Are wormholes real or just science fiction?

The answer

Wormholes (Einstein-Rosen bridges) are theoretically permitted by general relativity as tunnels connecting distant points in spacetime. However, naturally occurring wormholes, if they exist, would be subatomic and collapse instantly. Keeping a wormhole open large enough for travel would require 'exotic matter' with negative energy density - something not known to exist in sufficient quantities. Recent theoretical work using quantum entanglement (ER=EPR conjecture) suggests deep connections between wormholes and quantum physics. While they remain mathematically valid, no observational evidence for macroscopic wormholes has ever been found.