On September 14, 2015 at 09:50:45 UTC the two detectors of the Laser Interferometer Gravitational-Wave Observatory simultaneously observed a transient gravitational-wave signal. The signal sweeps upwards in frequency from 35 to 250 Hz with a peak gravitational-wave strain of 1.0×10(-21). It matches the waveform predicted by general relativity for the inspiral and merger of a pair of black holes and the ringdown of the resulting single black hole. The signal was observed with a matched-filter signal-to-noise ratio of 24 and a false alarm rate estimated to be less than 1 event per 203,000 years, equivalent to a significance greater than 5.1σ. The source lies at a luminosity distance of 410(-180)(+160)  Mpc corresponding to a redshift z=0.09(-0.04)(+0.03). In the source frame, the initial black hole masses are 36(-4)(+5)M⊙ and 29(-4)(+4)M⊙, and the final black hole mass is 62(-4)(+4)M⊙, with 3.0(-0.5)(+0.5)M⊙c(2) radiated in gravitational waves. All uncertainties define 90% credible intervals. These observations demonstrate the existence of binary stellar-mass black hole systems. This is the first direct detection of gravitational waves and the first observation of a binary black hole merger.

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The Observation of Gravitational Waves from a Binary Black Hole Merger

Gravitational Field of a Spinning Mass as an Example of Algebraically Special Metrics

http://cds.cern.ch/record/503806/files/0106045.pdf

New developments in the Casimir effect

The present invention provides a method for producing a nanoporous carbide-derived carbon composition with a tunable pore structure and a narrow pore size. Also provided are compositions prepared by the method.

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Nanoporous carbide derived carbon with tunable pore size

▪ Abstract We review recent experimental tests of the gravitational inverse-square law and the wide variety of theoretical considerations that suggest the law may break down in experimentally accessible regions.

Tests of the gravitational inverse-square law

On particle collisions in the gravitational field of the Kerr black hole

Scattering of particles with different masses and energy in the gravitational field of rotating black holes is considered both outside and inside the black hole. Expressions for scattering energy of particles in the center-of-mass reference frame are obtained. It is shown that the scattering energy of particles in this frame can acquire very large values not only for extremal black holes but also for nonextremal ones if one takes into account multiple scattering. Numerical estimates for the time needed for a particle to get ultrarelativistic energy are given.

On particle collisions near rotating black holes

Scattering of particles with different masses and energy in the gravitational field of rotating black holes is considered as outside as inside the black hole. Expressions for scattering energy of particles in the centre of mass system are obtained. It is shown that scattering energy of particles in the centre of mass system can obtain very large values not only for extremal black holes but also for nonextremal ones if one takes into account multiple scattering. Numerical estimates for the time needed for the particle to get ultrarelativistic energy are given.

On particles collisions near rotating black holes

Scattering of particles in the gravitational field of rotating black holes is considered. It is shown that scattering energy of particles in the centre of mass system can obtain very large values not only for extremal black holes but also for nonextremal ones. Extraction of energy after the collision is investigated. It is shown that due to the Penrose process the energy of the particle escaping the hole at infinity can be large. Contradictions in the problem of getting high energetic particles escaping the black hole are resolved.

On the collisions between particles in the vicinity of rotating black holes

Geodesic completeness needs that near the horizon of a black hole there exist “white hole” geodesics, coming from the region inside the horizon. We give a classification of all such geodesics with energies E/m ≤ 1 for the Schwarzschild and Kerr black holes. Collisions of particles moving along the “white hole” geodesics with those moving along “black hole” geodesics are considered. Formulas for the increase in the energy of collision in the centre of mass frame are obtained, and the possibility of observation of high energy particles arriving from a black hole on the Earth is discussed.

Yu. V. Pavlov

Papers

On particle collisions in the gravitational field of the Kerr black hole

On particle collisions near rotating black holes

On particles collisions near rotating black holes

On the collisions between particles in the vicinity of rotating black holes

Are black holes totally black