Newton's Open Problem: Earth's Figure and Universal Gravitation

I am writing a book with Oxford University Press that provides a new answer to a basic question: how did we come to have strong evidence for Isaac Newton's law of "universal" particle-to-particle gravitation? I argue that the answer lies buried in the history of physical geodesy, an often-overlooked research program aimed at deriving and measuring Earth's figure. For several centuries, correctly predicting Earth's figure was the most significant test for Newton's most controversial assumption: that the attraction of (celestial) bodies is the resultant force of the mutual attractions among their parts. Testing this assumption was a prerequisite for confirming that the motive forces observed in astronomy and on Earth's surface are instances of a "universal" force law.

My book reconstructs the history of the problem of the Earth’s figure from Newton's Principia up to the 1970s. Getting this history right is not only about setting the record straight. Gravitational physics has long served as a methodological paradigm for obtaining strong empirical evidence. Throughout my research, I show that the development of physical geodesy provides us with new lessons on how theorizing, measurement, and statistical inference contribute to empirical success in physical science.

Different geodetic measurement operations sketched in: Pierre Bouguer and Charles-Marie de La Condamine in La figure de la terre, Paris 1749.

Hydrostatic derivation of planetary equilibrium figure in: Alexis Clairaut, Théorie de la figure de la terre : tirée des principes de l'hydrostatique, Paris 1743.

Papers related to this project:

*Winner of the 2022 APS History and Philosophy of Physics Essay Price

*Winner of the 2021 Du Châtelet Price in Philosophy of Physics