Science fiction classic about the rise, fall and subsequent rise of a civilization where the peak catastrophe is known as the "crazy eddy point". Introduces the concept of frictionless toilets that don't have any water in them but I suspect the authors didn't think it all the way through - I don't recall a negative air pressure that would keep odours in their rightfull place. Nevertheless a fascinating read. I haven't read this for donkeys years which is why I'm searching for an e-copy.