Chapter 19 — The Anomalous Molecule

Water behaves unlike every other substance in ways that are all precisely necessary for biology. These are not incidental exceptions—each one is load-bearing for life as we know it.

Water expands when it freezes. Almost all liquids contract upon freezing; water does not. Ice is less dense than liquid water and floats. Lakes and ponds freeze from the surface downward, insulating liquid water beneath. Aquatic life survives winter. If ice sank, bodies of water would freeze solid from the bottom.

Water has an anomalously high specific heat, absorbing more energy per degree of temperature change than almost any other common substance. This moderates Earth's climate and enables precise temperature regulation in biological systems. It is a nearly universal solvent, dissolving more substances than almost any other liquid—essential for the chemistry of metabolism. Its high surface tension enables capillary action in plant vasculature. It is transparent to visible light, allowing photosynthesis below the water surface. Lawrence Henderson of Harvard catalogued these anomalous properties in 1913 and concluded that the fitness of the environment for life is as remarkable as the fitness of organisms for their environment.

Henderson, L.J. The Fitness of the Environment. Macmillan, 1913. Ball, P. Life's Matrix: A Biography of Water. Farrar, Straus and Giroux, 1999.

Chapter 20 — The Resonance Hoyle Found

Carbon is produced in stars through the triple-alpha process: three helium-4 nuclei must collide in rapid succession to form a carbon-12 nucleus. The intermediate step produces beryllium-8, which is unstable and decays in approximately one ten-quadrillionth of a second. The third helium nucleus must arrive within that window to produce carbon.

For this process to produce the universe's observed abundance of carbon, carbon-12 must have a nuclear resonance level at precisely the right energy to accommodate the collision. In 1953 Fred Hoyle predicted that carbon-12 must have a resonance at approximately 7.65 MeV. He made this prediction not from nuclear physics data but from the observation that carbon—and therefore life—exists: working backward from biology to required physics. Willy Fowler's group at Caltech measured the resonance and found it at 7.6549 MeV. It exists exactly where Hoyle predicted it must.

Hoyle was a committed atheist and one of the most prominent scientific opponents of the Big Bang. His response to the carbon resonance became one of the most cited admissions by a non-theist in the history of science: "A common sense interpretation of the facts suggests that a superintellect has monkeyed with physics, as well as with chemistry and biology, and that there are no blind forces worth speaking about in nature." He did not become a Christian. He never fully resolved the implications of what he said. But he said it.

Hoyle, F. "The Universe: Past and Present Reflections." Annual Review of Astronomy and Astrophysics 20 (1982): 1–35 (quote at p. 16). Dunbar, D.N.F. et al. "The 7.68-MeV State in C12." Physical Review 92 (1953): 649–650.