了解宇宙是如何运行的（2010）

How the Universe Works S10E02

Part 4 Aug. 5, 2022, 5:04 p.m.

The spacecraft for the Artemis
moon landing mission
将被包装成最佳的宇宙射线保护
will be packed for optimum
cosmic ray protection.
克里斯汀:所以有一种可以绕过质量限制的一种方法
CHRISTIAN: So one of the ways
you can get around
就是让所有的东西都
the mass limit is
to basically get dual use
有双重用途——你的补给
out of everything --
Your supplies,
你的燃料，你的水，你可以把它们用作防护
your fuel, your water, and you
can use those as shielding.
但事情没那么简单
But it's not that simple.
就像更强的子弹能穿透盔甲一样
Just as more powerful bullets
penetrate armor,
更强的宇宙射线也能穿透宇宙飞船的
more energetic cosmic rays
pierce the shielding
防护罩
on spaceships.
至于太阳射线——没错，你可以用一些材料
The solar ones --
Yeah, you can just put up some
一些屏蔽物，它通常会挡住它们
material, some shielding, and
it'll generally block them.
但更高能量的射线，它们可以
But the higher energy ones,
they can just burrow
钻过去
on through.
如果它们击中了保护宇航员的
If they hit one of the atoms
in the shielding that is
屏蔽层中的一个原子
protecting our astronauts,
就会产生大量粒子
it can create
a shower of particles.
达特纳尔:一个辐射粒子可能
DARTNELL: That radiation
particle might have missed
不会击中你体内的任何细胞
any of the cells in your body.
但现在当你把它变成了一场爆♥炸♥
But you've now turned it into
它会粉碎飞船里的一切
a blast, shredding through
everything in the spacecraft.
所以你的屏蔽就变成了
And so it turns out
your shielding becomes
宇宙射线用来对付你的武器
the weapon that the cosmic
rays use against you.
但 NASA 正在招募一个意想不到的盟友——太阳
But NASA is recruiting
an unexpected ally -- the sun.
我们能通过以毒攻毒来保护宇航员吗？
Can we protect our astronauts
by fighting fire with fire?
强大的宇宙射线穿透宇宙飞船
Powerful cosmic rays
smash through spaceships.
但是，比原子还小的物体如何携带足够的能量
But how can objects smaller
than an atom carry enough
对宇航员构成威胁呢？
energy to be
dangerous to astronauts?
移♥动♥的物体都携带能量
Moving objects carry energy.
我们称这为动能，当它们
We call this kinetic energy,
and when
撞击物体时，它们会转换能量
they strike something,
they transform that energy.
当我拍击我的手，我拳头的动能
When I hit my hand,
the kinetic energy of
转换成声音，热和振动
my fist transforms into sound
and heat and vibration.
我的手有点疼
My hand hurts a little from
因为那次拍击，因为能量的转换
that impact, from
the transformation of energy.
宇宙射线也是如此
It's the same thing
with cosmic rays.
当它们撞击人类的脑细胞或电脑芯片时
When they slam into a human
brain cell or a computer chip,
会释放一些能量，并造成损害
they dump some energy,
causing damage.
伤害的大小取决于它们的动能
How much damage depends on
their kinetic energy,
也取决于两件事
and that comes down
to two things --
质量和速度
Mass and speed.
直觉上，以相同速度运动的物体
Intuitively, things that are
moving at the same speed,
如果它们质量更大，就会携带更多的能量
if they're more massive,
they carry more energy.
一个更大的小行星撞击地球会比一个较小的小行星
A bigger asteroid slamming
into Earth will
造成更大的破坏
do more damage than
a smaller asteroid.
如果你把一个物体的质量翻倍
If you double
the mass of an object,
它的动能也翻倍
its kinetic energy also doubles.
虽然质量很重要
Although mass is important,
但它不如速度重要
it's not as important as speed.
奥卢西伊:速度比质量更重要
OLUSEYI: Speed matters
even more than mass.
动能的确直接取决于质量
The kinetic energy depends
directly on the mass,
但它更取决于速度的平方
but it depends on
the square of the speed.
这个意思就是，质量翻倍
Here's what that means --
You double the mass,
动能翻倍，速度翻倍
you have double the kinetic
energy, you double the speed,
动能就翻四倍
you have four times
the kinetic energy.
说到速度，宇宙射线是最重量级别的
When it comes to speed,
cosmic rays are the elite.
1991年探测到的一束
An ultra-high-energy cosmic ray
超高能宇宙射线以极快的速度
detected in 1991 hit
the atmosphere so fast,
撞击了大气层，科学家称其为“天哪粒子”
scientists called it the
"Oh My God Particle."
这个粒子的能量
This particle was higher
energy than they thought
比他们想象的要高得多
they would ever, ever see.
在犹他州的天空出现这条荧光条纹之前
Until this fluorescent
streak in the Utah sky,
没有人相信一个粒子能够以如此接近光速的速度
no one believed a particle
could reach the Earth traveling
到达地球，这使得
so close to the speed of light,
宇宙射线粒子比预期的
making cosmic ray particles
far more dangerous
要危险得多
than expected.
当你接近光速时
As you approach
the speed of light,
能量，动量，质量
energy, momentum, mass,
they start
就会呈现出与以往不同的作用
to act a little bit differently.
普莱特:爱因斯坦的相对论方程变得非常重要
PLAIT: Einstein's equations of
relativity become important,
因为物理发生了变化，它产生的能量
because the physics changes,
and the energy it has
变得非常非常强
becomes much, much,
much stronger.
奥卢塞伊:如果一个粒子以接近光速运动
OLUSEYI: If a particle is moving
at close to the speed of light,
这意味着它的能量几乎达到了
that means that its energy is
almost at the maximum allowed
物理定律允许的最大值
by the laws of physics.
塞勒:想到像质子这么小的东西
THALLER: It's amazing to think
that something as tiny as
竟然会对人类造成危险，真是令人惊讶
a proton could actually be
dangerous to a human being.
但最令人惊讶的是，质子的运动速度如此之快
But amazingly, that proton is
moving so fast,
它所携带的能量相当于一个以每小时100英里的速度
it carries as much energy
as a baseball
抛出的棒球所携带的能量
thrown at 100 miles an hour.
一个棒球含有超过一万亿的质子
A baseball contains over
a trillion, trillion protons.
想象一下一个粒子携带的所有能量
Imagine all that energy
carried by just one particle.
现在你知道这些有多危险了
So now you get a sense of just
how risky these can be.
像“天哪粒子”
Ultra-high-energy
cosmic rays like
这样的超高能量宇宙射线就像超音速导弹
the Oh My God Particle are
like supersonic missiles.
它们是速度最快的，但它们非常罕见
They are the fastest,
but they're so rare,
宇航员不太可能被它们击中
astronauts are unlikely
to be hit by one.
太阳宇宙射线就像BB球一样——数量丰富
Solar cosmic rays are like
BB pellets -- abundant,
但我们的宇宙飞船可以阻挡它们
but our spacecraft can
block them.
然而，对我们的宇航员来说
The biggest threat to
our astronauts,
最大的威胁是银河宇宙射线
however, are galactic
cosmic rays.
它们来自银河系的其他地方
They come from elsewhere
in the Milky Way.
它们的速度和频率
The combination of their speed
使它们成为最危险的射线
and frequency makes them