The classical model of finance (Markowitz, Sharpe, Black, Scholes, Fama) has, from the be-ginning, been challenged by the mathematician Benoit Mandelbrot (1924-2010). It shows that the normal distribution does not match the reality of the market, because it underesti-mates the extreme risks. Instead, we must use the power laws, such as the Pareto law. We show the implications of this fundamental change in the finance, but also in the manage-ment of companies (through the calculation of cost of capital). We try to update the underly-ing reasons for the existence of power laws in economics through the concept of entropy. We present new theoretical tools to understand price formation (the theory of diagonal proportion), bubbles (the notion of reflexivity), crisis (network concept), providing a com-prehensive response to the current crisis (a diversified monetary system). All these ways are very little or not at all exploited. They are mostly for the first time, made consistent around the notion of power law. This is a new way of understanding economic phenomena present-ed here.
