It is shown that linearized gravitational radiation confined in a cavity can achieve thermal equilibrium if the mean density of the radiation and the size of the cavity satisfy certain constraints. Is it possible, in principle, to confine gravitational radiation in a box, for a time long enough for it to achieve thermal equilibrium? This issue has been investigated before by various authors [1,...

The generation, as well as the detection, of gravitational radiation by means of charged superfluids is considered. One example of such a “charged superfluid” consists of a pair of Planck-mass-scale, ultracold “Millikan oil drops,” each with a single electron on its surface, in which the oil of the drop is replaced by superfluid helium. When levitated in a magnetic trap, and subjected to microw...

Let us declare that the most important devoir of any physical theory is to draw firm predictions for the outcome of laboratory experiments and astronomical observations. Unfortunately, the devoir is quite difficult to fulfill in the case of general relativity, essentially because of the complexity of the Einstein field equations, to which only few exact solutions are known. For instance, it is ...

An example of discontinuity of the energy-momentum tensor moving at superluminal velocity is discussed. It is shown that the gravita-tional Mach cone is formed. The power spectrum of the corresponding Cherenkov radiation is evaluated.

We give a short personally-biased review on the recent progress in our understanding of gravitational radiation reaction acting on a point particle orbiting a black hole. The main motivation of this study is to obtain sufficiently precise gravitational waveforms from inspiraling binary compact stars with a large mass ratio. For this purpose, various new concepts and techniques have been develop...

One of the conceptual tensions between quantum mechanics (QM) and general relativity (GR) arises from the clash between the spatial nonseparability of entangled states in QM, and the complete spatial separability of all physical systems in GR, i.e., between nonlocality implied by the superposition principle, and locality implied by the equivalence principle. Experimental consequences of this co...