Arbitrarily short geodesics in closed hyperbolic manifolds of every dimension

For an integer $n$, a closed hyperbolic $n$-manifold is a compact manifold locally isometric to $n$-dimensional hyperbolic space, and a closed geodesic is a geodesic that is periodic. Arbitrarily short geodesics conjecture. There exist closed hyperbolic $n$-manifolds with arbitrarily short geodesics. The paper proves the analogous assertion in dimension $4$ and explains that this conjecture would follow from the subsequent GFERF conjecture. Its status in the source is not specified.