Question to Weinberg: On Believing in Multiple Universes and Religious Faith

Gingerich: Steve, here’s a final question for you. You completely reject any notion of a divine designer, but on what basis beyond faith can you justify the idea of multiple universes being more valid?

Weinberg: Oh, I thought I had answered that but I would be happy to say it again. I don’t maintain that that idea is true. I mean, that is a possibility that has emerged and it remains a possibility. When I become convinced of its truth, it will be because the equations of physics that unify the various forces - quantum mechanics, relativity, all that - have that as a consequence. It won’t be an act of faith. It will be a deduction from laws which we, unfortunately, at present don’t know. Now you may say that it is an act of faith because we will not be able to observe these other Big Bangs, or these other terms in the wave function. But that’s the fate that science has been in for a long time. We don’t really observe quarks and we never will see the track of a quark. And yet we believe in quarks because the theories that have quarks in them work. And in the same way, if we come to that - and we have not yet come to that - we will believe in these other Big Bangs or these other terms in the wave function because the theories in which they appear work.

Gingerich: ... Ladies and gentlemen, let me just remind you ... that this is the very room in which in April of 1920 the very famous Shapley/Curtis debate on the scale of the universe took place; a debate that has gone down in astronomical lore ever sense. And I think you have been very lucky to have been present at this debate today which I suspect will also assume mythic proportions.

Contributed by: Sir John Polkinghorne and Steven Weinberg