5 problems

Let quantum gravity theories be theories whose gravitational path integrals include sums over spacetime topologies, and let gauge redundancies associated with topology change denot…

Let a Morse spacetime be a singular Lorentzian spacetime with isolated critical points where the Lorentz metric degenerates and spatial topology changes. Sorkin's conjecture. Causa…

Topology changes can produce singularities in spacetime, while string-theoretic methods may provide a framework for treating such singular behaviour. DeWitt's conjecture. There may…

Let $(\mathcal{M},h,f,\zeta)$ be a Morse geometry of dimension $n$, and let $(M,g)$ be the corresponding Morse spacetime. Assume that $f$ has a single critical point for each criti…

The cotangent-bundle counterexample conjecture. The $4$-manifold