今年的诺贝尔物理学奖意义深远 | 诺奖得主Wilczek专栏

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撰文 | Frank Wilczek (麻省理工学院教授、2004年诺贝尔奖得主）

翻译 | 胡风、梁丁当

获得今年诺贝尔物理学奖的研究解释了宇宙是如何从初期的均匀状态中，演化出我们今天所观察到的复杂性的。

Prize-winning research shows how the universe evolved from its uniform beginnings to the complexity we observe today. 

2019年的诺贝尔物理学奖颁给了詹姆斯·皮布尔斯 （James Peebles）、米歇尔·马约尔（Michel Mayor）和迪迪埃·奎洛兹（Didier Queloz）。其中，皮布尔斯因对宇宙物理理论的贡献独享一半奖金，而马约尔和奎洛兹因为发现了绕着类日恒星运动的太阳系外行星而共享另一半奖金。

Last week, the Nobel Prize in Physics went to James Peebles for theoretical contributions to physical cosmology, along with Michel Mayor and Didier Queloz for their work on exoplanets-distant planets that orbit stars other than our sun.

这些方向的研究从不同的角度帮助我们认识宇宙以及地球在宇宙中的位置。现代宇宙学表明，宇宙在诞生初期具有惊人的简单性和均匀性。系外行星的发现则揭示出了当前宇宙的复杂性与多样性。两者的对比引发出一个很大的疑问：宇宙的复杂性是如何从均匀性中产生的？ 

These lines of research both shed light on the universe and our position in it, but they do so from very different perspectives. Modern physical cosmology reveals that the universe started out amazingly simple and homogeneous, while the study of exoplanets reveals that at present it is complex and diverse. That contrast poses a big question: How did the complexity emerge?

在宇宙历史的初期，所有的物质都处于一种高温、致密、 近乎均匀的状态，并且迅速膨胀。这是标准宇宙大爆炸模型的核心思想。它能够解释许多天文观测结果，包括遥远星系远离我们的速度，以及不同化学元素的相对丰度。

Early in the history of the universe, all the matter in it was hot, dense and very nearly uniform. It was also rapidly expanding. Those ideas are the heart of the standard Big Bang model, which lets us account for many observations, including the fact that distant galaxies are moving away from us and the relative abundance of different chemical elements.

尤其值得一提的是，该模型预测宇宙中还残存着大爆炸的余晖--即充满了整个宇宙空间的微波背景辐射。所以不出意外，这个余晖被观测到了，为我们展示了早期宇宙的概貌。皮布尔斯先生将这些证据结合起来，构建出一个连贯的宇宙历史框架，阐明了它们是如何影响星系的大小、形状和分布的。

Notably, the model predicted the existence of a lingering Big Bang afterglow-the so-called microwave background radiation that fills all space. That afterglow was duly observed, providing a snapshot of the early universe. Mr. Peebles pulled those lines of evidence together into a coherent scenario of the history of the universe and spelled out its consequences for the size, shape and distribution of galaxies.

充盈着早期宇宙的炽热气体的分子运动与化学组成完全是随机的，非常接近物理学家们称之为“ 完全热平衡”的状态。一般来说，当系统达到了热平衡后，就会一直处于这个态：始终保持一种均匀单调的状态，不会衍生出任何结构乃至生命。

The early hot gas that filled the universe was completely random in its molecular motions and chemical mixing. It was, to a very good approximation, in the condition physicists call “complete thermal equilibrium.” Ordinarily, once systems reach complete thermal equilibrium they stay there. They remain uniform and featureless; they do not develop structure or “come to life.”

幸运的是，我们的宇宙逃脱了这种悲惨的命运。在万有引力对广袤时空的作用下，均匀态不再稳定，物质更加倾向于聚集在一起。于是，在引力的作用下，高度均匀的宇宙逐渐四分五裂开来，形成了巨大的类云状结构。

Our universe escaped that dismal fate primarily because gravity, acting over vast reaches of space and time, makes uniformity unstable. Gravity wants things to clump. Thus the material in the universe, at first highly uniform, fragmented under the influence of gravity into vast cloudlike structures.

刚开始，这些云还很稀薄飘渺。随着时间的推移，其中的物质在引力的持续影响下进一步发生凝聚。宇宙因而逐渐演化成今天的形态--在广袤、虚无的宇宙空间中零星散落着一个个星系，其中分布着恒星和行星。

At first the clouds were tenuous and wispy, but over time, under the continuing influence of gravity, their material condensed further. The matter in the universe gradually evolved into its present configuration: galaxies hosting stars and planets, all separated by yawning regions of nearly empty space.

构成行星的物质温度较低，密度较高。它们继续在一个新的层次上进行分化并衍生出更多的形式--形成复杂的化合物，甚至是形成智慧生命。由于行星相对较小，本身又不发光，我们很难从遥远的距离探测到它们的存在。马约尔先生和奎洛兹先生开创了系外行星探测技术的先河。从此以后，系外行星的探索不再只是科幻小说的情节。它迅速兴起为一个蓬勃发展的、由数据驱动的科技领域。

Planetary matter, cool and dense, then began to host another level of fragmentation and diversification: the emergence of complex chemistry, and even—in at least one case—intelligent life. Because planets are relatively small and emit no light of their own, it is very hard to detect them from far away. Mr. Mayor and Mr. Queloz pioneered the delicate technologies that have quickly taken exoplanetary astronomy from science fiction into a thriving, data-driven enterprise.

我们现在这个复杂宇宙大概就是这样形成的。人类已经建立了标准宇宙学来描述这一过程，虽然还有许多关键的细节尚待填补，但它的基本内容是很清晰并被广泛接受的，即从简单的初始状态按照简单的定律演化出丰富的复杂性，需要漫长的时间和大量的物质（也许不需要其他任何条件）。谢天谢地，我们的宇宙在这两方面都很丰富。 

This is a very broad-brush account of how the complex universe that we inhabit today could have emerged. Though many crucial details need filling in, the outlines are straightforward and widely accepted: The emergence of abundant complexity from simple beginnings and simple laws takes a long time and requires lots of matter (but maybe nothing else). Thankfully, our universe is blessed with plentiful supplies of both.

作者简介

Frank Wilczek：弗兰克·维尔切克是麻省理工学院物理学教授、量子色动力学的奠基人之一。因在夸克粒子理论（强作用）方面所取得的成就，他在2004年获得了诺贝尔物理学奖。

本文经授权转载自微信公众号「蔻享学术」。

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