  In a static spacetime, the Killing time can be used to measure the time
required for signals or objects to propagate between two of its orbits. By
further restricting to spherically symmetric cases, one obtains a natural
association between these orbits and timelike lines in Minkowski space. We
prove a simple theorem to the effect that in any spacetime satisfying the weak
energy condition the above signaling time is, in this sense, no faster than
that for a corresponding signal in Minkowski space. The theorem uses a
ormalization of Killing time appropriate to an observer at infinity. We then
begin an investigation of certain related but more local questions by studying
particular families of spacetimes in detail. Here we are also interested in
restrictions imposed by the dominant energy condition. Our examples suggest
that signaling in spacetimes satisfying this stronger energy condition may be
significantly slower than the fastest spacetimes satisfying only the weak
energy condition.
