44 SOME PHYSICAL FORCES EXEMPLIFIED IN MAN 



of big molecules — for instance, for the paracrystallinity of the regular molec- 

 ular arrays so common in tissue, such as in muscle fiber and in the aqueous 

 humor of the lens of the eye. 



Electromagnetic Force 



Although we live in the magnetic field of the earth, no information exists 

 on the response of a man to large changes in magnetic-field strength. To 

 small changes there is no response, as far as is known. Many molecular ef- 

 fects are known, however, of which the recent exploitation of the so-called 

 nuclear magnetic resonance phenomena, in which the location of a hydrogen 

 atom in a molecule and the arrangement of atoms in molecular complexes 

 can be learned, are exciting examples. 



However, on biological systems the effects of magnetic fields are yet poorly 

 understood. Small animals placed in fairly strong magnetic fields of ~4000 

 gauss (at $2/gauss, ' 1 lb> of electromagnet/ gauss) show inability to repro- 

 duce. Cell division and growth are inhibited. Interference with the collec- 

 tion of the mitotic apparatus in preparation for cell division is implicated. 

 In this respect the effect of a magnetic field is similar to the effects of X or 

 gamma rays. 



The effects of electromagnetic forces — oscillating forces of unknown na- 

 ture, which interact with both electric charges and magnetic poles, and with 

 other electromagnetic forces — are better understood and are most important 

 in the living system. In fact, the more the question is studied, the more it 

 is realized in how many aspects of inanimate as well as animate subjects, 

 electromagnetic forces play an important part. 



Usually electromagnetic phenomena are described by their interaction 

 energy, rather than force; this expedient enables us to by-pass their nature, 

 and concentrate upon their effects. An "oscillating potential" permeates 

 electromagnetic energy. It is a periodic function of time (see Figure 1-2). 

 The amount of energy in a packet depends only upon its number of cycles 

 per second. 



Because of their importance, Chapter 4 is devoted almost completely to 

 electromagnetic matters. 



Yet will all this preoccupation with force, the physicist still is unable to 

 cope with some really big ones, such as political "forces," and economic 

 "pressures." In "The Razor's Edge" (1944), W. Somerset Maugham con- 

 cludes: "Goodness is the greatest 'force' in the world!". . . . Unfortunately, 

 we cannot measure it. 



GENERALIZED FORCE 



Although temperature is not usually thought of as a force, it is the driving 

 force for heat-energy flow. Discussion on driving forces for several processes 

 which occur in the living system is contained in Chapter 7. 



