Stephen Hawking famously asked “what is it that breathes fire into the equations and makes a universe for them to describe?” [93]. In the context of the MUH, there is thus no breathing required, since the point is not that a mathematical structure describes a universe, but that it is a universe
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As a way out of this philosophical conundrum, I have suggested [12]) that complete mathematical democracy holds: that mathematical existence and physical existence
are equivalent, so that all mathematical structures have the same ontological status. This can be viewed as a form of radical Platonism, asserting that the mathematical
structures in Plato’s realm of ideas, the Mindscape of Rucker [6], exist “out there” in a physical sense [9], casting the socalled modal realism theory of David Lewis [92]
in mathematical terms akin to what Barrow [7, 8] refers to as “ in the sky”. If this theory is correct, then since it has no free parameters, all properties of all parallel universes (including the subjective perceptions of SAS’s in them) could in principle be derived by an infinitely
intelligent mathematician.
