John von Neumann was, undoubtedly, one of the true scientific geniuses of the 20th century. The main fields to which he contributed include different disciplines of pure and applied mathematics, mathematical and theoretical physics, logic, theoretical computer science and computer design. Von Neumann was also actively involved in politics, science management, served on a number of commissions and advisory committees and had a major impact on U.S. government decisions during, and especially after, the Second World War.