Water Molecule

 

Few things are more enchanting that the sub-molecular dance of the universe. And even fewer so avant-garde as the surreal performance of the most pedestrian of substances – water. The script reads like some sort of science fiction concoction itself. The New Scientist describes how water’s very bizarreness, and the ‘failure’ of its hydrogen bonds, makes life itself possible…

  • “Water’s life-giving properties exist on a knife-edge. It turns out that life as we know it relies on a fortuitous, but incredibly delicate, balance of quantum forces. Water is one of the planet’s weirdest liquids, and many of its most bizarre features make it life-giving. For example, its higher density as a liquid than as a solid means ice floats on water, allowing fish to survive under partially frozen rivers and lakes. And unlike many liquids, it takes a lot of heat to warm water up even a little, a quality that allows mammals to regulate their body temperature. But computer simulations show that quantum mechanics nearly robbed water of these life-giving features. Most of them arise due to weak hydrogen bonds that hold H2O molecules together in a networked structure. For example, it is hydrogen bonds that hold ice molecules in a more open structure than in liquid water, leading to a lower density. By contrast, without hydrogen bonds, liquid molecules move freely and take up more space than in rigid solid structures. How water continues to exist as a network of hydrogen bonds, in the face of these destabilising quantum effects, was a mystery. In 2009, theorist Thomas Markland, now at Stanford University in California, and colleagues suggested a reason why water’s fragile structure does not break down completely. They calculated that the uncertainty principle should also affect the bond lengths within each water molecule, and proposed that it does so in such a way as to strengthen the attraction between molecules and maintain the hydrogen-bond network. ‘Water fortuitously has two quantum effects which cancel each other out,’ Markland says.”

I’ve often written in praise of “weirdness” as a sort of embracing the failure to conform. We can thank our lucky stars water has made that embrace.

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