Physical Interpretation of Antigravity

Understand

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.