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. * Partly based on conference lectures at "String Field Theory-2015", Sichuan University, China, and at "Convergence", Perimeter Institute, Waterloo, ON, Canada.

beam. However it is not necessary to use laser light for the reconstruction and a small monochromatic source such as that formed by an iris diaphragm in front of a sodium lamp may be used. This method is not only safer but if only a low power laser is available yields brighter reconstructions. It is also instructive to observe the reconstructed image using a small white light source. Fine grain film holograms use relatively low spacial frequencies and thus have a small dispersive power compared with conventional holograms, so a quite well defined image may still be seen using white light and exhibiting coloured fringes.