In a finding that has met with surprise and some controversy in the scientific community, researchers at the Massachusetts Institute of Technology (MIT) and elsewhere have discovered a basic property that governs the way water and many other liquids behave as their temperature changes.

Liquids have long been known to exhibit a rapid change in properties near a point called the “glass transition temperature,” where the viscosity of the liquid—its “thickness,” or resistance to flow—becomes very large. But MIT professor Sow-Hsin Chen and his co-researchers have found a different transition point at a temperature about 20 to 30 percent higher, which they call the “dynamic crossover temperature.” This temperature may be at least as important as the glass transition temperature, and the viscosity at the dynamic crossover temperature seems to have a universal value for a large class of liquids (known as glass-forming liquids) that includes such familiar substances as water, ammonia, and benzene.

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