concept

Atmospheric disequilibrium

The condition of an atmosphere held far from chemical equilibrium, containing at once gases that should react and cancel each other out. A dead planet lets its air slide to the bottom of the energy hill - dry and inert, like Mars or Venus. A living planet is different in kind - organisms continually pump out reactive gases faster than they are destroyed, keeping the sky refusing to settle. The greater the disequilibrium, the clearer the sign of life. James Lovelock proposed this test in the 1960s.