Global Freezing

It's May and there is a chance of frost tonight in Philadelphia. It's been cold and damp here, which made me think of Kurt Vonnegut's novel, Cat's Cradle, where the whole world was in peril of freezing (or at least all the water).

In the novel Vonnegut proposes a new solid form of water, Ice IX, which is more stable that liquid water at "normal" pressures and temperatures. Once released into the world at large, it would catalyze the conversion of all liquid water to this solid form - permanently! Some analyses of the text suggest that Vonnegut's brother (who had a Ph.D. in physical chemistry from MIT) might have seeded this idea. Ice IX was not actually discovered until 1968, about 5 years after Cat's Cradle appeared (and doesn't catalyze the conversion of liquid water to a solid form).

We tend to think of only 3 phases of water: ice, liquid water and steam, but there are many forms of ice, each with a particular structure. Ice IX is stable at high pressures (several hundred atmospheres) and low temperatures. The pressures and temperatures of various forms of ice are summarized in a phase diagram here.

Hal Clement had a story called "Phases in Chaos" where the protagonist relied on his recall of the phase diagram of water to negotiate a complex extraterrestial undersea environment. You never know when you'll need to know a bit of physical chemistry!