Now all of a sudden he’s reading stuff by guys whose names are preceded by naval ranks and succeeded by M.D.s and Ph.D.s and they are going on for dozens of pages about the physics of nitrogen bubble formation in the knee, for example. There are photographs of cats strapped down in benchtop pressure chambers. Randy learns that the reason Doug Shaftoe doesn’t dive to one hundred and fifty-four meters is that certain age-related changes in the joints tend to increase the likelihood of bubble formation during the decompression process. He comes to terms with the fact that the pressure at the depth of the wreck is going to be fifteen or sixteen atmospheres, meaning that as he ascends to the surface, any nitrogen bubbles that happen to be rattling around in his body are going to get fifteen or sixteen times as large as they were to begin with and that this is true whether those bubbles happen to be in his brain, his knee, the little blood vessels of the eyeball, or trapped underneath his fillings. He develops a sophisticated layman’s understanding of dive medicine, which amounts to little because everyone’s body is different—hence the need for each diver to have a completely different dive plan. Randy will need to figure out his body fat percentage before he can even begin marking up his sheet of graph paper.