That is part of the definition I suggested. If we knew it was there, then it would be part of our universe. It's a one-way valve on knowledge but I still think

That is part of the definition I suggested. If we knew it was there, then it would be part of our universe. It's a one-way valve on knowledge but I still think it is useful to define it. There is plenty of work to be done on the definitions. Should we like to, we could have a more rigorous natural language regarding observables by defining a boundary for where the physical universe begins and ends. Shrödinger's wave function does not appear to be part of the physical universe but yet we have an odd kind of observation of it in the form of experimental verification of theory. The space of theoretical physics then becomes part of the greater universe. I think Penrose's ideas warrant more precisely defined language.