Its a slightly anthropocentric question isnt it Khandro? Are we, as a planet full of a myriad of different species of organic, thriving life, alone in the universe? It would seem extremely unlikely, given the sheer vastness of numbers of galaxies and stars and planets within the universe.
Are we, humans, as a conscious, intelligent species, alone in the universe? Slightly different question. Does intelligent life exist elsewhere in the universe? Probably. Just playing the numbers game should guarantee that. But at a stage in their civilisation where they can focus on such things as spaceflight and interaction with other races? Assuming, of course, that their drives and motivations are broadly similar to our own.Given the vastness of the universe, and the limits that form the basis of our current understanding of interstellar travel, that would seem extremely unlikely.Are we ever likely to meet and have meaningful, useful interactions with such a species? Much, much more difficult to say.. Should such an interaction occur, it seems far more likely that it would be at the instigation of an advanced alien species.....
As to the multiverse thing - its a theorectical construct, but regardless of the "thinness" of the "walls" that separate the various multiverses, communication or travel across such a boundary would be even more hypothetical, even less likely that developing FTL travel............