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This episode is sponsored by The Ridge.
本期节目由The Ridge赞助。
Go to ridge.com/SciShow and use promo code “scishow” to get 10% off your next order.
登录ridge.com/SciShow，使用“scishow”优惠码，下次订购可以享受10%的优惠。
Lasers are an incredible human invention.
激光是人类不可思议的发明。
They’re basically a way to hack light and turn it into this narrow beam that can do things like cut through metal and also perform super-precise surgery on people’s eyeballs.
激光基本上是一种获取光线并将其转变成这种窄光束的方法，这种光束可以切割金属，也可以在人们的眼球上进行超精确的手术。
But even though we came up with the idea on our own, humans didn’t actually make the first lasers.
但即便是我们提出了这个想法，但实际上并不是人类制造出的第一束激光。
Soon after these tools were invented in the 1950s and ’60s, scientists discovered natural lasers beaming through space.
20世纪50年代和60年代，这些工具发明后不久，科学家们就发现了穿越太空的天然激光。
They’re actually pretty common, and they’ve let us explore space in ways that wouldn’t otherwise be possible.
它们实际上很常见，激光能让我们以其他方式无法实现的方式探索太空。
Like many stories in physics, this one starts with Einstein, who came up with a theory back in 1917 called the quantum theory of radiation.
和物理学中的许多故事一样，这个故事始于爱因斯坦，他在1917年提出了辐射的量子理论。
In it, he predicted that it was possible to make certain waves of light line up and travel in sync, creating a very narrow, powerful beam.
在这篇论文中，他预测有可能让特定的光波排成一列并同步传播，从而产生一束非常狭窄而强大的光束。
A few decades later, in the 1950s, scientists started bringing his prediction to life in the lab.
几十年后，在20世纪50年代，科学家们开始在实验室中将他的预言付诸实践。
They’d start with a specific material, like a cloud of gas or a ruby.
他们会从一种特定的物质开始，比如气体云或红宝石。
Left alone, the electrons in these materials would mostly hang out in their lowest energy level.
如果不加以干扰，这些材料中的电子通常会以最低的能量停留在那里。
But atoms, and this is a very basic version of this, have different levels separated by fixed amounts of energy.
但是原子，这是一个非常基础的版本，有不同的能级，被固定的能量分开。
And if you shine a light into them with just the right frequency, they can absorb this energy, and their electrons will bump up to a higher energy level.
如果用合适的频率照射它们，它们就能吸收这些能量，电子也会上升到更高的能级。
So when scientists did this in the lab, they ended up with materials whose electrons were all in this excited state, except they were really unstable up there.
所以当科学家们在实验室里这么做的时候，最终得到的材料的电子都处于激发状态，只不过这些电子极不稳定。
If another photon of light came along with the right energy, it could easily bump an excited electron back down to its original energy level.
如果另一个光子带着合适的能量而来，它可以轻松将一个激发状态的电子撞回到原来的能级。
That set off a chain reaction where the excited electrons dropped back down all at once.
这引发了一个连锁反应，被激发的电子迅速降级。
And as they did, they would each release a packet of energy as light.
在此过程中，它们会以光的形式释放出一束能量。
Scientists called their new invention a laser, which stands for light amplification by stimulated emission of radiation.
科学家们称这个新发明为“激光”，意即通过辐射受激发射进行光放大。
“Stimulated emission” because you have to pump energy into a material to make it emit this light.
"受激发射"是因为你必须把能量注入到一种物质中让它发出这种光。
And it’s “amplified” because all of those waves of light that get released have the exact same amount of energy, and they travel perfectly in sync, with all their peaks and troughs lined up.
它之所以被“放大”，是因为所有这些被释放的光波具有完全相同的能量，而且它们完全同步地传播，所有的波峰波谷都排成一列。
Unlike light from a flashlight or the Sun, which is made of all different wavelengths that are not lined up at all, this light is extremely focused, and incredibly bright.
不像手电筒或太阳的光，它们是由各种不同的波长组成的，完全没有排列，这种光是非常集中的，而且非常明亮。
Lasers were a big hit, and the inventor, Charles Townes, won a Nobel Prize for his work.
激光获得了巨大成功，发明家查尔斯·汤斯因此获得了诺贝尔奖。
But soon after lasers were invented, astronomers discovered that they were not as new a thing as everyone thought.
但在激光被发明后不久，天文学家发现它们并不像人们想象的那么新鲜。
In 1963, researchers at U.C. Berkeley were studying light coming from the Orion Nebula, a bright, star-forming region in the Milky Way.
1963年，加州大学伯克利分校的研究人员正在研究猎户座星云发出的光，猎户座星云是银河系中一个明亮的恒星形成的区域。
They were trying to detect radio waves emitted by hydroxyl groups, molecules where oxygen is bonded to hydrogen, but the signal they picked up was way stronger than they expected.
他们试图探测氢氧分子羟基发出的无线电波，但他们接收到的信号比预期的要强烈得多。
Like, it implied that the gas was several thousand trillion degrees Celsius, which is way hotter than even stars.
比如，它暗示了气体有几千万亿摄氏度，甚至比恒星的温度高得多。
This result was so mind-boggling, they thought that they might be looking at a molecule they didn’t even know about, and they called it mysterium.
这个结果令人难以置信，他们以为自己看到的可能是一种还不了解的分子，他们称之为神秘分子。
Eventually, though, they confirmed that they had been looking at hydroxyl molecules all along, but the hydroxyl wasn’t emitting regular radio waves, it was emitting laser light.
不过，最终，他们确认了一直在观察羟基分子，但羟基发射的并不是有规律的无线电波，而是激光。
What they figured out was that clouds of hydroxyl molecules were getting pumped up by radiation from the gas, so their electrons were all excited into a higher energy level.
他们发现，在气体辐射的作用下，大量的羟基分子被激发出来，所以它们的电子都被激发到更高的能级。
As electrons fell back down to a lower energy level in a chain reaction, they were emitting synchronized waves of light.
在连锁反应中，当电子回落到较低的能量水平时，它们就会发出同步的光波。
And that was why the signal they were detecting was so bright, not because it was some strange, unidentified mysterium, and not because it was trillions of degrees Celsius.
这就是他们探测到的信号如此明亮的原因，不是因为它是某种奇怪的、未知的神秘，也不是因为它有数万亿摄氏度。
Now, people had predicted that it would be possible for natural processes to create lasers, even before it had been done in the lab, but no one was really looking because they thought natural lasers would be really rare.
人们已经预测过可以用自然的方法制造激光，甚至比实验室里的实验还要早，但是没有人真正关注，因为他们认为自然的激光非常罕见。
Turns out, though, they are not at all.
然而，事实证明，根本不是这样的。
Since the ’60s, lasers have been found all over the universe, in places like clouds of gas, red giant stars, even in the atmospheres of Mars and Venus.
自60年代以来，激光在宇宙各处被发现，在气体云、红巨星，甚至在火星和金星的大气层中都有。
These lasers aren’t the narrow beams of light that shoot out of a laser pointer or a barcode scanner, in fact, they can be light-years wide, but the phenomenon making that light works exactly like our laser technology.
这些激光不是从激光笔或条形码扫描器中射出的窄窄的光束，事实上，它们可以有好几光年宽，但让这些光工作的现象跟我们的激光技术完全一样。
It starts with a population of atoms or molecules with electrons in an excited state, which you can get from chemical reactions or collisions between particles, or when particles absorb specific frequencies of light.
它开始于一群处于激发态的带有电子的原子或分子，通过化学反应或粒子之间的碰撞，或者当粒子吸收特定频率的光时可以达到这种状态。
In nature, as electrons drop out of that excited state, the light that gets released is often at microwave frequencies, so it’s invisible to our eyes, but some lasers are visible, too.
在自然界中，当电子脱离激发态时，释放的光通常是以微波频率的，所以我们的眼睛是看不见的，但有些激光是可见的。
And now that we know they’re out there, they can all help us explore the universe.
既然我们知道了激光的存在，就可以用它帮助我们探索宇宙。
Like, the fact that lasers are so bright and focused means that we can detect them really deep into space, where we wouldn’t normally expect to detect things like gas emissions, which are usually pretty faint.
比如，激光的明亮和聚焦意味着我们可以在太空深处探测到它们，那里通常不会探测到微弱的气体排放之类的现象。
For instance, in regions where stars are being born, water vapor and methanol often emit laser light, which can help us see what’s going on in star-forming regions before that gas ignites into stars.
例如，在恒星诞生的区域，水蒸气和甲醇经常会发射激光，这可以帮助我们了解在气体燃烧成恒星之前，恒星形成区域发生了什么。
Researchers have even proposed that, under the right conditions, we could detect laser light from water in the atmospheres of exoplanets, which could help us figure out what environments might be suitable for life.
研究人员甚至提出，在合适的条件下，我们可以探测到系外行星大气层中的水发出的激光，这可以帮助我们弄清什么环境可能适合生命存活。
It turns out that as useful as modern lasers are, the old-school lasers that have always been out there still have a lot to show us.
事实证明，尽管现代激光很有用，但一直存在的老式激光仍然可以告诉我们很多信息。
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要集中精力不是一件易事，但如果你一直想让自己的生活更流畅，The Ridge可以帮你做到这一点。
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The Ridge钱包可以简化你携带的物品，帮助你减少杂乱。
It’s light, sleek, and made of two metal plates bound by an elastic band.
它轻便、光滑，由两块用松紧带绑起来的金属板制成。
And it can carry up to 12 cards and has room for cash.
它最多可以携带12张卡，还有空间放现金。
Each wallet is made with durable materials and has a lifetime warranty, and if it’s not for you, returns are free.
每个钱包都是由耐用材料制成，并且有终身保修，如果你不喜欢，可以免费退货。
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您可以登录ridge.com/SCISHOW并使用优惠码“SCISHOW”或点击描述中的链接，今天就可以享受10%的优惠，并且全球免费送货。
