Alternative cosmological theories

2019 ◽  
pp. 119-161
Author(s):  
Helge Kragh
Keyword(s):  
Standard Model ◽  
Cosmic Time ◽  
Big Bang ◽  
Field Equations ◽  
Static Universe ◽  
The Standard Model ◽  
Scientific Nature ◽  
Big Bang Model ◽  
The Universe ◽  
Alternative Theories

Since about 1970 the broadly accepted theory of the universe has been the standard hot big-bang model. However, there is and has always been alternative theories which challenge one or more features of the standard model or, more radically, question the scientific nature of cosmology. Is the universe governed by Einstein’s field equations? Is it really in a state of expansion? Did it begin with a big bang? The chapter discusses various alternative or heterodox theories in the period from about 1930 to 1980, among them the idea of a static universe and the conception that our universe evolves cyclically in infinite cosmic time. While some of these theories have been abandoned long ago, others still live on and are cultivated by a minority of cosmologists and other scientists.

scholarly journals Relativistic Cosmology with an Introduction to Inflation

Universe ◽  
2021 ◽  
Vol 7 (8) ◽  
pp. 276
Author(s):  
Muhammad Zahid Mughal ◽  
Iftikhar Ahmad ◽  
Juan Luis García Guirao
Keyword(s):  
Standard Model ◽  
Early Universe ◽  
Large Scale ◽  
Initial Conditions ◽  
Big Bang ◽  
Relativistic Cosmology ◽  
The Standard Model ◽  
Big Bang Model ◽  
The Big Bang ◽  
The Universe

In this review article, the study of the development of relativistic cosmology and the introduction of inflation in it as an exponentially expanding early phase of the universe is carried out. We study the properties of the standard cosmological model developed in the framework of relativistic cosmology and the geometric structure of spacetime connected coherently with it. The geometric properties of space and spacetime ingrained into the standard model of cosmology are investigated in addition. The big bang model of the beginning of the universe is based on the standard model which succumbed to failure in explaining the flatness and the large-scale homogeneity of the universe as demonstrated by observational evidence. These cosmological problems were resolved by introducing a brief acceleratedly expanding phase in the very early universe known as inflation. The cosmic inflation by setting the initial conditions of the standard big bang model resolves these problems of the theory. We discuss how the inflationary paradigm solves these problems by proposing the fast expansion period in the early universe. Further inflation and dark energy in fR modified gravity are also reviewed.

scholarly journals Relativistic Cosmology with an Introduction to Inflation

2021 ◽  
Author(s):  
Muhammad Zahid Mughal ◽  
Iftikhar Ahmad ◽  
Juan Luis GARCÍA GUIRAO
Keyword(s):  
Standard Model ◽  
Early Universe ◽  
Large Scale ◽  
Initial Conditions ◽  
Big Bang ◽  
Relativistic Cosmology ◽  
The Standard Model ◽  
Big Bang Model ◽  
The Big Bang ◽  
The Universe

In this review article the study of the development of relativistic cosmology and introduction of inflation in it is carried out. We study the properties of standard cosmological model developed in the framework of relativistic cosmology and the geometric structure of spacetime connected coherently with it. We examine the geometric properties of space and spacetime ingrained into the standard model of cosmology. The big bang model of the beginning of the universe is based on the standard model which succumbed to failure in explaining the flatness and the large-scale homogeneity of the universe as demonstrated by observational evidence. These cosmological problems were resolved by introducing a brief acceleratedly expanding phase in the very early universe known as inflation. Cosmic inflation by setting the initial conditions of the standard big bang model resolves these problems of the theory. We discuss how the inflationary paradigm solves these problems by proposing the fast expansion period in the early universe.

scholarly journals An allowed window for heavy neutral leptons below the kaon mass

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
Kyrylo Bondarenko ◽  
Alexey Boyarsky ◽  
Juraj Klaric ◽  
Oleksii Mikulenko ◽  
Oleg Ruchayskiy ◽  
...  
Keyword(s):  
Standard Model ◽  
Parameter Space ◽  
Big Bang ◽  
Majorana Fermions ◽  
Neutrino Masses ◽  
Beyond The Standard Model ◽  
Big Bang Nucleosynthesis ◽  
Kaon Mass ◽  
The Standard Model ◽  
The Universe

Abstract The extension of the Standard Model with two gauge-singlet Majorana fermions can simultaneously explain two beyond-the-Standard-model phenomena: neutrino masses and oscillations, as well as the origin of the matter-antimatter asymmetry in the Universe. The parameters of such a model are constrained by the neutrino oscillation data, direct accelerator searches, big bang nucleosynthesis, and requirement of successful baryogenesis. We show that their combination still leaves an allowed region in the parameter space below the kaon mass. This region can be probed by the further searches of NA62, DUNE, or SHiP experiments.

scholarly journals The Higgs boson and cosmology

2015 ◽  
Vol 373 (2032) ◽  
pp. 20140038 ◽  
Author(s):  
Mikhail Shaposhnikov
Keyword(s):  
Dark Matter ◽  
Higgs Boson ◽  
Standard Model ◽  
Structure Formation ◽  
Higgs Field ◽  
Big Bang ◽  
Seed Structure ◽  
Matter Production ◽  
The Standard Model ◽  
The Universe

I will discuss how the Higgs field of the Standard Model may have played an important role in cosmology, leading to the homogeneity, isotropy and flatness of the Universe; producing the quantum fluctuations that seed structure formation; triggering the radiation-dominated era of the hot Big Bang; and contributing to the processes of baryogenesis and dark matter production.

scholarly journals The H0 Key Project: Cepheids in NGC925, M101 and M100

1995 ◽  
Vol 155 ◽  
pp. 258-259
Author(s):  
S. M. G. Hughes
Keyword(s):  
Standard Model ◽  
Hubble Space Telescope ◽  
Big Bang ◽  
Distance Scale ◽  
Space Telescope ◽  
The Standard Model ◽  
Age Of The Universe ◽  
Extragalactic Distance Scale ◽  
The Big Bang ◽  
The Universe

AbstractAs part of the Extragalactic Distance Scale Key Project, the Hubble Space Telescope has been used to identify Cepheids in M100, M101 and NGC925, and to measure distances derived from the Cepheid PL relation. For M100, the distance of 17.1 ± 1.8 Mpc has been used to infer a preliminary value for H0 of ~ 80 km/s/Mpc, which brings the age of the Universe derived from the standard model of the Big Bang into conflict with the ages of the oldest stars.

scholarly journals Thermodynamics of the $$R_{\mathrm{h}}=ct$$ Universe: a simplification of cosmic entropy

2021 ◽  
Vol 81 (3) ◽  
Author(s):  
Fulvio Melia
Keyword(s):  
Standard Model ◽  
Second Law Of Thermodynamics ◽  
Big Bang ◽  
Second Law ◽  
Arrow Of Time ◽  
Physical Conditions ◽  
The Standard Model ◽  
The Big Bang ◽  
Low Entropy ◽  
The Universe

AbstractIn the standard model of cosmology, the Universe began its expansion with an anomalously low entropy, which then grew dramatically to much larger values consistent with the physical conditions at decoupling, roughly 380,000 years after the Big Bang. There does not appear to be a viable explanation for this ‘unnatural’ history, other than via the generalized second law of thermodynamics (GSL), in which the entropy of the bulk, $$S_\mathrm{bulk}$$ S bulk , is combined with the entropy of the apparent (or gravitational) horizon, $$S_{\mathrm{h}}$$ S h . This is not completely satisfactory either, however, since this approach seems to require an inexplicable equilibrium between the bulk and horizon temperatures. In this paper, we explore the thermodynamics of an alternative cosmology known as the $$R_{\mathrm{h}}=ct$$ R h = c t universe, which has thus far been highly successful in resolving many other problems or inconsistencies in $$\varLambda $$ Λ CDM. We find that $$S_{\mathrm{bulk}}$$ S bulk is constant in this model, eliminating the so-called initial entropy problem simply and elegantly. The GSL may still be relevant, however, principally in selecting the arrow of time, given that $$S_{\mathrm{h}}\propto t^2$$ S h ∝ t 2 in this model.

An Interview with the Physicist that Her Head in the Universe and Both Feet on the Earth

2019 ◽  
Author(s):  
Adib Rifqi Setiawan
Keyword(s):  
Standard Model ◽  
Particle Physics ◽  
Space Time ◽  
Additional Dimension ◽  
The Earth ◽  
The Standard Model ◽  
The Universe

Put simply, Lisa Randall’s job is to figure out how the universe works, and what it’s made of. Her contributions to theoretical particle physics include two models of space-time that bear her name. The first Randall–Sundrum model addressed a problem with the Standard Model of the universe, and the second concerned the possibility of a warped additional dimension of space. In this work, we caught up with Randall to talk about why she chose a career in physics, where she finds inspiration, and what advice she’d offer budding physicists. This article has been edited for clarity. My favourite quote in this interview is, “Figure out what you enjoy, what your talents are, and what you’re most curious to learn about.” If you insterest in her work, you can contact her on Twitter @lirarandall.

An Interview with the Physicist that Her Head in the Universe and Both Feet on the Earth

2019 ◽  
Author(s):  
Adib Rifqi Setiawan
Keyword(s):  
Standard Model ◽  
Particle Physics ◽  
Space Time ◽  
Additional Dimension ◽  
The Earth ◽  
The Standard Model ◽  
The Universe

Put simply, Lisa Randall’s job is to figure out how the universe works, and what it’s made of. Her contributions to theoretical particle physics include two models of space-time that bear her name. The first Randall–Sundrum model addressed a problem with the Standard Model of the universe, and the second concerned the possibility of a warped additional dimension of space. In this work, we caught up with Randall to talk about why she chose a career in physics, where she finds inspiration, and what advice she’d offer budding physicists. This article has been edited for clarity. My favourite quote in this interview is, “Figure out what you enjoy, what your talents are, and what you’re most curious to learn about.” If you insterest in her work, you can contact her on Twitter @lirarandall.

scholarly journals Complete leading-order standard model corrections to quantum leptogenesis

2020 ◽  
Vol 2020 (9) ◽  
Author(s):  
Paul Frederik Depta ◽  
Andreas Halsch ◽  
Janine Hütig ◽  
Sebastian Mendizabal ◽  
Owe Philipsen
Keyword(s):  
Standard Model ◽  
Gauge Coupling ◽  
Thermal Bath ◽  
Leading Order ◽  
Boltzmann Equations ◽  
The Standard Model ◽  
Majorana Neutrinos ◽  
Infinite Loop ◽  
First Time ◽  
The Universe

Abstract Thermal leptogenesis, in the framework of the standard model with three additional heavy Majorana neutrinos, provides an attractive scenario to explain the observed baryon asymmetry in the universe. It is based on the out-of-equilibrium decay of Majorana neutrinos in a thermal bath of standard model particles, which in a fully quantum field theoretical formalism is obtained by solving Kadanoff-Baym equations. So far, the leading two-loop contributions from leptons and Higgs particles are included, but not yet gauge corrections. These enter at three-loop level but, in certain kinematical regimes, require a resummation to infinite loop order for a result to leading order in the gauge coupling. In this work, we apply such a resummation to the calculation of the lepton number density. The full result for the simplest “vanilla leptogenesis” scenario is by $$ \mathcal{O} $$ O (1) increased compared to that of quantum Boltzmann equations, and for the first time permits an estimate of all theoretical uncertainties. This step completes the quantum theory of leptogenesis and forms the basis for quantitative evaluations, as well as extensions to other scenarios.

Naming the Big Bang

2012 ◽  
Vol 44 (1) ◽  
pp. 3-36 ◽  
Author(s):  
Helge Kragh
Keyword(s):  
Scientific Community ◽  
Big Bang ◽  
Consensus Model ◽  
Initial State ◽  
The Standard Model ◽  
Modern Cosmology ◽  
Fred Hoyle ◽  
The Big Bang ◽  
The Universe ◽  
Origin Of The Universe

The standard model of modern cosmology is known as the hot big bang, a name that refers to the initial state of the universe some fourteen billion years ago. The name Big Bang introduced by Fred Hoyle in 1949 is one of the most successful scientific neologisms ever. How did the name originate and how was it received by physicists and astronomers in the period leading up to the hot big bang consensus model in the late 1960s? How did it reflect the meanings of the origin of the universe, a concept that predates the name by nearly two decades? Contrary to what is often assumed, the name was not an instant success—it took more than twenty years before Big Bang became a household word in the scientific community. When it happened, it was used with different connotations, as is still the case. Moreover, it was used earlier and more frequently in popular than in scientific contexts, and not always relating to cosmology. It turns out that Hoyle’s celebrated name has a richer and more surprising history than commonly assumed and also that the literature on modern cosmology and its history includes many common mistakes and errors. An etymological approach centering on the name Big Bang provides supplementary insight to the historical understanding of the emergence of modern cosmology.

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