Wallace Sargent was an astronomer who used large telescopes to great effect. He concentrated on outstanding problems concerning both the origin of the elements and the cosmological evolution of primordial gas clouds. Despite a mainly theoretical education he became an expert spectroscopist and this enabled him to demonstrate that most helium was not formed in stars but was primordial, formed in the Big Bang. This helped to determine the photon : baryon ratio that emerged from it. He played a significant part in the search for the supermassive black holes that were predicted to be in the centres of many galaxies, as is now established. He is most famous for his systematic work with Alec Boksenberg FRS on the intervening hydrogen clouds seen in absorption in the spectra of distant quasars. From their work it appears that most of the 4% of the Universe (by mass) that is now considered to be in normal atoms or ions has indeed been detected, although it is seen at considerable look-back times.
- © 2015 The Author(s)
Published by the Royal Society