  The study of quantum mechanical few-body systems is a century old pursuit
relevant to countless subfields of physics. While the two-body problem is
generally considered to be well-understood theoretically and numerically,
venturing to three or more bodies brings about complications but also a host of
interesting phenomena. In recent years, the cooling and trapping of atoms and
molecules has shown great promise to provide a highly controllable environment
to study few-body physics. However, as is true for many systems where few-body
effects play an important role the few-body states are not isolated from their
many-body environment. An interesting question then becomes if or (more
precisely) when we should consider few-body states as effectively isolated and
when we have to take the coupling to the environment into account. Using some
simple, yet non-trivial, examples I will try to suggest possible approaches to
this line of research.
