In the 1930s, the pioneering Danish scientist Inge Lehmann (1888–1993) made a groundbreaking discovery about the nature of Earth. Analyzing data from earthquakes, she determined that the heart of the planet is a solid inner core. Her discovery overturned the widely accepted theory of the core being fluid, but she trusted her calculations: “If I am right, and I know I am,” she wrote in a letter. A fiercely independent thinker, Lehmann forever changed our understanding of our planet.

If I Am Right, and I Know I Am provides a powerful portrait of an extraordinary woman while guiding readers through the fascinating history of earth science. Hanne Strager tells the story of Lehmann’s life and accomplishments, recounting how she battled inner demons and a mental breakdown and how she overcame pervasive prejudice to forge her own path in a male-dominated scientific world. In Lehmann’s era, women were expected to conform to rigid roles and were discouraged from pursuing serious academic careers. Even as Lehmann became a leading geophysicist, she had to navigate not only gender bias but also the isolation of being a lone woman in an overwhelmingly male field. Strager also follows the traces of an elusive love letter linking Lehmann romantically to another woman. The first biography of Lehmann, this book seamlessly weaves together her personal life and scientific achievements, highlighting her resilience and brilliance.

Inge Lehmann deserves renewed attention not only for her contributions to illuminating the internal structure of our planet—which were fundamental indeed—but also for her accomplishments in the face of many professional and personal challenges. If I Am Right, and I Know I Am is a story of defiance, resilience, and, against many odds, startling professional achievement. But even more revealing, this is a story of the foundational personalities and interpersonal relationships during one of the most productive times for geology, when subfields like seismology were contributing to paradigmatic shifts in our understanding of a dynamic Earth. -- Arthur L. Lerner-Lam, Lamont-Doherty Earth Observatory of Columbia University
A remarkable yet little-known figure, Inge Lehmann made pivotal contributions to geology by decoding seismic data that settled many open questions, including the structure of Earth’s core, in the 1930s. This brilliant and extremely well-researched biography of a pioneering scientist chronicles her triumphs and tribulations, ultimately revealing the sheer joy of scientific discovery while documenting how science is powered by passion and perseverance. Beautifully written, it is a fascinating and must-read account for anyone interested in the history of scientific ideas and what the life of the mind entailed in the twentieth century. -- Priyamvada Natarajan, Joseph S. and Sophia S. Fruton Professor of Astronomy and professor of physics, Yale University
Strager intersperses some discussion about early geoscience throughout the book, always in an accessible manner and without oversimplifying. * Midwest Book Reviews *
We now have a biography of [Inge] Lehmann. [Author Hanne] Strager pieces together Lehmann’s life in great detail, as well as providing potted histories of the scientific areas that Lehmann contributed to. I came away from it with great admiration for Lehmann and an appreciation for how lonely life was for many women scientists even in recent history. * Kate Gardner, Physics World *

Hanne Strager is a biologist and acclaimed science writer. Her books include The Killer Whale Journals: Our Love and Fear of Orcas (2023), which received a National Outdoor Book Award. She is the director of exhibitions of The Whale in Norway and was formerly the director of exhibitions at the Natural History Museum of Denmark.