sentences:  In a similar note, Emanuel Derman expressed his disillusion with the enormous supply of empirical models unsupported by theory.He argues that, while "theories are attempts to uncover the hidden principles underpinning the world around us, as Albert Einstein did with his theory of relativity", we should remember that "models are metaphors – analogies that describe one thing relative to another".Well known hedge fund managers with expertise in trading volatility include Mark Spitznagel and Nassim Nicholas Taleb of Universa Investments, Paul Britton of Capstone Holdings Group, Andrew Feldstein of Blue Mountain Capital Management, and Nelson Saiers from Saiers Capital.