I have no intention in doubt世界纪录! I just wonder

how Track$Field Association deal with such small time difference(less than 0.05sec). Apparently, it will be affected by th environment. Does the association has some criteria in weather, site for the race. If you have done the physics exeperiment, you must know it has systematic and random errors in all the measurements. In experiment, we measure many times and average to minimize the error. But it is impossible in track race to run multiple times