Physical bases for a triad of biological similarity theories.

The dimensional analysis of physics, based on the MLT-system (M = mass, L = length, T = time), can be applied to the living world, from mycoplasmas (10(-13) g) to the blue whales (10(8) g). Body mass (M), or body weight (W), are utilized as convenient reference systems, since they represent the integrated masses of all elementary particles--at the atomic level--which conform an organism. A triad of biological similarities (mechanical, biological, transport) have been previously described. Each similarity was based on two postulates, of which the first was common to all three, i.e., the constancy of body density; whereas the second postulates were specific for each of the three theories. In this study a physical foundation for these second postulates, based on three universal constants of nature, is presented, these are: 1) the acceleration of gravity (g = LT-2); 2) the velocity of light (c = LT-1); and 3) the mass-specific quantum (h/m = L2T-1). The realm of each of these biological similarities is the following: 1) the gravitational or mechanical similarity (where g = constant), deals mainly with the relationship between a whole organism and its environment, particularly with locomotion. The acceleration of gravity (g) is also one of the determining factors of the "potential" energy (E = m.g.H), where m is the mass, and H is the height above the reference level; 2) the electrodynamic similarity (formerly biological similarity), (c = constant), is able to quantitatively define the internal organization of an organism from both a morphological and a physiological point of view.(ABSTRACT TRUNCATED AT 250 WORDS)