There really is not much math in the book, but I'll include it on this list of mathematical fiction on account of the following two little tidbits: There is a brief discussion of the metric on Minkowski space when the inventors of the WormCam first realize that the can use it to look back in time. A high school student uses the WormCam to look back at Pierre Fermat as he wrote the famous marginal note that inspired so much interest in the question of whether xⁿ+yⁿ=zⁿ has any solutions in the positive integers for n>3. Thus, he is able to determine whether Fermat actually knew a proof, had a mistaken proof, or was merely joking when he wrote that he knew a proof of the so-called "Fermat's Last Theorem".