Professor John Kielkopf
Department of Physics and Astronomy
University of Louisville

The foundation of my research program is in astrophysics, where almost all of our knowledge of the universe beyond our solar system derives from detecting light that has been emitted, absorbed, or scattered by atoms. Fascinating phenomena occur over times often too fast for us to recognize without instruments and an understanding of the fundamental physics. For example, collisions between atoms take place in a femtosecond, but averaging over billions of collisions, the spectrum of starlight is encoded with the temperature, pressure, and composition inside a star light years away, to be seen by us and decoded years after the light left the star. Similarly in our everyday world, our eyes and brain average over the scenes we perceive. We do not sense the sequence of images that make a movie, the pattern of footfalls for a galloping horse, or the time it takes for a flash of lightning to scatter within a cloud. My work deals with how the nature of the atoms and their environment is encoded in the light, and how we can extract information about the light source and the intervening matter from the photons which reach us.