Alcubierre Drive

The Alcubierre warp drive, while theoretically permitted by Einstein’s field equations, faces extreme physical and engineering constraints that make it currently unfeasible.

The drive requires a region of spacetime to contract in front of a spacecraft and expand behind it, effectively moving the craft faster than light relative to distant observers.

However, achieving this would demand “exotic matter” with negative energy density—something not known to exist in usable quantities.

Estimates suggest it would require mass-energy equivalent to multiple solar masses, though revised models have reduced this somewhat.

Maintaining a stable warp bubble also raises issues in quantum field theory, including potential instabilities and causality violations, as well as containment of the drive's boundary layer without destroying the payload.