Original: The multiverse ( or meta-universe , metaverse ) is the hypothetical set of multiple possible universes ( including the historical universe we consistently experience ) that together comprise everything that exists : the entirety of space , time , matter , and energy as well as the physical laws and constants that describe them .
Simplified: A multiverse ( or meta-universe ) is the theory of a set of multiple possible universes , including our universe , which make up reality .