Water, water, everywhere?

摘要

On Earth, no living organism can function without water. It is, in the words of Albert Szent-Gyorgyi, the matrix of life. But is it reasonable to assume that this maxim holds on other worlds too? Is life possible without water? NASA has stated explicitly that its strategy in searching for extraterrestrial life is to "follow the water". But is the space agency thereby overlooking other potentially fertile environments? A recent meeting of physicists, chemists, biochemists and microbiologists grappledwith the question of whether water-free life is feasible. No one can give a definitive negative answer, and neither can we expect the issue to be resolved by a show of hands. Rather, the task has to be that of reducing the basic question to smaller, tractable ones, in the hope that a framework might emerge for moving the discussion beyond mere speculation.