雙語暢銷書《艾倫圖靈傳》第6章:連接兩個世界(16)
People had thought about machines since the dawn of civilisation, but Computable Numbers had come up with a precise, mathematical definition of the concept of 'machine'.
People had thought equally long about communication, but here again it needed a modern mind, in this case Claude Shannon's, to provide a precise definition of the concepts involved.
人們在通信方面，也進行了很多思考，這個領域也需要現代化的思想，而正是克勞德·香農對此給出了精確的概念定義。Shannon had completed his first paper in this direction in 1940, and by 1943 his fundamental ideas were beginning to be used in Bell Laboratories, in whose mathematical department he was now employed.
1940年，香農完成了他的第一份在該領域的論文，並且在1943年，他的基本思想在貝爾實驗室開始得到應用。
He was consulted about the design of the X-system, which posed some of the questions answered by his work.
對於X系統的設計，有一部分問題，現在正需要由他來解答。The transmitter, the ionosphere, and the receiver, were a communication channel, in his terms; a channel with a limited capacity, and a channel plagued by noise.
從發送端，到電離層，再到接收者，這個鏈條，用他的話來說，是一條通信頻道。這是一條容量有限的、有噪音干擾的頻道，Into this channel had to be squeezed a signal.
發送信號即是進入該頻道。Shannon found ways to define channel capacity, noise, and signal, in terms of a precise measure of information.
香農提出了一套精確的方式，來定義這些頻道容量、噪音和信號。The problem of the communication engineer was that of encoding the signal in such a way as to make best use of the channel, and to prevent it being distorted by the noise;
通信工程的目標，就是更好地使用頻道，避免編碼信號因爲噪音而失真。Shannon found new precise theorems which placed limits upon what could be achieved.
香農精確地指出了其中的限制。There was not only a parallel between his work and Alan Turing's; there was a sort of reciprocity.
香農的工作，與艾倫·圖靈不是平行的，它們之間存在着交點。On his side Alan, although his main strength was in the logic of machines, had dipped into the study of information.
在香農看來，雖然艾倫的主要優勢是機器邏輯，但他對信息學也有研究。Not only was this true in general terms of all his cryptological work, but there was an even more specific point of contact.
從廣泛意義來說，艾倫的密碼學工作與信息學有很大關係，在具體實踐中，他們二人的思想還有更具體的聯繫。Shannon's measure of information was essentially the same as the Turing 'decibans'.
香農對信息的度量方法，本質上與圖靈的"分板"是一樣的。A ban of weight of evidence made something ten times as likely; a binary digit or bit of information made something twice as definite.
一板的證據權重，能使一個事件的概率變成10倍。一個二進制數，或者說一位信息，則能使一個事件的概率變成2倍。There were fundamental connections between the theories, although they were not free to discuss them.
這兩種理論有着本質的聯繫，但是他們不允許討論這些。Shannon only knew by implication why Alan was at Bell Labs at all.
香農只是通過一些暗示，知道了艾倫在貝爾實驗室是幹什麼的。
