Globular clusters (GCs) in the Milky Way have characteristic velocity dispersions that are consistent with the predictions of Newtonian gravity, and may be at odds with Modified Newtonian Dynamics (MOND). We discuss a modified gravity (MOG) theory that successfully predicts galaxy rotation curves, galaxy cluster masses and velocity dispersions, lensing, and cosmological observations, yet produc...

We explore off-diagonal deformations of ‘prime’ metrics in Einstein gravity (for instance, for wormhole configurations) into ‘target’ exact solutions in f (R, T )modified and massive/bi-metric gravity theories. The new classes of solutions may, or may not, possess Killing symmetries and canbe characterized by effective inducedmasses, anisotropic polarized interactions, and cosmological constant...

Abstract We study Morris–Thorne static traversable wormhole solutions in different modified theories of gravity. focus our on the quadratic gravity $$f({\mathscr {R}}) = {\mathscr {R}}+a{\mathscr {R}}^2$$ f ( R ) = +</mml:m...

Abstract The gravitino problem is investigated in the framework of extended gravity cosmologies. In particular, we consider f ( R ) gravity, most natural extension Hilbert–Einstein action, and $$f({\mathcal{T}})$$ f ( T ) teleparallel e...

Ju ly 20 0 8 je a n -f ra n co is P o d ev in on the very smallest scales—the voids in between the smallest known elementary particles—by quantum laws and possibly explain it in terms of some fundamental constituents. Superstring theory is often described as the leading candidate to fill this role, but it has not yet provided an answer to any of these pressing questions. Instead, following its ...

Abstract Atom interferometers have been developed in the last three decades as new powerful tools to investigate gravity. They were used for measuring gravity acceleration, gradient, and gravity-field curvature, determination of gravitational constant, investigation at microscopic distances, test equivalence principle general relativity theories modified gravity, probe interplay between quantum...