  Chandra has recently observed 1E0657-56, a hot merging system at z=0.3 (the
``bullet'' cluster), for 500 ks. I present some of the findings from this
dataset. The cluster exhibits a prominent bow shock with M=3.0+-0.4 (one of
only two known M>>1 shock fronts), which we use for a first test of the
electron-ion equilibrium in an intergalactic plasma. The temperatures across
the shock are consistent with instant shock-heating of the electrons; at 95%
confidence, the equilibration timescale is much shorter than the collisional
Spitzer value. Global properties of 1E0657-56 are also remarkable. Despite
being extremely unrelaxed, the cluster fits well on the Lx-T relation, yet its
total mass estimated from the M-T relation is more than twice the value
measured from lensing. This is consistent with simulations predicting that in
the middle of a merger, global temperature and X-ray luminosity may be
temporarily boosted by a large factor.
