Light Dragging Phenomenon and Expanding Wormholes

TL;DR

This paper investigates the dynamics of an expanding wormhole throat, showing that light may follow the expanding structure, with implications for understanding wormhole physics and light propagation in curved spacetime.

Contribution

It introduces the concept of light dragging along an expanding wormhole throat and analyzes the stress-energy distribution in such a spacetime.

Findings

Wormhole throat expands exponentially with satisfied flare-out condition.

Negative energy density near the throat resembles Casimir energy.

Light propagation may follow the expanding wormhole throat, indicating a light dragging phenomenon.

Abstract

The null geodesic congruence for the Lorentzian version of Hawking's wormhole is studied, in spherical Rindler coordinates. One finds that the wormhole throat expands exponentially and the "flare - out" condition is satisfied. A time reversal is equivalent with an inversion applied to the radial coordinate. The stress energy is mostly located near wormhole's throat and the anisotropic fluid is comoving with the spherical distribution of accelerating observers. Far from the throat (the light cone in Cartesian coordinates) the negative energy density acquires an expression similar with the Casimir energy density between two perfectly reflecting plates. We conjecture that the light propagation follows the throat of a preexisting expanding wormhole (a "light dragging" phenomenon).