Adam Riess

Adam Riess is an American astrophysicist whose measurements of distant Type Ia supernovae helped show that the universe’s expansion is accelerating.

Accelerating expansion of the universe: The observed increase over time in the rate at which the universe expands. Riess helped establish this surprising result through distant-supernova measurements.
Type Ia supernova: A stellar explosion whose relatively consistent peak luminosity makes it useful for measuring astronomical distances. Riess’s team used these explosions as distance indicators across cosmic time.
Saul Perlmutter: An American physicist who led the Supernova Cosmology Project and shared the 2011 Nobel Prize in Physics. Perlmutter’s collaboration independently discovered cosmic acceleration alongside Riess’s team.
Hubble constant: The present-day rate of cosmic expansion, relating galaxy recession speed to distance on large scales. Riess has led precise local measurements that contribute to the Hubble tension.
Nobel Prize in Physics: An annual award recognizing outstanding contributions to physics. Riess shared the 2011 prize for discovering the universe’s accelerating expansion.
Redshift: The increase in wavelength of light as its source moves away or space expands. Supernova redshifts supplied the expansion measurements paired with their inferred distances.
Brian Schmidt: An Australian-American astronomer who led the High-Z Supernova Search Team with Riess. Schmidt and Riess coordinated the team behind one of the 1998 reports.
Hubble tension: The discrepancy between early-universe and local measurements of the present-day expansion rate. Riess’s supernova-calibrated distance measurements yield a value higher than early-universe inferences.
Dark energy: The name for whatever drives the observed acceleration of cosmic expansion. The supernova discovery prompted dark energy to become a central cosmological problem.
Cosmic distance ladder: A sequence of astronomical methods that calibrate distances from nearby objects to the distant universe. Supernova distances rely on calibration steps that connect them to direct measurements.

Linked from 5 pages

Classical Cepheid variableRelated: His distance-scale research uses Cepheids to calibrate supernova measurements of cosmic expansion.