XV. 5]
THE ZEEMAN EFFECT
215
5. Magnetic or Relativity Doublets
Observations on the anomalous Zeeman effect lead to the
conclusion that optical doublets must have a magnetic origin.
It seems justifiable to apply the same reasoning to the case of
X-rays, although for X-rays Sommerfeld has interpreted terms
such as L n and Lni as simple relativity doublets and has shown
that their separations can be calculated accurately on that basis.
Lande * has pointed out that the relativity and optical doublet
separations can both be represented by the same general formula.
The view that the optical and X-ray doublets are essentially
similar in origin is borne out by the distribution of electrons in
various levels advocated by Stoner.
Sommerfeld draws the following important conclusion from
Larmor’s theorem :
“ The electron describes in the magnetic field the same path
as when no magnetic field is acting but doing so with respect
to a system of reference which is rotated with the velocity o.
Regarded from the standpoint of this system of reference the
orbits are traversed as if no field were present. Precession of
the system of reference and action of the magnetic field are
interchangeable and equivalent to one another.”
In view of this statement we may reverse the order and con
sider precession (as it occurs for instance in relativity theory) as
replaced by the action of a magnetic field. From a mathematical
standpoint it may be simpler to replace a magnetic field by a
motion of precession. From a physical standpoint it may be
simpler to replace a motion of precession by the action of a
magnetic field. These remarks are of importance in connection
with the work of Millikan and Bowen f on “ stripped ” atoms,
i.e. atoms which have been stripped of practically all their
electrons. These authors conclude that their results require one
of two alternatives : (1) discarding the relativity explanation of
X-ray and optical doublets and with it all relativity effects in
electronic orbits, or (2) introducing a dissymmetry not hereto
fore contemplated in atomic models, abandoning Bohr’s inter
penetration ideas and his assignment of azimuthal quantum
numbers.
Here, then, the older quantum theories led to conflicting
results. There appeared to be two different types of explana
tion, one in terms of relativity, the other in terms of a mag
netic field. By the employment of the spinning electron it is
possible to account for all the results in terms of a single theory.
* Lande, Zeits. /. Physik, vol. 24, p. 88, and vol. 25, p. 46, 1924.
t Millikan and Bowen, Phys. Rev., vol. 24, pp. 209, 223, 1924.