What is ‘multiple scattering’?

‘Multiple scattering’ means different things to different scientists, but a general definition might be ‘the interaction of fields with two or more obstacles’. For example, a typical multiple-scattering problem in classical physics is the scattering of sound waves by two rigid spheres. Further examples, such as the scattering of spherical electron waves by a cluster of atoms, can be found in condensed-matter physics [1379, 168, 422, 424, 423]. Many other examples will be discussed in this book.

The waves scattered by a single obstacle can be calculated in various well-known ways, such as by the method of separation of variables, T-matrix methods or integral-equation methods. All of these methods will be discussed in detail later.

If there are several obstacles, the field scattered from one obstacle will induce further scattered fields from all the other obstacles, which will induce further scattered fields from all the other obstacles, and so on. This recursive way of thinking about how to calculate the total field leads to another notion of multiple scattering; it can be used to actually compute the total scattered field – each step is called an order of scattering.