(掌聲)
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.
沒有人喜歡犯錯。 而我犯了個超級大錯。 我找出了我做錯什麼, 後續導致了一個發現, 完全改變了我們對於 地球和月球的看法。
I'm a planetary scientist, and my favorite thing to do is smash planets together.
我是行星科學家, 我最愛做的事情就是 把行星撞在一起。
(Laughter)
(笑聲)
In my lab, I can shoot at rocks using cannons like this one.
在我的實驗室,我可以用 像這樣的大砲對岩石開火。
(Cannon shot)
(大砲開火)
(Laughter)
(笑聲)
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.
依我的經驗,我可以產生出 在行星形成時的極端條件。 用電腦模型,我可以 讓行星整個相撞, 讓它們長大, 或是我也可以摧毀它們。
(Laughter)
(笑聲)
I want to understand how to make the Earth and the Moon and why the Earth is so different from other planets.
我想要了解,如何能 製造出地球和月球, 以及為什麼地球 和其他行星如此不同。
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.
關於地球和月球最初 如何形成的主要想法是 所謂的「大碰撞說」。 這個理論是火星大小的天體 撞擊了年輕的地球, 而月球是從該行星的盤狀分佈 碎片殘駭所形成。 這個理論能解釋許多月球的狀況, 但它有個巨大的瑕疵: 它預測,月球的主要成分 是那個火星大小的行星, 所以地球和月球是用 不同的材料生成的。 但,我們看到的並非如此。 地球和月球其實像是同卵雙胞胎。 行星的基因碼是寫在 元素的同位素中。 地球和月球有相同的同位素。 那就表示,地球和月球 是用同樣的材料生成的。
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.
地球和月球是雙胞胎, 這是很奇怪的事。 所有的行星都是由 不同的材料生成的, 所以它們都有不同的同位素, 它們都有自己的基因碼。 沒有任何其他行星體 有相同的基因關係。 只有地球和月球是雙胞胎。
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.
當我開始研究月球的起源時, 有些科學家想要推翻 整個大碰撞說。 他們不認為這個理論能夠解釋 地球和月球之間的特殊關係。 我們都在試圖提出新的想法。 問題是,沒有其他更好的想法。 所有其他想法都有更大的瑕疵。 所以,我們在試圖拯救大碰撞說。
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.
我的團隊中有一位 年輕的科學家建議, 我們可以試著改變 大碰撞說的自轉。 也許讓地球自轉速度更快, 就能混合更多材料, 並能解釋月球的形成。 撞擊地球的火星大小行星 已經被選定, 因為它可以形成月球, 並形成地球白天時間的長度。 大家真的很喜歡模型的這個部分。 但,如果地球的白天時間長度 是由其他因素決定的呢? 那麼,就會有更多大碰撞 都有可能形成月球。 我很好奇可能發生的狀況, 所以我試著模擬 自轉更快速的大碰撞, 我發現,的確有可能 用這個行星的材料組合 來生成一個盤。 我們相當興奮。 也許這種方式就能解釋月球。
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.
問題是,我們也發現, 這實在不太可能發生。 通常,生成的盤 都和這個星球不同, 看起來,若要用這種方式 生成我們的月球, 那會是天文學上的巧合, 大家很難接受 月球和地球的特殊關聯只是個意外。 大碰撞理論仍然在困境中, 我們仍然在試圖想出 月球是怎麼生成的。
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.
接著,有一天,我發現了我的錯誤。 我和我的學生在看 快速自轉大碰撞的資料。 那天,我們其實 並沒有在想月球的問題, 我們是在看那個行星。 因為撞擊的能量, 那個星球變得超級熱, 且有部分已經蒸發。 但那資料看起來並不像個行星。 它看起來相當奇怪。 這個行星和盤有著奇怪的連結。 我有種超興奮的感覺, 當有非常不對勁的狀況時, 可能會有很有趣的發現。
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.
在我所有的計算中, 我都假設有一個行星, 它周圍有一個分開的盤。 我們測試碰撞是否能夠 生成月球的方式, 就是計算那個盤中有什麼。 但,看起來不再是那麼簡單了。 我們犯的錯 是認為行星看起來 一定會是行星的樣子。 那天,我知道 大碰撞產生出來的是全新的東西。
I've had eureka moments. This was not one of them.
我有過靈光一現的時刻。 這個時刻並非其中之一。(笑聲)
(Laughter)
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?
我真的不知道到底怎麼回事。 我前面有著這個奇怪的新物體, 面對著要試圖搞懂它的挑戰。 當你面對未知時,該怎麼做? 到底要如何開始?
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.
我們質疑一切: 什麼是行星? 何時行星不再算是行星? 我們開始玩新的想法。 我們得要擺脫過去的思考方式, 透過「玩」,我可以 丟掉所有的資料、 真實世界中的所有規則, 解放我的大腦,讓它去探索。 我製造了一個心智空間, 在那裡,我可以嘗試 無法無天的想法, 接著把這些想法 帶回真實世界做測試, 我能學習。 透過「玩」,我們學了好多。 我把我的實驗室實驗 和電腦模型結合, 發現在大部分大碰撞之後, 地球都非常熱,熱到沒有表面。 只有一層很深層的氣體, 越深的地方密度越高。 地球本來可能像木星一樣。 沒有立足之地。 那只是問題的一部分。 我想要了解整個問題。 我無法放手這個挑戰,我想要想通 在大碰撞中到底發生了什麼事。 花了近兩年時間, 不斷把舊想法丟棄, 建立新想法, 我們才了解了那些資料, 搞懂那對月球的意涵是什麼。
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.
我發現了一種新的天文物體。 它不是行星。 它是由行星生成的。 行星是一個天體,它自己的重力 強到可以讓它形成圓形的形狀。 它會形成一個整體一起自轉。 若讓它更熱,自轉更快, 赤道就會越來越大, 直到達到臨界點。 若超過了臨界點, 赤道的材料會散佈成盤狀。 現在,它就打破了 所有身為行星的規則。 它不再能整體一起自轉了。 隨著它越長越大, 它的形狀不斷改變; 這個行星變成了某種新東西。
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.
我們把這項發現命名為: 索內斯蒂亞(synestia)。 我們採用的是女神 Hestia 的名字, 掌管爐灶和家庭的希臘女神, 因為我們認為地球 變成了這樣的角色。 字首 syn 意思是「全部一起」, 強調所有材料之間的連結。 當高熱與自轉速度將一個行星 推過了圓球形的極限時, 它就變成了索內斯蒂亞。
Would you like to see a synestia?
你們想要看看索內斯蒂亞嗎?
(Cheers)
(歡呼)
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.
這裡透過視覺呈現出來的 是我的其中一項模擬, 年輕的地球已經因為 先前的大碰撞而在快速自轉, 它的形狀變形了,但仍然 可以認出這是我們的星球, 因為它的表面有水。 碰撞的能量讓蒸發了地表、 水、大氣, 只花了幾個小時的時間 就把所有的氣體混合在一起。 我們發現,許多大碰撞 會產生索內斯蒂亞, 但這些燃燒、明亮的物體 沒有很長的生命。 它們會冷卻、縮小,轉變回行星。 當像地球這種岩石行星在成長時, 可能會有一次或數次 轉變為索內斯蒂亞。
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?
索內斯蒂亞讓我們有了一個新方法 可以解決月球起源的問題。 我們提出, 月球是在一個大型、 蒸汽的索內斯蒂亞中形成的。 岩石蒸汽濃縮成岩漿雨, 月球則從岩漿雨中生成。 月球和地球的連結會如此特殊, 是因為月球在地球內部形成, 當時地球是個索內斯蒂亞。 月球有可能在這個索內斯蒂亞 內部運行了很多年, 這時是看不見的。 當索內斯蒂亞在月球軌道 內部冷卻並縮小時, 月球就顯現出來了。 這個索內斯蒂亞再經過 數百年的冷卻之後, 就轉變成了地球。 在我們的新理論中, 大碰撞造成了一個索內斯蒂亞, 而這個索內斯蒂亞 分開成了兩個新天體, 創造出我們的地球和月球, 且讓它們擁有相同的同位素。 在宇宙各處都有 索內斯蒂亞被創造出來。 我們會了解這件事,是因為 我們在我們的想像中找到它們: 在我周遭的世界中, 我還遺漏了什麼? 有什麼是被我自己的假設 給遮蔽了,讓我無法看見?
The next time you look at the Moon, remember: the things you think you know may be the opportunity to discover something truly amazing.
下次當你抬頭看月亮時, 別忘了: 你認為你知道的事, 也許會是發現驚人新事物的機會。
(Applause)
(掌聲)