x l v i i i I N T R O D U C T I O N T O V O L U M E 1 3 final gesture of conciliation before leaving France, on 9 April Einstein visited the battlefields and ruins near Reims and St. Quentin (see Illustration 4). Einstein’s French hosts were equally pleased with the visit. Langevin wrote that “it produced here the best impression, far exceeding what I would have dared to hope” (Doc. 140). The writer Raymond de Rienzi expressed his enthusiasm for Einstein “as a messenger of peace” and quoted a French parliamentarian as saying that “Einstein in Paris is the beginning of healing of all the international insanity” (Doc. 267).[13] In Paris, Einstein encountered both competent and enthusiastic support as well as different kinds of skepticism toward his theory of relativity. His old colleague Edouard Guillaume, whom he knew from the days of his work at the Patent Office in Bern, made an appearance at the second discussion session at the Collège de France on 5 April. Guillaume’s appearance was preceded by commentary in the press, in Paris and elsewhere, that Einstein’s theory was to be disproved. But Guil- laume’s objections were dismissed rapidly by the mathematician Emile Borel,[14] and by Langevin, as being based largely on Guillaume’s failure to understand Ein- stein’s theory and to argue within its formal structure. Einstein, who had terminated his correspondence with Guillaume on this subject in December 1920 (see Vol. 10, Doc. 250), continued in his refusal to debate with or condemn Guillaume publicly (Nordmann 1922a, see Appendix B). A more intellectually serious kind of skepticism surfaced in the same session when Jacques Hadamard drew Einstein’s attention to Schwarzschild’s interior so- lution for the gravitational field of a point mass and asked Einstein about the (co- ordinate) singularity in the metric describing Schwarzschild’s solution. Einstein replied that a star with sufficient mass for the singularity to become manifest, which he jestingly named the “Hadamard catastrophe,” would indeed be a disaster for his theory. The astronomer Nordmann observed that the work of Eddington on what is now known as the Eddington limit suggested that stars could not easily grow larger once they became sufficiently bright, since their own radiation pressure would drive away matter. Einstein shrewdly expressed himself as being uncomfort- able with such arguments, but at the following session he arrived armed with a more relativistic argument. He pointed out that as the mass of a star increased toward the point at which the Schwarzschild singularity would appear, then, according to Schwarzschild’s interior solution, the pressure at the center of the star would be- come infinite (that is to say, there would be a physical singularity at the center of the star). He argued that the clocks near the center would stop and that therefore no physical process which could give rise to the singularity would continue, an inge- nious use of the curious features of the Schwarzschild space-time. Finally, the most subtle skepticism of all came in the form of a discussion launched by Paul Painlevé, which Nordmann, in his account of Einstein’s lectures