Physical invariants of biosignatures

Biosignature is one of the most important evidences of life available to re searchers. However, many complex physical and chemical phenomena can mimic prints of life so closely that special methods are required to make the dis tinction. In addition to that, life, in principle, can be composed of compo nents which are fundamentally different from those known on Earth. That is why identification of biosignatures should be based upon some phenomenologi cal invariants. Such invariants, within the framework of Newtonian formalis m, are introduced and discussed. (C) 1999 Elsevier Science B.V. All rights reserved.