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The universe as a whole evolves towards increasing entropy, or disorder --
整个宇宙的熵或混乱程度一直在增加，
a tendency physicists call the Second Law of Thermodynamics.
这种趋势被科学家称为热力学第二定律。
This movement toward disorganization might lead you to think that organized structures
这种混乱无序的趋势可能会让你认为有组织的结构
– like, say, living beings – would never spontaneously come into existence.
如生命——无法自行存在。
Of course entropy can go down in part of the universe -- you can trade a decrease in entropy in one place
当然，在宇宙的某个部分，熵可能在减少——你可以一个地方熵下降
(like cooling water so it crystallizes into ice) for an equal or larger increase in entropy somewhere else
（就像冷却水一样，它会结晶成冰）来换取其他地方相同或更多的熵增加
(like heating the back of your fridge). Order increases here, but only at the cost of decreasing order there.
（例如从冰箱后面放出热能）。这里的秩序增加，只会换来那里的混乱。
But we can still ask: why do intricate, complex structures come into being in the universe,
但是我们还是要问：如果宇宙的总体趋势越来越无序，
if the overall tendency is toward increasing disorder?
那么为什么宇宙中会出现错综复杂的结构呢？
The secret is that order and complexity are very different ideas.
秘密在于秩序和复杂性是非常不同的概念。
Entropy measures how many different ways you can make an arrangement of small-scale particles
熵衡量的是有多少种不同的方式可以将具有相同大尺度特性的小尺度粒子排列起来
that have the same large-scale properties: like, 37 degrees celsius, brown hair, good at soccer, and so on.
比如：37摄氏度、棕色头发、擅长踢足球等等。
There are lots of different ways!
方法有非常多！
Complexity, on the other hand, is a measure of how hard it is to describe a set of large-scale properties.
另一方面，复杂性衡量的是描述一组大规模属性的难度。
Simple systems are easy to describe; complex systems require a lot more information.
简单的系统易于描述；复杂的系统需要更多的信息。
For example, take a cup filled with half coffee and half milk.
例如，喝一杯半咖啡半牛奶的咖啡。
It starts off in a state with relatively low entropy – you could swap coffee molecules with each other,
它以一种相对低熵的状态开始——你可以随意互换咖啡分子
or milk molecules with each other, without changing things substantially.
或牛奶分子，而不会改变其根本性质。
But if you swapped coffee molecules with milk molecules that would be a noticeable change.
但如果你把咖啡分子和牛奶分子对调，这就有明显差别了。
It's also a simple setup -- milk on top, coffee on the bottom.
这也是简单状态——牛奶在上，咖啡在底部。
Now, as the milk and coffee begin to mix, entropy goes up – where they are mixed together,
现在，当牛奶和咖啡开始混合时，熵增加——此时它们混合在一起，
swapping some coffee molecules for milk molecules no longer makes much of a difference.
用牛奶分子交换一些咖啡分子也不再有什么区别。
But the system also becomes more complex - to describe what you see,
但这个系统也变得更加复杂——要描述这种画面，
you would have to specify exactly how all of those tendrils of milk and coffee intricately swirl into each other.
你必须精确地描述出，牛奶和咖啡是如何错综复杂地交织在一起的。
Continuing on, entropy keeps going up, until the milk and coffee are completely mixed together
继续下去，熵一直在增加，直到牛奶和咖啡完全混合在一起，
and swapping any molecules of coffee and milk with any others doesn't really make any difference at all.
和其他任何分子交换咖啡和牛奶实际上没有任何区别。
That's equilibrium, where there are a huge number of arrangements of the molecules that look essentially the same.
这就是平衡状态，分子有大量的排列方式看起来都是一样的。
But this highly-mixed equilibrium is once again simple: it's just a homogenous mixture of coffee and milk;
但这种高度混合的平衡也很简单：它只是咖啡和牛奶的同质混合物；
no more complicated fractal swirly stuff.
没有更复杂的分形螺旋状的东西。
This general principle is borne out time and time again: while entropy increases, complexity initially grows, then decays.
这个普遍的原理被一次又一次地证明：当熵增加时，复杂性开始增长，然后衰减。
Complexity can be a natural step along the path to increasing entropy. The best example is the universe itself.
复杂性是增加熵的自然步骤。最好的例子就是宇宙本身。
The early universe was very smooth and very dense: that's low-entropy, and also extremely simple.
早期的宇宙非常平滑，密度非常大：也就是低熵，而且复杂性低。
The far future will be smooth again, but very dilute: that's high-entropy, and again extremely simple.
遥远的未来将再次变得平滑，但会非常稀薄：那就是高熵，而且复杂性低。
It's now, in the medium-entropy middle, that things look complex.
现在，熵介于中间，而事物看起来很复杂。
Stars and galaxies and veins of minerals in rock and swirling clouds and amino acids and proteins and human beings and cats –
恒星、星系、岩石中的矿脉、漩涡云、氨基酸、蛋白质、人类和猫
we're at the exciting, beautiful stage of the coffee mixing!
我们正处于刺激而美丽的咖啡混合时代！
But just as with the coffee and milk, in the far distant future complexity will decrease again,
但就像咖啡和牛奶一样，在遥远的未来，复杂性将再次降低，
and complicated stuff like us will at last be simplified out of existence.
像我们这样复杂的东西最终将被简化而不复存在。
Hey, Henry here, thanks for watching.
感谢大家收看。
This is the third video in a series about time and entropy made in collaboration with physicist Sean Carroll.
本期视频是我们与物理学家Sean Carroll合作的时间与熵系列的第三集。
The series is supported with funding from Google's Making and Science initiative,
本系列由Google的Making and Science计划支持播出，
which seeks to encourage more young people (and people of all ages) to learn about
该计划旨在鼓励更多年轻人及各年龄人群学习
and fall in love with science and the world around them,
并爱上科学以及世界，
and the videos are based off of Sean's book "The Big Picture: On the Origins of Life, Meaning, and the Universe Itself,"
本书根据Sean的《The Big Picture: On the Origins of Life, Meaning, and the Universe Itself》改编，
which you can find online or in bookstores around the world.
大家可以在线上或线下观看。
