Gravitational memory makes wormholes more stable ⚡ экспресс
A class of traversable wormholes is investigated with an effective Casimir source supplemented by gravitational memory. On a time-dependent gravitational background, the vacuum polarization acquires a permanent shift, resulting in an energy density expressed as the sum of the usual negative term ~r^{-4} and a positive correction ~r^{-7}. The shape function is derived from Einstein's equations, and the redshift function from a barotropic equation of state with a regularity condition. The flare-out condition determines the allowed memory parameter and separates regimes dominated by Casimir versus phantom matter. Analysis of energy conditions shows inevitable violation of the radial null energy condition at the throat. The shadow radius computed for allowed solutions agrees with EHT observations of M87*. Gravitational memory softens the Casimir support, alters throat geometry, and modifies the internal stress distribution.
Wormholes — tunnels through curved spacetime, allowed by general relativity. To be stable, they need repulsive energy — the kind that pushes apart rather than attracts. A source can be the Casimir effect, discovered by Hendrik Casimir: two plates in a vacuum are drawn together as if the space between them pushes them outward.
A gravitational wave passing through a wormhole leaves behind a strain — gravitational memory: a trace that doesn't fade away. Inside the tunnel, this trace adds ordinary energy to the repulsive kind, blending them. Near the throat, the repulsion is stronger, while along the sides the tunnel is held more gently — the wormhole becomes stable.
Recalculating the shape, the authors showed: such a wormhole casts a shadow like a black hole, precisely matching the silhouette of M87* measured by the Event Horizon Telescope. A surprise: if several waves have passed, the imprints stack up, and the shadow may quiver. Perhaps telescopes are already seeing these objects, not yet distinguishing them from black holes.
🎯 The Casimir effect was predicted by Hendrik Casimir in 1948 over a cup of coffee while discussing the properties of the vacuum.
🎬 The wormhole as a portal is familiar from the movie Interstellar, where the scientific basis was laid by [scientist:Kip Thorne]Kip Thorne[/scientist].