Loading Events

« All Events

  • This event has passed.

Caspar Jacobs (Merton College): How (Not) to Define Inertial Frames

30 January 2023, 2:00 pm3:30 pm

This will be a hybrid lecture: you can attend in person in our usual LAK 2.06 seminar room, or on Zoom:

 Join On Zoom

Meeting ID: 852 3006 9457
Passcode: 297258

Abstract: It is nearly impossible to open a textbook on Newtonian mechanics without encountering the concept of inertial frames: frames which are uniquely privileged by the theory’s dynamics. In this paper, I argue that extant definitions of inertial frames are unsatisfactory. I criticise two common definitions of inertial frames: law-based definitions, according to which inertial frames are simply those in which the laws are true (in their simplest form), and structure-based definitions, according to which inertial frames are those that are `adapted’ to spacetime structure. Both definitions misclassify certain non-Newtonian worlds as Newtonian. I then offer a new, symmetry-based definition of inertial frames. This definition follows from the dynamical symmetries of Newtonian mechanics, and so offers a non-conventional way of specifying the dynamically privileged frames. This result clarifies the foundations of Newtonian mechanics and accounts for the empirical success of coordinate-dependent formulations of it.

Caspar Jacobs is a junior research fellow at Merton College, University of Oxford. His main research areas are philosophy of physics and philosophy of science. He’s also interested in the metaphysics of quantities, and in Early Modern history and philosophy of science.


30 January 2023
2:00 pm – 3:30 pm
Event Category:


Bryan W. Roberts


LAK 2.06
Lakatos Building
London, WC2A 2AE United Kingdom
+ Google Map