Adam Riess

Origins and early life

Adam Riess was born on 16 December 1969 in Washington, D.C., and was born into a Jewish family; his father's family had emigrated from Germany, and his grandfather Curt Riess was a journalist and war correspondent. He grew up in Warren Township, New Jersey, where his father ran a frozen-foods distribution business and his mother worked as a clinical psychologist, and he has two sisters, the psychiatrist Gail Saltz and the artist Holly Hagerman.

He graduated from MIT in 1992 and took a doctorate at Harvard in 1996 under Robert Kirshner and William Press, on a method for turning exploding stars into accurate distance markers by correcting for intervening dust.

Work and career

A Type Ia supernova is useful precisely because its brightness is nearly always the same, so how faint it looks tells you how far away it is, and its colour shift tells you how fast it is receding. Riess was a young postdoctoral fellow at Berkeley when the numbers came back from the High-z Supernova Search Team, which he led with Brian Schmidt: the most distant supernovae were fainter than they should have been, meaning the universe had expanded further than expected — it was not slowing down under gravity but accelerating.

Saul Perlmutter's rival team reached the same conclusion, and the 1998 result put back into cosmology a term it had long discarded: a dark energy that makes up most of the universe and that nobody can yet explain.

Recognition

Riess moved to the Space Telescope Science Institute in 1999 and to Johns Hopkins in 2006, and shared the 2006 Shaw Prize and the 2011 Nobel Prize in Physics with Schmidt and Perlmutter. His later measurements of the expansion rate disagree with the value inferred from the cosmic microwave background, a discrepancy known as the Hubble tension, which is now one of the open problems of the field.