This is how Cédric Villani puts it [Birth of a theorem, p.38]:
What’s in a norm
Author: Ole Peters
Fellow, London Mathematical Laboratory.
External Professor, Santa Fe Institute.
https://twitter.com/ole_b_peters
Winner take all
Michael Mauboussin recently re-tweeted an article by Jason Zweig in the Wall Street Journal titled “Disturbing New Facts About American Capitalism”.
The article summarizes reports of an increasing concentration of economic power (market capitalization, profits etc) in ever smaller numbers of American companies, so-called super-star companies in their respective sectors. Well-known examples are Google (or Alphabet) and Apple. But the trend, Zweig says, is broader, also occurring in supermarkets and real estate services.
Gas in a box or nuclear explosion?
This post is about mindset, culture, implicit assumptions. The big assumption in neoclassical economics is ergodicity, or equilibrium, or stationarity, or stability — basically the idea that nothing ever changes fundamentally. Things may fluctuate but they always return to some state of normality. Naively, that doesn’t fit with the idea of a growing economy, innovation, and change. So something’s up. I’ll explore what that is by replacing the mental image of stability with something that doesn’t return to normality: a nuclear explosion.
Reproducibility and weak ergodicity breaking
The term “weak ergodicity breaking” helps categorize things by their ergodic properties:
- ergodic
- strongly non-ergodic
- weakly non-ergodic
This list is chronological, in that there used to be an implicit belief that everything was ergodic (from 1654), then the realization that some things are strongly non-ergodic (1850s — 1870s), and then the discovery that things can be a lot more subtle (with Jean-Philippe Bouchaud coining the term “weak ergodicity breaking” in 1992).
Continue reading “Reproducibility and weak ergodicity breaking”
