Glowing disks ripping holes in the skyline are not where physicists started when they checked the portals in Thor: The Dark World. The real entry point was the geometry of spacetime: could a shortcut between distant regions be made consistent with Einstein’s field equations without destroying whoever steps through.
Researchers turned to traversable wormhole solutions, the Morris Thorne metric and the stress energy tensor that encodes how matter curves spacetime. By plugging realistic mass and distance scales into these equations, they asked what kind of energy density would be required to hold a wormhole throat open long enough for a person sized traveler, while keeping tidal forces within human tolerance and avoiding an event horizon that would turn the portal into a one way black hole.
The math pointed to violations of classical energy conditions, demanding so called exotic matter with negative energy density that must be large, stable and controllable. Known quantum effects like the Casimir effect do produce negative energy, but only at microscopic scales and with severe quantum inequality limits. That gap between cinematic city spanning portals and tiny laboratory level fluctuations is where Thor stays firmly in fantasy, even if the spacetime diagrams on the whiteboard are drawn straight from real relativity.
