  The lightcone singularity at the origin is resolved by blowing up the
singular point to $CP^1$. The Lorentz group acts on the resolved lightcone and
has $CP^1$ as a special orbit. Using Wigner's method of associating unitary
irreducible representations of the Poincar\'e group to particle states, we find
that the special orbit gives rise to new vacuum states. These vacuum states are
labelled by the principal series representations of $SL(2,C)$. Some remarks are
included on the applications of these results to gauge theories and
asymptotically flat spacetimes.
