arXiv subjects

Sisir Roy

Publications and source records attributed to Sisir Roy.

27 records · Page 2Linked to original sources

arXiv2006

Statistical Analysis of Quasar Data and Hubble Law

The linearity of the Hubble relationship (i.e. between m and z) has been tested for galaxies and supernovea for low redshifts. We have studied this relationship for quasars for data taken from Veron Cetti Catalogue(2003).The data from Veron Cetti Catalogue for quasars appear to be truncated. The data have been analyzed using various statistical methods which are suitable for analysing the truncated data. This analysis shows lineraity (in log z) of Hubble law for very small z but non-linearity for high redshift.This will shed new light not only on the quasar astronomy but also in the cosmological debate.

astro-ph↗

arXiv2003

Geometroneurodynamics

Hilbert space structure is assumed as a valid geometric description for neurodynamics, i.e., for applying any kind of quantum formalism in brain dynamics. The orientation selectivity of the neurons is used as a justification to construct a type of statistical distance function which is proportional to the usual distance (or angle) between orientations of the neurons. The equivalence between the statistical distance and the Hilbert-space distance is discussed within this framework. It gives rise to the possibility of reanalysing the issue of measurement and information processing in the brain function

quant-ph↗

arXiv2003

The Time Dependence of Fundamental Constants and Planck Scale Physics

A real aether model of the vacuum proposed by Allen Rothwarf based upon a degenerate Fermion fluid of polarizable particle-antiparticle pairs, leads to a big bang model of the universe where the velocity of light varies inversely with the square root of the cosmological time. Here, this model is used to determine the time dependence of certain fundamental constants, i.e. permittivity, permeability of free space : the Gravitational constant, and the Planck units: length, time and mass.

astro-ph↗

arXiv2003

Variation of Physical constants, Redshift and the Arrow of time

Theories of fundamental physics as well as cosmology must ultimately not only account for the structure and evolution of the universe and the physics of fundamental interactions, but also lead to an understanding of why this particular universe follows the physics that it does. Such theories must ultimately lead to an understanding of the values of the fundamental constants themselves. However, all such efforts have failed, leaving fundamental constants outside of any physical theories. In this paper we take a different approach than the usual evolutionary picture where the physics itself is assumed invariant. We study numerical relations among fundamental constants starting from relationships first proposed by Weinberg (1972). We have shown (Kafatos et al.2000) that they turn out to be equivalent to the relations found by Dirac (1937). Then a new scaling hypothesis relating the speed of light $c$ and the scale of the universe $R$ is explored.

astro-ph↗

arXiv2003

Quantum processes, space-time representation and brain dynamics

The recent controversy of applicability of quantum formalism to brain dynamics has been critically analysed. The prerequisites for any type of quantum formalism or quantum field theory is to investigate whether the anatomical structure of brain permits any kind of smooth geometric notion like Hilbert structure or four dimensional Minkowskian structure for quantum field theory. The present understanding of brain function clearly denies any kind of space-time representation in Minkowskian sense. However, three dimensional space and one time can be assigned to the neuromanifold and the concept of probabilistic geometry is shown to be appropriate framework to understand the brain dynamics. The possibility of quantum structure is also discussed in this framework.

quant-ph↗

arXiv2002

Sheaf Cohomology and Geometrical Approach to EPR Non-locality

A consistent geometrical approach to EPR non-locality as well as other non-local effects in QM like the Aharanov-Bohm effect, Berry phase, Gauge theories within Yang-Mills theory etc. is possible within the framework of sheaf cohomology. This sheds new light on our understanding on non-local correlations in QM, and provides a fundamental mathematical approach to fundamental problems in physics.

quant-ph↗

arXiv2001

(Quantum) Space-Time as a Statistical Geometry of Fuzzy Lumps and the Connection with Random Metric Spaces

We develop a kind of pregeometry consisting of a web of overlapping fuzzy lumps which interact with each other. The individual lumps are understood as certain closely entangled subgraphs (cliques) in a dynamically evolving network which, in a certain approximation, can be visualized as a time-dependent random graph. This strand of ideas is merged with another one, deriving from ideas, developed some time ago by Menger et al, that is, the concept of probabilistic- or random metric spaces, representing a natural extension of the metrical continuum into a more microscopic regime. It is our general goal to find a better adapted geometric environment for the description of microphysics. In this sense one may it also view as a dynamical randomisation of the causal-set framework developed by e.g. Sorkin et al. In doing this we incorporate, as a perhaps new aspect, various concepts from fuzzy set theory.

gr-qc↗

arXiv1999

Shift of Spectral Lines due to Dynamic Multiple Scattering and Screening Effect: Implications for Discordant Redshifts

The frequency shift of spectral lines from astronomical objects is most often explained by the Doppler Effect arising in relative motion and the broadening of a particular line is supposed to depend on the absolute temperature, pressure or the different line of sight velocities. The Wolf effect on the other hand deals with correlation induced spectral changes and explains both the broadening and shift of the spectral lines. In this framework a sufficient condition for redshift has been derived and when applicable the shift is shown to be larger than broadening. Under this condition of larger shift than broadening we find a critical source frequency below which no spectrum is analyzable for a particular medium. This gives rise to new type of screening effect which may play significant role both at laboratory scale as well as in the astronomical domain. We apply a simple interpretation of the discordant redshifts in galaxy-quasar associations.

astro-ph↗

arXiv1999

Broadening of Spectral Lines due to Dynamic Multiple Scattering and the Tully-Fisher Relation

The frequency shift of spectral lines is most often explained by the Doppler Effect in terms of relative motion, whereas the Doppler broadening of a particular line mainly depends on the absolute temperature. The Wolf effect on the other hand deals with the correlation induced spectral change and explains both the broadening and shift of the spectral lines. In this framework a relation between the width of the spectral line is related to the redshift z for the line and hence with the distance. For smaller values of z a relation similar to the Tully-Fisher relation can be obtained and for larger values of z a more general relation can be constructed. The derivation of this kind of relation based on dynamic multiple scattering theory may play a significant role in explaining the overall spectra of quasi stellar objects. We emphasize that this mechanism is not applicable for nearby galaxies, $z \leq 1$.

astro-ph↗