Living Matter

 1.     The molecules of living matter have a complexity not found in inanimate nature. New methods for dealing with them lead to a third kind of biophysics which seeks, in combination with biochemistry, to understand properties of organic inatter in terms of the atomic make-up, the reactions, and the arrangements of these giant molecules. Underlying biophysics is a search for a scientifically adequate definition of the term alive. All interpretations of nature use intuitive concepts which mark the present limits of our intellectual perception; and alive involves such a concept. Its scientific indefiniteness is immediately apparent when, for instance, we ask if viruses are alive. Information that will make our definition more precise is coming from many sources, but there is a widespread feeling that the study of viruses-those denizens of a seeming twilight zone between the living and the nonliving-can supply much of it. Evidently biophysics in its essence is more than either the use of physical tools by the biologist or the application of physical precision of thought to problems of biology. Law in physics has been established with the aid of simple systems manipulated by the experimenter. Although many of the attributes of living matter can be analyzed through such systems, life is a coordinated activity of entire organisms never fully under the experimenter's control. The alteration in physical thinking needed to deal with this situation may prove to be the most important consequence of our growing concern with living matter.