ESHS/HSS Annual Meeting

Deriving Gravity: 20th Century Machian Models and the Zitterbewegung Hypothesis

• In Event: Shifting Perspectives on Histories of Gravity and Mass 1

English Abstract

This talk examines the overlooked history of alternative theories of gravity that derive gravitation as a necessary consequence of the relativity of inertia—an idea usually associated with “Mach’s principle.” Soon after general relativity (GR) was developed, it became clear that Einstein’s generally covariant framework failed to realise Mach’s idea as intended since GR grants autonomous dynamics to the metric rather than grounding them in matter relations. Throughout the 20th century, leading physicists such as Erwin Schrödinger, Robert Dicke, and Dennis Sciama sought to implement Mach’s principle more fully, with several proposals profoundly influencing the mid-century renaissance of GR and its cosmological implications. My talk focuses on a lesser-known subclass of these theories—those of Reissner (1915), Barbour (1975), and Cook (1976)—which independently derive gravity as a byproduct of the relativity of inertia combined with the hypothesis that elementary particles vibrate. While relative particle motion defines inertial frames,the additional “internal motion” of particles produces an attractive force without the need to postulate an independent gravitational potential. In the models of Barbour (1975) and Cook (1976) this internal motion is identified it with the zitterbewegung of elementary particles which occurs at c and gives an emergent gravito-static force of the correct order of magnitude (according to cosmological criteria). I conclude by noting that this realist interpretation of quantum zitterbewegung has also been leveraged to develop a kinetic theory of “rest-energy” since the 1990s (Hestenes, 1990). The talk would fit nicely into the session on the history of alternative theories of gravity and concepts of mass, touching on both of these topics through a highly original and under-explored approach to gravity that combines quantum mechanics with considerations of the cosmos as a whole.

Author

• Jonathan Emile Fay, University of Bristol