Zobrazeno 1 - 10
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pro vyhledávání: '"Rajendra P. Gupta"'
Autor:
Rajendra P. Gupta
Publikováno v:
Universe, Vol 10, Iss 6, p 266 (2024)
Relaxing the temporal constancy constraint on coupling constants in an expanding universe results in Friedmann equations containing terms that may be interpreted as dark energy and dark matter. When tired light (TL) was considered to complement the r
Externí odkaz:
https://doaj.org/article/c2e739e1a3c54d829a77aac973a716ac
Autor:
Rajendra P. Gupta
Publikováno v:
The Astrophysical Journal, Vol 964, Iss 1, p 55 (2024)
The primary purpose of this paper is to see how well a recently proposed new model fits (a) the position of the baryon acoustic oscillation (BAO) features observed in the large-scale distribution of galaxies and (b) the angular size measured for the
Externí odkaz:
https://doaj.org/article/6c23bc850c8c4516a34becdcf038f378
Publikováno v:
Symmetry, Vol 15, Iss 3, p 709 (2023)
A scalar–tensor theory of gravity was considered, wherein the gravitational coupling G and the speed of light c were admitted as space–time functions and combined to form the definition of the scalar field ϕ. The varying c participates in the de
Externí odkaz:
https://doaj.org/article/0d192631420e477fb766427648baed5e
Autor:
Rajendra P. Gupta
Publikováno v:
Symmetry, Vol 15, Iss 2, p 259 (2023)
Dirac, in 1937, proposed the potential variation of coupling constants derived from his large numbers hypothesis. Efforts have continued since then to constrain their variation by various methods, including astrophysical and cosmological observations
Externí odkaz:
https://doaj.org/article/f443f311040249fa9fe6354cf0652735
Autor:
Rajendra P. Gupta
Publikováno v:
Universe, Vol 9, Iss 2, p 70 (2023)
Equations governing the evolution of a star involve multiple coupling constants. Thus, the time it spends as a main-sequence star can be expected to depend on whether or not such constants vary over the time scale of stellar evolution. When the star
Externí odkaz:
https://doaj.org/article/8ac87d3ed2994ee782b3bbeb45c56d68
Autor:
Rajendra P. Gupta
Publikováno v:
Galaxies, Vol 7, Iss 3, p 77 (2019)
We have used the varying physical constant approach to resolve the flatness problem in cosmology. Friedmann equations are modified to include the variability of speed of light, gravitational constant, cosmological constant, and the curvature constant
Externí odkaz:
https://doaj.org/article/8d29f1741eb94521ace86dc154ddaf89
Autor:
Rajendra P. Gupta
Publikováno v:
Galaxies, Vol 7, Iss 3, p 67 (2019)
We have shown that the Hubble constant H 0 embodies the information about the evolutionary nature of the cosmological constant Λ , gravitational constant G , and the speed of light c . We have derived expressions for the time evolution of G / c 2
Externí odkaz:
https://doaj.org/article/6ff26dc07cf24c91aa69d0ca462ba426
Autor:
Rajendra P. Gupta
Publikováno v:
Galaxies, Vol 7, Iss 2, p 55 (2019)
We have developed a cosmological model by allowing the speed of light c, gravitational constant G and cosmological constant Λ in the Einstein filed equation to vary in time, and solved them for Robertson-Walker metric. Assuming the universe is flat
Externí odkaz:
https://doaj.org/article/ce66c726a5984aaeb5836de8ae820233
Autor:
Rajendra P. Gupta
Publikováno v:
Universe, Vol 5, Iss 5, p 102 (2019)
Many models have been proposed to explain the intergalactic redshift using different observational data and different criteria for the goodness-of-fit of a model to the data. The purpose of this paper is to examine several suggested models using the
Externí odkaz:
https://doaj.org/article/1da563b1b26945b2984ccfcdf57e9530
Autor:
Rajendra P. Gupta
Publikováno v:
Universe, Vol 4, Iss 10, p 104 (2018)
By relaxing the constraint of adiabatic universe used in most cosmological models, we have shown that the new approach provides a better fit to the supernovae Ia redshift data with a single parameter, the Hubble constant H0, than the standard ΛCDM m
Externí odkaz:
https://doaj.org/article/febae85d8b374862b18d732b9d63a3f7