JB: Is there any way of testing your idea observationally?
BARBOUR: I cannot as yet see any direct experimental way of testing this particular idea. What is needed above all is development of the mathematics. In my view, quantum cosmology is rather like the quantum physics of the stationary states of huge molecules, and the development of ideas used in atomic and molecular physics might help. Quite a lot of work has already been done in this direction in the program I mentioned earlier. But in principle predictions can be made in the context of the Wheeler DeWitt equation. However, nearly all of them at this stage are rather difficult because of the mathematics. You're dealing with complicated systems, you don't know how to find the solutions; there's a whole lot of issues there.
Another issue is that cosmology is a special subject because it's dealing with a unique thing. There is only one universe. There's a philosophical question: how can you do real science on a unique object?
JB: Have you ever considered that the world is an invention, and there's not an a priori existence before discoveries of people like yourself?
BARBOUR: I believe in the world; I'm a realist, but it remains a conjecture.
JB: Isn't this a kind of naive materialism? Wallace Stevens addressed the idea that the words of the world are the life of the world. Norman O. Brown noted that nature isn't created ... it is said. But I don't know of any notable physicists today who are seriously concerned with the role that language plays in the creation of reality.
BARBOUR: The words are meaning something. What impresses me is that, despite what you say, the rules of the game of science have stayed amazingly constant, despite the fantastic changes in how we see the world. Basically, the assumption has always been that that there are material things that move around subject to the constraints of geometry. There is change subject to order. Science or at least physics has been about establishing how those changes take place and describing them mathematically. Every now and then they lead to a dramatic new way in looking at the world, but the rules of the game have always been the same really, going right back to geometry and ancient astronomy.
I personally believe the world is still probably very much richer than we imagine,
and that we still may well be only just scratching the surface of it. If you climb
a mountain range you get different views as you go up. When you've got to the
top you can understand what you could see lower down, but you couldn't understand
it properly when you were lower down. I see the progress of science being like
that, that suddenly completely new vistas are opened up, and you find new ways
to think about it. I do think we are discovering the world, not inventing it.
But John Wheeler sometimes seems to suggest that we create the universe. He thinks