$2\mathrm{.}12$ Here is a device that allegedly violates the second law of themodynamies. Consider the surface of rotation shown in heavy lines in the accompanying sketch. It is made up of parts of the surfaces of two confocal ellipsoids of revolution, and that of a sphere. The inside surface is a perfect mirror. The foci are labeled A and $B.$

Problems

$29$

The argument goes is follows: If two black bodies of equal tenperature are initially placed at A and $B,$ then all the radiation from A will reach $B,$ but not vice versa, because radiation from $B$ hilting the spherical surface will be reflected back. Therefore, the temperature of $B$ will incrense spontaneously, while that of A will decrense spontaneously, and this would violate the second law.