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

Determinations of the motion of the sun with respect to the extra-galactic nebulae have involved a K term of several hundred kilometers which appears to be variable. Explanations of this paradox have been sought in a correlation between apparent radial velocities and distances, but so far the results have not been convincing. The present paper is a re-examination of the question, based on only those nebular distances which are believed to be fairly reliable.

Distances of extra-galactic nebulae depend ultimately upon the application of absolute-luminosity criteria to involved stars whose types can be recognized. These include, among others, Cepheid variables, novae, and blue stars involved in emission nebulosity. Numerical values depend upon the zero point of the period-luminosity relation among Cepheids, the other criteria merely check the order of the distances. This method is restricted to the few nebulae which are well resolved by existing instruments. A study of these nebulae, together with those in which any stars at all can be recognized, indicates the probability of an approximately uniform upper limit to the absolute luminosity of stars, in the late-type spirals and irregular nebulae at least, of the order of M (photographic) = −6.3.1 The apparent luminosities of the brightest stars in such nebulae are thus criteria which, although rough and to be applied with caution, furnish reasonable estimates of the distances of all extra-galactic systems in which even a few stars can be detected.

Finally, the nebulae themselves appear to be of a definite order of absolute luminosity, exhibiting a range of four or five magnitudes about an average value M (visual) = −15.2.1 The application of this statistical average to individual cases can rarely be used to advantage, but where considerable numbers are involved, and especially in the various clusters of …

A Relation Between Distance and Radial Velocity Among Extra-Galactic Nebulae

We propose a distorted optical waveguide around a microsphere to mimic curved spacetimes caused by the “gravitational fields”. Gravitational lensing effects analogues are experimentally demonstrated and this can be used to prospective light harvesting.

https://absimage.aps.org/image/MAR14/MWS_MAR14-2013-000010.pdf

Trapping light by mimicking gravitational lensing

The observation of quantum Hawking radiation and its entanglement in an analogue black hole was recently reported. A subsequent note (arXiv:1609.03803) criticized the study. Version 2 of the note was recently presented. The note suffers from technical difficulties which invalidate its main claims. We answer all of the comments in the note and show that the criticisms are not valid. We also answer a comment made by the author of the note in a different forum.

Response to the recent note concerning the observation of quantum Hawking radiation and its entanglement in an analogue black hole

Regularization-based independent control of an external electromagnetic actuator to avoid singularity in the spatial manipulation of a microrobot

The conventional approach to transformation optics starts with a virtual space and determines a complicated material profile in physical space, to achieve unconventional phenomena. The authors take a reverse approach, and find that the conformal singularities in the refractive-index profile are equivalent to topological defects. Optical splitting and illusion effects are confirmed. They furthermore fabricate a device with a positive topological defect, and demonstrate its light-bending functionality. Their methods could be used to connect conventional geometric optics with on-chip applications.

Conformal Singularities and Topological Defects from Inverse Transformation Optics

Versatile optical devices are designed from anisotropic and gradient materials based on transformation optics, which are usually hard to realize. Here, by utilizing conformal equivalence, we demonstrate that a flat gradient index optical thin-film waveguide is equivalent to a curved homogenous optical thin-film waveguide for light rays. Such a relationship provides us an alternative method to design optical devices with either an inhomogeneous medium or equivalently curved surfaces made from only a homogeneous material, leading to applications on on-chip optical devices. Moreover, we provide a prototype of the curved optical thin-film waveguide without rotational symmetry, which can serve as a concave lens. Our work gives a conformal landscape of a two-dimensional gradient refractive-index profile from the geometric optics perspective.

Conformal Landscape of a Two-Dimensional Gradient Refractive-Index Profile for Geometrical Optics

The authors realize a flexible optical experiment system to simulate a wormhole by applying a two dimensional embedded curved waveguide. By observing the beam propagation in the waveguide, they demonstrate a strong gravitational effect on wavepackets around a wormhole and study the onset of a tidal force effect

Simulation of giant tidal force of wormhole using curved optical spaces

According to modern cosmology, expansion of the universe is due to the metric changing of spacetime itself. Here, we propose to mimic an expanding universe by utilizing optical interference and helicoid waveguides. The evolution of interference pattern in the helicoid waveguide is investigated theoretically and experimentally. For precise measurements, we design an air helicoid waveguide which allows us to investigate the wave front of laser beams from the waveguide. Redshift of a Gaussian wave packet in the expanding universe is demonstrated with high precision, showing that the helicoid waveguide acts as a parabolic gradient index lens exactly. The proposed waveguide structure can be used as an efficient waveguide adapter.

Runqiu He

Papers

Conformal Singularities and Topological Defects from Inverse Transformation Optics

Conformal Landscape of a Two-Dimensional Gradient Refractive-Index Profile for Geometrical Optics

Simulation of giant tidal force of wormhole using curved optical spaces

Mimicking an expanding universe by optical interference in a helicoid waveguide.