Combining the Copernican and Anthropic Principles
by David Sims
THE Copernican principle, generalized, is that the place we occupy in our universe is nothing special. We are not, for example, at the center of the universe. We are, instead, in the boonies of a typical spiral galaxy at the edge of the Virgo galaxy cluster near the fringe of a supercluster called Laniakea.
But the anthropic principle says that we are in a special place, with the specialness being that we must be in a part of the universe where life can evolve into complex forms, and the universe must be such that such places can exist.
When you put the two principles together, the resulting prediction you can make is that we are in the the most common kind of universe that is consistent with our own existence. The fundamental constants of nature are “fine tuned” — but only to a certain extent. The degree of fine-tuning in our universe is improbable, but even less likely higher degrees of fine-tuning can be imagined. It’s possible, for example, to imagine a universe in which life could exist everywhere, even in interstellar space. Our universe isn’t so fruitful as this. Indeed, it is almost, but not quite, barren.
Our universe is one in which most places are hostile to life, with a small proportion of exceptional places which are hospitable, exactly as you might expect from a merger of the Copernican principle with the anthropic principle. The constants of nature — the cosmological constant, the strong nuclear force constant, the Coulomb constant, the gravitational constant, the masses of protons and neutrons, and so on, are, in our universe, just barely within the range where life might occur in certain exceptionally favorable parts of it.
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