THE SOURCE OF STELLAR ENERGY 
301 
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The difference of temperature between terrestrial and stellar conditions 
seems quite inadequate to account for any appreciable stimulation of 
transmutation or annihilation of matter; and this is the chief ground on 
which censorship of our theories is likely. For example, it is held that the 
formation of helium from hydrogen would not be appreciably accelerated 
at stellar temperatures, and must therefore be ruled out as a source of 
stellar energy. But the helium which we handle must have been put to 
gether at some time and some place. We do not argue with the critic who 
urges that the stars are not hot enough for this process; we tell him to go 
and find a hotter place. 
Indeed the formation of helium is necessarily so mysterious that we 
distrust all predictions as to the conditions required. The attention paid 
to temperature, so far as it concerns the cookery of the helium atom, seems 
to neglect the adage “First catch your hare....” How the necessary 
materials of 4 mutually repelling protons and 2 electrons can be gathered 
together in one spot, baffles imagination. One cannot help thinking that 
this is one of the problems in which the macroscopic conception of space 
has ceased to be adequate, and that the material need not be at the same 
place (macroscopically regarded) though it is linked by a relation of 
proximity more fundamental than the spatial relation. 
According to one line of thought we should only expect liberation of 
subatomic energy on a large scale if the electrons had great speed; 
it is not very clear how the fast electrons are expected to operate, but 
there is always the chance that if the electron were endowed with enough 
energy it might do something surprising. At stellar temperatures the mean 
speed is small compared with /3 rays, so that there is not much chance of 
a surprise. There must be some electrons in a Maxwellian distribution with 
speeds considerably in excess of the mean, but this makes no great difference. 
So far as temperature speed is concerned there will be in the whole of the 
sun only one electron or ion with an energy as high as 5.10~ 7 ergs; compare 
this with the energy of the fastest /3 particles 30.10~ 7 ergs, or of the fastest 
a particles 130.10“ 7 ergs. It would seem that there are no particles in a 
star of energy great enough to provoke subatomic processes except, of 
course, those shot out by the processes themselves. 210 
210. If local electric fields are formed by circulation in the interior 
of a star as they are in our atmosphere, it is possible that the electrons 
may acquire speeds higher than the temperature speeds and so work more 
damage. In this connection reference must be made to an idea brought 
forward by C. T. R. Wilson*. Ordinarily the maximum energy which a 
particle can acquire in an electric field corresponds to the drop of potential 
in its own free path. If we start with a slow-moving ¡3 particle in our 
* Proc. Camb. Phil. Soc. 22, p. 534 (1924).