arXiv subjects

Michael Good

Publications and source records attributed to Michael Good.

3 recordsLinked to original sources

arXiv2021

Constraining the swiss-cheese IR-fixed point cosmology with cosmic expansion

In a recent work, it has been proposed that the recent cosmic passage to a cosmic acceleration era is the result of the existence of small anti-gravity sources in each galaxy and clusters of galaxies. In particular, a swiss-cheese cosmology model which relativistically integrates the contribution of all these anti-gravity sources on galactic scale has been constructed assuming the presence of an infrared fixed point for a scale dependent cosmological constant. The derived cosmological expansion provides explanation for both the fine tuning and the coincidence problem. The present work relaxes the previous assumption on the running of the cosmological constant and allows for a generic scaling around the infrared fixed point. Our analysis reveals in order to produce a cosmic evolution consistent with the best $\Lambda$CDM model, the IR-running of the cosmological constant is consistent with the presence of an IR-fixed point.

gr-qc↗

arXiv2020

Radiation from an inertial mirror horizon

The purpose of this study is to investigate radiation from asymptotic zero acceleration motion where a horizon is formed and subsequently detected by an outside witness. A perfectly reflecting moving mirror is used to model such a system and compute the energy and spectrum. The trajectory is asymptotically inertial (zero proper acceleration)-ensuring negative energy flux (NEF), yet approaches light-speed with a null ray horizon at a finite advanced time. We compute the spectrum and energy analytically.

gr-qc↗

arXiv2020

Unruh-like effects: Effective temperatures along stationary worldlines

We study the detailed balance temperatures recorded along all classes of stationary, uniformly accelerated worldlines in four-dimensional Minkowski spacetime, namely along (i) linear uniform acceleration, (ii) cusped, (iii) circular, (iv) catenary, and (v) helix worldlines, among which the Unruh temperature is the particular case for linear uniform acceleration. As a measuring device, we employ an Unruh-DeWitt detector, modeled as a qubit that interacts for a long time with a massless Klein-Gordon field in the vacuum state. The temperatures in each case (i) - (v) are functions of up to three invariant quantities: curvature or proper acceleration, $\kappa$, torsion, $b$, and hypertorsion, $\nu$, and except for the case (i), they depend on the transition frequency difference of the detector, $\omega$. We investigate numerically the behavior of the frequency-dependent temperatures for different values of $\kappa$, $b$, and $\nu$ along the stationary worldlines (ii) - (v) and evaluate analytically the regimes where the temperatures recorded along the different worldlines coincide with each other in terms of relevant asymptotic limits for $\kappa$, $b$, or $\nu$, and discuss their physical meaning. We demonstrate that the temperatures in cases (ii) - (v) dip under the Unruh temperature at low frequencies and go above the Unruh temperature for large $|\omega|$. It is our hope that this study will be relevant to the design of experiments seeking to verify the Unruh effect or generalizations thereof.

gr-qc↗