It is apparent from the history of science, that few-body problems have
an interdis- ciplinary character. Newton, after solving the two-body
problem so brilliantly, tried his hand at the Sun-Earth-Moon system.
Here he failed in two respects: neither was he able to compute the
motion of the moon accurately, nor did he understand the reason for
that. It took a long time to understand the fundamental importance of
Newton's failure, and only Poincare realised what was the fundamental
difficulty in Newtons programme. Nowadays, the term deterministic chaos
is associated with this problem. The deep insights of Poincare were
neglected by the founding fathers of Quantum Physics. Thus history was
repeated by Bohr and his students. After quantising the hydrogen atom,
they soon found that the textbook case of a three-body problem in atomic
physics, the 3He-atom, did not yield to the Bohr-Sommerfeld quantisation
methods. Only these days do people realise what precisely were the
difficulties connected to this semi- classical way of treating quantum
systems. Our field, as we know it today, began in principle in the early
1950's, when Watson sketched the outlines of three-body scattering
theory. Mathematical rigour was achieved by Faddeev and thereafter, at
the beginning of the 1960's, the quantum three-body prob- lem, at least
as far as short-range forces were concerned, w&s tamed. In the years
that followed, through the work of others, who first applied Faddeev's
methods, but later added new techniques, the three-and four-body
problems became fully housebroken.