Astronomy as well as molecular physics describe non-relativistic motion
by an interaction of the same form: By Newton's respectively by
Coulomb's potential. But whereas the fundamental laws of motion thus
have a simple form, the n-body problem withstood (for n > 2) all
attempts of an explicit solution. Indeed, the studies of Poincare at the
end of the last century lead to the conclusion that such an explicit
solution should be impossible. Poincare himselfopened a new epoch for
rational mechanics by asking qual- itative questions like the one about
the stability of the solar system. To a largeextent, his work, which was
critical for the formation of differential geometry and topology, was
motivated by problems arising in the analysis of the n-body problem
([38], p. 183). As it turned out, even by confining oneselfto
questions ofqualitativenature, the general n-body problem could not be
solved. Rather, simplified models were treated, like planar motion or
the restricted 3-body problem, where the motion of a test particle did
not influence the other two bodies.