scholarly journals Review on the Pseudocomplex General Relativity and Dark Energy

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Peter O. Hess
Keyword(s):  
General Relativity ◽  
Dark Energy ◽  
Mass Distribution ◽  
Accretion Disc ◽  
Cosmological Models ◽  
Standard Theory ◽  
Theory Of Relativity ◽  
Emission Profile ◽  
Evolution Of The Universe ◽  
The Universe

A review will be presented on the algebraic extension of the standard Theory of Relativity (GR) to the pseudocomplex formulation (pc-GR). The pc-GR predicts the existence of a dark energy outside and inside the mass distribution, corresponding to a modification of the GR-metric. The structure of the emission profile of an accretion disc changes also inside a star. Discussed are the consequences of the dark energy for cosmological models, permitting different outcomes on the evolution of the universe.

scholarly journals DARK ENERGY IN PRACTICE

2010 ◽  
Vol 25 (29) ◽  
pp. 5253-5331 ◽  
Author(s):  
DOMENICO SAPONE
Keyword(s):  
General Relativity ◽  
Dark Energy ◽  
Complete List ◽  
Late Time ◽  
Evolution Of The Universe ◽  
Late Time Acceleration ◽  
Energy Models ◽  
Acceleration Of The Universe ◽  
The Universe ◽  
Alternative Theories

In this paper we review a part of the approaches that have been considered to explain the extraordinary discovery of the late time acceleration of the Universe. We discuss the arguments that have led physicists and astronomers to accept dark energy as the current preferable candidate to explain the acceleration. We highlight the problems and the attempts to overcome the difficulties related to such a component. We also consider alternative theories capable of explaining the acceleration of the Universe, such as modification of gravity. We compare the two approaches and point out the observational consequences, reaching the sad but foresightful conclusion that we will not be able to distinguish between a Universe filled by dark energy or a Universe where gravity is different from General Relativity. We review the present observations and discuss the future experiments that will help us to learn more about our Universe. This is not intended to be a complete list of all the dark energy models but this paper should be seen as a review on the phenomena responsible for the acceleration. Moreover, in a landscape of hardly compelling theories, it is an important task to build simple measurable parameters useful for future experiments that will help us to understand more about the evolution of the Universe.

scholarly journals The growth of astrophysical understanding

2009 ◽  
Vol 5 (S260) ◽  
pp. 22-32
Author(s):  
Martin Harwit
Keyword(s):  
General Relativity ◽  
Dark Matter ◽  
Dark Energy ◽  
Particle Physics ◽  
High Energy ◽  
Standard Theory ◽  
Independent Evidence ◽  
Fundamental Particles ◽  
New Form ◽  
The Universe

Since this symposium commemorated Galileo's discoveries and was concerned with astronomy and culture, I thought I might examine the extent to which culture affects how we view, depict, and ultimately come to understand the Universe around us. Twenty-five years ago, Andrew Pickering, wrote Constructing Quarks – A Sociological History of Particle Physics, (Pickering 1984) a book that enormously annoyed the high-energy physics community, perhaps because it contained a disquieting dose of truth. Pickering argued that the theory of fundamental particles, the particles that make up the atomic nucleus, and break up or fuse into myriad other particles when smashed into each other, was a construct that physicist had pieced together, through a process he termed a “communally congenial representation of reality”. Physicists, he claimed, had arrived at a so-called “standard theory” of particle physics that was not an inherent description of Nature, but “deeply rooted in common-sense intuitions about the world and our knowledge of it”. Instead, Pickering surmised that a better depiction of particle physics would eventually be found, which would appear unrecognizably different from what had come to be the accepted way of viewing Nature's fundamental particles. Today, many particle physicists would be more likely to agree with Pickering than they were then. Although the standard theory has successfully survived a quarter of a century of testing, its scope is known to be limited. It fails to properly accommodate gravity. And the string theories, brane theories, and other attempts of particle physicists to produce a coherent theory of all the known forces of nature have so different a structure from the standard theory, topologically, as well as in terms of numbers of spatial dimensions, that they share little recognizable resemblance. So, we may ask, was Pickering right? Are physicists and astronomers just constructing congenial representations that bear little relation to the inherent structure of the Universe we inhabit? In astronomy, we have by now embraced what we term the “concordance model” based on general relativity, which we assert has led to tremendous strides in understanding the evolution of the Universe. But we find ourselves forced to postulate a new form of matter, dark matter, the existence of which is supported by little independent evidence, and we find ourselves forced to postulate the existence of a new form of energy, dark energy, for which there is similarly little independent evidence. Perhaps both these postulates will someday soon be justified. But we may equally well find a need for viewing the Universe in a totally different way that encompasses general relativity only as a limiting case, but embraces dark matter and dark energy as a natural consequence. Such a depiction might then be just as mind-bogglingly different from what we conceive today, as Einstein's postulate was, when he first annunciated it, that the speed of light would always appear the same no matter how fast an observer was moving toward or away from its source. How could that be, it violated every conceivable human intuition?

Albert Einstein’s Epistemic Virtues and Vices

2021 ◽  
Vol 58 (4) ◽  
pp. 175-195
Author(s):  
Vladimir P. Vizgin ◽  
Keyword(s):  
Field Theory ◽  
General Relativity ◽  
General Theory ◽  
Special Theory ◽  
Theory Of Relativity ◽  
Mathematical Aspect ◽  
General Theory Of Relativity ◽  
Special Theory Of Relativity ◽  
Epistemic Virtues ◽  
The Universe

The article is based on the concepts of epistemic virtues and epistemic vices and explores A. Einstein’s contribution to the creation of fundamental physical theories, namely the special theory of relativity and general theory of relativity, as well as to the development of a unified field theory on the basis of the geometric field program, which never led to success. Among the main epistemic virtues that led Einstein to success in the construction of the special theory of relativity are the following: a unique physical intuition based on the method of thought experiment and the need for an experimental justification of space-time concepts; striving for simplicity and elegance of theory; scientific courage, rebelliousness, signifying the readiness to engage in confrontation with scientific conventional dogmas and authorities. In the creation of general theory of relativity, another intellectual virtue was added to these virtues: the belief in the heuristic power of the mathematical aspect of physics. At the same time, he had to overcome his initial underestimation of the H. Minkowski’s four-dimensional concept of space and time, which has manifested in a distinctive flexibility of thinking typical for Einstein in his early years. The creative role of Einstein’s mistakes on the way to general relativity was emphasized. These mistakes were mostly related to the difficulties of harmonizing the mathematical and physical aspects of theory, less so to epistemic vices. The ambivalence of the concept of epistemic virtues, which can be transformed into epistemic vices, is noted. This transformation happened in the second half of Einstein’s life, when he for more than thirty years unsuccessfully tried to build a unified geometric field theory and to find an alternative to quantum mechanics with their probabilistic and Copenhagen interpretation In this case, we can talk about the following epistemic vices: the revaluation of mathematical aspect and underestimation of experimentally – empirical aspect of the theory; adopting the concepts general relativity is based on (continualism, classical causality, geometric nature of fundamental interactions) as fundamental; unprecedented persistence in defending the GFP (geometrical field program), despite its failures, and a certain loss of the flexibility of thinking. A cosmological history that is associated both with the application of GTR (general theory of relativity) to the structure of the Universe, and with the missed possibility of discovering the theory of the expanding Universe is intermediate in relation to Einstein’s epistemic virtues and vices. This opportunity was realized by A.A. Friedmann, who defeated Einstein in the dispute about if the Universe was stationary or nonstationary. In this dispute some of Einstein’s vices were revealed, which Friedman did not have. The connection between epistemic virtues and the methodological principles of physics and also with the “fallibilist” concept of scientific knowledge development has been noted.

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 ON POSSIBLE GEOMETRIC AND ASTROPHYSICAL EFFECTS OF NONLINEAR SPINOR FIELDS IN THE MEGAMIR, MACROWORLD AND MICROWORLD

Metaphysics ◽  
2020 ◽  
pp. 82-93
Author(s):  
V. G Krechet
Keyword(s):  
General Relativity ◽  
Gravitational Interaction ◽  
Space Time ◽  
Elementary Particles ◽  
Nonlinear Spinor ◽  
Evolution Of The Universe ◽  
Spinor Fields ◽  
Astrophysical Objects ◽  
Local Space ◽  
The Universe

In this article, within the framework of general relativity, the possible effect of the gravitational interaction of Dirac nonlinear spinor fields on the evolution of the Universe, on the formation of astrophysical objects and on the formation of the geometry of the local space-time of elementary particles with spin ħ / 2 is considered.

scholarly journals Cosmology from multimeasure multifield model

2019 ◽  
Vol 34 (19) ◽  
pp. 1950099 ◽  
Author(s):  
Denitsa Staicova ◽  
Michail Stoilov
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Model Potential ◽  
Higgs Mechanism ◽  
Evolution Of The Universe ◽  
Slow Roll ◽  
Cosmological Application ◽  
Proposed Model ◽  
Model Setup ◽  
The Universe

We consider the cosmological application of a (variant of) relatively newly proposed model1 unifying inflation, dark energy, dark matter, and the Higgs mechanism. The model was originally defined using additional non-Riemannian measures, but it can be reformulated into effective quintessential model unifying inflation, dark energy and dark matter. Here, we demonstrate numerically that it is capable of describing the entire evolution of the Universe in a seamless way, but this requires some revision of the model setup. The main reason is that there is a strong effective friction in the model, a feature which has been neglected in the pioneer work. This improves the model potential for proper description of the evolution of the Universe, because the friction ensures a finite time inflation with dynamically maintained low-value slow-roll parameters in the realistic scenarios. In addition, the model predicts the existence of a constant scalar field in late Universe.

scholarly journals Generalized Phenomenological Models of Dark Energy

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Prasenjit Paul ◽  
Rikpratik Sengupta
Keyword(s):  
General Relativity ◽  
Dark Energy ◽  
Energy Density ◽  
Cosmological Constant ◽  
Phenomenological Models ◽  
Einstein Field Equations ◽  
Field Equations ◽  
Free Parameters ◽  
The Universe ◽  
Matter Energy

It was first observed at the end of the last century that the universe is presently accelerating. Ever since, there have been several attempts to explain this observation theoretically. There are two possible approaches. The more conventional one is to modify the matter part of the Einstein field equations, and the second one is to modify the geometry part. We shall consider two phenomenological models based on the former, more conventional approach within the context of general relativity. The phenomenological models in this paper consider a Λ term firstly a function of a¨/a and secondly a function of ρ, where a and ρ are the scale factor and matter energy density, respectively. Constraining the free parameters of the models with the latest observational data gives satisfactory values of parameters as considered by us initially. Without any field theoretic interpretation, we explain the recent observations with a dynamical cosmological constant.

Evolution of the Universe with two rotating fluids

2020 ◽  
Vol 35 (02n03) ◽  
pp. 2040042
Author(s):  
V. F. Panov ◽  
O. V. Sandakova ◽  
E. V. Kuvshinova ◽  
D. M. Yanishevsky
Keyword(s):  
General Relativity ◽  
Dark Energy ◽  
Scalar Field ◽  
Bianchi Type ◽  
Relativity Theory ◽  
Anisotropic Fluid ◽  
Rotating Fluids ◽  
General Relativity Theory ◽  
Exponential Expansion ◽  
The Universe

An anisotropic cosmological model with expansion and rotation and the Bianchi type IX metric has been constructed within the framework of general relativity theory. The first inflation stage of the Universe filled with a scalar field and an anisotropic fluid is considered. The model describes the Friedman stage of cosmological evolution with subsequent transition to accelerated exponential expansion observed in the present epoch. The model has two rotating fluids: the anisotropic fluid and dust-like fluid. In the approach realized in the model, the anisotropic fluid describes the rotating dark energy.

scholarly journals DO RECENT SUPERNOVAE Ia OBSERVATIONS TEND TO RULE OUT ALL THE COSMOLOGIES?

2007 ◽  
Vol 16 (10) ◽  
pp. 1641-1651 ◽  
Author(s):  
RAM GOPAL VISHWAKARMA
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Gravitational Lensing ◽  
Weakly Interacting Massive Particles ◽  
Cosmological Models ◽  
Accelerated Expansion ◽  
Standard Candle ◽  
Expansion Of The Universe ◽  
The Universe ◽  
Rule Out

Dark energy and the accelerated expansion of the universe have been the direct predictions of the distant supernovae Ia observations which are also supported, indirectly, by the observations of the CMB anisotropies, gravitational lensing and the studies of galaxy clusters. Today these results are accommodated in what has become the concordance cosmology: a universe with flat spatial sections t = constant with about 70% of its energy in the form of Einstein's cosmological constant Λ and about 25% in the form of dark matter (made of perhaps weakly-interacting massive particles). Though the composition is weird, the theory has shown remarkable successes at many fronts. However, we find that as more and more supernovae Ia are observed, more accurately and towards higher redshift, the probability that the data are well-explained by the cosmological models decreases alarmingly, finally ruling out the concordance model at more than 95% confidence level. This raises doubts against the "standard candle"-hypothesis of the supernovae Ia and their use in constraining the cosmological models. We need a better understanding of the entire SN Ia phenomenon in order to extract cosmological consequences from them.

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