Stephen Hawking recently stated that we do not need God to explain where everything comes from. Theoretical physics can provide the answer. My question to Hawking is: How does he explain the laws that were functioning with the Big Bang? Where do these laws come from? Physical laws are predictable, orderly events on which we can rely. Science is about testing knowledge against stated criteria or laws. So why is reality knowable (having laws to uncover, to use to our benefit)?

Not having read Hawking's book, I can't present _his_ answer; I'll try to respond to the question from the standpoint of someone who--as Hawking seems to do--thinks that theoretical physics is the ultimate explanatory authority.

The question of where did the laws in virtue of which phenomena are to be explained come from amounts to the question of what explains why the particular laws of physics that apply to our world do apply to it.

It seems to me that someone with Hawking's views would probably might that this simply is a question that we cannot answer at the moment: we lack the information necessary to give such an explanation, although, in principle, one could give such an explanation, and one might even--I can't do this, but someone else might--sketch the form that such an explanation would take. (I don't think that someone who shared Hawking's conviction could state conclusively that this is a question that cannot be answered: to do so would be to bet against science.)

The position that Hawking seems to be taking is one that certain philosophers are drawn to as well: for a strong statement of this sort of position, that I think would tend to support the answer that I gave on its behalf, you might check out Penelope Maddy's book, _Second Philosophy_.

I too have not read Hawking's book, but from reviews I've read Hawking's argument is based on a theory of multiple universes he develops as an application of brane cosmology, which is an application of membrame theory (or M-theory), which itself is a theoretical development from string theory.

In extremely general terms, this theoretical perspective seeks to explain the physical constants and physical laws in our universe by appeal to the diversity of physical and constants throughout the set of universes within the "multiverse," which is conceived of something like a set of separate space-times each governed by a different physical laws and constants.

Hopefully panelists with expertise in these esoteric areas can chime in with more details, but with respect to the "God question" the reviews I have read represent Hawking as arguing that the "structure" of the multiverse provides a satisfactory explanation of the existence of a space-time that contains the physical laws and constants of our universe. What I don't know, however, is whether there is anything within multiverse theories to block a regress of explanation: If we do not need to appeal to God to explain the existence of a single space-time within the multiverse, do we need to appeal to God to explain the existence of the multiverse in the first place, its cosmological "structure," etc.?

Also, this may be an obvious point but is worth stating nonetheless: These physical theories are not yet well-developed, much less demonstrated as true -- or, indeed, as far as I can tell, have been developed to a point where we know they are capable of being demonstrated as true.

To follow up on my earlier response: In the February 10, 2011 edition of the New York Review of Books, Steven Weinberg has an excellent review of Hawking and Mlodinow's book. The review, which is also published online at URL http://www.nybooks.com/articles/archives/2011/feb/10/universes-we-still-dont-know , addresses some aspects of your question -- and also contains some good information about the theories that Hawking and Mlodinow are attempting to popularize.

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