Cosmology, Relativity, and Gravity Commons^™

Chemical Potential In The First Law For Holographic Entanglement Entropy, David Kastor, Sourya Ray, Jennie Traschen

David Kastor

Entanglement entropy in conformal field theories is known to satisfy a first law. For spherical entangling surfaces, this has been shown to follow via the AdS/CFT correspondence and the holographic prescription for entanglement entropy from the bulk first law for Killing horizons. The bulk first law can be extended to include variations in the cosmological constant Λ, which we established in earlier work. Here we show that this implies an extension of the boundary first law to include varying the number of degrees of freedom of the boundary CFT. The thermodynamic potential conjugate to Λ in the bulk is called …

Non-Vacuum Ads Cosmologies And The Approach To Equilibrium Of Entanglement Entropy, Sebastian Fischetti, David Kastor, Jennie Traschen

David Kastor

We extend standard results for vacuum asymptotically locally AdS (AlAdS) spacetimes, showing that such spacetimes can be constructed as foliations where the induced metric on each hypersurface satisfies Einstein's equation with stress-energy. By an appropriate choice of stress-energy on the hypersurfaces, the resulting AlAdS spacetime satisfies Einstein's equation with a negative cosmological constant and physical stress tensor. We use this construction to obtain AlAdS solutions whose boundaries are FRW cosmologies sourced by a massless scalar field or by a perfect fluid obeying the strong energy condition. We focus on FRW universes that approach Minkowski spacetime at late times, yielding AlAdS …

Basic Astronomy Labs, Terry L. Smith, Michael D. Reynolds, Jay S. Huebner

Jay S Huebner

Providing the tools and know-how to apply the principles of astronomy first-hand, these 43 laboratory exercises each contain an introduction that clearly shows budding astronomers why the particular topic of that lab is of interest and relevant to astronomy. About one-third of the exercises are devoted solely to observation, and no mathematics is required beyond simple high school algebra and trigonometry.Organizes exercises into six major topics—sky, optics and spectroscopy, celestial mechanics, solar system, stellar properties, and exploration and other topics—providing clear outlines of what is involved in the exercise, its purpose, and what procedures and apparatus are to be used. …

Gravitational Wave Astrophysics With Compact Binary Systems, Eric Addison

Eric Addison

Perihelion Precession In General Relativity, Charles G. Torre

Charles G. Torre

This is a Maple worksheet providing a relatively quick and informal sketch of a demonstration that general relativistic corrections to the bound Kepler orbits introduce a perihelion precession. Any decent textbook will derive this result. My analysis aligns with that found in the old text "Introduction to General Relativity", by Adler, Bazin and Schiffer. The plan of the analysis is as follows. * Model the planetary orbits as geodesics in the (exterior) Schwarzschild spacetime. * Compute the geodesic equations. * Simplify them using symmetries and first integrals. * Isolate the differential equation expressing the radial coordinate as a function of …

Magnetic Fields In An Expanding Universe, David Kastor, Jennie Traschen

David Kastor

We find a solution to 4D Einstein-Maxwell theory coupled to a massless dilaton field describing a Melvin magnetic field in an expanding universe with 'stiff matter' equation of state parameter w=+1. As the universe expands, magnetic flux becomes more concentrated around the symmetry axis for dilaton coupling a<1/3√ and more dispersed for a>1/3√. An electric field circulates around the symmetry axis in the direction determined by Lenz's law. For a=0 the magnetic flux through a disk of fixed comoving radius is proportional to the proper area of the disk. This result disagrees with the usual expectation based on a test magnetic field that this …

The Spacetime Geometry Of A Null Electromagnetic Field, Charles G. Torre

Charles G. Torre

We give a set of local geometric conditions on a spacetime metric which are necessary and sufficient for it to be a null electrovacuum, that is, the metric is part of a solution to the Einstein-Maxwell equations with a null electromagnetic field. These conditions are restrictions on a null congruence canonically constructed from the spacetime metric, and can involve up to five derivatives of the metric. The null electrovacuum conditions are counterparts of the Rainich conditions, which geometrically characterize non-null electrovacua. Given a spacetime satisfying the conditions for a null electrovacuum, a straightforward procedure builds the null electromagnetic field from …

Experiments On Detection Of Cosmic Ether, Vildyan Yanbikov

Vildyan Yanbikov

Proof of the existence of the world ether in outer space may be a measure of the speed relative to the cosmic vacuum. Provides a description of the optical device which is aimed to measure the speed and direction of motion with respect to the space of emptiness. The principle of the optical device is based on the phenomenon of stellar aberration.

Shielding Of A Gravitational Field In Outer Space, Vildyan Yanbikov

Vildyan Yanbikov

The study presents a model of shielding gravitational fields protons space. Screening of gravitation based on the principle: Elementary particle with the rest mass. And which are in free fall. Escapes all gravitational fields in which it is located. In the present work determined the strength of the gravitational field of an infinite half-space. Defined cross-section of proton escape the gravitational field. Calculated radius of action of gravitational forces in space. We obtain a formula for determining the distance to the galaxy by its «red» offset. The researchers calculated the life time of a photon in space. Determined the size …

Transformation Of Co-Ordinates And Time At Movement On Inertia Regarding Absolute Outer Space, Vildyan Yanbikov

Vildyan Yanbikov

Proof of the existence of the world ether in outer space may be a measure of the speed relative to the cosmic vacuum. Describes an optical device which is aimed to measure the speed and direction of motion with respect to the space of emptiness. The principle of the optical device is based on the phenomenon of stellar aberration.

Модуляция Гравитационного Поля Земли, Vildyan Yanbikov

Vildyan Yanbikov

На поверхности земной гравитации проявляется во всех макроскопических явлений. Сила притяжения земли могут быть легко измерены. Приложить силу тяжести, чтобы превратить его в переменном гравитационном поле (гравитационных волн). Для этого модулированных гравитационного поля Земли. Рассмотрим устройство, которое модулирует гравитационного поля Земли.

Transverse And Longitudinal Mass Moving In The Inertial Frame Of Reference, Vildyan Yanbikov

Vildyan Yanbikov

Based on the speed of the spread of vector interaction in a moving inertial frame of reference. A calculation of the transversal and longitudinal mass of elementary particles.