Whither Astro?

On the dual interpretation of zero-curvature Friedmann-Robertson-Walker models

“…In order to avoid the important drawbacks of Eckart's theory, we shall use transport equations derived from the Israel-Stewart approach [9][10][11]. However, since these equations are going to be evaluated immediately after the system leaves the perfect fluid (or the quasi-perfect fluid) regime, then the truncated version of the theory leads to the same result as the full theory, and therefore the former will be used here.…”

Scalar-tensor gravity theory for dynamical light velocity

“…If this observational evidence is correct, then the implications for cosmology are remarkable. Attempts to explain this phenomenon include "quintesssence" [2], the cosmological constant [3], a domain wall dominated universe [4] and non-perturbative vacuum contributions to the effective action of a massive scalar field [5]. In general it would appear that the cosmological fluid is dominated in the present universe by an exotic energy density, which has a negative pressure and which did not play an important role in the early universe.…”

Turbulent Dynamos and Magnetic Helicity

“…The origin of these cosmical magnetic fields has been explained mainly by dynamo theory [3], which is one of the most active research areas across multiple subdisciplines of physics. In particular, generation of an electromotive force (EMF) along a mean field by turbulence, or the well-known α effect [4], is an essential process in amplifying large-scale magnetic fields [5]. Experimentally, the α effect has been observed in toroidal laboratory plasmas [6].Recently, there has been growing awareness that a topological constraint on the observed magnetic field, the conservation of magnetic helicity, may play an important role in solar flare evolution [7].…”