Michael Hammer Society of Fellows

Each year, IDSS selects postdoctoral fellows and students in the doctoral program in Social & Engineering Systems (SES) to join the Michael Hammer Society of Fellows. To-date, 34 Hammer Doctoral Fellows and 6 Hammer Postdoctoral Fellows carry on the legacy of Michael Hammer.

Michael Hammer was a visionary engineer, business leader, author, and MIT professor who made a remarkable impact on both MIT and the nation’s engineering and business landscape. For more on Michael Hammer and the Hammer Fellowship, including selection criteria, see our Hammer Fellowships page.

2025-2026 Fellows

Mehrdad Ghadiri

Postdoctoral Hammer Fellow
Mehrdad Ghadiri is a Michael Hammer Postdoctoral Fellow at IDSS, working with Professors Ali Jadbabaie and Alberto Abadie. As a computer scientist and applied mathematician, Mehrdad is broadly interested in fundamental problems in algorithms, linear algebra, optimization, and statistics with significant practical and societal applications. He is currently focused on problems in causal inference, numerical linear algebra, and large language models with applications in econometrics and network design, aiming to develop more efficient and reliable algorithms in these areas. His research has been recognized with several awards, including the INFORMS George B. Dantzig Dissertation Award (Honorable Mention), the Sigma Xi Best Ph.D. Thesis Award, Georgia Tech’s College of Computing Outstanding Doctoral Dissertation Award, and the Borealis AI Global Fellowship Award. Mehrdad earned his Ph.D. in Computer Science in the Algorithms, Combinatorics, and Optimization (ACO) program at Georgia Tech under the supervision of Santosh Vempala. During his doctoral studies, he developed algorithms for fundamental problems in optimization, causal inference, and tensor decompositions.

Tai-Long He

Postdoctoral Hammer Fellow
Tai-Long He is a Michael Hammer Postdoctoral Fellow at MIT IDSS, working with Professor Daniel Varon. He is an atmospheric scientist interested in using remote sensing and machine learning to quantify human emissions of greenhouse gases and air pollutants. His current research focuses on detecting facility-level methane leaks using satellite observations. Tai-Long received his Ph.D. in Atmospheric Physics in 2022 and his Honours Bachelor of Science in Physics in 2016, both from the University of Toronto.

Levi Grenier

Doctoral Student Hammer Fellow
Levi Grenier is a doctoral student in IDSS. His research focuses on group decision-making, and his current work examines the effect of social influence on those processes. Previously, Levi worked under Professor Vicky Yang as a predoctoral research associate in the System Dynamics group at the MIT Sloan School of Management. Levi studied applied mathematics at Colorado School of Mines. In his work, he hopes to improve our understanding of collective action in groups — or the lack of it — to arrive at actionable conclusions for policy and management.

Edrian Paul Liao

Doctoral Student Hammer Fellow
Edrian ‘Ed’ Liao is a first-year Ph.D. student at the MIT Institute for Data, Systems, and Society (IDSS). As an international student from the Philippines, he is passionate about enabling computational sustainability in under-resourced rural and urban communities. His research explores community-centered AI for climate adaptation planning and disaster risk management, as well as the design of AI and environmental policy frameworks for the developing world. In 2025, he earned his B.S.E. in Electrical and Computer Engineering and Computer Science from Duke University, where he was a Karsh International Scholar. He also completed a certificate in Science and Society, focusing on the social and ethical implications of emerging technologies in the Global South.

Yanchen Liu

Doctoral Student Hammer Fellow
Yanchen Liu is a Social and Engineering Systems PhD student at MIT IDSS. His research interests mainly lie in AI/LLM safety, alignment, and scalable oversight. Previously, He obtained his Master’s degree from Harvard University, where he worked with Prof. Hima Lakkaraju and his Bachelor’s degree in Computer Science (with Highest Honors) from the Technical University of Munich, with a minor in Computational Linguistics at Ludwig Maximilian University of Munich, supervised by Prof. Hinrich Schütze. Also, he had the opportunity to visit the Stanford NLP Group, collaborating with Prof. Diyi Yang for one year.

Ryan Hardesty Lewis

Doctoral Student Hammer Fellow
Ryan Hardesty Lewis is an IDSS doctoral student advancing machine learning, real-time simulation, and decentralized digital-twin systems for robotics, automation, and large-scale geospatial systems. He has collaborated with Dr. Junfeng Jiao at UT Austin’s Urban Information Lab and with Dr. Anthony Townsend and Michael Samuelian at Cornell Tech’s Urban Tech Hub on deployable tools that bridge research and practice. He holds M.S. degrees from Cornell (Information Systems) and the Technion (Applied Information Science) and a B.S. in mathematics with honors from the University of Texas at Austin.