SURVEY OF THE PROBLEM
25
ccurring in the
l Thus we can
anta at a very
id mouthful it
n. But in the
id cannot take
p is ready it is
i traps are in
fficient is pro-
for the stellar
m of Table 3.
ire the atom’s
to measure its
>y the hungry
Lption by the
attention not
:tron capture),
on coefficients,
emission must
. It is only a
V-
ie emission or
hysical theory
ar weight, the
large influence
Lid extend the
lim to predict
l density with
ch seems most
lictions pretty
3. This part of
p feeling that
3 waiting just
ie discordance
y factors and
n a star. The
•mpared with
results which
l observation,
m the mathe
matical investigations we may be equipped with a general knowledge
of the conditions to be studied and of the interplay of the various
factors.
Other problems will arise in the course of our work. The Cepheid
variables, considered to be pulsating stars, give opportunities for develop
ment and test of the theory. Of special interest is the theory of the
White Dwarfs—incredible but apparently true. The problem of the source
of a star’s energy will be considered; by a process of exhaustion we are
driven to conclude that the only possible source of a star’s energy is
subatomic; yet it must be confessed that the hypothesis shows little
disposition to accommodate itself to the detailed requirements of
observation, and a critic might count up a large number of “fatal”
objections.
Those portions of thermodynamics and the quantum theory which are
essential for our astronomical investigations are developed ab initio in
Chapters n and nr. It is not expected that these Chapters can take the
place of a regular treatise; nor has it been our aim to give a particularly
elementary exposition suitable for a first approach to the subject. It can
probably be assumed that everyone interested in astrophysical problems
has picked up sporadically the leading ideas of atomic structure and
quanta, and is familiar with some of the numerous experimental applica
tions. The systematic outline here offered may help him to arrange these
ideas and fill up the gaps in their sequence. Although the discussion is
given in the form of mathematical deduction, it must be understood that
when, as in these two Chapters, the results at every stage are subject to
close test by experiment, the purpose of the argument is to exhibit the
inner connection of the various phenomena and not to persuade the sceptic
that the phenomena must occur. Consequently, although a reasonable
degree of rigour is required, the laborious exploration and closing of every
possible loophole is of secondary importance and would be out of place
in a brief survey.
Chapters iv-xi contain the main theme of investigation—the study of
the internal condition of a star. The culminating point is Chapter vn,
where the comparison with observation is made. Roughly speaking, the
mechanics of the problem is placed before this, and the physics is placed
afterwards. That is because the study of absorption, ionisation, electrical
energy, etc., in the light of atomic physics would if undirected lead us
far away from astronomical problems; and it is necessary first to ascertain
what are the points of special astronomical importance, the doubts to be
settled, and the difficulties to be discussed. We need to have a clear idea
of how our results will react on observable properties of the stars. I do
not think that any order of development would have avoided the numerous
cross-references forward as well as backward.
/