The problem of negative total energy of certain mass systems in classical gravity and its connection with the existence of space-time singularities is brie y summarized. Some attempts to solve this problem are discussed, pointing out especially the possibility that rest masses of a gravitating systems could depend on the strength of the gravitational eld. The results are confronted with some ex...

We present a high-resolution lunar gravity field model (LGM2011) that provides gravity accelerations, free-air gravity anomalies, selenoid undulations and vertical deflections over the entire Moon’s surface. LGM2011 is based on the Japanese SELENE mission that provides the lowand medium-frequency constituents of the gravity field, down to spatial scales of ~78 km. At spatial scales between ~78 ...

A relativistic modified gravity (MOG) called Scalar-Tensor-Vector Gravity (STVG) desribes a self-consistent, stable gravity theory that contains Einstein’s general relativity in a well-defined limit. The theory has an extra degree of freedom, a vector field called a “phion” field whose curl is a skew symmetric field that couples to matter (“fifth force”). The spacetime geometry is described by ...

the grace mission has provided scientific community time-variable gravity field solutions with high precision and on a global scale. the grace mission was launched on march 2003. this mission consists of two satellites that pursue each other in their orbit. distance between two satellites in orbit is measured continuously to an accuracy of better than 1 micron using kbr system placed in satelli...

We present the first direct measurement of the gravity-field curvature based on three conjugated atom interferometers. Three atomic clouds launched in the vertical direction are simultaneously interrogated by the same atom interferometry sequence and used to probe the gravity field at three equally spaced positions. The vertical component of the gravity-field curvature generated by nearby sourc...

We show how classical spacetime emerges from quantum gravity through the study of a quantum FRW cosmological model coupled to a free massive scalar field using a new asymptotic expansion method of the Wheeler-DeWitt equation. It is shown that the coherent states of the nonadiabatic basis of a particular generalized invariant give rise to the quantum back reaction of matter field proportional to...

In contrast to gravity in the weak-field regime, which has been subject to numerous experimental tests, gravity in the strong-field regime is largely unconstrained by observations. We show that gravity theories that pass solar system tests, but that diverge from general relativity in the strong-field regime, predict neutron stars with significantly different properties than their general relati...

In both Newtonian gravity and Einstein there is no force on a test particle located inside spherical cavity cut out of static, spherically symmetric mass distribution. Inside the exterior matter decoupled external field effect that could act particle. However, for potentials other than potential or geometries Ricci flat ones this longer case, then an effect. We explore possibility in various al...