Sara Imari Walker

Sara Imari Walker is an American theoretical physicist and astrobiologist with research interests in the origins of life, astrobiology, physics of life, emergence, complex and dynamical systems, and artificial life. She is a co-founder of the astrobiology social network SAGANet, and on the board of directors for Blue Marble Space, a nonprofit education and science organization.

Education and background Walker was born and raised in Connecticut. She attended Cape Cod Community College and studied at the Florida Institute of Technology, where she graduated cum laude earning a B.S. in physics in 2005. She earned her Ph.D. in physics and astronomy in 2010 from Dartmouth College.

Career After graduating from Dartmouth, Walker began a postdoctoral fellowship at the Georgia Institute of Technology working at the NSF/NASA Center for Chemical Evolution. She became a faculty member for the Center for Social Dynamics and Complexity, as well as a graduate faculty member for the Department of Physics and Complex Systems Initiative at ASU in 2014. She seeks to develop new theories of physics to explain what life is, how it emerged, and what signs of life might look like on other planets. She is currently working on developing new technology to detect possible signs of life with NASA as a Principle Investigator for their Interdisciplinary Consortia for Astrobiology Research (iCAR). She uses mathematical models to investigate chemical evolution and the development of networks on Prebiotic Earth. She looks at information flow in biotic and abiotic systems to further define life and its emergence. Some of the highlights of her work in this field so far are:

The origin of homochirality Walker has studied the possible mechanisms of the origin of homochirality, which is a key problem in the origin of life. In her research she has used several models such as the Sandars polymerization model, the Langevin equation, and the activation-polymerization-epimerization-depolymerization (APED) model to imitate potential prebiotic conditions for autocatalytic polymerization networks. Walker et al. discovered that only networks with long polymers show potential to produce significant spontaneous asymmetrical chirality in speculative early Earth conditions. It was shown that in biological systems the components are subordinate to the whole, in what is called top-down causation. They also determined that living systems have a separation of data from machinery, and non-trivial replication. Walker has shown theoretically how the occurrence of these biotic traits in an abiotic system present a possible framework for the origin of life. She has had press coverage in dozens of news sources, and been active on multiple media platforms. She is a co-founder of the astrobiology social network SAGANet, and was a guest scientist on the educational website I'm a Scientist: Get Me Out of Here!.

Her book Life as No One Knows It: The Physics of Life's Emergence came out in 2024.

Organizations Walker is a member of multiple scientific organizations, including the Blue Marble Space Institute of Science, the NASA Astrobiology Institute, the Foundational Questions Institute (FQXI), and the International Society for Artificial Life, serving on its board of directors. She is also a member of the Complex Systems Society and is on the board of directors for Blue Marble Space. Fellow, ASU-SFI Center for Biosocial Complex Systems, Arizona State University and Santa Fe Institute 2015 – 2018 Fourth Prize, Foundational Questions Institute Essay Contest 2012. NASA Postdoctoral Program Fellowship, NASA Astrobiology Institute 2011 Gordon F. Hull Fellowship, Dartmouth College 2009 – 2010 New Hampshire Space Grant/NASA Graduate Fellowship, NH Space Grant 2007 – 2008