Modified Gravity (MOG), the speed of gravitational radiation and the event GW170817/GRB170817A

Understand

Modified gravity (MOG) is a covariant, relativistic, alternative gravitational theory whose field equations are derived from an action that supplements the spacetime metric tensor with vector and scalar fields.

• Both gravitational (spin 2) and electromagnetic waves travel on null geodesics of the theory's one metric.
• Despite a recent claim to the contrary, MOG satisfies the weak equivalence principle and is consistent with observations of the neutron star merger and gamma ray burster event GW170817/GRB170817A.