mentalni prostor u kojem sam mogla ispitivati nevjerojatne ideje pa ih prenijeti u stvarni svijet i testirati ih, mogla sam učiti. Igrajući se, toliko smo toga naučili. Spojila sam laboratorijske eksperimente s računalnim modelima i otkrila da je nakon većine velikih udara Zemlja toliko vruća, da nema površine. Postoji samo debeli sloj plina koji s dubinom postaje sve gušći. Zemlja je bila poput Jupitera. Bez čvrstog tla pod nogama. Ali to je bio samo dio problema. Htjela sam potpuno razumjeti. Nisam mogla odustati od izazova da otkrijem što se zaista dogodi pri velikim udarima. Bile su potrebne gotovo dvije godine odbacivanja starih rješenja i stvaranja novih, da shvatimo podatke i što to znači za Mjesec.
I discovered a new type of astronomical object. It's not a planet. It's made from planets. A planet is a body whose self-gravity is strong enough to give it its rounded shape. It spins around all together. Make it hotter and spin it faster, the equator gets bigger and bigger until it reaches a tipping point. Push past the tipping point, and the material at the equator spreads into a disk. It's now broken all the rules of being a planet. It can't spin around together anymore, its shape keeps changing as it gets bigger and bigger; the planet has become something new.
Otkrila sam novu vrstu nebeskog tijela. Nije planet. Nastalo je od planeta. Planet je tijelo čija je gravitacija dovoljno snažna da mu daje okrugli oblik. Sve zajedno rotira. Ako mu povećavaš temperaturu i brzinu rotacije, ekvator raste do točke u kojoj izgubi ravnotežu. Ako ustrajemo iza te točke, materijal na ekvatoru raširi se u prsten. Prekršena su sva pravila kojima definiramo planet. Ne može više rotirati zajedno, kako raste i raste, oblik mu se mijenja; planet preraste u nešto novo.
We gave our discovery its name: synestia. We named it after the goddess Hestia, the Greek goddess of the hearth and home, because we think the Earth became one. The prefix means "all together," to emphasize the connection between all of the material. A synestia is what a planet becomes when heat and spin push it over the limit of a spheroidal shape.
Svom smo otkriću dali ime: sinestija. Nazvali smo ga po božici Hestiji, grčkoj božici ognjišta i doma, jer smatramo da je Zemlja postala upravo to. Prefiks ima značenje "zajedno", naglašava poveznicu čitavog materijala. Planet postane sinestija kad ga temperatura i rotacija izguraju izvan granica sferoidnog oblika.
Would you like to see a synestia?
Želite li vidjeti sinestiju?
(Cheers)
(Klicanje)
In this visualization of one of my simulations, the young Earth is already spinning quickly from a previous giant impact. Its shape is deformed, but our planet would be recognizable by the water on its surface. The energy from the impact vaporizes the surface, the water, the atmosphere, and mixes all of the gases together in just a few hours. We discovered that many giant impacts make synestias, but these burning, bright objects don't live very long. They cool down, shrink and turn back into planets. While rocky planets like Earth were growing, they probably turned into synestias one or more times.
Na ovom prikazu jedne od mojih simulacija, mlada Zemlja već rotira brzo zbog prethodnog velikog udara. Oblik joj je deformiran, ali moguće ju je prepoznati po vodi na njenoj površini. Energija udara pretvara u plin površinu, vodu, atmosferu i izmiješa sve plinove za samo nekoliko sati. Otkrili smo da mnogi veliki udari stvaraju sinestije, ali ova sjajna užarena tijela ne opstaju dugo. Ohlade se, stisnu i ponovno postanu planeti. Dok nastaju, stjenoviti planeti kao Zemlja vjerojatno se barem jednom pretvore u sinestiju.
A synestia gives us a new way to solve the problem of the origin of the Moon. We propose that the Moon formed inside a huge, vaporous synestia. The Moon grew from magma rain that condensed out of the rock vapor. The Moon's special connection to Earth is because the Moon formed inside the Earth when Earth was a synestia. The Moon could have orbited inside the synestia for years, hidden from view. The Moon is revealed by the synestia cooling and shrinking inside of its orbit. The synestia turns into planet Earth only after cooling for hundreds of years longer. In our new theory, the giant impact makes a synestia, and the synestia divides into two new bodies, creating our isotopically identical Earth and Moon. Synestias have been created throughout the universe. And we only just realized that by finding them in our imagination: What else am I missing in the world around me? What is hidden from my view by my own assumptions?
Sinestija nam pruža novo rješenje za problem postanka Mjeseca. Mi predlažemo da je Mjesec nastao unutar ogromne plinovite sinestije. Nastao je iz kiše magme, nastale kondenzacijom vaporiziranih stijena. Zemlja i Mjesec posebno su povezani jer je Mjesec nastao unutar Zemlje dok je Zemlja bila sinestija. Mjesec je mogao godinama orbitirati unutar sinestije, skriven. Otkrilo ga je sinestijino hlađenje i stiskanje unutar vlastite orbite. Sinestija postaje planet Zemlja tek nakon stotina godina hlađenja. Po našoj novoj teoriji, velikim udarom nastala je sinestija koja se razdijelila u dva nova tijela, stvorivši izotopski identične Zemlju i Mjesec. Sinestije su nastajale po čitavom svemiru. Shvatili smo to tek sada, pronašavši ih u našoj mašti. Što mi je još promaklo u svijetu koji me okružuje? Što još ne vidim zbog vlastitih pretpostavki?
The next time you look at the Moon, remember: the things you think you know may be the opportunity to discover something truly amazing.
Kada sljedeći put pogledate u Mjesec, sjetite se: ono što mislite da znate može biti prilika da otkrijete nešto stvarno nevjerojatno.
(Applause)
(Pljesak)