On August the sixth 1945, the US aircraft, Enola Gay, dropped an atomic bomb on the city of Hiroshima, instantly killing 70,000 people. When Japan refused to surrender, a second bomb was dropped on Nagasaki three days later. Many believe the bombings quickened the end of the Second World War. But it came at a terrible human cost, which some have called a crime against humanity.
The invention of the atomic bomb, which resulted from the cooperation between the US military and some of the world’s leading scientific minds, was known as The Manhattan Project. In this programme we’ll take a look into the science and the politics of The Manhattan Project, and as usual, we’ll learn some new vocabulary as well.
Even before World War Two, scientists had known about the potential energy inside uranium, the heaviest metal in the periodic table – a diagram which groups the chemical elements into rows and columns according to their atomic number and symbol. The challenge for science was learning how to unleash this potential energy in a controlled way. We’ll hear more soon, but first I have a question for you, Rob. I mentioned that uranium is the heaviest element in the periodic table, but which is the lightest? a) hydrogen; b) carbon c) oxygen.
Well, oxygen is a gas, so it must pretty light. I’ll say c) oxygen.
嗯，氧气是一种气体，所以它一定很轻。我会说 c） 氧气。
Sam(山姆)
OK, Rob, we’ll find out the answer later in the programme. First, let’s find out a bit more about the science of uranium from Frank Close, an Oxford professor of theoretical physics, in conversation with BBC Radio 4 programme, In Our Time.
好的，罗伯，我们稍后会在节目中找到答案。首先，让我们从牛津大学理论物理学教授弗兰克·克洛斯与BBC Radio 4节目《In Our Time》的对话中了解更多关于铀科学的信息。
Prof Frank Close(Frank Close 教授)
In 1938 the discovery was made that if you use uranium, the atoms of uranium, which are the heaviest that occur naturally in the periodic table, they’re very fragile… and the discovery was that if you just almost touched them with a single neutron, that’s a nuclear particle, the uranium was like a drop of water, it would just break apart, split in two… and this action of splitting the uranium has become known as fission.
Atoms of uranium are very fragile – easily broken or damaged. In 1938, it was discovered that when nuclear particles called neutrons were fired at uranium atoms, they would split, or break in two.
This process of splitting uranium, or fission, did two things. First, it released huge amounts of energy, a billion times more than would be released in a normal chemical reaction.
这种分裂铀或裂变的过程做了两件事。首先，它释放了大量的能量，比正常化学反应释放的能量多十亿倍。
Rob(罗伯)
Secondly, the act of splitting atoms released two more neutrons. These new neutrons were freed to hit more uranium, creating four neutrons, which in turn were freed and created eight, then sixteen and so on, making what’s known as a chemical chain reaction.
In everyday English, a chain reaction is a series of events where each event becomes the cause of the next.
在日常英语中，连锁反应是一系列事件，其中每个事件都成为下一个事件的原因。
Rob(罗伯)
The politics behind the development of the atomic bomb was no less complex than the science. In the same year that Hitler invaded Poland, two Jewish scientists exiled from Nazi Germany - Rudolf Peierls, and Otto Frish - first realised uranium’s power as a weapon of war. Listen as Professor Frank Close takes up the story for BBC Radio 4 programme, In Our Time:
原子弹发展背后的政治并不亚于科学。在希特勒入侵波兰的同一年，两位从纳粹德国流亡的犹太科学家 —— 鲁道夫·皮尔斯和奥托·弗里什 —— 首次意识到铀作为战争武器的威力。请听弗兰克·克洛斯教授为BBC Radio 4节目《在我们的时代》讲述这个故事：
Prof Frank Close(Frank Close 教授)
Having had the idea and the shock of the discovery, you immediately then think, ‘maybe scientists in Germany have already had the same idea and come to the same conclusions – could Hitler already be building such a weapon?’ And in their memorandum which they wrote and reached the British government they said it’s conceivable that Germany is in fact developing this weapon, and the only defence against it is to have one yourself.
After their discovery, Peierls and Frish were worried that the Nazis had already found out how to weaponize uranium. It was conceivable, or believable, that Germany was building an atomic bomb.
They shared this terrifying thought in their famous memorandum – a short written report on a specific topic. As soon as US President Franklin Roosevelt read it, he started the Manhattan Project, and the race to build an atomic bomb began.
In a strange twist of history, it turned out that Hitler hadn’t been building atomic bombs at all. And Hiroshima, the Japanese city destroyed in 1945, was rebuilt and stands as a symbol of peace today.
Let’s end on a lighter note, Sam, with your question.
山姆，让我们以更轻松的方式结束你的问题。
Sam(山姆)
Yes, I asked which is the lightest element in the periodic table. It’s A, hydrogen, the lightest of all gases which come at the very start of the periodic table, having the atomic number 1.
Ah, if only I’d remembered what our chemistry teacher taught us about the periodic table – a chart grouping all the chemical elements according to their atomic number.
Let’s recap the rest of the vocabulary too. If something is fragile it’s easily broken.
让我们也回顾一下其余的词汇。如果某样东西很脆弱，它很容易被打破。
Rob(罗伯)
To split something means to break it into two parts.
拆分某物意味着将其分成两部分。
Sam(山姆)
A chain reaction happens when one event becomes the cause of the next.
当一个事件成为下一个事件的原因时，就会发生连锁反应。
Rob(罗伯)
A memorandum is a short, written report on a specific topic.
备忘录是关于特定主题的简短书面报告。
Sam(山姆)
And finally, the adjective conceivable means believable. That brings us to the end of our programme! We hope you’ll join us again soon for more interesting issues and useful vocabulary. Bye for now!
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