We summarize the main ideas of General Relativity and Lorentzian geometry,
leading to a proof of the simplest of the celebrated Hawking-Penrose
singularity theorems. The reader is assumed to be familiar with Riemannian
geometry and point set topology.
We give an elementary derivation of the Montgomery phase formula for the
motion of an Euler top, using only basic facts about the Euler equation and
parallel transport on the 2-sphere (whose holonomy is seen to be responsible
for the geometric phase). We also give an approximate geometric interpretation
of the geometric phase for motions starting close to an unstable equilibrium
point.