Chinese Acad Sci, Inst High Energy Phys, Beijing 100039, Peoples R China
; Chinese Acad Sci, Interdisciplinary Ctr Theoret Studies, Beijing 100080, Peoples R China
; Chinese Acad Sci, Grad Sch, Coll Phys Sci, Beijing 100049, Peoples R China
We study the island universe model, in which initially the universe is in a cosmological constant sea, then the local quantum fluctuations violating the null energy condition create the islands of matter, some of which might correspond to our observable universe. We examine the possibility that the island universe model is regarded as an alternative scenario of the origin of observable universe.