Well, it's convenient. It removes the need for proof. Replace
magnetic monopole with any other thing we can't find and you can
see the danger in this line of thinking. God is too far away.
The parallel universes don't have a measurable impact. The
M-brane is prior to the Big Bang event and therefore not
observable. So to me, best to leave them as convenient
constructs in lieu of something better but not to lean too
heavily on them imo.
