D O C . 2 3 4 R E S P O N S E T O A N D E R S O N 3 6 1
Published in Astronomische Nachrichten 221, No. 5300 (1924): cols. 329–330). Dated 15 April 1924.
The note replies to Anderson’s response (Anderson 1923b) to Einstein 1923m (Doc. 57), in
which it is claimed that in an electron gas the index of refraction may be larger than unity. The basis
of this claim is an expression for the index of refraction derived by Paul Drude in his electron theory
In Anderson 1923b, Anderson also claims that the electron gas would only be opaque if its
absorption coefficient is of the same order of magnitude as in normal gases, which one cannot prove;
and that equilibrium does exist in the gas. Neither of these points is addressed here.