It's really been a long time since we've known about fusion.

事實上我們知道核融合的存在已經很久了。

We've known about fusion since 1920,

早在1920年我們就知道核融合的存在，

when Sir Arthur Stanley Eddington

當時 亞瑟·斯坦利·愛丁頓爵士

and the British Association for the Advancement of Science

與 英國科技促進協會

conjectured that that's why the sun shines.

推測核融合就是太陽發光的原因。

I've always been very worried about resource.

我總是在擔心資源問題。

I don't know about you, but

我不知道你們的狀況，

when my mother gave me food,

當我媽媽給我食物

I always sorted the ones I disliked

我總是把不喜歡的分成一組，

from the ones I liked.

把喜歡的分成一組。

And I ate the disliked ones first,

我會先吃不喜歡的，

because the ones you like, you want to save.

因為你會想把喜歡的留下來。

And as a child you're always worried about resource.

只是一個小孩就知道擔心資源問題了。

And once it was sort of explained to me

某天我突然發現

how fast we were using up the world's resources,

世界上的資源被我們耗用有多快時，

I got very upset,

我開始煩腦，

about as upset as I did when I realized

就像我當知道

that the Earth will only last about five billion years

地球大概只剩50億年的壽命

before it's swallowed by the sun.

之後就會被太陽吞噬一樣令我煩惱。

Big events in my life,

這些是我生命中的大事，

a strange child.

真是個奇怪的小孩。

(Laughter)

(笑聲)

Energy, at the moment, is dominated by resource.

能源產量目前受制於資源的存量。

The countries that make a lot of money out of energy

因為能源賺了很多錢的國家

have something underneath them.

地底下都有許多資源。

Coal-powered industrial revolution in this country --

這些國家經歷了燃煤動力的工業革命 -

oil, gas, sorry.

石油，天然氣(和屁同一個字)，抱歉。

(Laughter)

(笑聲)

Gas, I'm probably the only person

當 Putin 關掉天然氣閥門時，

who really enjoys it when Mister Putin

我大概是唯一高興的人，

turns off the gas tap, because my budget goes up.

因為我的預算會變多。

We're really dominated now

我們正受制於那些

by those things that we're using up faster and faster and faster.

被我們快速消耗的東西。

And as we try to lift billions of people out of poverty

而當我們試圖幫助第三世界、

in the Third World, in the developing world,

發展中國家數十億人們脫離貧困時，

we're using energy faster and faster.

我們正加速使用能源。

And those resources are going away.

這些資源終將耗盡。

And the way we'll make energy in the future

未來我們取得能源的方法

is not from resource,

不再是利用資源，

it's really from knowledge.

而是依靠知識。

If you look 50 years into the future,

未來的50年，

the way we probably will be making energy

我們大概會用下列三種方式

is probably one of these three,

來獲取能源(太陽能、核分裂、核融合)，

with some wind, with some other things,

加上風力以及其他方式，

but these are going to be the base load energy drivers.

但這三項將是主要來源。

Solar can do it, and we certainly have to develop solar.

太陽能可以當主力，我們也勢必要發展太陽能。

But we have a lot of knowledge to gain before we can make solar

但我們還需要許多知識

the base load energy supply for the world.

來讓太陽能變成世界的主要能源。

Fission.

核分裂。

Our government is going to put in six new nuclear power stations.

我們的政府將要蓋六座新的核電廠。

They're going to put in six new nuclear power stations,

他們蓋了六座新的核電廠，

and probably more after that.

之後可能還會蓋更多。

China is building nuclear power stations. Everybody is.

中國正在蓋核電廠。每個國家都是。

Because they know that that is one sure way

因為他們知道這是確定可以

to do carbon-free energy.

獲取無碳能源的方式。

But if you wanted to know what the perfect energy source is,

如果你想知道什麼是完美的能源來源，

the perfect energy source is one

完美的能源來源是那種

that doesn't take up much space,

不會佔太多空間，

has a virtually inexhaustible supply,

幾乎可以無限制的供應，

is safe, doesn't put any carbon into the atmosphere,

而且安全，不會釋放任何碳進入大氣中，

doesn't leave any long-lived radioactive waste:

不會留下任何長久的放射性廢棄物，

it's fusion.

那就是核融合。

But there is a catch. Of course there is always a catch in these cases.

但其中有個難題。美好的東西都有些困難。

Fusion is very hard to do.

核融合很難達成。

We've been trying for 50 years.

我們已經試了50年。

Okay. What is fusion? Here comes the nuclear physics.

好。什麼是核融合呢？要講核子物理學了。

And sorry about that, but this is what turns me on.

不好意思，這話題讓我很興奮。

(Laughter)

(笑聲)

I was a strange child.

我是個奇怪的小孩。

Nuclear energy comes for a simple reason.

核能產生的原因很簡單。

The most stable nucleus is iron, right in the middle of the periodic table.

最安定的原子核是鐵，在週期表的正中央。

It's a medium-sized nucleus.

它是一個中等大小的原子核。

And you want to go towards iron if you want to get energy.

想得到能量就要趨向鐵原子的大小。

So, uranium, which is very big, wants to split.

所以，像鈾這種很大的原子傾向於分裂。

But small atoms want to join together,

但小的原子傾向於融合，

small nuclei want to join together

小的原子核傾向於融合在一起

to make bigger ones to go towards iron.

以接近鐵原子的大小。

And you can get energy out this way.

以這種方式你就能獲得能量。

And indeed that's exactly what stars do.

事實上這就是恆星所做的事。

In the middle of stars, you're joining hydrogen together to make helium

在恆星的中心，氫原子聚在一起形成氦原子，

and then helium together to make carbon,

氦原子聚合在一起形成碳原子，

to make oxygen, all the things that you're made of

然後形成氧原子，

are made in the middle of stars.

你體內一切物質都是如此產生的。

But it's a hard process to do

但這是很困難的過程，

because, as you know, the middle of a star is quite hot,

因為恆星的中心是非常炙熱的，

almost by definition.

至少定義上是如此。

And there is one reaction

有一種反應，

that's probably the easiest fusion reaction to do.

大概是最簡單的核融合反應。

It's between two isotopes of hydrogen, two kinds of hydrogen:

發生在兩個氫的同位素之間，是兩種氫原子，

deuterium, which is heavy hydrogen,

一個是氘，也就是重氫

which you can get from seawater,

可以從海水取得，

and tritium which is super-heavy hydrogen.

一個是氚，也就是超重氫。

These two nuclei, when they're far apart, are charged.

當這兩種原子核距離很遠時，他們因為本身的電荷，

And you push them together and they repel.

把它們推近時會相斥。

But when you get them close enough,

但當你把它們推的夠近時，

something called the strong force starts to act

一種叫強交互作用力的力量就會開始作用

and pulls them together.

將它們拉近在一起。

So, most of the time they repel.

所以大部分時候它們會互斥。

You get them closer and closer and closer and then at some point

逐漸將它們靠近到達某一個距離時

the strong force grips them together.

強交互作用力就會把它們拉近在一起。

For a moment they become helium 5,

這時他們會形成氦5，

because they've got five particles inside them.

因為總共有5個粒子。

So, that's that process there. Deuterium and tritium goes together

這就是最簡單的核融合反應。氘和氚聚合在一起

makes helium 5.

形成氦5。

Helium splits out, and a neutron comes out

氦分裂出來時，會釋放一個中子

and lots of energy comes out.

還有大量的能量。

If you can get something to about 150 million degrees,

如果你能讓某個東西到達一億五千萬度時，

things will be rattling around so fast

裡面的原子會快速亂竄，

that every time they collide in just the right configuration,

當它們正確碰撞在一起時，

this will happen, and it will release energy.

這個反應就會發生，並釋放出能量。

And that energy is what powers fusion.

而這能量就是核融合的能源。

And it's this reaction that we want to do.

這就是我們想進行的反應。

There is one trickiness about this reaction.

這個反應有個棘手的地方。

Well, there is a trickiness that you have to make it 150 million degrees,

當然讓它達到一億五千萬度也很棘手，

but there is a trickiness about the reaction yet.

但在反應之前還有一個棘手的地方。

It's pretty hot.

相當麻煩。

The trickiness about the reaction is that

那棘手的地方是反應中需要的

tritium doesn't exist in nature.

氚 並不存在於自然界。

You have to make it from something else.

你必須由其它方式來得到它。

And you make if from lithium. That reaction at the bottom,

你可以由鋰得到它。反應式寫在下面，

that's lithium 6, plus a neutron,

這是鋰6，加上一個中子，

will give you more helium, plus tritium.

就會形成氦以及一個氚。

And that's the way you make your tritium.

這就是獲得氚的方法。

But fortunately, if you can do this fusion reaction,

所幸，如果你能進行核融合反應，

you've got a neutron, so you can make that happen.

你就可以得到一個中子，也就可以產生氚。

Now, why the hell would we bother to do this?

那麼，為什麼我們要大費周章做這件事？

This is basically why we would bother to do it.

這就是原因。

If you just plot how much fuel

如果你把我們剩下的燃料

we've got left, in units of

以全世界的耗用量作為單位

present world consumption.

畫成這張圖。

And as you go across there you see

你就可以看到

a few tens of years of oil -- the blue line, by the way,

石油只剩幾十年－－對了，

is the lowest estimate of existing resources.

藍線是對現有資源最低的估計。

And the yellow line is the most optimistic estimate.

黃線是最樂觀的估計。

And as you go across there you will see

你就可以看到

that we've got a few tens of years, and perhaps 100 years

我們還剩下幾十年，

of fossil fuels left.

也許100年的化石燃料。

And god knows we don't really want to burn all of it,

而我們還真的不想把它全部燒掉。

because it will make an awful lot of carbon in the air.

因為這樣會產生大量的碳跑進大氣裡。

And then we get to uranium.

此外，還有鈾。

And with current reactor technology

以現有的技術而言

we really don't have very much uranium.

我們其實不剩多少鈾。

And we will have to extract uranium from sea water,

我們將得從海水中萃取鈾，

which is the yellow line,

也就是這條黃線，

to make conventional nuclear power stations

好讓傳統的核電廠

actually do very much for us.

繼續運作

This is a bit shocking, because in fact our government

這很令人震驚，因為事實上我們的政府

is relying on that for us to meet Kyoto,

正倚靠它來遵守京都議定書的協定

and do all those kind of things.

以及其他相關的事情。

To go any further you would have to have breeder technology.

接下來，還有增殖技術。

And breeder technology is fast breeders. And that's pretty dangerous.

增殖技術是種高速增殖反應。非常危險。

The big thing, on the right,

最重要的一項，在右邊，

is the lithium we have in the world.

就是世界上蘊藏的鋰。

And lithium is in sea water. That's the yellow line.

鋰在海水之中。就是這條黃線。

And we have 30 million years worth of fusion fuel in sea water.

海水中約有可使用3千萬年的核融合燃料。

Everybody can get it. That's why we want to do fusion.

每個人都能取得。這就是為什麼我們要核融合。

Is it cost-competitive?

它是否有價格競爭力？

We make estimates of what we think it would cost

我們以我們所知道的來估計

to actually make a fusion power plant.

建造核融合發電廠所需的花費。

And we get within about the same price

算出來的結果

as current electricity.

與現有的電廠差不多。

So, how would we make it?

那麼我們要怎麼去實現它呢？

We have to hold something at 150 million degrees.

我們必須把一億五千萬度的東西裝起來。

And, in fact, we've done this.

而事實上，我們也辦到了。

We hold it with a magnetic field.

我們運用磁場。

And inside it, right in the middle of this toroidal shape, doughnut shape,

在這個超環形，甜甜圈形狀的東西裡面，