Definition of parallel universe in US English:

parallel universe

(also parallel world)

noun

Physics
  • 1(in quantum mechanics) a universe theorized as existing alongside our own, although undetectable.

    ‘the concept of parallel universes is not widely accepted in physics, but is gaining ground’
    • ‘Could black holes be routes from our Universe to the other parallel universes?’
    • ‘This "wormhole" may connect two parallel universes, or even distant parts of the same universe.’
    • ‘In the multiverse explanation there is a vast multiplicity of parallel worlds in which all possible laws of physics exist.’
    • ‘You probably haven't heard of the many-worlds theory in quantum mechanics, but a lot of people consider the idea of parallel universes.’
    • ‘One puzzle, however, is that, according to Einstein's equations, the funnel of a black hole necessarily connects our universe with a parallel universe.’
    • ‘Another brane—a parallel universe—resides a subsubatomic distance away.’
    • ‘If our universe is not unique, i.e., if we are but one of perhaps an infinite number of parallel universes, then one can logically posit that our particular universe is fine-tuned only because if it were not, we wouldn't be here to talk about it.’
    1. 1.1 (in fantasy or science fiction) a world conceived of as coexisting with and having certain similiarities to the known world but different from it in some fundamental way.
      ‘they are whisked out of World War II London into the spectacular parallel universe known as Narnia’
      ‘a trilogy of fantasy novels taking place across many parallel worlds’
      figurative ‘the senator accused her of living in a parallel universe’
      • ‘Gradually, she is becoming immersed in the parallel universe that is the world of football.’
      • ‘They live in some airy-fairy arty-farty parallel universe in which the world is seen as owing writers a living - and a very handsome living at that.’
      • ‘War of Glory is a 3D fantasy MMORPG themed with battles taken place within three parallel universes and an overlapping one.’
      • ‘Twilight has its own parallel world, its own fan culture that has been forming on the net since day one.’
      • ‘Parallel universes are a venerable tradition in science fiction and fantasy.’
      • ‘Monty Python is reminiscent of Lewis Carroll's Through the Looking-Glass, in which the author creates a parallel universe governed by rules which appear ridiculous to the reader, but are entirely logical within their own dimension.’
      • ‘What parallel universe had he been living in?’
      • ‘Older musicians will know, of course, that Mr Pratchett is the creator of the Discworld, a parallel universe or fantasy world which contains not only humans but also trolls, golems, and assorted other wonders.’
      • ‘To be in London this past week, though, was to live in a parallel world, a place where football means football and not administrators and insolvency experts and lawyers and accountants.’
      • ‘If ever you need proof that the equity markets inhabit a parallel universe then look at the way they treat technology.’
      • ‘She's a celebrity in a parallel world that passes under the radar for most of us.’
      • ‘Celebrities are fascinating because they live in a parallel universe - one that looks and feels just like ours yet is light-years beyond our reach.’
      • ‘Either I grew up in a parallel universe, or things have gone awfully soft in the two decades since I graduated.’
      • ‘Each in their own way is drawn to what appears to be a parallel world and the characters inhabiting it are brilliantly sketched.’
      • ‘The Treasury, however, still lives in something of a parallel world’
      • ‘The house is haunted - and it's about as haunted as a house can get, including the occasional door being opened to parallel worlds.’