48 Quotes by Leonard Susskind

If necessity is the mother of invention, laziness is the father. The Einstein summation convention is the offspring of this happy marriage.

Heat is the energy of random chaotic motion, and entropy is the amount of hidden microscopic information.

There is a philosophy that says that if something is unobservable – unobservable in principle – it is not part of science. If there is no way to falsify or confirm a hypothesis, it belongs to the realm of metaphysical speculation, together with astrology and spiritualism. By that standard, most of the universe has no scientific reality – it’s just a figment of our imaginations.