宇宙时空之旅：未知世界（2020）

Cosmos: Possible Worlds S01E12

Part 4 Aug. 24, 2022, 10:56 a.m.

对卡珊德拉而言 "预知"是一种诅咒
For Cassandra, knowing was a curse.
但"知"也可能是最大的庇佑
But it can also be the greatest of blessings.
我说另一个故事给你听
Let me tell you another story.
很久很久以前世界上没有冰箱
Once upon a time, there were no refrigerators.
以前很难在夏天防止食物腐坏
It used to be hard to keep food from spoiling in the summertime.
有一种人是专门送冰的"冰人"
There was a person called the "iceman."
他会上门卖♥♥给你大块冰
He would come to your house and sell you a big block of ice.
放在所谓的"冰柜"里
You'd keep it in something called an "icebox" to preserve
保存各种容易腐坏的食物
the kinds of food that spoil quickly.
不过这样很麻烦因为冰块不断融化
But that was a drag because the ice kept melting.
水滴的满地都是
It would drip all over the floor.
有人就想到另一种冷藏食物的办法
So somebody thought up another way to keep food cold.
这是一种气动系统用氨或二氧化硫当做冷冻剂
It was a gas powered system that used ammonia or sulfur dioxide as a coolant.
再也不用费力搬运冰块
No more lugging blocks of ice.
这有什么坏处？
What could be bad about that?
这种化学成分不仅有毒
The chemicals were not only poisonous,
而且难闻还会外漏
they smelled terrible and there were leaks.
人们迫切需要可替代的冷冻剂
A substitute coolant was badly needed.
可以在冰箱内部循环
One that would circulate inside the refrigerator,
即使外漏也不会毒害任何人
but would not poison anyone if the refrigerator leaked,
丢到垃圾场也没有危险
or pose a danger if it was sent to the junkyard.
不会让人反胃
Something that wouldn't make you sick,
不会造成双眼灼热不会吸引蚊虫
wouldn't burn your eyes, or attract bugs,
甚至不会让猫咪难受
or even bother the cat.
不过在整个自然界似乎不存在这种东西
But in all of nature, no such material seemed to exist.
于是美国的化学家发明了一种分子
So chemists in the United States invented a class of molecules.
这些由更小的原子构成的群体
Little collections of even tinier things called atoms,
以前不曾出现在地球上
that had never existed on Earth before.
他们命名为氟氯碳化物
They called them chlorofluorocarbons,
也就是氯氟烃因为其中包含一个以上的碳原子
or CFCs, because they were made up of one or more carbon
几个氯和氟原子
atoms and some chlorine and/or fluorine atoms.
这种新分子的功效卓著
These new molecules were wildly successful,
远超过发明者的预期
far exceeding the expectations of their inventors.
氯氟烃不只成为主要的冰箱冷冻剂
Not only did CFCs become the chief coolant in refrigerators,
也是空调的冷媒
but also in air conditioners.
氯氟烃的功能众多
There were so many things you could do with CFCs.
可以用来推出一团团发泡的刮胡膏
People used them to propel great fluffy mounds of shaving cream.
保护发型不被风雨破坏
And to protect your hair from wind and rain.
而且有了氯氟烃推进剂
It was also the propellant that made fire extinguishers
灭火器和喷漆罐才这么好玩
and spray paint cans so much fun.
可以喷射绝缘发泡剂
It was good for foam insulation,
工业溶剂和清洗剂
industrial solvents and cleansing agents.
这些化学物品最有名的品牌是氟利昂
The most famous brand name of these chemicals was Freon,
杜邦的一个商标
a trademark of DuPont.
用了几十年似乎从来没有任何坏处
It was used for decades and no harm ever seemed to come from it.
大家都觉得安全得不得了
Safe as safe could be, everyone figured.
直到1970年代初期加州大学尔湾分校
Until, in the early 1970s, two atmospheric chemists at the
两位大气化学家
University of California, Irvine
研究地球的大气层
were studying Earth's atmosphere.
马里奥·莫利纳是墨西哥移♥民♥
Mario Molina was a Mexican immigrant,
一位年轻的激光化学家
a young laser chemist.
舍伍德·罗兰是化学动力学家
Sherwood Rowland was a chemical kineticist,
研究的是分子和气体在不同环境下的运动
someone who studied the motions of molecules and gases under varying conditions.
他来自俄亥俄州小镇
He was from a small town in Ohio.
莫利纳渴望提升学术功力
Molina wanted to grow as a scientist.
想找到一个研究计划让他在学术道路上有所进展
He was looking for a project that would take him as far from his previous research experience as possible.
他很想知道
He wondered.
往空调机外漏的氟利昂分子
What happens to those Freon molecules when they
究竟去了哪里？
leak out of the air conditioner?
在这个时代阿波罗宇航员仍然
This was a time when the Apollo astronauts were still
定期登陆月球
making regularly scheduled trips to the Moon.
NASA考虑每周发射
And NASA was contemplating weekly launches of
一艘航♥天♥飞船
a space shuttle.
燃烧那么多火箭燃料会不会伤害平流层?
Would all that burning rocket fuel pose a danger to the stratosphere,
即地球大气层和太空的交界
that place where Earth's atmosphere meets the blackness of space?
科学研究往往如此
And this is how science works a lot of the time.
你想解决一个问题
You set out to solve one problem,
却意外发现了完全不同的现象
and you happen on a completely different, unexpected phenomenon.
这些化学惰性高又"无害"的氯氟烃
Those wonderfully inert, "harmless" CFCs,
刮胡刀和发胶的神奇分子
the magic molecules of shaving cream and hair spray,
并未在我们用完之后消失
didn't simply vanish when we were done with them.
而是在太空边缘度过后半生
They had an afterlife at the edge of space,
累积了好几万亿的分子
where they accumulated in the trillions.
在地球的高空默默聚集
They were silently congregating high above the Earth,
而且不安好心
and they were up to no good.
莫利纳和罗兰骇然发现
Molina and Rowland were alarmed to discover that the
遮蔽太阳紫外线让我们免受辐射伤害的保护层
CFCs had thinned the protective layer that shielded
被氯氟烃破坏
us from the Sun's harmful ultraviolet radiation.
而且情况不断恶化
And it was getting worse all the time.
当氯氟烃的分子被紫外线照射时
When UV light hits a CFC molecule,
会分解出氯原子
it strips away the chlorine atoms.
释放的氯原子开始吞噬
Once that happens, the chlorine atoms start devouring
宝贵的臭氧分子
the precious ozone molecules.
地球在25亿年前
It wasn't until our planet developed an ozone layer,
发展出臭氧层后
about two and a half billion years ago,
生物才能安全离开海洋登上陆地
that it was safe for life to leave the ocean for the land.
一个氯原子会破坏10万个臭氧分子
A single chlorine atom can destroy 100,000 ozone molecules.
氯氟烃无所不在
CFCs were in everything.
厂商没有氯氟烃就无以为继
And the manufacturers couldn't imagine a world without it.
企业对这些危险的回应是
The corporate response to this danger was that the
相关科学尚未确立
science hadn't been settled.
大家很难相信我们这个物种
People had a hard time believing that we had become
已经有足够力量灭绝地球生物
powerful enough as a species to endanger life on the planet.
他们为天空臭氧层的流失
They looked for non-human causes for the loss of the
寻找非人为因素
ozone in the sky.
里根政♥府♥的一名官员建议大家
One Reagan administration official suggested that
涂抹更多的防晒霜戴上帽子和太阳眼镜
everyone just wear more sunblock and put on a hat and sunglasses.
但科学家指出浮游生物
But the scientists pointed out that the plankton,
也就是位于全球食物链底层的小植物
those tiny plants at the base of the global food chain,
以及比较大的植物不可能破坏臭氧层
and the larger plants, were unlikely to do so.
莫利纳和罗兰继续不断警告世人
Molina and Rowland tirelessly worked to warn the world.
罗兰：如果最后我们只是袖手旁观
ROWLAND: What's the use of having developed a science
静待预言成真
well enough to make predictions,
那为什么要发展能够预测未来的科学呢？
if in the end, all we're willing to do is stand around and wait for them to come true?
罗兰和卡珊德拉原本只能苦苦相劝
Rowland and Cassandra would've had a lot to talk about.
但后来奇迹出现
But then something amazing happened.
全球发出呼吁
There was a global outcry.
世界各地的人纷纷参与
People all over the world got involved.
1960年代全球妇女要求终止大气核试验
In the 1960s, the women of the world demanded an end to atmospheric nuclear testing
因为她们不想
because they didn't want to
喂宝宝喝毒乳汁
nurse their babies with poisoned milk.
到了80年代消费者要求企业停止制♥造♥氯氟烃
Then, in the '80s, consumers demanded that the corporations stop manufacturing CFCs.
你知道吗小家伙？
And you know what, little one?
政♥府♥居然听进去了
The governments listened.
197个国家禁止使用氯氟烃
CFCs were banned in 197 countries.
差不多囊括全球所有国家
That's just about as many countries as there are on this planet.
所以你可以少担心
And that's why this is one danger you can cross
一个危险
off your worry list.
后来臭氧层越来越厚
The ozone layer has been getting thicker ever since.
但如果不是这样呢
But what would've happened if Rowland and Molina
如果罗兰和莫利纳不曾对平流层好奇
hadn't been curious about the stratosphere,
或他们的警告和卡珊达拉一样被忽略？
or if their warnings had been ignored as Cassandra's were?
到你四十岁生日那天
By the time of your 40th birthday,
地球上的臭氧层几乎
the ozone would have been all but gone from
消失殆尽
the entire planet.
你永远别想带你的小孩
You would never have been able to take your own little ones
出去晒太阳
out to bask in the sunshine.
粮食农作物大歉收
The food crops would have completely failed.
靠农作物为生的草食动物灭绝
The herbivores, those who live off them, would have died out.
肉食动物能靠它们的尸体活一段时间
The carnivores would subsist on their corpses for a while,