418 BELL SYSTEM TECHS ICAI. .lOlRXAL 



ma\' do \ery nearly as he pleases with the ekclinns and the rei^ion 

 they occupy. No tlata can be iinoked in suppori him nor to 

 confute. 



Having expounded the merits of the nuclear atom, I will proceed 

 to undo my work in part by pointing out its great and grave defect. 

 No less a defect than this, that it is impossible. It cannot e.xist. 

 Even if it were brought into existence miraculousK' at an instant, it 

 could not survive, for it carries the seeds of its own dissolution within 

 itself. For if at that initial instant all of the electrons were at rest 

 relatively to the nucleus, tliey would immediately start towards it, 

 fall into it, and expire. Of course, this con-secjuence is so obvious 

 that the notion of stationary electrons would not even occur to any- 

 one ha\ing a bowing acquaintance with mechanics. Such a person 

 would immediately assume that the electrons were in motion around 

 the nucleus as the planets are around the sun; he would convert the 

 nuclear atom-model into what I might call a siin-attd- planets atom- 

 model, the nucleus pla\ing the role of the sun, the electrons those of 

 the planets. .Such an idea is alluring in the extreme; it implies that 

 Nature acts similarly in great things and in small, copying the solar 

 system within the atom; and this is most acceptable, partly because 

 of its philosophical beauty and partly because it enables us to use 

 the intellectual methods and habits accjuired in thestud\- of astrononn-, 

 relieving us of the labor of acquiring new ones. I'nfortunately it is 

 as untenable as the idea that the electrons stand still. For owing 

 to the radiation of energy which continualK' goes on from accelerated 

 electrified particles, an electron cannot describe a circle or an ellipse 

 about a nucleus, as a planet may about the sun; it can only describe 

 a narrowing spiral, ending in a collision lietween electron ,iiui nucleus. 

 The nuclear atom is not stable nor enduring; and liic liikuiiua is 

 complete. 



The only recourse is to make some cntireK' rii-w and unpreccdenttd 

 assumption; for instance, that the electrons, in s()itc of c\er> thing, 

 can stand still in certain positions without falling into liie nucleus; or 

 that they, in spite of everj'thing, can rc\olve interminably in certain 

 closed orbits without spiralling into the nucleus. Such a modifica- 

 tion of the nuclear atom is, of course, essentially a denial of it. .\n 

 atom composed of masses and electrostatic charges, jilus certain 

 restrictive rules or arbitrary assertions, is no longer simply an atom 

 composed of masses and electrostatic charges. Instead of giving 

 to our ultimate particles a few properties selected from among the 

 ones which matter en masse displays to our senses or our instruments. 



