雙語暢銷書《艾倫圖靈傳》第7章:運轉起來(56)
If the states of a Turing machine could be compared with 'states of mind', then its physical embodiment could be compared with a brain.
One important aspect of this comparison, important to anyone who was concerned with the mystery of mind, the apparent paradox of free will and determinism, was that the Turing machine model was one independent of physics.
這個類比中有一個關鍵之處，對所有關心思維奧祕的人來說都非常重要，那就是圖靈機模型是不依賴物理實體的。The argument from Laplacian physical determinism could be shrugged aside with the observation that no such prediction could ever be performed in practice.
拉普拉斯式的物理決定論，在現實中是無法實現的，因此這可能會成爲一個反對它的理由。
This rebuttal could not be applied to a Turing machine, in which everything that happened could be described in terms of a finite set of symbols, and worked out with complete precision in terms of discrete states.
但這種理由，對圖靈機是不成立的，在圖靈機模型中，一切都可以用有限的符號集來描述，而且以離散的狀態來精確地運行。Later he would articulate this himself:
艾倫自己表述說：The prediction which we are considering is however rather nearer to practicability than that considered by Laplace.
我們的模型比拉普拉斯的更具有現實性。The system of the 'universe as a whole' is such that quite small errors in the initial conditions can have an overwhelming effect at a later time.
他所考慮的宇宙整體，是這樣的一個系統，初始狀態的微小偏差，會在後面產生巨大的影響。The displacement of a single electron by a billionth of a centimetre at one moment might make the difference between a man being killed by an avalanche a year later, or escaping.
某時刻的一個電子偏移10納米，就能決定某個人在一年後死於雪崩。It is an essential property of the mechanical systems which we have called 'discrete state machines' that this phenomenon does not occur.
而機械系統的基本性質，就是不會發生這種情況，我們稱之爲離散狀態機。
