On the kinematic interpretation of cosmological redshifts

We describe what is essentially a correct solution to the kinematic interpretation of cosmological redshifts in standard cosmological model. In the framework of "stretching of space" point of view of the spatially homogeneous and isotropic Robertson-Walker space-time of standard cosmological model, we study so-called "lookforward" history of expanding universe, subject to certain rules, in order to overcome the ambiguity of the parallel transport of source four-velocity along the null geodesic to an observer. We interpret the cosmological redshifts as the accumulation of a series of infinitesimal "relative" spectral shifts along the path of light consequent on recession. The crux of our solution is the kinetic recession velocity of comoving astronomical object, which is always subluminal even for large redshifts of order one or more, so that it does not violate the fundamental physical principle of causality. Our analysis establishes a straightforward kinematic relationship of overall cosmological redshift and kinetic recession velocity, which is utterly distinct from a familiar global Doppler shift formula. A difference of global Doppler velocity and kinetic recession velocity, for redshifts 0.9 ≤ z ≤ 800, is ≥ 0.072c, where a maximum value, 0.187c, is reached at redshifts z = 4.5 - 5.1. A general solution is reduced to a global Doppler shift along the null geodesic. We discuss the implications for the case of a zero-density cosmological model of Milne universe, whereas a correspondence to the more usual special relativity notion of relative speed retains. In Table 1, we are summing up kinetic recession velocities of some typical distant astronomical objects with spectroscopic redshift determinations collected from the literature.

A molecular absorption line survey towards the AGN of Hydra-A

ABSTRACT We present Atacama Large Millimetre/submillimetre Array observations of the brightest cluster galaxy Hydra-A, a nearby (z = 0.054) giant elliptical galaxy with powerful and extended radio jets. The observations reveal CO(1−0), CO(2–1), 13CO(2–1), CN(2–1), SiO(5–4), HCO+(1–0), HCO+(2–1), HCN(1–0), HCN(2–1), HNC(1–0), and H2CO(3–2) absorption lines against the galaxy’s bright and compact active galactic nucleus. These absorption features are due to at least 12 individual molecular clouds that lie close to the centre of the galaxy and have velocities of approximately −50 to +10 km s−1 relative to its recession velocity, where positive values correspond to inward motion. The absorption profiles are evidence of a clumpy interstellar medium within brightest cluster galaxies composed of clouds with similar column densities, velocity dispersions, and excitation temperatures to those found at radii of several kpc in the Milky Way. We also show potential variation in a ∼10 km s−1 wide section of the absorption profile over a 2 yr time-scale, most likely caused by relativistic motions in the hot spots of the continuum source that change the background illumination of the absorbing clouds.

A measurement of the Hubble constant from angular diameter distances to two gravitational lenses

The local expansion rate of the Universe is parametrized by the Hubble constant, H0, the ratio between recession velocity and distance. Different techniques lead to inconsistent estimates of H0. Observations of Type Ia supernovae (SNe) can be used to measure H0, but this requires an external calibrator to convert relative distances to absolute ones. We use the angular diameter distance to strong gravitational lenses as a suitable calibrator, which is only weakly sensitive to cosmological assumptions. We determine the angular diameter distances to two gravitational lenses, 810−130+160 and 1230−150+180 megaparsec, at redshifts z=0.295 and 0.6304. Using these absolute distances to calibrate 740 previously measured relative distances to SNe, we measure the Hubble constant to be H0=82.4−8.3+8.4 kilometers per second per megaparsec.

Does gravity operate between galaxies? Observational evidence re-examined

The redshifts and luminosities of type 1A supernovae are conventionally fitted with the current paradigm, which holds that the galaxies are locally stationary in an expanding metric. The fit fails unless the expansion is accelerating; driven perhaps by ‘dark energy’. Is the recession of the galaxies slowed down by gravity or speeded up by some repulsive force? To shed light on this question the redshifts and apparent magnitudes of type 1A supernovae are re-analysed in a cartesian frame of reference omitting gravitational effects. The redshift is ascribed to the relativistic Doppler effect which gives the recession velocity when the light was emitted; if this has not changed, the distance reached and the luminosity follow immediately. This simple concept fits the observations surprisingly well with the Hubble constant H 0 =62.9±0.3 km s −1 Mpc −1 . It appears that the galaxies recede at unchanging velocities, so on the largest scale there is no significant intergalactic force. Reasons for the apparent absence of an intergalactic force are discussed.

Mapping of the Granular Flow during the Irreversible Deformation Processes in Spatially Extended Polycrystalline Systems

The objective of this work is to obtain the mapping of the granular flow during the irreversible deformation processes in spatially extended polycrystalline systems (SEPCS) in order to describe and analyse the phenomenology and mechanics of the granular flow. In general, it was established for commercial alloys that, the granular flow is linked with the hyperbolic motion due to dislocation dynamics and self accommodation of grains. Also, the recession velocity of grains in the stain field on the surface of SEPCS increased with the distance along the tension axis from the origin of the coordinate system of reference. This behaviour is very similar to the Hubble flow associated with the expansion process of the universe, where the recession velocity of the galaxies increased in a linear relationship with their distance. In this physical framework the main results are analysed in the context of the unified interpretation of the Hubble flow, plastic flow and super plastic flow [1-6].

On the Phenomenology and Mechanics of Super Plastic Flow in Advanced Structural Materials

In connection with ancient and recent view on cosmology, it is interesting to note that our universe could be a spherical crystal and it moves as a crystal in a relative position with others spherical universes, where the Burgers vector for cellular dislocations dynamics is the Hubble length: λH=1.32x1026m. The expansion process of this polycrystalline spatially extended system obey the hyperbolic granular flow, which it is due to an accelerated motion manifested during the deformation process of super plastic advanced structural universes in a similar behaviour of super plastic advanced structural materials. Consequently, in this work the phenomenology and mechanics of super plastic flow are analyzed in the context of the unified interpretation of Hubble flow, plastic flow and super plastic flow, where the combination of fundamentals constants with the natural Planck length, allows obtain in a closed agreement with the Orowan equation the magnitude of the nature Burgers vector of dislocation in the cosmic structure for the universe as follow: 1.62 10 . 35 3 0 x m c H G b P − ⊥ ⊥ ⊥ = = = = h λ ρ ν Where, b⊥ = magnitude of the nature Burgers vector for the universe (b⊥ = 1.62x10-35m), λP = Planck length (λP = 1.62x10-35m), H0 = the Hubble parameter (H0=70 (km/sec)/Mpc = 2.26854593 x10-18s-1), ρ⊥ = dislocation density (ρ⊥ = 1.273x1011 dislocations/m2) in the universe. ν⊥ = the recession velocity of galaxies related with dislocations dynamics in the cosmic structure (ν⊥ = 1100x103 m/s, it is the recession velocity of the Virgo super cluster at 16 Mpc distance). h = h / 2π . Here h = the Planck constant (h = 6.6262x10-34 Joule-s), G = the Newtonian constant (G = 6.67259x10-11 m3/kg s2) and c = the speed of light (c = 299 792 458 m/s) [1-3].

Expanding Confusion: Common Misconceptions of Cosmological Horizons and the Superluminal Expansion of the Universe

We use standard general relativity to illustrate and clarify several common misconceptions about the expansion of the universe. To show the abundance of these misconceptions we cite numerous misleading, or easily misinterpreted, statements in the literature. In the context of the new standard ΛCDM cosmology we point out confusions regarding the particle horizon, the event horizon, the ‘observable universe’ and the Hubble sphere (distance at which recession velocity = c). We show that we can observe galaxies that have, and always have had, recession velocities greater than the speed of light. We explain why this does not violate special relativity and we link these concepts to observational tests. Attempts to restrict recession velocities to less than the speed of light require a special relativistic interpretation of cosmological redshifts. We analyze apparent magnitudes of supernovae and observationally rule out the special relativistic Doppler interpretation of cosmological redshifts at a confidence level of 23σ.

Laser non-conduction limited heating and prediction of surface recession velocity in relation to drilling

Lasers find application in modifying the characteristics of metallic surfaces in industry. In the present study, a laser non-conduction heating situation is investigated and the recession velocity of the surface is computed after considering: (a) constant temperature evaporation at the surface and (b) the steady evaporation condition. It is found that, in the initial phase of evaporation, the velocity of the liquid-vapour interface (recession velocity) predicted from constant temperature evaporation at the surface condition is more realistic than that corresponding to the steady evaporation situation. Moreover, as evaporation progresses, the magnitude of the surface temperature increases because of recoil pressure developed at the vapour-liquid interface. Consequently, the surface temperature rises and the recession velocity is determined from a steady heating situation in place of that predicted from constant temperature evaporation at the surface condition.

Testing extragalactic H2O masers against the thin disk model: the present and the future

Water maser emission is detected towards the nuclei of 22 galaxies, all of them showing some sign of nuclear activity. Except for a couple of cases, maser features have been found only within 150 km s−1 of the systemic galaxy recession velocity but are often offset from systemic within that window. Spectral features in maser-detected galaxies are monitored regularly and these observations show that velocity drifts like those seen in the systemic masers of NGC 4258 are rare. Hence the conclusion that either masers in other galaxies are generally located farther from the central black hole than in NGC 4258, that the black holes in those galaxies are less massive than the one in NGC 4258, or that the masers' acceleration is in the plane of the sky (as in the case of maser gas at the projected extremities of an edge-on disk). Assuming the disk model holds, the last of these options leads to the possibility that, despite the relative faintness of high velocity maser features in the case of NGC 4258, the brightest maser emission originates from the projected edges of the disk, in general. A selection effect would have caused a bias, then, in previous surveys whereby masers in larger, more slowly rotating disks are favorably detected. New wide-bandwidth capabilities at the 100-m Effelsberg telescope and the emergence of the GBT will help to overcome any such bias and provide new examples of maser sources.