Accelerating universe in the context of "Saul Perlmutter"

In physical cosmology and astronomy, dark energy is a proposed form of energy that affects the universe on the largest scales. Its primary effect is to drive the accelerating expansion of the universe. It also slows the rate of structure formation. Assuming that the lambda-CDM model of cosmology is correct, dark energy dominates the universe, contributing 68% of the total energy in the present-day observable universe while dark matter and ordinary (baryonic) matter contribute 27% and 5%, respectively, and other components such as neutrinos and photons are nearly negligible. Dark energy's density is very low: 7×10 g/cm (6×10 J/m in mass-energy), much less than the density of ordinary matter or dark matter within galaxies. However, it dominates the universe's mass–energy content because it is uniform across space.

The first observational evidence for dark energy's existence came from measurements of supernovae. Type Ia supernovae have constant luminosity, which means that they can be used as accurate distance measures. Comparing this distance to the redshift (which measures the speed at which the supernova is receding) shows that the universe's expansion is accelerating. Prior to this observation, scientists thought that the gravitational attraction of matter and energy in the universe would cause the universe's expansion to slow over time. Since the discovery of accelerating expansion, several independent lines of evidence have been discovered that support the existence of dark energy.

The Supernova Cosmology Project is one of two research teams that determined the likelihood of an accelerating universe and therefore a positive cosmological constant, using data from the redshift of Type Ia supernovae. The project is headed by Saul Perlmutter at Lawrence Berkeley National Laboratory, with members from Australia, Chile, France, Portugal, Spain, Sweden, the United Kingdom, and the United States.

This discovery was named "Breakthrough of the Year for 1998" by Science Magazine and, along with the High-Z Supernova Search Team, the project team won the 2007 Gruber Prize in Cosmology and the 2015 Breakthrough Prize in Fundamental Physics. In 2011, Perlmutter was awarded the Nobel Prize in Physics for this work, alongside Adam Riess and Brian P. Schmidt from the High-Z team.

Adam Guy Riess (born December 16, 1969) is an American astrophysicist and Bloomberg Distinguished Professor at Johns Hopkins University and the Space Telescope Science Institute. He is known for his research in using supernovae as cosmological probes. Riess shared both the 2006 Shaw Prize in Astronomy and the 2011 Nobel Prize in Physics with Saul Perlmutter and Brian Schmidt for providing evidence that the expansion of the universe is accelerating.

Riess has been at the center of a growing scientific debate about the so-called “Hubble tension” — a discrepancy between measurements of the universe’s expansion rate using nearby supernovae, and measurements inferred from the cosmic microwave background radiation using the Standard Model of cosmology. Riess’s data has prompted questions and further testing to determine if the Standard Model still adequately describes the universe.

Brian Paul Schmidt (born 24 February 1967) is an American Australian astrophysicist at the Australian National University's Mount Stromlo Observatory and Research School of Astronomy and Astrophysics. He was the Vice-Chancellor of the Australian National University (ANU) from January 2016 to January 2024. He is known for his research in using supernovae as cosmological probes. He previously held a Federation Fellowship and a Laureate Fellowship from the Australian Research Council, and was elected a Fellow of the Royal Society (FRS) in 2012. Schmidt shared both the 2006 Shaw Prize in Astronomy and the 2011 Nobel Prize in Physics with Saul Perlmutter and Adam Riess for providing evidence that the expansion of the universe is accelerating.