Why different measurements of material properties sometimes give different results

It is very hard to take a photo of a hummingbird flapping its wings 50 times per second. The exposure time has to be much shorter than the characteristic time scale of the wing beat, otherwise you will only see a colorful blur. A similar problem is encountered in solid-state physics, where the aim is to determine the magnetic properties of a material. The magnetic moment at a certain location can change very quickly. Therefore, researchers require measuring methods that are fast enough to resolv...