A Universe Fine-tuned For Life

Gravity is roughly 10^39 times weaker than electromagnetism. If gravity had been 10^33 times weaker than electromagnetism, "stars would be a billion times less massive and would burn a million times faster."

The nuclear weak force is 10^28 times the strength of gravity. Had the weak force been slightly weaker, all the hydrogen in the universe would have been turned to helium (making water impossible, for example).

A stronger nuclear strong force (by as little as 2 percent) would have prevented the formation of protons--yielding a universe without atoms. Decreasing it by 5 percent would have given us a universe without stars.

If the difference in mass between a proton and a neutron were not exactly as it is--roughly twice the mass of an electron--then all neutrons would have become protons or vice versa. Say good-bye to chemistry as we know it--and to life.

The very nature of water--so vital to life--is something of a mystery (a point noticed by one of the forerunners of anthropic reasoning in the nineteenth century, Harvard biologist Lawrence Henderson). Unique amongst the molecules, water is lighter in its solid than liquid form: Ice floats. If it did not, the oceans would freeze from the bottom up and earth would now be covered with solid ice. This property in turn is traceable to the unique properties of the hydrogen atom.

The synthesis of carbon--the vital core of all organic molecules--on a significant scale involves what scientists view as an astonishing coincidence in the ratio of the strong force to electromagnetism. This ratio makes it possible for carbon-12 to reach an excited state of exactly 7.65 MeV at the temperature typical of the centre of stars, which creates a resonance involving helium-4, beryllium-8, and carbon-12--allowing the neceesary binding to take place during a tiny window of opportunity 10-17 seconds long.

(From God the Evidence: The Reconciliation of Faith and Reason in a Postsecular World by Patrick Glynn, as quoted by Dave Hunt in Cosmos, Creator and Human Destiny)