Can life exist in the Antarctic ice, in the deep subsurface, in dilute sulfuric acid, in hot springs-even on Mars? What degree of high or low temperature, pressure, or salt concentration can living cells tolerate? In recent years, scientists have discovered many single-cell creatures that exist in-in fact, are perfectly adapted to-extreme environments that were considered uninhabitable just one or two decades ago. In Life on the Edge, author Michael Gross explores how microorganisms adapt to their hostile environments and how they affect our current definition of the normal conditions for life. He also describes the vast implications of these extremophiles and other amazing creatures-from potential breakthroughs in medicine and biotechnology to the search for life elsewhere in the universe.