New Derivation of Redshift Distance without Using Power Expansions

2021 ◽  
Author(s):  
Steffen Haase
Keyword(s):  
Hubble Parameter ◽  
Scale Parameter ◽  
Physical Distance ◽  
Isotropic Universe ◽  
Cosmological Redshift ◽  
Walker Metric ◽  
Moving Coordinate ◽  
Spatially Homogeneous ◽  
The Universe ◽  
Theoretical Results

Here we use the flat Friedmann-Lemaitre-Robertson-Walker metric describing a spatially homogeneous and isotropic universe to derive the cosmological redshift distance in a way which differs from that which can be found in the astrophysical literature. We use the co-moving coordinate re (the subscript e indicates emission) for the place of a galaxy which is emitting photons and ra (the subscript a indicates absorption) for the place of an observer within a different galaxy on which the photons - which were traveling thru the universe - are absorbed. Therefore the real physical distance - the way of light - is calculated by D = a(t0) ra - a(te) re. Here means a(t0) the today’s (t0) scale parameter and a(te) the scale parameter at the time of emission (te) of the photons. Nobody can doubt this real travel way of light: The photons are emitted on the co-moving coordinate place re and are than traveling to the co-moving coordinate place ra. During this traveling the time is moving from te to t0 (te ≤ t0) and therefore the scale parameter is changing in the meantime from a(te) to a(t0). Using this right way of light we calculate some relevant classical cosmological equations (effects) and compare these theoretical results with some measurements of astrophysics. As one result we get e.g. the today’s Hubble parameter H0a ≈ 62.34 km/(s Mpc). This value is smaller than the Hubble parameter H0,Planck ≈ 67.66 km/(s Mpc) resulting from Planck 2018 data [12] which is discussed in the literature.

scholarly journals Geometry of the Universe and Its Relation to Entropy and Information

2013 ◽  
Vol 2013 ◽  
pp. 1-3 ◽  
Author(s):  
Ioannis Haranas ◽  
Ioannis Gkigkitzis
Keyword(s):  
Hubble Parameter ◽  
Space Time ◽  
Ricci Scalar ◽  
Friedmann Model ◽  
Walker Metric ◽  
The Universe

In an effort to investigate a possible relation between geometry and information, we establish a relation of the Ricci scalar in the Robertson-Walker metric of the cosmological Friedmann model to the number of informationNand entropyS. This is with the help of a previously derived result that relates the Hubble parameter to the number of informationN. We find that the Ricci scalar has a dependence which is inversely proportional to the number of informationNand entropyS. Similarly, a nonzero number of information would imply a finite Ricci scalar, and therefore space time will unfold. Finally, using the maximum number of information existing in the universe, we obtain a numerical value for the Ricci scalar to beO(10-52) m-2.

VALIDITY OF THE THERMODYNAMICAL PROPERTIES OF THE DARK ENERGY MODEL WITH THE EQUATION OF STATE: w = w0 + w1 · z(1 + z)/(1 + z2)

2011 ◽  
Vol 26 (12) ◽  
pp. 885-892 ◽  
Author(s):  
LILI XING ◽  
JIANBIN CHEN ◽  
YUANXING GUI ◽  
ERIC M. SCHLEGEL ◽  
JIANBO LU
Keyword(s):  
Dark Energy ◽  
Equation Of State ◽  
Event Horizon ◽  
Dark Energy Model ◽  
Apparent Horizon ◽  
Parametric Model ◽  
Isotropic Universe ◽  
Thermodynamical Properties ◽  
Spatially Homogeneous ◽  
The Universe

We investigate the validity of the thermodynamical properties of the universe in a new parametric model of dark energy with the equation of state w = w0 + w1 · z(1 + z)/(1 + z2). In the spatially homogeneous and isotropic universe, assuming that the temperature and entropy in cosmology is as in a black hole, we examine the thermodynamical properties of the universe bounded by the apparent horizon and the event horizon respectively. By analysis, we find that the first and the second laws of thermodynamics are valid inside the apparent horizon, while they break down inside the event horizon.

scholarly journals A PROPOSED SCALE-DEPENDENT COSMOLOGY FOR THE INHOMOGENEOUS UNIVERSE

1996 ◽  
Vol 05 (03) ◽  
pp. 293-312 ◽  
Author(s):  
C.W. KIM ◽  
J. SONG
Keyword(s):  
Hubble Parameter ◽  
Globular Clusters ◽  
Observational Cosmology ◽  
Energy Tensor ◽  
Stress Energy Tensor ◽  
Inhomogeneous Universe ◽  
Stress Energy ◽  
Walker Metric ◽  
Age Of The Universe ◽  
The Universe

We propose a scale-dependent cosmology with the stress-energy tensor of viscous fluid, in which the Robertson-Walker metric and the Einstein equation are generalized in such a way that Ω0, H0 and the age of the Universe all become scale-dependent. Its implications on the observational cosmology and possible modifications of the standard Friedmann cosmology are discussed. For example, since the age of the Universe in this model depends on the local values of Ω0 and the Hubble parameter, the age of the locally open Universe even with the high value of hubble parameter can be long enough to accommodate the measured ages of the oldest stars and globular clusters.

scholarly journals From Quantum Unstable Systems to the Decaying Dark Energy: Cosmological Implications

2018 ◽  
Vol 2018 ◽  
pp. 1-8
Author(s):  
Aleksander Stachowski ◽  
Marek Szydłowski ◽  
Krzysztof Urbanowski
Keyword(s):  
Dark Energy ◽  
Time Reversal ◽  
Hubble Parameter ◽  
Decay Process ◽  
Time Dependent ◽  
Time Reversal Symmetry ◽  
Exponential Form ◽  
Cosmological Time ◽  
Evolution Of The Universe ◽  
The Universe

We consider a cosmology with decaying metastable dark energy and assume that a decay process of this metastable dark energy is a quantum decay process. Such an assumption implies among others that the evolution of the Universe is irreversible and violates the time reversal symmetry. We show that if we replace the cosmological time t appearing in the equation describing the evolution of the Universe by the Hubble cosmological scale time, then we obtain time dependent Λ(t) in the form of the series of even powers of the Hubble parameter H: Λ(t)=Λ(H). Our special attention is focused on radioactive-like exponential form of the decay process of the dark energy and on the consequences of this type decay.

scholarly journals Do we come from a quantum anomaly?

2019 ◽  
Vol 28 (14) ◽  
pp. 1944002 ◽  
Author(s):  
Spyros Basilakos ◽  
Nick E. Mavromatos ◽  
Joan Solà Peracaula
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Energy Density ◽  
Hubble Parameter ◽  
Vacuum Energy ◽  
Vacuum Energy Density ◽  
Quantum Anomaly ◽  
Inflationary Phase ◽  
Axion Field ◽  
The Universe

We present a string-based picture of the cosmological evolution in which (CP-violating) gravitational anomalies acting during the inflationary phase of the universe cause the vacuum energy density to “run” with the effective Hubble parameter squared, [Formula: see text], thanks to the axion field of the bosonic string multiplet. This leads to baryogenesis through leptogenesis with massive right-handed neutrinos. The generation of chiral matter after inflation helps in cancelling the anomalies in the observable radiation- and matter-dominated eras. The present era inherits the same “running vacuum” structure triggered during the inflationary time by the axion field. The current dark energy is thus predicted to be mildly dynamical, and dark matter should be made of axions. Paraphrasing Carl Sagan [ https://www.goodreads.com/author/quotes/10538.Carl_Sagan .]: we are all anomalously made from starstuff.

scholarly journals Testing Predictions of the Quantum Landscape Multiverse 3: The Hilltop Inflationary Potential

Symmetry ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 520
Author(s):  
Eleonora Di Valentino ◽  
Laura Mersini-Houghton
Keyword(s):  
Quantum Entanglement ◽  
Lower Limit ◽  
Hubble Parameter ◽  
Susy Breaking ◽  
Weak Lensing ◽  
Planck Data ◽  
The Universe ◽  
Breaking Scale ◽  
Inflationary Models ◽  
Origin Of The Universe

Here we test the predictions of the theory of the origin of the universe from the landscape multiverse, against the 2015 Planck data, for the case of the Hilltop class of inflationary models, for p = 4 and p = 6 . By considering the quantum entanglement correction of the multiverse, we can place just a lower limit on the local ’SUSY-breaking’ scale, respectively b > 8.7 × 10 6 G e V at 95 % c.l. and b > 1.3 × 10 8 G e V at 95 % c.l. from Planck TT+lowP, so the case with multiverse correction is statistically indistinguishable from the case with an unmodified inflation. We find that the series of anomalies predicted by the quantum landscape multiverse for the allowed range of b, is consistent with Planck’s tests of the anomalies. In addition, the friction between the two cosmological probes of the Hubble parameter and with the weak lensing experiments goes away for a particular subset, the p = 6 case of Hilltop models.

scholarly journals Notes on Cosmology

1972 ◽  
Vol 44 ◽  
pp. 404-406 ◽  
Author(s):  
J. Pachner
Keyword(s):  
Point Of View ◽  
World Model ◽  
Present Epoch ◽  
Cosmological Principle ◽  
Cosmic Evolution ◽  
Cosmic Space ◽  
Walker Metric ◽  
Theory Of Gravitation ◽  
Isotropic Expansion ◽  
The Universe

The present short notes on cosmology start with two conclusions based on observational data. The first of them is the well-known conclusion that the Universe from the global point of view is at the present epoch of its evolution in a uniform and isotropic expansion. If we accept the very convincing arguments of Bondi (1962) that the geometry of the cosmic space is Riemannian, its properties are described at the present epoch of the cosmic evolution by the well-known Robertson-Walker metric expressing the cosmological principle (Robertson, 1935, 1936; Walker, 1936). The form of the geodesical lines depends on the assumed theory of gravitation. For instance, in the closed Friedman world model they are cycloids with a singularity at the start of the expansion.

scholarly journals Thermodynamics of the viscous f(T,B) gravity in the new agegraphic dark energy model

2020 ◽  
Vol 35 (20) ◽  
pp. 2050166 ◽  
Author(s):  
A. Pourbagher ◽  
Alireza Amani
Keyword(s):  
Dark Energy ◽  
Hubble Parameter ◽  
Dark Energy Model ◽  
Apparent Horizon ◽  
Second Law Of Thermodynamics ◽  
Energy Model ◽  
Accelerated Expansion ◽  
Agegraphic Dark Energy ◽  
New Agegraphic Dark Energy ◽  
The Universe

In this paper, we first obtain the energy density by the approach of the new agegraphic dark energy model, and then the [Formula: see text] gravity model is studied as an alternative to the dark energy in a viscous fluid by flat-FRW background, in which [Formula: see text] and [Formula: see text] are torsion scalar and boundary term. The Friedmann equations will be obtained in the framework of modified teleparallel gravity by tetrad components. We consider that the universe dominates with components such as matter and dark energy by an interacting model. The Hubble parameter is parameterized by the power-law for the scale factor, and then we fit the corresponding Hubble parameter with observational data constraints. The variation of the equation of state (EoS) for dark energy is plotted as a function of the redshift parameter, and the accelerated expansion of the universe is explored. In what follows, the stability of the model is also studied on the base of the sound speed parameter. Finally, the generalized second law of thermodynamics is investigated by entropies of inside and on the boundary of the apparent horizon in thermodynamics equilibrium.

scholarly journals AN OPEN INFLATIONARY MODEL FOR DIMENSIONAL REDUCTION AND ITS EFFECTS ON THE OBSERVABLE PARAMETERS OF THE UNIVERSE

2005 ◽  
Vol 20 (11) ◽  
pp. 2449-2453
Author(s):  
KORAY KARACA ◽  
SELÇUK BAYIN
Keyword(s):  
Phase Transition ◽  
Cosmological Model ◽  
Boundary Conditions ◽  
Dimensional Reduction ◽  
Higher Dimensions ◽  
Inflationary Model ◽  
Early Stages ◽  
Isotropic Cosmological Model ◽  
Spatially Homogeneous ◽  
The Universe

Assuming that higher dimensions existed in the early stages of the universe where the evolution was inflationary, we construct an open, singularity-free, spatially homogeneous and isotropic cosmological model to study the effects of dimensional reduction that may have taken place during the early stages of the universe. We consider dimensional reduction to take place in a stepwise manner and interpret each step as a phase transition. By imposing suitable boundary conditions we trace their effects on the present day parameters of the universe.

Constraints on the dark side of the universe (3D universe) and observational Hubble parameter data

2011 ◽  
Vol 41 (12) ◽  
pp. 1452-1468
Author(s):  
Cong MA ◽  
TongJie ZHANG ◽  
Han ZHANG ◽  
Shuo YUAN ◽  
Cong ZHANG
Keyword(s):  
Hubble Parameter ◽  
Dark Side ◽  
The Universe
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