If there is one universe, and we're the only life, that's remarkable. If there are many universes (multiverse), then it's plausible only 1 instance of life for

If there is one universe, and we're the only life, that's remarkable. If there are many universes (multiverse), then it's plausible only 1 instance of life forms in a few of them, and we might be the only life in the entire visible universe. Is there a name for this theory? I share this because I frequently see assumptions that there must be other life somewhere.