Why nature is not the sum of its parts

摘要

One of the grand aims of science is to explain every aspect of nature in terms of simple, fundamental laws - but is this possible? A team of physicists claims to have found a hint that some things simply cannot be computed, and that nature could be more than the sum of its parts. The idea of reductionism, a key tool in science for centuries, holds that everything in nature can ultimately be understood by gaining knowledge of its constituent parts. The laws of fluid flows, for example, can bernderived from the deeper laws of atomic and molecular motion, which in turn follow from quantum physics.rnIn 1972, physicist Philip Anderson pointed out that there could be a problem with this approach. Anderson suggested that some systems may be more than the sum of their parts. He championed "emergence" - the notion that important kinds of organisation might emerge in systems of many interacting parts, but not follow in any way from the properties of those parts. If so, then even perfect knowledge of the physics at onernlevel would be inadequate for understanding organisation at higher levels. This conjecture has been debated ever since.