D dimensional neutral black strings wrapped on a circle are related to
(D−1) dimensional charged black holes by boosts. We show that the boost has
to be performed in the covering space and the boosted coordinate has to be
compactified on a circle with a Lorentz contracted radius. Using this fact we
show that the transition between Schwarzschild black holes to black p-branes
observed recently in M theory is the well-known black hole- black string
transition viewed in a boosted frame. In a similar way the correspondence point
where an excited string state goes over to a neutral black hole is mapped
exactly to the correspondence point for black p-branes. In terms of the p
brane quantities the equation of state for an excited string state becomes
identical to that of a 3+1 dimensional massless gas for all p. Finally, we
show how boosts can be used to relate Hawking radiation rates. Using the known
microscopic derivation of absorption by extremal 3-branes and near-extremal 5D
holes with three large charges we provide a microscopic derivation of
absorption of 0-branes by seven and five dimensional Schwarzschild black holes
in a certain regime.Comment: Some references added, minor clarifications (harvmac, 16 pages
