2. James Simons, Ph.D.

In the past year, Simons has soared six spots on the Forbes 2011 World’s Billionaires List to No. 74, with a net worth of $10.6 billion. The hedge fund he founded, Renaissance Technologies, has grown to become a $15 billion firm, which continues to climb in value seemingly regardless of what the market does. He moves up one spot this year on this list, too. Self-made tycoon, intellectual, philanthropist—Simons thrives where others crumble because he is, quite simply, a genius. An MIT grad who began his career as a theoretical mathematician, he cracked codes for the U.S. Department of Defense during Vietnam before developing an algorithmic model for trading that would propel his career. For Simons, it’s not enough. He puts his fortune to work—pushing the envelope of cutting-edge scientific research in the fields of physics, genetics, math and biology; and unlocking the mysteries of autism through the charitable Simons Foundation, which he cofounded with his wife, Marilyn. Power to Simons means making the world a better place.