上次说到现在，用大语言模型来翻译油管上的英文视频，可以获得和母语类似的沉浸式观看感受。而且大语言模型翻译的准确度和流畅度完全达到了人类的水平，比以前的翻译工具好到不知道哪里去了。最近又用这种办法，看了一部《真理元素》的科普视频。之前英文版也看过，但多少还是有一点一知半解。这次翻译之后再来看，理解变得更深，可以对借款关系有更好的理解。
视频的主题讲的是物理学中最被误解的概念——熵这个概念有多被误解。只要问一个简单的问题就知道：你去街上随便找几个受过基本教育的人，问我们人类和地球上的生物从太阳那里获得的是什么？百分之九十的人回答会是能量。然后你再追问，你知道我们地球大概利用了太阳照射的能量中的多少吗？可以猜一下。于是人们就会做出各种各样的答案，从百分之十到百分之五十，不等。
但真实的答案会让人惊掉下巴。实际上，能量总是守恒的。当然在宇宙的大尺度下是不守恒的，但在太阳系这个范围来说，还是守恒的。所以太阳传递给地球的能量和地球散发到太空中的能量，实际上是大致相等的。如果地球从太阳吸收的能量比散射到太空去的能量少的话，那地球就会成为一个大温室，将会越来越热。所以人类或者地球上的生物利用了太阳能量这一说法是不准确的。人类真正利用的东西实际上是更低的熵。
但是关于熵的定义却有很多的误解和不准确。一般的科普材料都会把熵解释成混乱的程度，这个定义不算错误，但容易造成误解。毕竟严格来说，混乱其实是一个主观的概念。打个比方，如果你去某人家里一看，发现他家里布置得非常混乱，你不知道你想要的东西摆放在哪里。但是对这个家的主人来说，他确实如数家珍。如果你问他，他可以很短时间内找出想要的任何物品，那么这个屋子对他来说就不是混乱的，而对外来的客人来说却是混乱的。
事实上，熵更准确的定义是一种宏观状态所对应的微观状态的数量。因为我们人类的观察和记忆能力有限，往往把很多微观上不同的状态看作相同的宏观状态。这种宏观状态对应的微观状态数量越多，宏观熵就越大。更好的说法是，熵代表着某个宏观物体或者宏观状态所隐藏的信息的量。
为什么说我们人类利用的不是来自太阳的能量，而是来自太阳的低熵？还要从熵的发现过程说起。随着牛顿力学的建立和许多伟大科学家的努力，近代物理学的大厦在十九世纪初已经搭建完成，而这也引发了工业革命。我们知道工业革命发源地是英国，但很快它就扩散到了欧洲大陆。一个紧跟其后的追赶者就是法国。法国有一位名叫卡诺的工程师，他曾经在拿破仑的军中服役。拿破仑在滑铁卢战败之后，他的帝国也随之湮灭。卡诺的精神也受到了很大的打击。不过很快，他又找到了方向，他要改进蒸汽机，让军事上失败的法国在工业上超过英国。
但是无论他如何改进设计，蒸汽机的能量利用效率都无法达到百分之百。后来人们发现，这是因为有一部分能量通过气缸壁或者飞轮的发热散失到了环境当中，这部分能量是无法被充分利用的。在经过凯尔文和波尔兹曼等伟大物理学家的研究基础上，热力学创立了。人们终于知道，这些能量处于高熵状态，无法被应用。
关于这个概念，我之前看过物理学家费曼的一个演讲，其中有一个非常生动的比喻。他说，当你洗完澡后用一条干毛巾擦身体，一开始毛巾是干的，没有水分，你身上的水分就会被毛巾吸走。你的皮肤变干了，毛巾变湿了。你继续擦，虽然毛巾已经湿了，但它的水分仍然比你皮肤上的水分少。这意味着每次你从皮肤上抹掉的水分比毛巾上转移到皮肤的水分多。你的皮肤越来越干。但是，这个过程会在某个时刻达到临界点，也就是毛巾的湿润程度与你皮肤的水润程度相同时刻。此时，从微观上看，水分子仍在毛巾与皮肤之间转移，但是从毛巾转移到皮肤上的水分与你从皮肤转移到毛巾上的水分一样多。此时，你的皮肤不再变干，毛巾也失去了吸水的作用，虽然它还是能吸一些水。
Since last time, using a large language model to translate English videos on YouTube, you can get an immersive viewing experience similar to that of your native language. Moreover, the accuracy and fluency of the translation of the large language model have fully reached the human level, which is better than the previous translation tools. Recently, I used this method to watch a popular science video of "Elements of Truth". I have seen the English version before, but I still know a little bit about it. After this translation, the understanding becomes deeper, and you can have a better understanding of the loan relationship.
The topic of this video is about one of the most misunderstood concepts in physics - how misunderstood is the concept of entropy. Just ask a simple question: You go to some random person on the street with a basic education and ask what do we humans and the creatures of the earth gain from the sun? Ninety percent will say energy. And then you ask, do you know roughly how much energy our planet uses from the sun? You can guess. And so people will come up with a variety of answers, ranging from 10 percent to 50 percent.
But the real answer is jaw-dropping. In fact, energy is always conserved. Of course, it is not conserved on the large scale of the universe, but in the scope of the solar system, it is conserved. So the amount of energy that the sun sends to the Earth and the amount of energy that the Earth sends out into space are actually roughly equal. If the Earth absorbed less energy from the sun than it scattered into space, the earth would become a big greenhouse and would get hotter and hotter. So it's not accurate to say that humans or organisms on Earth use the sun's energy. What humans are really taking advantage of is actually lower entropy.
However, there are many misunderstandings and inaccuracies about the definition of entropy. General popular science materials interpret entropy as the degree of chaos, a definition that is not wrong, but misleading. After all, chaos is, strictly speaking, a subjective concept. For example, if you go to someone's home and find that their home is arranged in a very chaotic way, you don't know where you want to put things. But to the owner of this house, he was a treasure. If you ask him, he can find any item he wants in a short time, then the room is not chaotic for him, but chaotic for visitors.
In fact, entropy is more accurately defined as the number of microscopic states corresponding to a macroscopic state. Because of our limited ability to observe and remember, we tend to regard many different micro states as the same macro state. The greater the number of microscopic states corresponding to this macroscopic state, the greater the macroscopic entropy. It is better to say that entropy represents the amount of information hidden in a macroscopic object or state.
Why is it that we humans use not the energy from the sun, but the low entropy from the sun? Let's start with the discovery of entropy. With the establishment of Newtonian mechanics and the efforts of many great scientists, the edifice of modern physics was completed at the beginning of the 19th century, which also triggered the Industrial Revolution. We know that the Industrial Revolution originated in Britain, but it soon spread to the European continent. A close runner-up is France. There was a French engineer named Carnot who had served in Napoleon's army. After Napoleon's defeat at Waterloo, his empire came to an end. Kano's spirit has also taken a big hit. Soon, however, he found a way to improve the steam engine and enable France, a military failure, to overtake Britain in industry.
But no matter how much he improved the design, the steam engine could never be 100 percent efficient. Later, it was found that this was because some of the energy was lost to the environment through the heat of the cylinder wall or flywheel, and this part of the energy could not be fully utilized. On the basis of the work of great physicists such as Kelvin and Boltzmann, thermodynamics was created. It finally became clear that these energies were in a state of high entropy and could not be applied.
About this concept, I saw a lecture by the physicist Feynman earlier, and there is a very vivid analogy. He said that when you wipe your body with a dry towel after a shower, the moisture from your body will be sucked away by the towel, which is dry and devoid of moisture at first. Your skin gets dry, your towel gets wet. You continue to rub, and although the towel is wet, it still has less moisture than the moisture on your skin. This means that each time you remove more water from the skin than is transferred to the skin from the towel. Your skin is getting dry. However, the process will reach a tipping point at some point, which is when the towel is as moist as your skin is hydrated. At this point, the water molecules are still transferring between the towel and the skin, but as much water is transferred from the towel to the skin as you are from the skin to the towel. At this point, your skin is no longer dry, and the towel has lost its ability to absorb water, although it can still absorb some water.
