Saul Perlmutter (born September 22, 1959) is a U.S. astrophysicist at the

Lawrence Berkeley National Laboratory Lawrence Berkeley National Laboratory (LBNL), commonly referred to as the Berkeley Lab, is a United States Department of Energy National Labs, United States national laboratory that is owned by, and conducts scientific research on behalf of, t ...

and a professor of physics at the

University of California, Berkeley The University of California, Berkeley (UC Berkeley, Berkeley, Cal, or California) is a public land-grant research university in Berkeley, California. Established in 1868 as the University of California, it is the state's first land-grant u ...

. He is a member of both the

American Academy of Arts & Sciences The American Academy of Arts and Sciences (abbreviation: AAA&S) is one of the oldest learned societies in the United States. It was founded in 1780 during the American Revolution by John Adams, John Hancock, James Bowdoin, Andrew Oliver, and ...

and the

American Philosophical Society The American Philosophical Society (APS), founded in 1743 in Philadelphia, is a scholarly organization that promotes knowledge in the sciences and humanities through research, professional meetings, publications, library resources, and communit ...

, and was elected a

Fellow A fellow is a concept whose exact meaning depends on context. In learned or professional societies, it refers to a privileged member who is specially elected in recognition of their work and achievements. Within the context of higher education ...

of the

American Association for the Advancement of Science The American Association for the Advancement of Science (AAAS) is an American international non-profit organization with the stated goals of promoting cooperation among scientists, defending scientific freedom, encouraging scientific respons ...

in 2003. He is also a member of the

National Academy of Sciences The National Academy of Sciences (NAS) is a United States nonprofit, non-governmental organization. NAS is part of the National Academies of Sciences, Engineering, and Medicine, along with the National Academy of Engineering (NAE) and the Nati ...

. Perlmutter shared the 2006

Shaw Prize in Astronomy The Shaw Prize is an annual award presented by the Shaw Prize Foundation. Established in 2002 in Hong Kong, it honours "individuals who are currently active in their respective fields and who have recently achieved distinguished and signifi ...

, the 2011 Nobel Prize in Physics, and the 2015

Breakthrough Prize in Fundamental Physics The Breakthrough Prize in Fundamental Physics is one of the Breakthrough Prizes, awarded by the Breakthrough Prize Board. Initially named Fundamental Physics Prize, it was founded in July 2012 by Russia-born Israeli entrepreneur, venture cap ...

with Brian P. Schmidt and

Adam Riess 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 cosmologic ...

for providing evidence that the expansion of the universe is accelerating. Since 2021, he has been a member of the

President’s Council of Advisors on Science and Technology The President's Council of Advisors on Science and Technology (PCAST) is a council, chartered (or re-chartered) in each administration with a broad mandate to advise the president of the United States on science and technology. The current PCAST w ...

(PCAST).

Education

Saul Perlmutter was born one of three children in the

Ashkenazi Jew Ashkenazi Jews ( ; he, יְהוּדֵי אַשְׁכְּנַז, translit=Yehudei Ashkenaz, ; yi, אַשכּנזישע ייִדן, Ashkenazishe Yidn), also known as Ashkenazic Jews or ''Ashkenazim'',, Ashkenazi Hebrew pronunciation: , singu ...

ish family of

Daniel D. Perlmutter Daniel is a masculine given name and a surname of Hebrew language, Hebrew origin. It means "God is my judge"Hanks, Hardcastle and Hodges, ''Oxford Dictionary of First Names'', Oxford University Press, 2nd edition, , p. 68. (cf. Gabriel (given ...

, professor emeritus of chemical and biomolecular engineering at

University of Pennsylvania The University of Pennsylvania (also known as Penn or UPenn) is a private research university in Philadelphia. It is the fourth-oldest institution of higher education in the United States and is ranked among the highest-regarded universitie ...

, and Felice (Feige) D. Perlmutter (née Davidson), professor emerita of

Temple University Temple University (Temple or TU) is a public state-related research university in Philadelphia, Pennsylvania. It was founded in 1884 by the Baptist minister Russell Conwell and his congregation Grace Baptist Church of Philadelphia then called Ba ...

’s School of Social Administration. His maternal grandfather, the

Yiddish Yiddish (, or , ''yidish'' or ''idish'', , ; , ''Yidish-Taytsh'', ) is a West Germanic language historically spoken by Ashkenazi Jews. It originated during the 9th century in Central Europe, providing the nascent Ashkenazi community with a ver ...

teacher Samuel Davidson (1903–1989), emigrated to

Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...

(and then with his wife Chaika Newman to New York) from the Bessarabian town of Floreşti in 1919. Perlmutter spent his childhood in the Mount Airy neighborhood of

Philadelphia Philadelphia, often called Philly, is the largest city in the Commonwealth of Pennsylvania, the sixth-largest city in the U.S., the second-largest city in both the Northeast megalopolis and Mid-Atlantic regions after New York City. Sinc ...

. He went to school in nearby

Germantown Germantown or German Town may refer to: Places Australia * Germantown, Queensland, a locality in the Cassowary Coast Region United States * Germantown, California, the former name of Artois, a census-designated place in Glenn County * Ge ...

; first

Greene Street Friends School Greene Street Friends School is a coeducational school under the care of Green Street Monthly Meeting of the Religious Society of Friends. Located in Germantown, Philadelphia, Greene Street serves 320 students in grades Pre-K to 8. History In De ...

for the elementary grades, followed by

Germantown Friends School Germantown Friends School (GFS) is a coeducational independent PreK–12 school in the Germantown neighborhood of Philadelphia, Pennsylvania, in the United States under the supervision of Germantown Monthly Meeting of the Religious Society of Fr ...

for grades 7 through 12. He graduated with an AB in physics from

Harvard Harvard University is a private Ivy League research university in Cambridge, Massachusetts. Founded in 1636 as Harvard College and named for its first benefactor, the Puritan clergyman John Harvard, it is the oldest institution of higher le ...

''magna cum laude'' in 1981 and received his PhD in physics from the

, in 1986. Perlmutter's PhD thesis titled "An Astrometric Search for a Stellar Companion to the Sun" described the development and use of an automated telescope to search for Nemesis candidates under Richard A. Muller. At the same time, he was using this telescope to search for Nemesis and

supernova A supernova is a powerful and luminous explosion of a star. It has the plural form supernovae or supernovas, and is abbreviated SN or SNe. This transient astronomical event occurs during the last evolutionary stages of a massive star or when ...

e, which would lead him to his award-winning work in cosmology. Perlmutter attributes the idea for an automated supernova search to Luis Alvarez, a 1968 Nobel laureate, who shared his idea with Perlmutter's research adviser.

Work

Perlmutter heads the

Supernova Cosmology Project 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 S ...

at Lawrence Berkeley National Laboratory. It was this team along with the competing High-z Supernova Search Team led by Riess and Schmidt, which found evidence of the

accelerating expansion of the universe Observations show that the expansion of the universe is accelerating, such that the velocity at which a distant galaxy recedes from the observer is continuously increasing with time. The accelerated expansion of the universe was discovered duri ...

based on observing

Type Ia supernova A Type Ia supernova (read: "type one-A") is a type of supernova that occurs in binary systems (two stars orbiting one another) in which one of the stars is a white dwarf. The other star can be anything from a giant star to an even smaller white ...

in the distant universe. Type Ia supernova occurs whenever a

white dwarf star A white dwarf is a stellar core remnant composed mostly of electron-degenerate matter. A white dwarf is very dense: its mass is comparable to the Sun's, while its volume is comparable to the Earth's. A white dwarf's faint luminosity comes f ...

gains enough additional mass to pass above the

Chandrasekhar limit The Chandrasekhar limit () is the maximum mass of a stable white dwarf star. The currently accepted value of the Chandrasekhar limit is about (). White dwarfs resist gravitational collapse primarily through electron degeneracy pressure, compa ...

, usually by stealing additional mass from a

companion star A binary star is a system of two stars that are gravitationally bound to and in orbit around each other. Binary stars in the night sky that are seen as a single object to the naked eye are often resolved using a telescope as separate stars, in wh ...

. Since all Type Ia supernovae are believed to occur in essentially the same way, they form a

standard candle The cosmic distance ladder (also known as the extragalactic distance scale) is the succession of methods by which astronomers determine the distances to celestial objects. A ''direct'' distance measurement of an astronomical object is possible o ...

whose intrinsic luminosity can be assumed to be approximately the same in all cases. By measuring the apparent luminosity of the explosion from Earth, researchers can then infer the distance to supernova. Comparing this inferred distance to the apparent redshift of the explosion allows the observer to measure both the distance and relative velocity of the supernova. The Supernova Cosmology Project concluded that these distant supernovae were receding more quickly than would be expected due to the Hubble expansion alone, and, by inference, the expansion of the universe must have been accelerated over the billions of years since the supernovae occurred. The High-z Team also came to a similar conclusion. The two teams' reports were published within weeks of each other, and their conclusions were readily accepted by the scientific community due to corroborating theories. This conclusion has subsequently been supported by other lines of evidence. These findings reinvigorated research into the nature of the universe, and especially into the role of

dark energy In physical cosmology and astronomy, dark energy is an unknown form of energy that affects the universe on the largest scales. The first observational evidence for its existence came from measurements of supernovas, which showed that the univ ...

. For this work Perlmutter was awarded the 2011 Nobel Prize in Physics, shared jointly with Riess and Schmidt. Perlmutter is also a lead investigator in the

Supernova/Acceleration Probe The Joint Dark Energy Mission (JDEM) was an Einstein probe that planned to focus on investigating dark energy. JDEM was a partnership between NASA and the U.S. Department of Energy (DOE). In August 2010, the Board on Physics and Astronomy of ...

project, which aims to build a satellite dedicated to finding and studying more supernovae in the distant universe. The goal is to more precisely determine the rate at which the universe has been accelerating. He is also a participant in the

Berkeley Earth Surface Temperature Berkeley Earth is a Berkeley, California-based independent 501(c)(3) non-profit focused on land temperature data analysis for climate science. Berkeley Earth was founded in early 2010 (originally called the Berkeley Earth Surface Temperature pro ...

project, which aims to increase our understanding of recent

global warming In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to E ...

through improved analyses of climate data. Perlmutter is a professor and currently teaches at UC Berkeley.

Awards and recognition

Nobel Prize 2011-Nobel lectures KVA-DSC 7973

In 2002, Perlmutter won the

Department of Energy A Ministry of Energy or Department of Energy is a government department in some countries that typically oversees the production of fuel and electricity; in the United States, however, it manages nuclear weapons development and conducts energy-rel ...

's E. O. Lawrence Award in Physics. In 2003, he was awarded the California Scientist of the Year Award, and, in 2005, he won the

John Scott Award John Scott Award, created in 1816 as the John Scott Legacy Medal and Premium, is presented to men and women whose inventions improved the "comfort, welfare, and happiness of human kind" in a significant way. "...the John Scott Medal Fund, establish ...

and the Padua Prize. In 2006, he shared the Shaw Prize in

Astronomy Astronomy () is a natural science that studies astronomical object, celestial objects and phenomena. It uses mathematics, physics, and chemistry in order to explain their origin and chronology of the Universe, evolution. Objects of interest ...

with

and Brian P. Schmidt. The same year, Perlmutter won the

Antonio Feltrinelli International Prize The Feltrinelli Prize (from the Italian "Premio Feltrinelli", also known as "International Feltrinelli Prize" or "Antonio Feltrinelli Prize") is an award for achievement in the arts, music, literature, history, philosophy, medicine, and physical a ...

. Perlmutter and his team shared the 2007 Gruber Cosmology Prize (a $500,000 award) with Schmidt and the High-Z Team for discovering the accelerating expansion of the universe. In 2010, Perlmutter was named a Miller Senior Fellow of the

Miller Institute The Miller Institute for Basic Research in Science was established on the University of California, Berkeley, campus in 1955 after Adolph C. Miller and his wife, Mary Sprague Miller, made a donation to the university. It was their wish that the d ...

at the

University of California Berkeley The University of California, Berkeley (UC Berkeley, Berkeley, Cal, or California) is a public land-grant research university in Berkeley, California. Established in 1868 as the University of California, it is the state's first land-grant univ ...

. In 2011, Perlmutter and Riess were named co-recipients of the

Albert Einstein Medal The Albert Einstein Medal is an award presented by the Albert Einstein Society in Bern. First given in 1979, the award is presented to people for "scientific findings, works, or publications related to Albert Einstein" each year. Recipients ...

. Perlmutter shared the 2011 Nobel Prize in Physics with Riess and Schmidt. The Nobel Prize includes a SEK 10 million cash award (approximately US$1.5 million). Perlmutter received one-half of the cash prize, while Riess and Schmidt shared the other half. In 2014, Perlmutter received the Golden Plate Award of the

American Academy of Achievement The American Academy of Achievement, colloquially known as the Academy of Achievement, is a non-profit educational organization that recognizes some of the highest achieving individuals in diverse fields and gives them the opportunity to meet ...

. Perlmutter, Schmidt, Riess and their teams shared the 2015

with $3 million to be split among them. A

United States Department of Energy The United States Department of Energy (DOE) is an executive department of the U.S. federal government that oversees U.S. national energy policy and manages the research and development of nuclear power and nuclear weapons in the United Stat ...

2020

supercomputer A supercomputer is a computer with a high level of performance as compared to a general-purpose computer. The performance of a supercomputer is commonly measured in floating-point operations per second ( FLOPS) instead of million instructions ...

is named Perlmutter in his honor.

Family

Saul Perlmutter has two sisters: Shira Perlmutter (b. 1956), a lawyer, and Tova Perlmutter (b. 1967), a nonprofit executive. He is married to Laura Nelson, an anthropologist at

, and has one daughter, Noa.

Popular culture

Reference to Saul Perlmutter was made on the CBS television comedy series ''

The Big Bang Theory ''The Big Bang Theory'' is an American television sitcom created by Chuck Lorre and Bill Prady, both of whom served as executive producers on the series, along with Steven Molaro, all of whom also served as head writers. It premiered on C ...

'' during the 2011 episode "The Speckerman Recurrence". In the episode, the character

Sheldon Cooper Sheldon Lee Cooper, Ph.D., Sc.D., is a fictional character in the CBS television series ''The Big Bang Theory'' and its spinoff series ''Young Sheldon'', portrayed by actors Jim Parsons and Iain Armitage respectively (with Parsons as the latter ...

watches the Nobel award ceremony on his laptop, and jealously berates Perlmutter: "Look at Dr. Saul Perlmutter up there, clutching that Nobel prize. What's the matter Saul, you afraid somebody's going to steal it? Like you stole Einstein's cosmological constant?" Then later: "Oh, now Perlmutter's shaking the King's hand. Yeah, check for your watch, Gustaf, he might have lifted it." Perlmutter was also referenced in the 2011 episode of ''The Big Bang Theory'', "The Rhinitis Revelation". In a conversation with his mother, Sheldon says, "I’ve got a treat for us tomorrow, Mom. I’m taking you to see Saul Perlmutter give a lecture about his Nobel Prize-winning work in cosmology. And the best part is, at the Q and A afterward, I’ve worked up a couple of Q’s that will stump his sorry A." Later in the episode, Sheldon criticises the lecture and questions the decision to award Perlmutter a Nobel Prize.