Really NEJ, that's interesting. So why did he put it in a pop physics book I wonder? I'm just reading The GrandDesign at the moment. A bit misleading isn't it?
It's not a controversial point I'm making. Notice that Hawking couched it in terms of "according to M-Theory," which is a subset of string theory.
Note the following excerpt from an interview with a leading string theory researcher, Brian Green:
Do you think string theory will ever be accepted as widely as, say, the theory of general relativity? What would it take for that to happen?
Well, the real reason why general relativity is widely accepted is because it made predictions that were borne out by experimental observations. The primary one that put general relativity on the map was its prediction of the bending of starlight by the sun, which in 1919 was confirmed by observation during a solar eclipse. That was the moment when general relativity emerged from the realm of theory and entered the realm of being a piece of reality as we know it.
For string theory to have the kind of acceptance of general relativity, it's got to do the same thing. It's got to make a prediction that is borne out by some experiment. And as yet, we haven't quite gotten to the stage where we can make definitive predictions which, if they're found, the theory was right, and if they're not found, the theory was wrong.
But we have gotten to the stage where we can make some rough predictions for things that might happen at the future accelerators that are now being built, in particular one in Geneva, Switzerland, called the Large Hadron Collider, which should be ready about 2007 or 2008. If some of the predictions that string theory says might happen are borne out through experiment at that accelerator, then I think it's quite possible that string theory would be as accepted as general relativity.
http://www.pbs.org/wgbh/nova/physics/conversation-with-brian-greene.html