From Crooked Timber, a list of Iron Laws of the Universe
Given that Paul Krugman is reminding us all of Stein’s Law (“Things that can’t go on forever, don’t”), I thought I’d remind everyone of Davies’ Corolloraries:
1. Things that can’t go on forever, go on much longer than you think they will.
2. Corollorary 1 applies even after taking into account Corollorary 1.
Lots of interesting comments on that page adding additional laws, including – Keynes’ remark that “The market can stay irrational longer than you can stay solvent” is paralleled by (ahem) Teresa Nielsen Hayden’s observation that “The Invisible Hand is not to human scale.”
Also, Hofstadter’s Rule, which states that everything takes longer than you think it will, even after you take Hofstadter’s Rule into account.
See also Wikipedia’s category of Adages for many more of these including: