Electron-Impact Ionization Of Atoms: Finally Solving The Most Basic Example. C. William McCurdy Lawrence Berkeley National Laboratory Electron impact ionization of atoms and molecules is one of the most basic phenomena in low-energy collision physics. It is responsible for forming and sustaining low-temperature plasmas that are used in applications ranging from fluorescent lighting to the processing of silicon chips.  Since the invention of quantum mechanics, even the simplest example of the collisional breakup of a system of charged particles, ,has resisted solution, never having been ¡§reduced to computation¡¨.  The reason is that, even though the asymptotic form of the wave function for ionization was first given by Peterkop and Rudge almost 40 years ago, the formal theory of ionization has thus far proved too difficult to apply in a complete scattering calculation ¡V even with modern massively parallel supercomputers.   We have solved this problem by an approach that separates the computation of the wave function from the calculation of cross sections from it.      The story involves exotic mathematics, basic quantum mechanics, and large-scale computation, and appeared on the cover of last issue of Science in the 1900s [Rescigno, Baertschy, Isaacs and McCurdy, Science, 286, 2474 (1999)].   This seminar will tell that story and describe developments in accurate calculations on electron-impact ionization since then.