Scaled analogue experiments in electromagnetic scattering

Abstract

Bertrand Russell famously contemplated a table: ‘depending upon the angle one has upon looking at it, and the way the light and shadows fall across it, it will appear one way to one observer, another way to another. Since no two people can see it from precisely the same point of view, and since the light falls on it differently from different points of view, it will not look the same to anyone’, he noted, and the philosopher asked ‘But if that is so, does it make any sense to say what the real shape (or color, or texture) the table REALLY is?’ To the physicist it makes sense to deduce as many properties of an object as possible and to predict what it would look like under different observing conditions. These are the inverse respectively direct problems of electromagnetic scattering. It is interesting that it is through experience acquired by observing (and active ‘experimentation’ in part through play) that humankind and other life forms develop the ability to deduct what their observations signify, and interpretation requires no theoretical knowledge. This illustrates that observations and ‘trial-and-error’ experience suffice to work out the inverse problem in scattering theory to some level that has practical use, at least in the realms of geometric optics where the physics of interaction simplify.