1. if the multiverse is real then there are infinite universes with huge alien/lifeform densities.
2. random lifeforms are far more likely to be in high life density universes than low, and to see alien lifeforms everywhere.
3. therefore if there's a multiverse us not seeing aliens is practically statistically impossible, so there isn't one (p<infinitesimal).
qed
many quantum worlds and most cosmology btfo
someone send me my nobel