Probability and Philosophical Value of Multiverse Theories

In this century, the proliferation of multiverse theories transformed people's perception of reality once again, expanding the boundary of the cosmos to include an infinity of "infinite" universes. However, such speculations are inherently proofless, which arouses heated debate around the multiverse's likelihood and potential impact on our universe. Focusing on these two aspects, this article reviews nine prominent multiverse theories raised in Brian Greene's Hidden Reality and Michio Kaku's In Parallel world and considers the philosophical value of current multiverse research. This article reveals the limitations of the Observer First world view adopted by the scientific method and discusses an alternative World First perspective in understanding reality, which would revolute the relationship between physics and philosophy as disciplines.