It turned out there was a substantial body of evidence for Lyell's assumption - we can skip the details here, except to say that the first big public debates concerned how river valleys were formed. (Was it the biblical flood or gradual erosion? This topic was as hot in the 1820s as the topic of God-versus-Darwin is today.) Uniformitarianism took over the study of geology, and then biology, and then cosmology. Throughout the 20th century, essentially all important theorists have worked from the assumption that the constants of physics, and the behavior of the heavens, have been uniform throughout all history.

When the Big Bang was concept was first proposed, by the Belgian priest Georges Lemaître, one of the objections to the idea was that it violated uniformitarianism, since compressing all the substance of the entire universe into a single point (a "primordial atom," as Lemaître said) could not happen under known physical law. As evidence of the Big Bang has accumulated - mainly, that the galaxies are racing outward from what appears to have been an ancient central location, as if once flung apart - theorists have adjusted the theory to say that the primordial condition, in the instant before the Bang, was governed by unknown physical laws. But the Big Bang brought current physics into being, and nothing as changed since.

Now the Australia astronomers suggest that laws of physics can change. If they're right, what might this mean?

Short answer: we have absolutely no idea.

Supposing that a creator God is behind the universe, who can say what the celestial master plan calls for? Perhaps one set of physical laws was necessary to cause the Big Bang, another to nurture the early universe, another is in force now - seeming unalterable on the time-scale that we can observe - while still other physical laws will be employed in the future. What might other, future sets of physical laws make possible? That's unknowable, but it is worth pointing out that many of the world's religions (including the monotheist faiths Judaism, Christianity and Islam) describe current temporal existence as a transitory phase that will be replaced someday with a better form of life. If there is a fundamentally different form of life to come - perhaps a spiritual form - different physical laws may be required.

And supposing that the universe is entirely natural, if the physical constant alpha is evolving - however slowly, by our standards - other principles of physics may be evolving too. Perhaps in an entirely natural universe, the far future may include forms of existence not possible under current physical law, such as a naturally arising spiritual plane.

In either case, the "alpha" finding reminds us that the human quest to understand the universe is only in its infancy. There is so much about the heavens we don't know - and so many reasons to feel filled with wonder.

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