The “many worlds” interpretation of quantum mechanics is an attempt to resolve the “measurement problem” by saying that all such measurements occur and define a branching reality. The quantum space time is reduced, or amplified, into a stupendously multifarious and phantasmogoric static space-time, and our subjective life journey is held to be an illusion, with the apparent “nowness” that we experience occurring at all times and places equally, and with equal conviction of uniqueness.
This construct bears no resemblance whatsoever to the popular notion of parallel universes, which includes the possibility of people and objects moving between them.
“The Elegant Universe” by Brian Greene...you might enjoy it.