Ion Motion in Gases, A Colloquium in Honor of Dr. Ian Gatland
The history of drift-tube measurements of gaseous ion transport coefficients is reviewed, with an emphases on the contributions made by Dr. Gatland. The use of experimental measurements of such coefficients in testing ion-neutral interaction potentials over wide ranges of internuclear separation is illustrated through recent tests of ab initio potentials. Finally, the use of such data with recent theoretical advances is shown to have implications for ion-neutral reactions of importance in the ionosphere. ...
Nobel Colloquium: Surveying the Accelerating Universe with Supernovae
In 1998 two rival teams of astronomers studying exploding white dwarf stars, called type Ia supernovae, came to the surprising conclusion that the expansion of the Universe is speeding up. This discovery of "the accelerating Universe" ushered in a revolution in our cosmological understanding. I will describe the steps leading to this discovery, and how observations of supernovae from telescopes on the ground and in space can be used to trace the history of cosmic expansion. The continued study of these stellar explosions will shed light on the mysterious "dark energy" that dominates and drives our accelerating Universe.
