OK, so the inescapable key of David Deutsch’s world view is that the Everett / Wheeler idea of many worlds forming the multiverse, is … well … fundamental to all of reality.
I’ve said twice – once after his introduction and again after reading the whole of his Fabric of Reality – that Deutsch argues his case convincingly. The real world behaves virtually “as if” it was as it really is. However convincing, boy, is that gonna be hard to absorb into a natural world view.
Christian Hauck provided some helpful links to Max Tegmark’s MIT work on the parallel universes aspect of the multiverse. Hmmm – do I really want to go there ? Seems unavoidable – I may be some time.