Adam Riess shared the Nobel Prize in Physics for observations of galaxy motions that shocked even him. Yes, the Universe was expanding as Hubble showed 75 years prior, but the swelling of space that launched with the Big Bang wasn’t slowing down as would be expected. Instead, the expansion is getting faster, as though something is driving the Universe on. Retrofitting the observations, astronomers tried to measure the acceleration’s mysterious, propulsive source. An unknown, unseen, unidentified, invisible form of energy was implicated and, for lack of a specific culprit, was eventually dubbed the enigmatic Dark Energy. What Dark Energy is, nobody knows.

The 2011 Nobel citation for Riess and his collaborators notes only, “the discovery of the accelerating expansion of the Universe through observations of distant supernovae," with no mention of Dark Energy. No direct detection, discovery, or compelling theoretical model for Dark Energy exists.

Now the plot has thickened. Riess continues to observe the Universe and finesse his measurement of the expansion rate, known as the Hubble expansion, in homage to the great astronomer. Once again, he has been shocked by what he discovered. His results conflict with other credible observations of the Universe. This has led to a conundrum-bordering-on-crisis in cosmology. Riess is perplexed and openly wonders if there is more to discover about the Dark Energy that is credited to his Nobel Prize winning work. He refers to the conflict as the Hubble Tension. If the tension does not resolve, the implications are profound for our past and our future. Is Dark Energy losing its umph? Will Dark Energy dilute away entirely, or even reverse its polarity, pulling the universe back to collapse into a big crunch? Will the Universe relive the Big Bang, but in reverse?

Join host Janna Levin in conversation with Adam Riess and Licia Verde, a representative of a new generation of astronomers. The trio will discuss one of the most contested issues dominating our understanding of the Universe: the puzzle of its expansion.

Before and after the conversation, there will be grooves by DJ Black Helmet and stargazing in the garden with the Amateur Astronomers’ Association, weather-permitting. Fresh Handmade Dumplings (MOMO) and more by Dumpling Spot NYC will be available for purchase throughout the evening.

Program Speakers

Adam Riess is a Bloomberg Distinguished Professor at John Hopkins University, the Thomas J. Barber Professor in Space Studies, and a distinguished astronomer at the Space Telescope Science Institute. A member of the National Academy of Sciences, he earned his bachelor’s degree in physics from MIT and his PhD from Harvard. Riess’s research focuses on measuring the expansion rate of the Universe using supernovae (exploding stars) and Cepheids (pulsating stars). He leads the SHOES Team to refine measurements of the Hubble Constant and the Higher-z Team to discover the most distant type of supernovae, probing the origin of cosmic acceleration.

In 2011, Riess was awarded the Nobel Prize in Physics and received the Albert Einstein Medal for the discovery that the expansion rate of the Universe is accelerating, a phenomenon widely attributed to mysterious "dark energy." His work has also been recognized with a MacArthur Fellowship, the Gruber Cosmology Prize, and the Shaw Prize in Astronomy.

Licia Verde is a cosmologist and Institució Catalana de Recerca i Estudis Avançats (ICREA) Professor at the University of Barcelona, where since 2010 she has led the Cosmology and Large Scale Structure Group at the Instituto de Ciencias del Cosmos. She earned her physics degree from the University of Padova and her PhD from the University of Edinburgh before holding postdoctoral appointments at Rutgers and Princeton, where she joined the science team of NASA’s Wilkinson Microwave Anisotropy Probe mission. She became faculty at University of Pennsylvania before moving to Barcelona.

Verde’s research explores the large-scale structure of the Universe and the nature of dark energy, with contributions to the Baryon Acoustic Oscillations Survey and the Dark Energy Spectroscopic Instrument. She also serves as the Scientific Director of both the Journal of Cosmology and Astroparticle Physics and of the Instituto de Ciencias del Cosmos of University of Barcelona. Her honors include the Premi Rei Jaume I for Fundamental Science and the 2019 Lodewijk Woltjer Lecture of the European Astronomical Society.

Janna Levin is the founding director of sciences at Pioneer Works and the co-editor-in-chief of Broadcast. She is a professor of physics and astronomy at Barnard College of Columbia University. A Guggenheim fellow, she has contributed to an understanding of black holes and cosmology and frequently contributes to documentaries and the news. She has authored books on black holes and the Universe as well as a PEN award–winning novel. Her most recent book is Black Hole Survival Guide.

Participant Bios

Andrea Lauer is an artist and designer whose work spans costume and set design, styling, and innovation across the arts and sciences. With over fifty national and international production credits—including Broadway, music tours, and television—her designs have been featured in Vogue, Rolling Stone, and Interview. Andrea is the founder of RISEN DIVISION, a sustainable fashion label known for its signature jumpsuits. Her practice explores the intersection of storytelling, material culture, and embodied experience, often incorporating technology, sustainability, and symbolic forms. She is a Pioneer Works Resident Alum, and she collaborates on the Scientific Controversies series to create collectible patches, bandanas, and artifacts that visually interpret complex scientific ideas with bold, poetic design.

DJ Black Helmet (Azikiwe Mohammed) is a New York Based DJ and musician who specializes in long form live mixes and generative ambient works. He has performed at venues such as Elsewhere, Bembe, Pioneer Works, Public Records, Roulette Intermedium, The Highline, MoMA, and MoMa PS1. He currently has a weekly radio show on WFMU’s Give The Drummer Radio called Your Boy Black Helmet Radio. He is founder and director of the Black Painters Academy, the home for the New Davonhaime Food Bank, a food bank based in Manhattan’s Chinatown, focusing on health equity and community wellness.

This program is supported by the Simons Foundation's Science, Society and Culture division, and the Alfred P. Sloan Foundation Program in Public Understanding of Science and Technology, bridging the two cultures of science and the arts.