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In the Industrial Revolution, it was a great discovery that the use of interchangeable parts was a powerful principle that would allow you to do mass production, to make things efficiently.
在工业革命中，一个伟大的发现是，使用可互换零件是一种强大的原则，它让你可以大规模生产，高效地制造东西。
And people worked hard to make precise machinery so that you could have these reproducible parts.
人们努力制造精密的机器，这样就能造出可复制的零件。
Nature has been using that principle, however, for billions of years with great artistry to create the world around us.
然而，数十亿年来，大自然一直在以极高的艺术性使用这一原则来创造我们这个世界。
People sometimes ask, "What does it all mean?"
人们有时会问：“这意味着什么？”
That's a very hard question to address because it's not clear what an answer would look like.
这是一个很难回答的问题，因为我们并不知道答案是什么。
The question that I found much more fruitful is: "Does the world embody beautiful ideas?"
我觉得一个更能见效的问题是：“这个世界呈现了美好的思想吗？”
"What is the world and what is beauty?"
“世界是什么，美是什么？”
What is beauty, is something that art and philosophy and human culture addresses.
美是什么，它是艺术、哲学和人类文化要解决的问题。
What is the world, of course, is the kind of question that science addresses.
当然，世界是什么，是科学要解决的问题。
We've gotten this extraordinary grip on the fundamental laws.
我们已经非常精通这个世界的基本法则。
They're very strange, but they have a kind of internal logic and beauty.
它们很奇怪，但它们有一种内在的逻辑和美。
Some of the things that people at the beginning of this adventure were hoping for, and had in their visions, was the idea that the world embodies harmonies.
在这场冒险之旅开始时，人们希望并在他们的愿景中看到的一些事情是，世界体现了和谐。
They were hoping that our sense of harmony somehow agreed with what nature likes to use in her construction of the world the idea that symmetry and mathematical perfection provide the building principles that the world embodies.
他们希望我们的和谐感在某种程度上符合大自然在构建世界时所习惯的东西--对称和完美的数学提供了世界所体现的构建原则。
Einstein was a great hero of mine, and he's played an important role in my life.
爱因斯坦是我心目中的大英雄，他在我的生活中扮演了重要的角色。
He advanced the idea that symmetry is what's very basic to the operation of fundamental law.
他提出了这个观点：对称性是基本定律运作的基础。
Consider a circle: A circle is a very symmetric object.
以圆为例：圆是一个非常对称的物体。
You can rotate it around its center by any angle and, although every point on the circle may move, the circle as a whole doesn't change.
你可以把圆绕中心旋转任何角度，虽然圆上的每个点都会移动，但圆作为一个整体不会改变。
And that's what makes it symmetric in the intuitive sense.
所以它给人的感觉就是对称的。
You can change it, you can make changes on it, which might've changed it, but although they transform each part of it, don't transform the thing as a whole.
你可以改变它，你对它的改变可能会改变它，但尽管它们改变了圆的每一个部分，却不会改变这个整体。
The great advantage of that definition is that you can apply it in very broad contexts, not only to describing the symmetry of objects, but to describing the symmetry of physical laws or the symmetry of equations.
这个定义的最大优点是，你可以在非常广泛的背景下应用它，不仅能用它描述物体的对称性，还可以描述物理定律的对称性或方程的对称性。
The idea that the laws of physics don't change as a function of time is also a symmetry.
物理定律不会随着时间的变化而改变的观点也是一种对称。
Symmetry is a very powerful constraint on our description of the world that nature seems to respect in many ways.
对称是我们对世界描述的强大限制，这些描述在很多方面都受到大自然的尊重。
The kind of symmetry that leads to quantum chromodynamics or general relativity or quantum electrodynamics is mathematically considerably more complex, but it's the same idea.
导致量子色动力学或广义相对论或量子电动力学的对称性在数学上要复杂得多，但它们的概念是相同的。
There are transformations of the equations that change the different terms in them.
只不过是方程进行了变换，改变了其中的不同项。
So they might change an electric field into a magnetic field or a magnetic field into a combination of electric and magnetic that change the way the equations look, but don't change their consequences.
他们可能会将电场变为磁场，或者将磁场变为电和磁的组合--这会改变方程的外观，但不会改变它们的结果。
That's the kind of equations that are like the circles among equations; are ones that have this symmetry property.
这类方程就像方程中的圆；就是那种具有对称性的方程。
