Is the universe fine-tuned for life?

The fundamental constants of physics - the strength of gravity, the balance of forces, the expansion rate of the universe - sit within an extraordinarily narrow range that permits life. Tweak many of them by a tiny fraction and no stars, planets, or chemistry could form.

There are three options: this fine-tuning is due to physical necessity, to chance, or to design. Necessity has no evidence behind it; chance has to invoke an unobserved multiverse to explain away the odds. Design remains a serious, simpler explanation. As the psalmist saw long before the physics, "The heavens declare the glory of God" (Psalm 19:1).