실체에 이르는 길(로저 펜로즈)
http://scienceon.hani.co.kr/archives/13582
preface
- 분수와 equivalence class 의 예
1 The roots of science
- the main thrust of this book has to do with the first of these mysteries: the remarkable relationship between mathematics and the actual behaviour of the physical world.
homogeneity
(every point the same) and isotropy (every direction the same),