Meaning of mirror universe | Babel Free

Definitions

1. An alternative universe within a fictional work, separate from the universe normally depicted, where familiar characters and settings are present but in a systematically "reversed" manner, often by being evil or otherwise hostile.
2. A hypothetical universe, a counterpart to this universe but with certain elementary particles reversed in a specific way.
   rare

Examples

“Star Trek: The Original Series introduced a mirror universe in which humans had aggressively conquered parts of the galaxy rather than forming the peaceful Federation, and the setting was revisited in several of the franchise's spinoff shows.”

“A mirror universe of fermions and forces isomorphic to but distinct from those we see couples directly to our universe only by gravity. […] Consequent effects are contrary to experiment. The possible existence of such a mirror universe is thereby excluded.”

CEFR level