Relativistic Theory of the Behavior of Irregularities in an Expanding World Model

This chapter presents the full relativistic analysis of the evolution of mass clustering. The full relativistic theory is needed to deal with three important aspects of density irregularities in the early universe. First, when the pressure is high the relativistic active gravitational mass and inertial mass associated with pressure affect the dynamics. Second, when the mean density is high, a fluctuation of even modest fractional amount containing a modest mass can have a large effect on the space curvature. One is thus led to deal with the interaction of speculations on the nature of the mass distribution and of the geometry in the early universe. Third, the horizon shrinks to zero at the time of the big bang: the seed fluctuations out of which galaxies might form were larger than the horizon and so were not in causal connection reckoned from the time of the big bang. Of course, this curious point applies as well to the homogeneous background: it was somehow contrived that all parts of the universe now visible were set expanding with quite precise uniformity even though an observer could not have discovered this much before the present epoch.

Bondi accretion in the spherically symmetric Johannsen–Psaltis spacetime

The Johannsen–Psaltis spacetime explicitly violates the no-hair theorem. It describes rotating black holes with scalar hair in the form of parametric deviations from the Kerr metric. In principle, black hole solutions in any modified theory of gravity could be written in terms of the Johannsen–Psaltis metric. We study the accretion of gas onto a static limit of this spacetime. We utilise a recently proposed pseudo–Newtonian formulation of the dynamics around arbitrary static, spherically symmetric spacetimes. We obtain a potential that generalises the Paczyński–Wiita potential to the static Johannsen–Psaltis metric. We also perform a fully relativistic analysis of the geodesic equations in the static Johannsen–Psaltis spacetime. We find that positive (negative) values of the scalar hair parameter, $$\epsilon _{3}$$ϵ3, lower (raise) the accretion rate. Similarly, positive (negative) values of $$\epsilon _{3}$$ϵ3 reduce (increase) the gravitational acceleration of radially infalling massive particles.

Chernobyl’s Lesser Known Design Flaw: The Chernobyl Liquidator Medal—An Educational Essay

The honorary Chernobyl Liquidator Medal depicts pathways of alpha, gamma, and beta rays over a drop of blood, signifying the human health impacts of the Chernobyl accident. A relativistic analysis of the trajectories depicted on the Chernobyl Liquidator Medal is conducted assuming static uniform magnetic and electric fields. The parametric trajectories are determined using the energies of alpha (α) and beta (β) particles relevant to the Chernobyl nuclear power plant accident and compared with the trajectories depicted on the liquidator medal. For minimum alpha particle velocity of 0.0512c, the beta particle trajectory depicted on the medal is highly unlikely to have come from a naturally occurring nuclear decay process. The parametric equations are used to determine the necessary beta energies to reproduce the depicted trajectories. This article documents the unfortunate misrepresentation of a famous scientific experiment on an honorary medal and illustrates the importance of better communication between artists and scientists.

Relativistic analysis of application of Helmholtz theorem to classical electrodynamics

In this work we discuss the relationship between the instantaneous-action-at-a-distance solutions of Maxwell’s equations obtained using Helmholtz theorem and the Lorentz’s invariant solutions of the same equations obtained using Special Relativity postulates. We show that Special Relativity postulates are not consistent with Helmholtz’s theorem in the presence of charges and currents, but in the vacuum, without charges and currents, Helmholtz’s theorem and Special Relativity agree because the instantaneous-action-at-a-distance solutions can be eliminated using a gauge transformation.