Alex Wellerstein is a historian of science and nuclear technology. He is a professor at the Stevens Institute of Technology in Hoboken, New Jersey, in the Science and Technology Studies program in the School of Humanities, Arts, and Social Sciences, and is currently a visiting researcher at the Nuclear Knowledges program at the Center for International Studies at Sciences Po in Paris, France.

His first book, Restricted Data: The History of Nuclear Secrecy in the United States (University of Chicago Press, 2021), is the first attempt at a comprehensive history of how nuclear weapons ushered in a new period of governmental and scientific secrecy in the USA.

His second book, The Most Awful Responsibility: Truman and the Secret Struggle for Control of the Atomic Age, was published in December 2025 by HarperCollins, and is a new, surprising history of Truman and the atomic bomb, from Hiroshima through the Korean War.

Other current projects include: research into the past, present, and potential future of Presidential nuclear weapons use authority; software for making full-scale nuclear war simulations; and a video game about life after a full-scale nuclear war set in the early 1980s.

His writings on the history of nuclear weapons have appeared in The New Yorker, The Atlantic Magazine, Harper’s Magazine, and the Washington Post, among other venues, and his online nuclear weapon effects simulator, the NUKEMAP, has been used by over 50 million people globally.

Since 2024 he regularly writes a blog on the post-apocalyptic imagination in fact and fiction: Doomsday Machines.

Since 2011 he has occasionally updated a blog about nuclear history and secrecy: Restricted Data.