Toward Nonlocal Electrodynamics of Accelerated Systems

We revisit acceleration-induced nonlocal electrodynamics and the phenomenon of photon spin-rotation coupling. The kernel of the theory for the electromagnetic field tensor involves parity violation under the assumption of linearity of the field kernel in the acceleration tensor. However, we show that parity conservation can be maintained by extending the field kernel to include quadratic terms in the acceleration tensor. The field kernel must vanish in the absence of acceleration; otherwise, a general dependence of the kernel on the acceleration tensor cannot be theoretically excluded. The physical implications of the quadratic kernel are briefly discussed.

Toward Nonlocal Gravitation

Is gravity nonlocal? Einstein interpreted the principle of equivalence of inertial and gravitational masses to mean that there exists a profound relationship between inertia and gravitation. Based on Einstein’s fundamental insight, it would seem natural to extend history dependence to the gravitational domain. However, it is not clear how to develop a nonlocal extension of Einstein’s local principle of equivalence. To go forward, we therefore choose an indirect approach based on a certain analogy with electromagnetism. In a material medium, the electromagnetic constitutive relations are nonlocal and this fact leads to the nonlocal electrodynamics of media. It turns out that general relativity can be formulated in a form that resembles the electrodynamics of media. Making the corresponding gravitational constitutive relations nonlocal would then lead to nonlocal GR. This indirect approach is adopted in the rest of this book.