Scalar-Tensor Gravity Theory For Dynamical Light Velocity

A gravity theory is developed with the metric ${\hat g}_{\mu\nu}= {g}_{\mu\nu}+B\partial_\mu\phi\partial_\nu\phi$. In the present universe the additional contribution from the scalar field in the metric ${\hat g}_{\mu\nu}$ can generate an acceleration in the expansion of the universe, without negative pressure and with a zero cosmological constant. In this theory, gravitational waves will propagate at a different speed from non-gravitational waves. It is suggested that gravitational wave experiments could test this observational signature.Comment: 14 pages latex file. Additional material added. Accepted for publication in Physics Letters

Static post-Newtonian equivalence of GR and gravity with a dynamical preferred frame

A generally covariant extension of general relativity (GR) in which a dynamical unit timelike vector field is coupled to the metric is studied in the asymptotic weak field limit of spherically symmetric static solutions. The two post-Newtonian parameters known as the Eddington-Robertson-Schiff parameters are found to be identical to those in the case of pure GR, except for some non-generic values of the coefficients in the Lagrangian.Comment: 13 pages; v.2: minor editing, signs corrected, version to appear in PRD; v. 3: signs corrected in eqn (3

A scalar-tensor cosmological model with dynamical light velocity

The dynamical consequences of a bimetric scalar-tensor theory of gravity with a dynamical light speed are investigated in a cosmological setting. The model consists of a minimally-coupled self-gravitating scalar field coupled to ordinary matter fields in the standard way through the metric: \metric_{\mu\nu}+B\partial_\mu\phi\partial_\nu\phi. We show that in a universe with matter that has a radiation-dominated equation of state, the model allows solutions with a de Sitter phase that provides sufficient inflation to solve the horizon and flatness problems. This behaviour is achieved without the addition of a potential for the scalar field, and is shown to be largely independent of its introduction. We therefore have a model that is fundamentally different than the potential-dominated, slowly-rolling scalar field of the standard models inflationary cosmology. The speed of gravitational wave propagation is predicted to be significantly different from the speed of matter waves and photon propagation in the early universe.Comment: 12 pages, uses amsart and amssymb. Minor corrections, to appear in Phys. Lett.

Comments on "Note on varying speed of light theories"

In a recent note Ellis criticizes varying speed of light theories on the grounds of a number of foundational issues. His reflections provide us with an opportunity to clarify some fundamental matters pertaining to these theories

The dynamical stability of the static real scalar field solutions to the Einstein-Klein-Gordon equations revisited

We re-examine the dynamical stability of the nakedly singular, static, spherical ly symmetric solutions of the Einstein-Klein Gordon system. We correct an earlier proof of the instability of these solutions, and demonstrate that there are solutions to the massive Klein-Gordon system that are perturbatively stable.Comment: 13 pages, uses Elsevier style files. To appear in Phys. Lett.

Variable-Speed-of-Light Cosmology from Brane World Scenario

We argue that the four-dimensional universe on the TeV brane of the Randall-Sundrum scenario takes the bimetric structure of Clayton and Moffat, with gravitons traveling faster than photons instead, while the radion varies with time. We show that such brane world bimetric model can thereby solve the flatness and the cosmological constant problems, provided the speed of a graviton decreases to the present day value rapidly enough. The resolution of other cosmological problems such as the horizon problem and the monopole problem requires supplementation by inflation, which may be achieved by the radion field provided the radion potential satisfies the slow-roll approximation.Comment: 18 pages, LaTeX, revised version to appear in Phys. Rev.

Could thermal fluctuations seed cosmic structure?

We examine the possibility that thermal, rather than quantum, fluctuations are responsible for seeding the structure of our universe. We find that while the thermalization condition leads to nearly Gaussian statistics, a Harrisson-Zeldovich spectrum for the primordial fluctuations can only be achieved in very special circumstances. These depend on whether the universe gets hotter or colder in time, while the modes are leaving the horizon. In the latter case we find a no-go theorem which can only be avoided if the fundamental degrees of freedom are not particle-like, such as in string gases near the Hagedorn phase transition. The former case is less forbidding, and we suggest two potentially successful ``warming universe'' scenarios. One makes use of the Phoenix universe, the other of ``phantom'' matter.Comment: minor corrections made, references added, matches the version accepted to PR

A time-space varying speed of light and the Hubble Law in static Universe

We consider a hypothetical possibility of the variability of light velocity with time and position in space which is derived from two natural postulates. For the consistent consideration of such variability we generalize translational transformations of the Theory of Relativity. The formulae of transformations between two rest observers within one inertial system are obtained. It is shown that equality of velocities of two particles is as relative a statement as simultaneity of two events is. We obtain the expression for the redshift of radiation of a rest source which formally reproduces the Hubble Law. Possible experimental implications of the theory are discussed.Comment: 7 page

Structural and functional insights into non-structural proteins of coronaviruses

Coronaviruses (CoVs) are causing a number of human and animal diseases because of their zoonotic nature such as Middle East respiratory syndrome (MERS), severe acute respiratory syndrome (SARS) and coronavirus disease 2019 (COVID-19). These viruses can infect respiratory, gastrointestinal, hepatic and central nervous systems of human, livestock, birds, bat, mouse, and many wild animals. The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a newly emerging respiratory virus and is causing CoVID-19 with high morbidity and considerable mortality. All CoVs belong to the order Nidovirales, family Coronaviridae, are enveloped positive-sense RNA viruses, characterised by club-like spikes on their surfaces and large RNA genome with a distinctive replication strategy. Coronavirus have the largest RNA genomes (~26–32 kilobases) and their expansion was likely enabled by acquiring enzyme functions that counter the commonly high error frequency of viral RNA polymerases. Non-structural proteins (nsp) 7–16 are cleaved from two large replicase polyproteins and guide the replication and processing of coronavirus RNA. Coronavirus replicase has more or less universal activities, such as RNA polymerase (nsp 12) and helicase (nsp 13), as well as a variety of unusual or even special mRNA capping (nsp 14, nsp 16) and fidelity regulation (nsp 14) domains. Besides that, several smaller subunits (nsp 7– nsp 10) serve as essential cofactors for these enzymes and contribute to the emerging “nsp interactome.” In spite of the significant progress in studying coronaviruses structural and functional properties, there is an urgent need to understand the coronaviruses evolutionary success that will be helpful to develop enhanced control strategies. Therefore, it is crucial to understand the structure, function, and interactions of coronaviruses RNA synthesizing machinery and their replication strategies. © 202

What we do and do not know about the s-process

AGB stars are the source for the main component of the $s$-process. Here we discuss both the properties which are reasonably well known and those which still suffer from substantial uncertainties. In the former case, we are fairly sure that the $s$-process contribution from AGB stars comes from masses between about 1 and 3 \msun, and the dominant neutron source is the $^{13}$C$(\alpha$,n)$^{16}$O reaction. In the latter category remains the formation mechanism for the $^{13}$C-pocket. Attempts at including rotation seem to inhibit neutron capture reactions. Explaining the observations seems to require a spread in the size of the $^{13}$C-pocket so some stochastic process, such as rotation, must be involved.Comment: To be published in Nuclear Physics A; Invited Review for "Nuclei in the Cosmos VIII", Vancouver, July 200