Prominent physicists are divided about whether any other universes exist outside of our own. Some physicists say the multiverse is not a legitimate topic of scientific inquiry. Some physicists say the multiverse is not a legitimate topic of scientific inquiry.  Concerns have been raised about whether attempts to exempt the multiverse from experimental verification could erode public confidence in science and ultimately damage the study of fundamental physics.  Some have argued that the multiverse is a philosophical notion rather than a scientific hypothesis because it cannot be empirically falsified. The ability to disprove a theory by means of scientific experiment has always been part of the accepted scientific method.  Paul Steinhardt has famously argued that no experiment can rule out a theory if the theory provides for all possible outcomes. 
In 2007, Nobel laureate Steven Weinberg suggested that if the multiverse existed, "the hope of finding a rational explanation for the precise values of quark masses and other constants of the standard model that we observe in our Big Bang is doomed, For their values would be an accident of the particular part of the multiverse in which we live. "