our sense of wonder.”
The best that physicists can do to satisfy this sense of wonder, Weinberg seemed to believe, is to discover their holy grail, the final theory. “This may happen in a century or two,” he has written, “and if it does then I think that physicists will be at the extreme limits of their powers of explanation.”
The final theory envisaged by Weinberg promises to go far beyond current physics in clarifying the origins of the universe. It might, for instance, show how space and time emerged from still more fundamental entities that we as yet have no conception of. But it is hard to see how even a final theory could explain why there is a universe instead of nothing at all. Are the laws of physics somehow to inform the Abyss that it is pregnant with Being? If so, where do the laws themselves live? Do they hover over the world like the mind of God, commanding to exist? Or do they inhere within the world, amounting to a mere summary of what goes on inside it?
Cosmologists like Stephen Hawking and Alex Vilenkin sometimes entertain the first possibility, only to be perplexed by it. Here, for example, is Vilenkin on the “quantum tunneling” by which, he submits, the universe might have been born from nothing at all: “The tunneling process is governed by the same fundamental laws that describe the subsequent evolution of the universe. It follows that the laws should be ‘there’ even prior to the universe itself. Does this mean that the laws are not mere descriptions of reality and can have an independent existence of their own? In the absence of space, time, and matter, what tablets could they be written upon? The laws are expressed in the form of mathematical equations. If the medium of mathematics is the mind, does this mean that mind should predate the universe?” As to whose mind this might be, Vilenkin passes over that question in silence.
Hawking, too, has admitted to bafflement over the ontological status, and seeming potency, of the laws of physics: “What is it that breathes fire into the equations and makes a universe for them to govern? Is the ultimate unified theory so compelling that it brings about its own existence?”
If the ultimate laws of physics, like Plato’s eternal and transcendent Forms, did have a reality of their own, that would only raise a new mystery—two mysteries, in fact. The first is the one that bothered Hawking. What gives these laws their ontic clout, their “fire”? How do they reach out and make a world? How do they force events to obey them? Even Plato needed a divine craftsman, a “demiurge,” to do the actual work of fashioning the world according to the blueprint that the Forms provided.
The second mystery that arises if the laws of physics have their own transcendent reality is even more basic: Why should those laws exist? Why not some other set of laws or, even simpler, no laws at all? If the laws of physics are Something, then they cannot explain why there is Something rather than Nothing, since they are a part of the Something to be explained.
So consider the other possibility—that the laws of physics have no ontological status of their own. On this view, these laws do not hover over the world or exist prior to it in any way. Rather, they are merely the most general possible summary of patterns of events within the world. On this view, the planets don’t orbit the sun because they “obey” the law of gravity; instead, the law of gravity (or rather, the general theory of relativity, which superseded it) summarizes a regular pattern in nature, a pattern that includes the planetary orbits.
Suppose the laws of physics—even the deepest laws, those that will make up the hoped-for final theory—are indeed just summaries of what goes on in the world. Then how can those laws explain anything? Perhaps they can’t. That was what Ludwig Wittgenstein thought. “The whole modern conception of the world,” Wittgenstein wrote in his Tractatus, “is founded on the illusion that the so-called laws of nature are the explanations of natural phenomena. Thus people today stop at the laws of nature, treating them as something inviolable, just as God and Fate were treated in past ages.”
Weinberg clearly does not share this Wittgensteinian skepticism. Physicists aren’t like priests or oracles. They really do explain things. Explanation is what has happened when they are moved to say, “Aha!” To