Computers could model all the processes of life -- but not on every scale, from atom to organism, all at the same time. So the field had split three ways. In one camp, traditional molecular biochemists continued to extend their painstaking calculations, solving Schrödinger's equation more or less exactly for ever larger systems, working their way up to entire replicating strands of DNA, whole mitochondrial sub-assemblies, significant patches of the giant carbohydrate chain-link fence of a cell wall [...] but spending ever more on computing power for ever diminishing returns. At the other end of the scale were Copies: elaborate refinements of whole-body medical simulations, originally designed to help train surgeons with virtual operations, and to take the place of animals in drug tests. A Copy was like a high-resolution CAT scan come to life, linked to a medical encyclopedia to spell out how its every tissue and organ should behave [...] walking around inside a state-of-the-art architectural simulation. A Copy possessed no individual atoms or molecules; every organ in its virtual body came in the guise of specialized sub-programs which knew (in encyclopedic, but not atomic, detail) how a real liver or brain or thyroid gland functioned [...] but which couldn't have solved Schrödinger's equation for so much as a single protein molecule. All physiology, no physics.

— Permutation City by Greg Egan