你觉得你能用光做一个黑洞吗？
Do you think you could you make a black hole out of light?
这可能听起来像个诡异的问题或者浴室狂想
That might sound like a trick question, or like something straight out of the “showerthoughts”
之类的
subreddit.
但是物理学家认为用光制造一个黑洞是有可能的
But physicists say that it should be possible to create a black hole out of nothing but
这种黑洞被称为光黑洞 在德语中的意思是球形闪电
light — called a kugelblitz, after the German word for “ball lightning.”
但是他们也不确定如果你真的试着去做会发生什么
Even though they have no idea what would actually happen if you tried to do it.
在此之前我们先来说说标准的黑洞
Before we talk about that though, let’s talk about the more standard black holes.
一般来说 当大量物质压缩在很小的空间内
Usually, a black hole forms when a lot of matter is packed into very little space, which
加大了自身密度就会形成黑洞
increases its density.
当物质密度达到一定程度 其表面引力会强到
If the matter is dense enough, the gravity at its surface becomes so strong that nothing,
就连光线都不能逃脱
not even light, can escape its clutches.
如果要将地球变成黑洞 你需要将地球上6万亿兆
So to make the Earth into a black hole, you would have to compress its 6 trillion trillion
千克的石头 水以及金属压缩成直径16毫米的球体
kilograms of rock and water and metal down into a sphere with a diameter of just 16 millimeters.
这得多大密度啊
That’s how dense I’m talking about.
但是现在我们只是刚刚开始
But we’re just getting started here.
爱因斯坦教会我们质能方程E=mc∧2
Einstein taught us that E=mc^2.
换句话说 物质中蕴含的能量相当于
In other words, that the energy stored in a bit of matter is equal to its mass times
其质量乘以光速的平方
the speed of light squared.
这就意味着在很小的的物质中也存在巨大的能量 就像原子能
This means that there are huge amounts of energy in tiny bits of matter, like atoms
核能以及核武器就建立在原子能的基础上
— which is the basic idea behind nuclear power and nuclear weapons.
这就说明能量有时候跟物质有相同的表现
It also means that energy can sometimes act like matter.
光虽然没有质量 但是它有能量
Now, light doesn’t have any mass, but it does have energy.
根据质能方程 引力不能区分能量与质量
And, thanks to E=mc^2, gravity can’t tell the difference between energy and matter — and
可以同时作用于两者
pulls on them both.
然后这就引出了一个有趣的可能性
And this raises an interesting possibility.
制造黑洞只需要将大量物质挤压到一起
All it takes to make a black hole is to pack a bunch of matter in one place, and gravity
而引力对光跟物质一视同仁
treats light just like it treats matter.
所以理论上可以利用光制造光的黑洞
So you could theoretically make a black hole out of nothing but light — a kugelblitz.
然而制造一个光的黑洞需要非常非常多的光
Creating a kugelblitz would take a really, really incredible amount of light, though
我们来逆推爱因斯坦的质能方程
— because now we’re working with Einstein’s famous equation in the opposite direction.
首先 我们有一小块物质可以制造大量能量
Before, we had a tiny amount of matter producing a huge amount of energy.
现在 我们需要用光提供大量能量
Now, we have to supply a ton of energy — in the form of light — for it to act like tiny
让它表现出一点物质的形态
bits of matter.
然后话题回到设想中用地球制造的黑洞
So let’s go back to that hypothetical black hole with the mass of the Earth.
如果我们想要用光制造一个一样的黑洞 我们需要
If we wanted to make that same black hole out of light, how much light would would we
多少光？
need?
地球上所有的光？
All of the lights on Earth?
一天内地球受到的太阳光？
All of the sunlight that hits the Earth in a day?
一年内？
In a year?
那么太阳一年内释放的所有太阳光呢？
What about all of the sunlight put out by the Sun over the course of an entire year?
差的远呢
Not even close.
为了制造类似地球黑洞的光黑洞 我们需要10年内
To get an Earth-mass kugelblitz, we would need all of the light put out over 10 years
距离地球350光年范围内所有恒星释放的光线 并将它们压缩成
by all of the stars within 350 light-years of Earth – all squished into a bit of space
蚊子大小
the size of a mosquito.
好吧 这是很多光
Okay, that’s a lot of light.
但是如果我们想要制造一个小很多的黑洞呢？
But what if we wanted to make a black hole that was way, way smaller?
我不知道 一艘泰坦尼克号一样的大游轮 大概50
Like, I don’t know… the mass of a big cruise ship, like the Titanic … about 50
万千克？
million kilograms?
为了制造这样的小黑洞 你需要将过去一年照射到
To make a kugelblitz that small, you’d need to squeeze all of the sunlight that hit Earth
地球上的光线体积压缩到比质子还小8000倍
last year into a volume 8,000 times smaller than a proton.
将这么多光塞到一个地方真是难以想象
It’s hard to even imagine how so much light could get shoved into one place — or any
在可以预见的未来科技也难以完成很小的一部分
sort of technology that could accomplish even a fraction of that in the foreseeable future.
然而哪怕这件事情实现了 这里又有另外一个问题
But even if it could happen, there’s another problem:
制造一个光黑洞需要将如此多的光能放到如此小的空间
Making a kugelblitz means that you have to pump so much light-energy into such a tiny
它的温度会变得非常高 毕竟热量就是一团能量
region of space that it would get really hot, since heat is just a form of energy.
我们说的是宇宙大爆炸之后
We are taking, hotter than the universe was a hundredth of a millionth of a trillionth of a trillionth
第一亿兆兆兆分之一秒时的温度
of a trillionth of a second after the Big Bang.
在这种极端温度下 我们了解的物理可说是不再适用
And at that extreme temperature, physics as we know it just sort of stops working: space
空间液化 引力没有意义 我们不能描述任何事情
turns soupy, gravity is nonsense, and we have no idea how to describe anything.
所以当太空变得这么热 引力可能乱套以至于
So if space gets that hot, gravity might go haywire and not be able to form black holes
不再能形成黑洞
at all any more.
或者引力可能变得更强 形成黑洞只需要
Or maybe gravity would get super strong and form a black hole with a million times less
我们认为所需要能量的无数分之一倍
energy than we think it should take right now.
我们只是不知道 我们可能永远都不会知道
We just don’t know, we might never know.
现在 根据爱因斯坦的质能方程
For now, it seems like kugelblitzes might be theoretically possible, based on Einstein’s
好像理论上光黑洞能够存在
basic equations relating energy and mass.
这是个很酷的主意 用大量高压中的光制造一个
It’s a cool idea: using lots of highly focused light to create a black hole, something that
连光都不能脱离的黑洞
even light can’t escape from.
但是我们不知道我们或者宇宙如何制造一个光黑洞
But we have no idea how we — or the universe — would make one, or even if there’s some
或者是否会有一些未发现的自然规律禁止光黑洞存在
undiscovered law of nature that forbids it from existing.
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