The Kavli Network Effect: Risa Wechsler

Over the past quarter century, The Kavli Foundation has partnered with scientists at the forefront of discovery. Through 20 international Kavli Institutes — along with fellowships, funding programs and other collaborative initiatives — we see brilliant minds connect with one another, exchange ideas and explore the deepest questions about the universe, from the vastness of space to the workings of the human brain.

This series, The Kavli Network Effect, explores stories of scientific discovery, connection and collaboration by highlighting scientists who are part of the Kavli ecosystem. Each profile traces how encounters throughout this community have shaped individuals’ careers, leaving lasting impacts on their approaches to research, leadership and mentoring.

Part 3 profiles a cosmologist’s ascension to a Kavli Institute directorship. Read part 1 of this series here, and part 2 of this series here.

Risa Wechsler is known for her work on some of the world’s most ambitious sky surveys, including the Dark Energy Survey (DES), the Dark Energy Spectroscopic Instrument (DESI) and the NSF-DOE Vera C. Rubin Observatory’s Legacy Survey of Space and Time (LSST) — telescopic titans that have transformed how scientists study the universe. Yet, early in her career, she identified more as a pure theorist, someone who uses models and simulations to explain how galaxies form and evolve, rather than as a “big project” person. Wechsler credits her Kavli Institute experiences — being immersed in an environment where theorists, observers and instrument builders worked side by side — with helping her blossom into the leader and leading scientist she is today.

Since 2018, she has served as director of the Kavli Institute for Particle Astrophysics and Cosmology (KIPAC) at Stanford University, where she continues to leverage gargantuan galaxy surveys to probe the growth of structure in the universe. By bringing together theory and large-scale data, those investigations are ferreting out dark matter and dark energy — the duo of mysterious entities that constitute the bulk of the cosmos and have largely determined its history and evolution.

Originally from Seattle, Wechsler obtained her doctorate in physics from the University of California, Santa Cruz. She then ventured to the Midwestern United States — first to the University of Michigan and then to the University of Chicago, where in 2003 she became a Hubble Fellow at the recently inaugurated Kavli Institute for Cosmological Physics (KICP).

While at KICP, plans were just developing for DES, which eventually completed an observational campaign that ran from 2013 to 2019 and mapped hundreds of millions of galaxies. Wechsler’s simulations informed the initial proposal, survey design and early algorithm development. “Helping develop the science case for a large survey was really exciting,” she says. “Working with colleagues at KICP and around the world — and thinking big about what the data could unlock — whetted my appetite for doing science at a larger scale.”

Wechsler came to appreciate the institutional culture at KICP, which empowered fellows to pursue multiple projects with genuine independence. “I benefited tremendously as a postdoc from having the independence and flexibility to be able to take my research in the most exciting directions,” says Wechsler. She attributes the culture in part to the Kavli endowment — a model of stable, flexible support she has seen work splendidly at KIPAC for more than two decades. When early-career researchers aren’t tied to constrained funding sources, they can pursue ideas across projects and disciplines, creating a culture that values both individual initiative and shared progress. “That joint sense of independence and collaboration is something we’ve really tried to foster at KIPAC,” she says.

As for how she came to KIPAC, you could say Wechsler followed both her heart and her head. “My heart has always been in the Bay Area,” she says. Initially, however, Stanford was not on her radar because the university did not have a major astronomy program. That changed with KIPAC’s founding in 2003. The new institute brought together Stanford physics and astronomy with SLAC National Lab, a particle physics and instrumentation powerhouse, along with new researchers and support from The Kavli Foundation to advance multiple related fields under the umbrella of astrophysics.

“KIPAC quickly became a really exciting place for the science that I wanted to do,” says Wechsler. “We would not have been able to create such a vibrant astrophysics institute at Stanford without the substantial commitments from Stanford, SLAC, and The Kavli Foundation.”

After joining KIPAC as faculty in 2006, Wechsler helped build KIPAC’s leadership role in DES and contributed to LSST, the latter of which is just beginning a decade-long observing campaign at the Vera C. Rubin Observatory in Chile. She later took on a leadership role in DESI, serving as its first co-spokesperson starting in 2014. Together, these projects are mapping hundreds of millions of galaxies, revealing how invisible forces like dark matter and dark energy have shaped the universe over time. Over her years in the Kavli ecosystem, Wechsler has found that her connections with KICP have fostered fruitful collaborations — and she has seen many young researchers build their own paths of success leveraging networks across Kavli Institutes.

“Kavli support doesn’t just fund science — it helps create the conditions for young researchers to lead, collaborate, and take intellectual risks,” says Wechsler. “That’s been transformative, and it’s a part of Fred Kavli’s legacy that I deeply value.”