MIT '92

Adam Riess

Nobel Prize Winner

Adam Riess, the Krieger-Eisenhower Professor in Physics and Astronomy and a Gilman Scholar at The Johns Hopkins University, and a scientist at the Space Telescope Science Institute, was awarded the 2011 Nobel Prize in Physics by the Royal Swedish Academy of Sciences. The academy recognized him for leadership in the High-z Team’s 1998 discovery that the expansion rate of the universe is accelerating, a phenomenon widely attributed to a mysterious, unexplained “dark energy” filling the universe.

Riess (pronounced “Reese”), 41, shared the prize with Saul Perlmutter, an astrophysicist at the University of California, Berkeley, and the Lawrence Berkeley Laboratory, whose Supernova Cosmology Project team published similar results shortly after those published by Riess and High-z teammate Brian Schmidt, of the Australian National University. Both teams shared the Peter Gruber Foundation’s 2007 Cosmology Prize – a gold medal and $500,000 – for the discovery of dark energy, which Science Magazine called “The Breakthrough Discovery of the Year” in 1998. The researchers also shared the 2006 Shaw Prize in astronomy for the same discovery.

Considered the most prestigious prize in the world, the Nobel has been awarded for achievements in physics, chemistry, physiology or medicine, literature and peace since 1901 by the Nobel Foundation in Stockholm, Sweden. Riess received a medal and diploma and shared a cash award of $1.49 million.

An overjoyed Riess thanked the Nobel Foundation for the award and said, “My involvement in the discovery of the accelerating universe and its implications for the presence of dark energy has been an incredibly exciting adventure. I have also been fortunate to work with tremendous colleagues and powerful facilities. I am deeply honored that this work has been recognized.”

Education and Career Path

The youngest child of a psychologist mother and an engineer-turned-entrepreneur father, Riess grew up in Warren, N.J. An exceptionally inquisitive boy, Riess was teaching an adult class in computer programming at the age of 13. His parents were proud of Riess’s intelligence and accomplishments, but kept him grounded and humble by requiring him to work part-time in his father’s New York-style delicatessen, washing dishes and bussing tables, he said in a 2008 article in  Johns Hopkins Magazine.

Riess is a 1992 graduate of Massachusetts Institute of Technology, where he majored in physics and minored in history. (He is an avid sports fan, and wrote his final research paper on baseball’s 1919 “Black Sox” scandal.) He earned his doctorate in astrophysics from Harvard University in 1996. From 1996 to 1999, the period when the dark energy discovery was made, Riess was a Miller Fellow at the University of California, Berkeley.

Since then, Riess has led rigorous efforts to use the Hubble Space Telescope to increase the precision of the dark energy findings, which are important not only for comprehending the makeup of the universe, but also for understanding its history and future and in unraveling other important questions in theoretical physics.

Riess’s accomplishments have been recognized with a number of prestigious awards. In 2008, he won a $1 million John T. and Catherine D. MacArthur Foundation “Fellowship Grant,” also known as a “genius grant.” That same year, he was among the 212 fellows elected to the 228th class of the American Academy of Arts and Sciences. In 2007, he shared The Peter Gruber Foundation’s Cosmology Prize – a gold medal and $500,000 — and in 2006, he won the $1 million Shaw Prize, considered by some to be “the Nobel of the East.” In 2009, Riess was elected to the National Academy of Sciences.


Riess led the study for the High-z Supernova Search Team of highly difficult and precise measurements – across 7 billion light years – that resulted in the remarkable 1998 discovery that many believe has changed astrophysics forever: an accelerated expansion of the universe propelled by dark energy.

“We originally set out to use a special kind of exploding star called ‘supernovae’ to measure how fast the universe was expanding in the past and to compare it to how fast it is expanding now,” Riess remembered. “We anticipated finding that gravity had slowed the rate of expansion over time. But that’s not what we found.”

Instead, Riess’ team was startled to discern that the rate of expansion was actually speeding up.

“If you tossed a ball into the air and it kept right on going up instead of falling to the ground, you’d be pretty surprised. Well, that’s about how surprised we were to get that result,” Riess said.

These startling observations sent the team back to the idea – first proposed by Albert Einstein but later rejected as his “biggest blunder” – that the so-called vacuum of space might produce a sort of “anti-gravity” energy that could act repulsively, accelerating the expansion of the universe.

“Suddenly, that idea made sense,” said Riess, who posits that dark energy may account for up to 70 percent of the universe. However, exactly what dark energy is and how it behaves remains among the most pressing questions in astrophysics today.

“One of the most exciting things about dark energy is that it seems to live at the very nexus of two of our most successful theories of physics: quantum mechanics, which explains the physics of the small, and Einstein’s Theory of General Relativity, which explains the physics of the large, including gravity,” he said.

“Currently, physicists have to choose between those two theories when they calculate something. Dark energy is giving us a peek into how to make those two theories operate together. Nature somehow must know how to bring these both together, and it is giving us some important clues. It’s up to us to figure out what [those clues] are saying.”

Current Research and Interests

Many cosmologists say that understanding dark energy is the biggest challenge in cosmology and physics. Riess and his team are trying to measure dark energy’s two most fundamental properties: how stable it is and how it has changed with the evolving universe.

Riess is continuing his Hubble Space Telescope observations of distant supernovae to characterize dark energy. He also is involved in searching for the exploding stars with the Panoramic Survey Telescope and Rapid Response System, a series of ground-based telescopes at the University of Hawaii’s Institute for Astronomy. The sky survey is expected to find thousands of new supernovae.

In another method, Riess and his team, called SH0ES (Supernova H0 the Equation of State), are analyzing pulsating stars, called Cepheid variables, with the Hubble telescope to refine the measurement of the universe’s expansion rate. The new results are helping scientists zero in on the properties of dark energy.