※ 引述《sokalula (so卡嚕啦)》之銘言：
: 很多科幻題材的作品都說未來是無限多的走向
: 一切都取決你當下的決定
: 意思是說 未來有很多個
: 這樣也間接的想說世界線的存在
: 但如果未來根本不會改變呢
: 唯一的未來就是你選擇的那個走向呢？
: 不管你做什麼選擇都早就是決定好的了
: 有鄉民聽的懂我的意思嗎
https://en.wikipedia.org/wiki/Ergodic_theory
中文番作「遍歷理論」？
Ergodic theory is a branch of mathematics that studies dynamical systems with
an invariant measure and related problems. Its initial development was
motivated by problems of statistical physics
動態系統中的積分不變量。
http://news.softpedia.com/news/What-is-ergodicity-15686.shtml
Many scientists agree that ergodicity is one of the most important concepts
in statistics. So, what is it?
多數科學家同意遍歷性是統計學中做重要的概念。那，它究竟是什麼？
Suppose you are concerned with determining what the most visited parks in a
city are. One idea is to take a momentary snapshot: to see how many people
are this moment in park A, how many are in park B and so on. Another idea is
to look at one individual (or few of them) and to follow him for a certain
period of time, e.g. a year. Then, you observe how often the individual is
going to park A, how often he is going to park B and so on.
假設你要研究某個城市中的哪個公園最常被造訪。一個方法是選一個時間點，看有多少人
在A公園，或B公園，以此類推。另一個方法是追蹤一個人，例如在一年內，然後紀錄
一年內他分別造訪某公園的次數。
Thus, you obtain two different results: one statistical analysis over the
entire ensemble of people at a certain moment in time, and one statistical
analysis for one person over a certain period of time. The first one may not
be representative for a longer period of time, while the second one may not
be representative for all the people.
這兩個方法會得出不同結果，而且各自在其母群體中代表性都不夠。
The idea is that an ensemble is ergodic if the two types of statistics give
the same result. Many ensembles, like the human populations, are not ergodic.