Radial motion into an Einstein-Rosen bridge

TL;DR

This paper analyzes the radial motion of particles into an Einstein-Rosen bridge, showing that such wormholes are geodesically complete and could be the true nature of astrophysical black holes, possibly linking to other universes.

Contribution

It demonstrates the geodesic completeness of Einstein-Rosen bridges and distinguishes their physical properties from Schwarzschild black holes, suggesting they could be the actual structure of black holes.

Findings

Timelike geodesics in wormholes are complete.

Discontinuity in the expansion scalar at the horizon.

Einstein-Rosen bridges may represent actual black holes with other universes inside.

Abstract

We consider the radial geodesic motion of a massive particle into a black hole in isotropic coordinates, which represents the exterior region of an Einstein-Rosen bridge (wormhole). The particle enters the interior region, which is regular and physically equivalent to the asymptotically flat exterior of a white hole, and the particle's proper time extends to infinity. Since the radial motion into a wormhole after passing the event horizon is physically different from the motion into a Schwarzschild black hole, Einstein-Rosen and Schwarzschild black holes are different, physical realizations of general relativity. Yet for distant observers, both solutions are indistinguishable. We show that timelike geodesics in the field of a wormhole are complete because the expansion scalar in the Raychaudhuri equation has a discontinuity at the horizon, and because the Einstein-Rosen bridge is represented by the Kruskal diagram with Rindler's elliptic identification of the two antipodal future event horizons. These results suggest that observed astrophysical black holes may be Einstein-Rosen bridges, each with a new universe inside that formed simultaneously with the black hole. Accordingly, our own Universe may be the interior of a black hole existing inside another universe.