" The Einstein equivalence equation has, in effect, begun the ‘dematerialization’ of physical reality. The only way in which the world can still be described as the ‘material’ world, or the term materialism can preserve its original significance, is to redefine ‘matter’. But how? Materialism, if one wants to retain the term, seems to have unexpectedly become a much more open doctrine. "

― Paul C.W. Davies , Information and the Nature of Reality: From Physics to Metaphysics