Special Physics Seminar

Why is general relativity a geometric theory?
The role of the strong equivalence principle

Harvey R. Brown

Oxford University

Bimetric theories of gravitation, whether empirically correct or not, are a reminder that a dynamical metric field need not have chrono-geometric significance: its null geodesics need not characterize the motion of light, nor need it be surveyed by physical rods and clocks. In standard GR, the chronometric nature of the metric field is a consequence of the strong equivalence principle, which is not a consequence of the Einstein field equations. It is argued that in understanding the special theory of relativity as the appropriate limit of general relativity, the interpretation of special relativity that best tallies with this insight is the dynamical one defended by Pauli, J�nossy, Bell and others.