  Geodesic incompleteness is a problem in both general relativity and string
theory. The Weyl invariant Standard Model coupled to General Relativity
(SM+GR), and a similar treatment of string theory, are improved theories that
are geodesically complete. A notable prediction of this approach is that there
must be antigravity regions of spacetime connected to gravity regions through
gravitational singularities such as those that occur in black holes and
cosmological bang/crunch. Antigravity regions introduce apparent problems of
ghosts that raise several questions of physical interpretation. It was shown
that unitarity is not violated but there may be an instability associated with
negative kinetic energies in the antigravity regions. In this paper we show
that the apparent problems can be resolved with the interpretation of the
theory from the perspective of observers strictly in the gravity region. Such
observers cannot experience the negative kinetic energy in antigravity
directly, but can only detect in and out signals that interact with the
antigravity region. This is no different than a spacetime black box for which
the information about its interior is encoded in scattering amplitudes for
in/out states at its exterior. Through examples we show that negative kinetic
energy in antigravity presents no problems of principles but is an interesting
topic for physical investigations of fundamental significance.
