Related papers: Testing the null energy condition with precise dis…
The assumptions that "light propagates along null geodesics of the spacetime metric" and "the number of photons is conserved along the light path" lead to the distance duality relation (DDR), $\eta = D_L(z) (1 + z)^{-2}/D_A(z) = 1$, with…
Given a null geodesic $\gamma_0(\lambda)$ with a point $r$ in $(p,q)$ conjugate to $p$ along $\gamma_0(\lambda)$, there will be a variation of $\gamma_0(\lambda)$ which will give a time-like curve from $p$ to $q$. This is a well-known…
Distance measurements to Type Ia supernovae (SNe Ia) at cosmological distances indicate that the Universe is accelerating and that a large fraction of the critical energy density exists in a component with negative pressure. Various…
Recently Sumi et al. (2011) reported evidence for a large population of planetary-mass objects (PMOs) that are either unbound or orbit host stars in orbits > 10 AU. Their result was deduced from the statistical distribution of durations of…
We use a Bayesian approach to derive the distance probability distribution for one object from its parallax with measurement uncertainty for two spatial distribution priors, viz. a homogeneous spherical distribution and a galactocentric…
Over the past decade, the BeSSeL Survey and the VERA project have measured trigonometric parallaxes to approximately 250 massive, young stars using VLBI techniques. These sources trace spiral arms over nearly half of the Milky Way. What is…
Double source lensing provides a dimensionless ratio of distance ratios, a "remote viewing" of cosmology through distances relative to the gravitational lens, beyond the observer. We use this to test the cosmological framework, particularly…
In this paper, the null geodesics and gravitational lensing in a nonsingular spacetime are investigated. According to the nature of the null geodesics, the spacetime is divided into several cases. In the weak deflection limit, we find the…
We recently presented a series of dark energy theorems that place constraints on the equation of state of dark energy ($\wdark$), the ime-variation of Newton's constant ($\dot G$), and the violation of energy conditions in theories with…
We consider two point charges in electrostatic interaction between them within the framework of a nonlinear model, associated with QED, that provides finiteness of their field energy. We argue that if the two charges are equal to each other…
We discuss a new formalism for light propagation which can be used within the regime of validity of geometric optics, but with no limitation on the scales of interest: from inside the Galaxy to the ultra-large scales of cosmology. One of…
We show that tunnelling between two degenerate minima, as allowed in a finite volume, leads to a non-extensive symmetric ground state. This results in Null Energy Condition violation for sufficiently low temperatures, when a continuous set…
The accuracy of stellar distances inferred purely from parallaxes degrades rapidly with distance. Proper motion measurements, when combined with some idea of typical velocities, provide independent information on stellar distances. Here I…
From the equivalence principle and true gravitational (G) time dilation experiments it is concluded that ``matter is not invariable after a change of relative position with respect to other bodies''. As a general principle (GP), such…
Spectroscopic methods allow to measure energy differences with unrivaled precision. In the case of gravity resonance spectroscopy, energy differences of different gravitational states are measured without recourse to the electromagnetic…
I present a novel method for measuring lens masses for microlensing events. By combining a measured lens flux with the microlens parallax vector pi_E, it is possible to derive the mass of the lens system without knowing the angular size of…
Hubble Space Telescope (HST) Fine Guidance Sensor (FGS) trigonometric parallax observations were obtained to directly determine distances to five nearby M-dwarf / M-dwarf eclipsing binary systems. These systems are intrinsically interesting…
A major problem in the interpretation of microlensing events is that the only measured quantity, the Einstein time scale t_E, is a degenerate combination of the three quantities one would like to know, the mass, distance, and speed of the…
This article describes a parallax experiment performed by undergraduate physics students at Queensland University of Technology. The experiment is analogous to the parallax method used in astronomy to measure distances to the local stars.…
We show that there are isometrically nonequivalent Robertson-Walker metrics which have the same set of geodesics. While one of these metrics satisfies the Einstein equations of pure dust without a cosmological constant, all the other…