What would you say is the most important discovery made in the past few centuries?
对你来说，在过去几个世纪里，人类最重大的发现是什么？
Is it the computer? The car? Electricity? Or maybe the discovery of the atom?
电脑？汽车？电？还是原子的发现？
I would argue that it is this chemical reaction:
我认为应该是以下的化学反应：
a nitrogen gas molecule plus three hydrogen gas molecules gets you two ammonia gas molecules.
一个氮气分子加上三个氢气分子，反应产生两个氨气分子。
This is the Haber process of binding nitrogen molecules in the air to hydrogen molecules, or turning air into fertilizer.
这个叫做哈伯制氨法，它将空气中的氮气分子与氢气分子结合，将空气变为肥料。
Without this reaction, farmers would be capable of producing enough food for only 4 billion people;
如果没有哈伯制氨法，那么全世界的粮食产量最多只能养活40亿人，
our current population is just over 7 billion people.
而我们现在的世界人口超过70亿。
So, without the Haber process, over 3 billion people would be without food.
所以，如果没有哈伯制氨法，超过30亿人将没有食物。
You see, nitrogen in the form of nitrate, NO3, is an essential nutrient for plants to survive.
硝酸盐（NO3）中的氮元素是植物生长所必需的营养。
As crops grow, they consume the nitrogen, removing it from the soil.
农作物在生长时从土壤中吸收氮。
The nitrogen can be replenished through long, natural fertilization processes like decaying animals,
通过自然的方式来补充土壤中的氮则需要很长时间，比如从动物尸体的腐烂过程中产生，
but humans want to grow food much faster than that.
但是人们往往需要在更短时间内耕种农作物。
Now, here's the frustrating part: 78% of the air is composed of nitrogen,
让大家特别头疼的是：虽然氮气占空气成分的78%，
but crops can't just take nitrogen from the air because it contains very strong triple bonds, which crops cannot break.
但是农作物不能直接从空气中吸收氮气，因为氮气分子拥有坚固的三键结构，很难被农作物破坏。
What Haber did basically was figure out a way to take this nitrogen in the air and put it into the ground.
哈伯找到了一种能够把空气里的氮吸取出来，然后注入土壤中的方法。
In 1908, the German chemist Fritz Haber developed a chemical method for utilizing the vast supply of nitrogen in the air.
在1908年，德国化学家弗里茨·哈伯发明了一种化学方法，有效地将空气中丰富的氮资源利用起来。
Haber found a method which took the nitrogen in the air and bonded it to hydrogen to form ammonia.
他的这种方法把空气中的氮气与氢气结合，形成氨气。
Ammonia can then be injected into the soil, where it is quickly converted into nitrate.
氨气可以被注入土壤中，并且很快地被转化成硝酸盐。
But if Haber's process was going to be used to feed the world,
但是如果要用哈伯制氨法来保证世界粮食产量，
he would need to find a way to create a lot of this ammonia quickly and easily.
他就需要找到一种能够快速且容易的制造氨气的方法。
In order to understand how Haber accomplished this feat, we need to know something about chemical equilibrium.
为了理解哈伯是怎样完成此壮举的，我们首先需要了解一些关于化学平衡的知识。
Chemical equilibrium can be achieved when you have a reaction in a closed container.
化学平衡可以在密封容器里进行反应时被达到。
For example, let's say you put hydrogen and nitrogen into a closed container and allow them to react.
例如，你把氢气和氮气放入密封容器中让它们进行反应。
In the beginning of the experiment, we have a lot of nitrogen and hydrogen, so the formation of ammonia proceeds at a high speed.
在实验刚刚开始的时候，我们有许多的氮气和氢气，它们高速地发生反应，形成氨气。
But as the hydrogen and nitrogen react and get used up,
但是，持续的反应渐渐消耗氢气和氮气，
the reaction slows down because there is less nitrogen and hydrogen in the container.
因为容器中氢气和氮气的量减少，反应速度随之减慢。
Eventually, the ammonia molecules reach a point where they start to decompose back into the nitrogen and hydrogen.
最终，氨气分子到达一个临界点，它们开始分解成氮气和氢气。
After a while, the two reactions, creating and breaking down ammonia, will reach the same speed.
此后，两种化学反应，即氨气的形成和分解，将渐渐达到同样的速度。
When these speeds are equal, we say the reaction has reached equilibrium.
当它们等速时，反应便被称为达到了化学平衡。

This might sound good, but it's not when what you want is to just create a ton of ammonia.
这听起来不错，但其实不然，因为你仅仅是想制造一吨纯的氨气。
Haber doesn't want the ammonia to break down at all,
哈伯不想让反应产生的氨气分解，
but if you simply leave the reaction in a closed container, that's what will happen.
但如果让此化学反应在密封容器中自由进行，氨气便会分解。
Here's where Henry Le Chatelier, a French chemist, can help.
法国化学家亨利·路易·勒夏特列帮上了忙。
What he found was that if you take a system in equilibrium and you add something to it,
他发现，如果你向已达到化学平衡的系统里加上一些东西，
like, say, nitrogen, the system will work to get back to equilibrium again.
比如氮气，那么这个系统会自动调整，以重新回到平衡。
Le Chatelier also found that if you increase the amount of pressure on a system,
勒夏特列还发现，如果增大系统的压力，
the system tries to work to return to the pressure it had.
为了返回到以前的压力状态，系统将继续反应。
It's like being in a crowded room.
就像在一个拥挤的房间里一样。
The more molecules there are, the more pressure there is.
分子的数量越多，系统的压力就越大。
If we look back at our equation, we see that on the left-hand side, there are four molecules on the left and just two on the right.
让我们看看这个反应的化学方程式，在方程式的左边有四个分子，而方程式的右边只有两个分子。
So, if we want the room to be less crowded, and therefore have less pressure,
所以，为了让房间变得不那么拥挤，以至减小压力，
the system will start combining nitrogen and hydrogen to make the more compact ammonia molecules.
氮气和氢气的合成反应会重新开始，产生更加小巧的氨气分子。
Haber realized that in order to make large amounts of ammonia,
哈伯意识到，为了制造大量的氨气，
he would have to create a machine that would continually add nitrogen and hydrogen
他必须首先创造一台机器，可以连续不断地注入氢气和氮气，
while also increasing the pressure on the equilibrium system, which is exactly what he did.
并且持续增加平衡系统的压力，他做到了。
Today, ammonia is one of the most produced chemical compounds in the world.
今天，氨气是世界上被制造得最多的化合物之一。
Roughly 131 million metric tons are produced a year, which is about 290 billion pounds of ammonia.
每年大约有1亿3千1百万公吨的氨气被产出，重量大约为2900亿磅。
That's about the mass of 30 million African elephants, weighing roughly 10,000 pounds each.
这相当于3千万头每头约1万磅重的非洲大象的总重。
80% of this ammonia is used in fertilizer production,
80%的氨气被用于制造肥料，
while the rest is used in industrial and household cleaners and to produce other nitrogen compounds, such as nitric acid.
剩下的20%被用于工业和家庭用的清洁剂中，以及制造其它氮化物，例如硝酸。
Recent studies have found that half of the nitrogen from these fertilizers is not assimilated by plants.
最近的研究显示，化肥中一半的氮都没有被植物吸收。
Consequently, the nitrogen is found as a volatile chemical compound in the Earth's water supplies and atmosphere,
之后，我们发现氮是具挥发性的化合物，积存在地球的水和大气中，
severely damaging our environment.
对我们的环境造成极大污染。
Of course, Haber did not foresee this problem when he introduced his invention.
当然，在哈伯发明制氮法时，他并没有预见到这个问题。
Following his pioneering vision, scientists today are looking for a new Haber process of the 21st century,
继承哈伯的开创性的发明，今日的科学家们在找寻一种21世纪的新制氮法，
which will reach the same level of aid without the dangerous consequences.
它既可以达到制氮的目的，又不会给人类带来危险的后果。