文档介绍：Nobel Lecture: Fractional quantization*R. B. LaughlinDepartment of Physics, Stanford University, Stanford, California 94305[S0034-6861(99)01104-6]One of my favorite times in the academic year occursin early spring when I give my class of extremely brightgraduate students, who have mastered quantum me-chanics but are otherwise unsuspecting and innocent, atake-home exam in which they are asked to deduce su-perˉuidity from ?rst principles. There is no doubt a spe-cial place in hell being reserved for me at this very mo-ment for this mean trick, for the task is , like the fractional quantum Hall effect, isan emergent phenomenonDa low-energy collective ef-fect of huge numbers of particles that cannot be deducedfrom the microscopic equations of motion in a rigorousway and that pletely when the system istaken apart (Anderson, 1972). There are prototypes forsuperˉuids, of course, and students who memorize themhave taken the ?rst step down the long road to under-standing the phenomenon, but these are all approximateand in the end not deductive at all, but ?ts to experi-ment. The students feel betrayed and hurt by this expe-rience because they have been trained to think in reduc-tionist terms and thus to believe that everything notamenable to such thinking is unimportant. But nature ismuch more heartless than I am, and those students whostay in physics long enough to seriously confront theexperimental record e to understand thatthe reductionist idea is wrong a great deal of the time,and perhaps always. mon response in the earlystages of learning is that superconductivity and thequantum Hall effect are not fundamental and thereforenot worth taking seriously. When this happens I justopen up the AIP Handbook and show the disbelieverthat the accepted values ofeandhare de?ned by theseeffects, and that ends that. The world is full of things forwhich one's understanding, ., one's ability to predictwhat will happen in an experiment, is degraded by tak-ing th