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Автор: Grafiati

Опубліковано: 14 березня 2023

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1

Sato, K. "The Very Early Universe." Transactions of the International Astronomical Union 20, no. 1 (1988): 656–58. http://dx.doi.org/10.1017/s0251107x00007495.

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In recent years, the research on the very early universe has shown quite remarkable developments. As is well known, this development was brought about by the introduction of the Grand Unified Theories (GUTs) into cosmology. These theories have not only enabled us to trace the evolution of the Universe back to the very early stage at temperatures of 1016 GeV or higher, but also introduced various new aspects into cosmology, such as baryogenesis, phase transitions and topological defects (monopoles, etc.). In particular, inflation, which grew out of the study of GUT phase transition, is the most important and fascinating outcome.

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2

Smeenk, Chris. "Predictability crisis in early universe cosmology." Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern Physics 46 (May 2014): 122–33. http://dx.doi.org/10.1016/j.shpsb.2013.11.003.

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3

Singh, C. P. "Bulk viscous cosmology in early Universe." Pramana 71, no. 1 (July 2008): 33–48. http://dx.doi.org/10.1007/s12043-008-0139-4.

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4

Krauss, Lawrence M. "New gravitational tests of early universe cosmology." General Relativity and Gravitation 18, no. 7 (July 1986): 723–30. http://dx.doi.org/10.1007/bf00768636.

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5

Maggiore, Michele. "Gravitational wave experiments and early universe cosmology." Physics Reports 331, no. 6 (July 2000): 283–367. http://dx.doi.org/10.1016/s0370-1573(99)00102-7.

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6

Bojowald, Martin. "The early universe in loop quantum cosmology." Journal of Physics: Conference Series 24 (January 1, 2005): 77–86. http://dx.doi.org/10.1088/1742-6596/24/1/010.

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7

Brevik, Iver, Øyvind Grøn, Jaume de Haro, Sergei D. Odintsov, and Emmanuel N. Saridakis. "Viscous cosmology for early- and late-time universe." International Journal of Modern Physics D 26, no. 14 (December 2017): 1730024. http://dx.doi.org/10.1142/s0218271817300245.

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From a hydrodynamicist’s point of view the inclusion of viscosity concepts in the macroscopic theory of the cosmic fluid would appear most natural, as an ideal fluid is after all an abstraction (exluding special cases such as superconductivity). Making use of modern observational results for the Hubble parameter plus standard Friedmann formalism, we may extrapolate the description of the universe back in time up to the inflationary era, or we may go to the opposite extreme and analyze the probable ultimate fate of the universe. In this review, we discuss a variety of topics in cosmology when it is enlarged in order to contain a bulk viscosity. Various forms of this viscosity, when expressed in terms of the fluid density or the Hubble parameter, are discussed. Furthermore, we consider homogeneous as well as inhomogeneous equations of state. We investigate viscous cosmology in the early universe, examining the viscosity effects on the various inflationary observables. Additionally, we study viscous cosmology in the late universe, containing current acceleration and the possible future singularities, and we investigate how one may even unify inflationary and late-time acceleration. Finally, we analyze the viscosity-induced crossing through the quintessence-phantom divide, we examine the realization of viscosity-driven cosmological bounces, and we briefly discuss how the Cardy–Verlinde formula is affected by viscosity.

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8

Kafatos, Menas. "Limitations of Observational Cosmology." International Astronomical Union Colloquium 123 (1990): 543–50. http://dx.doi.org/10.1017/s0252921100077642.

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AbstractUnlike the usual situation with theoretical physics which is testable in the laboratory, in cosmological theories of the universe one faces the following problems: The observer is part of the system, the universe, and this system cannot be altered to test physical theory. Even though one can in principle consider any part of the observable universe as separate from the acts of observation, the very hypothesis of big bang implies that in the distant past, space-time regions containing current observers were part of the same system. One, therefore, faces a situation where the observer has to be considered as inherently a part of the entire system. The existence of horizons of knowledge in any cosmological view of the universe is then tantamount to inherent observational limits imposed by acts of observation and theory itself. For example, in the big bang cosmology the universe becomes opaque to radiation early on, and the images of extended distant galaxies merge for redshifts, z, of the order of a few. Moreover, in order to measure the distance of a remote galaxy to test any cosmological theory, one has to disperse its light to form a spectrum which would cause confusion with other background galaxies. Since the early universe should be described in quantum terms, it follows that the same problems regarding quantum reality and the role of the observer apply to the universe as a whole. One of the most fundamental properties of quantum theory, non-locality, may then apply equally well to the universe. Some of the problems facing big bang cosmology, like the horizon and flatness problems, may not then be preconditions on theoretical models but may instead be the manifestations of the quantum nature of the universe.

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9

Kafatos, Menas. "Knowledge Limits in Cosmology." Symposium - International Astronomical Union 168 (1996): 431–38. http://dx.doi.org/10.1017/s0074180900110307.

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In cosmology one faces the observational challenge that knowledge about distant regions of the universe is dependent on assumptions one makes about these regions which are themselves coupled to the observations. Within the framework of the Friedmann-Robertson-Walker big bang models the universe becomes opaque to its own radiation at z ≈ 1,000 and the earlier, and more distant, regions of the universe are not directly accessible through observations. Other challenges exist such as possible merging of extended distant sources and confusion of spectra from distant galaxies. One, therefore, encounters horizons in our understanding of the universe. Such horizons exist in any mode of description. To use the quantum analogy, the observer is always part of the system under study, the universe, and a description of the universe entails including the observer and observing apparatus. Since the early universe should be described in quantum terms, it follows that non-locality in the universe is not an a-priori requirement but the outcome of the observing process itself. As such, the flatness and horizon problems may not be preconditions on theoretical models.

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10

Al-Fadhli, Mohammed B. "On Spacetime Duality and Bounce Cosmology of a Dual Universe." Physical Sciences Forum 2, no. 1 (February 22, 2021): 61. http://dx.doi.org/10.3390/ecu2021-09291.

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The recent Planck Legacy 2018 release confirmed the existence of an enhanced lensing amplitude in the cosmic microwave background (CMB) power spectra. Notably, this amplitude is higher than that estimated by the lambda cold dark matter model, which prefers a positively curved early Universe with a confidence level greater than 99%. In this study, the pre-existing curvature is incorporated to extend the field equations where the space-time worldlines are utilised to model the evolution of the Universe with reference to the scale factor of the early Universe and its radius of curvature upon the emission of the CMB. The worldlines reveal both positive and negative solutions, implying that matter and antimatter of early Universe plasma evolved in opposite directions as distinct Universe sides during a first decelerating phase. The worldlines then indicate a second accelerated phase in reverse directions, whereby both sides free-fall towards each other under gravitational acceleration. The simulation of the predicted conformal curvature evolution demonstrates the fast orbital speed of the outer stars owing to external fields exerted on galaxies as they travel through conformally curved space-time. Finally, the worldlines predict an eventual time-reversal phase comprising rapid spatial contraction that culminates in a Big Crunch, signalling a cyclic Universe. These findings reveal that the early Universe’s plasma could be separated and evolved into distinct sides of the Universe that collectively and geometrically inducing its evolution, physically explaining the effects attributed to dark energy and dark matter.

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11

DORÉ, OLIVIER. "THREE YEARS WMAP RESULTS AND EARLY UNIVERSE COSMOLOGY." Modern Physics Letters A 22, no. 25n28 (September 14, 2007): 1853–55. http://dx.doi.org/10.1142/s0217732307025066.

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12

Seife, C. "COSMOLOGY: A Slanted View of the Early Universe." Science 306, no. 5694 (October 8, 2004): 213b. http://dx.doi.org/10.1126/science.306.5694.213b.

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13

Hivon, E. "COSMOLOGY: A New Window to the Early Universe." Science 298, no. 5597 (November 15, 2002): 1349–50. http://dx.doi.org/10.1126/science.1078736.

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14

Singh, C. P., and A. Beesham. "Early universe cosmology with particle creation: kinematics tests." Astrophysics and Space Science 336, no. 2 (July 6, 2011): 469–77. http://dx.doi.org/10.1007/s10509-011-0781-z.

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15

Steigman, Gary. "A quick and dirty early universe/ cosmology course." Nuclear Physics B - Proceedings Supplements 37, no. 3 (January 1995): 61–67. http://dx.doi.org/10.1016/0920-5632(94)00789-x.

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16

Schroeder, Paul. "The Universe is Otherwise—5/26 Edition." World Journal of Social Science Research 8, no. 3 (June 12, 2021): p1. http://dx.doi.org/10.22158/wjssr.v8n3p1.

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There are significant issues when defining the universe. Original theories over time were limited and led to mistakes under more detailed investigation. The components of early models remain and misdirect our ongoing understanding of the Universe. This leads to today’s questionable cosmology. The current cosmology is called the standard model.

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17

Mughal, Muhammad Zahid, Iftikhar Ahmad, and Juan Luis García Guirao. "Relativistic Cosmology with an Introduction to Inflation." Universe 7, no. 8 (July 30, 2021): 276. http://dx.doi.org/10.3390/universe7080276.

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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.

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18

Rajantie, Arttu. "Higgs cosmology." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 376, no. 2114 (January 22, 2018): 20170128. http://dx.doi.org/10.1098/rsta.2017.0128.

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The discovery of the Higgs boson in 2012 and other results from the Large Hadron Collider have confirmed the standard model of particle physics as the correct theory of elementary particles and their interactions up to energies of several TeV. Remarkably, the theory may even remain valid all the way to the Planck scale of quantum gravity, and therefore it provides a solid theoretical basis for describing the early Universe. Furthermore, the Higgs field itself has unique properties that may have allowed it to play a central role in the evolution of the Universe, from inflation to cosmological phase transitions and the origin of both baryonic and dark matter, and possibly to determine its ultimate fate through the electroweak vacuum instability. These connections between particle physics and cosmology have given rise to a new and growing field of Higgs cosmology, which promises to shed new light on some of the most puzzling questions about the Universe as new data from particle physics experiments and cosmological observations become available. This article is part of the Theo Murphy meeting issue ‘Higgs cosmology’.

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19

Li, Li-Fang, and Jian-Yang Zhu. "Thermodynamics in Loop Quantum Cosmology." Advances in High Energy Physics 2009 (2009): 1–9. http://dx.doi.org/10.1155/2009/905705.

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Loop quantum cosmology (LQC) is very powerful to deal with the behavior of early universe. Moreover, the effective loop quantum cosmology gives a successful description of the universe in the semiclassical region. We consider the apparent horizon of the Friedmann-Robertson-Walker universe as a thermodynamical system and investigate the thermodynamics of LQC in the semiclassical region. The effective density and effective pressure in the modified Friedmann equation from LQC not only determine the evolution of the universe in LQC scenario but also are actually found to be the thermodynamic quantities. This result comes from the energy definition in cosmology (the Misner-Sharp gravitational energy) and is consistent with thermodynamic laws. We prove that within the framework of loop quantum cosmology, the elementary equation of equilibrium thermodynamics is still valid.

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20

Park, Youngsoo, and Eduardo Rozo. "Concordance cosmology?" Monthly Notices of the Royal Astronomical Society 499, no. 4 (September 1, 2020): 4638–45. http://dx.doi.org/10.1093/mnras/staa2647.

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ABSTRACT We propose a new intuitive metric for evaluating the tension between two experiments, and apply it to several data sets. While our metric is non-optimal, if evidence of tension is detected, this evidence is robust and easy to interpret. Assuming a flat Lambda cold dark matter (ΛCDM) cosmological model, we find that there is a modest 2.2σ tension between the Dark Energy Survey (DES) Year 1 results and the Planck measurements of the cosmic microwave background. This tension is driven by the difference between the amount of structure observed in the late-time Universe and that predicted from fitting the Planck data, and appears to be unrelated to the tension between Planck and local estimates of the Hubble rate. In particular, combining DES, baryon acoustic oscillations, big bang nucleosynthesis, and supernovae measurements recover a Hubble constant and sound horizon consistent with Planck, and in tension with local distance–ladder measurements. If the tension between these various data sets persists, it is likely that reconciling all current data will require breaking the flat ΛCDM model in at least two different ways: one involving new physics in the early Universe, and one involving new late-time Universe physics.

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21

Burbidge, G., F. Hoyle, and J. V. Narlikar. "Quasi-Steady State Cosmology." Symposium - International Astronomical Union 159 (1994): 293–99. http://dx.doi.org/10.1017/s0074180900175199.

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The standard big bang cosmology has the universe created out of a primeval explosion that not only created matter and radiation but also spacetime itself. The big bang event itself cannot be discussed within the framework of a physical theory but the events following it are in principle considered within the scope of science. The recent developments on the frontier between particle physics and cosmology highlight the attempts to chart the history of the very early universe.

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22

Shapiro, Paul R. "Chemistry in the Early Universe." Symposium - International Astronomical Union 150 (1992): 73–82. http://dx.doi.org/10.1017/s0074180900089737.

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Galaxies and the first stars in the universe formed billions of years ago as a result of the cooperative effects of gravitational collapse and nonequilibrium chemistry. Gravity drew the primordial gas together into lumps; the formation of the first molecules in the universe, simple diatomic molecules like H2, H2+, HD, HeH+, LiH, and LiH+, may then have ensured that the heat generated by gravitational collapse and shock waves was radiated away rapidly enough to allow the gravitational collapse and fragmentation of these gaseous lumps to proceed to the point of forming stars and galaxies. We briefly mention a few of the latest studies of this primordial chemistry, including that in the evolving intergalactic medium (IGM) in a Cold Dark Matter (CDM) model cosmology and that in radiative shocks in the early universe.

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23

AL-NOWAISER, A. A., MURAT ÖZER, and M. O. TAHA. "A NONSINGULAR UNIVERSE IN STRING COSMOLOGY." International Journal of Modern Physics D 08, no. 01 (February 1999): 43–49. http://dx.doi.org/10.1142/s0218271899000055.

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We consider the low-energy effective string action in four dimensions including the leading order-α′ terms. An exact homogeneous solution is obtained. It represents a nonsingular expanding cosmological model in which the tensor fields tend to vanish as t→∞. The scale factor a(t) of the very early universe in this model has the time dependence [Formula: see text]. The violation of the strong energy condition of classical General Relativity to avoid the initial singularity requires that the central charge deficit of the theory be larger than a certain value. The significance of this solution is discussed.

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24

CHAUDHURI, A. K. "PHENOMENOLOGICAL STRING COSMOLOGY AND ITS IMPLICATIONS." International Journal of Modern Physics A 15, no. 03 (January 30, 2000): 335–47. http://dx.doi.org/10.1142/s0217751x0000015x.

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We have explored the possibility that the universe at very early stage was dominated by (macroscopic) heterotic strings. We have found that the dimensionless parameter Gμ for the heterotic strings varies from 10-2 to 10-4 as the universe evolve from the matter dominance to radiation dominance. This led to the interesting consequence of epoch dependent gauge coupling constant. The gauge coupling constant at early times was found to be much stronger than the present strong interaction.

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25

COULE, D. H. "VARYING c COSMOLOGY AND PLANCK VALUE CONSTRAINTS." Modern Physics Letters A 14, no. 35 (November 20, 1999): 2437–46. http://dx.doi.org/10.1142/s0217732399002534.

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It has been suggested that by increasing the speed of light during the early universe various cosmological problems of standard big bang cosmology can be overcome, without requiring an inflationary phase. However, we find that as the Planck length and Planck time are then made correspondingly smaller, and together with the need that the universe should not re-enter a Planck epoch, the higher c models have very limited ability to resolve such problems. For a constantly decreasing c, the universe will quickly becomes quantum gravitationally dominated as time increases: the opposite to standard cosmology where quantum behaviour is only ascribed to early times.

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26

Norris, John E. "Very Metal-Poor Stars and the Early Universe." Proceedings of the International Astronomical Union 13, S334 (July 2017): 3–10. http://dx.doi.org/10.1017/s1743921317008900.

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AbstractVery metal-poor stars ([Fe/H] < –2.0) inform our understanding of the formation and evolution of the Galaxy, and the physical conditions in the earliest star-forming environments of the Universe. They play an integral part in the paradigms of stellar populations, stellar archaeology, and near-field cosmology. We review the carbon-rich and carbon-normal sub-populations of the most iron-poor stars, providing insight into chemical enrichment at the earliest times in the Universe. We also discuss the role of very metal-poor stars in providing insight into the Galaxy’s halo, thick disk, and bulge, and the promise they hold for the future. A comparison between the abundances obtained for the nine most Fe-poor stars ([Fe/H] < –4.5) (all but one of which is C-rich) with abundances obtained from far-field cosmology suggests that the former are the most chemically primitive objects yet observed and probably older than the DLA- and sub-DLA systems for which data are currently available from far-field studies.

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27

Lilly, Simon, Rachel L. Webster, L. Campusano, S. Charlot, L. DaCosta, D. Koo, O. Lahav, et al. "Commission 47: Cosmology." Proceedings of the International Astronomical Union 1, T26A (December 2005): 291–98. http://dx.doi.org/10.1017/s1743921306004728.

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Abstract2002–2005 has seen rapid progress in cosmology with the publication of the 1st year WMAP results and analyses of large scale red-shift surveys, ushering in an era of “precision cosmology”. There has been steady progress, too, in the discovery and study of quasars and galaxies in the early Universe.

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28

Domènech, Guillem, and Misao Sasaki. "Cosmology of strongly interacting fermions in the early universe." Journal of Cosmology and Astroparticle Physics 2021, no. 06 (June 1, 2021): 030. http://dx.doi.org/10.1088/1475-7516/2021/06/030.

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29

Joy, M. "COSMOLOGY: Probing the Early Universe with the SZ Effect." Science 291, no. 5509 (March 2, 2001): 1715–17. http://dx.doi.org/10.1126/science.291.5509.1715.

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30

Easther, Richard, Brian R. Greene, Mark G. Jackson, and Daniel Kabat. "Brane gases in the early universe: thermodynamics and cosmology." Journal of Cosmology and Astroparticle Physics 2004, no. 01 (January 26, 2004): 006. http://dx.doi.org/10.1088/1475-7516/2004/01/006.

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31

Lidsey, James E. "Early universe dynamics in semi-classical loop quantum cosmology." Journal of Cosmology and Astroparticle Physics 2004, no. 12 (December 15, 2004): 007. http://dx.doi.org/10.1088/1475-7516/2004/12/007.

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32

Brandenberger, Robert. "Do we have a theory of early universe cosmology?" Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern Physics 46 (May 2014): 109–21. http://dx.doi.org/10.1016/j.shpsb.2013.09.008.

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33

UL HAQ ANSARI, RIZWAN, and P. K. SURESH. "PHASE TRANSITIONS IN HIGHER DIMENSIONAL COSMOLOGY." International Journal of Modern Physics A 25, no. 01 (January 10, 2010): 113–22. http://dx.doi.org/10.1142/s0217751x10047944.

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We have considered five-dimensional massive scalar field coupled to gravity and evaluated the one-loop effective potential in higher dimensions. It is demonstrated that nonminimally coupled φ4 theory can be regularized in five dimensions. Temperature dependent one-loop correction and critical temperature βc are computed. The phase transitions in the early universe depend on the space–time curvature R and scalar gravitational coupling ξ. A brief discussion of symmetry restoration is also presented and the nature of phase transitions in the early universe is found to be of second order.

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34

Dumin, Yurii V. "Nonlocal Quantum Effects in Cosmology." Advances in High Energy Physics 2014 (2014): 1–8. http://dx.doi.org/10.1155/2014/241831.

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Since it is commonly believed that the observed large-scale structure of the universe is an imprint of quantum fluctuations existing at the very early stage of its evolution, it is reasonable to pose the question: do the effects of quantum nonlocality, which are well established now by the laboratory studies, manifest themselves also in the early universe? We try to answer this question by utilizing the results of a few experiments, namely, with the superconducting multi-Josephson-junction loops and the ultracold gases in periodic potentials. Employing a close analogy between the above-mentioned setups and the simplest one-dimensional Friedmann-Robertson-Walker cosmological model, we show that the specific nonlocal correlations revealed in the laboratory studies might be of considerable importance also in treating the strongly nonequilibrium phase transitions of Higgs fields in the early universe. Particularly, they should substantially reduce the number of topological defects (e.g., domain walls) expected due to independent establishment of the new phases in the remote spatial regions. This gives us a hint on resolving a long-standing problem of the excessive concentration of topological defects, inconsistent with observational constraints. The same effect may be also relevant to the recent problem of the anomalous behavior of cosmic microwave background fluctuations at large angular scales.

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35

AKDENIZ, K. GEDIZ, METIN ARIK, HAŞIM MUTUŞ, and EMINE RIZAOĞLU. "COASTING KALUZA–KLEIN COSMOLOGY." Modern Physics Letters A 06, no. 17 (June 7, 1991): 1543–46. http://dx.doi.org/10.1142/s0217732391001652.

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Kaluza–Klein cosmologies where an early coasting universe followed by radiation dominance is naturally obtained as a consequence of the solution of the cosmological field equations are investigated. It is shown that such cosmologies are free of the horizon problem.

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36

Chatterjee, S. "Primordial nucleosynthesis in higher dimensional cosmology." Proceedings of the International Astronomical Union 5, S268 (November 2009): 39–40. http://dx.doi.org/10.1017/s1743921310003844.

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AbstractWe investigate nucleosynthesis and element formation in the early universe in the framework of higher dimensional cosmology. We find that temperature decays less rapidly in higher dimensional cosmology, which we believe may have nontrivial consequences vis-a-vis primordial physics.

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37

Addazi, Andrea. "Brane bounce from logarithmic entropic corrections in the bulk." International Journal of Modern Physics A 32, no. 28n29 (October 19, 2017): 1750174. http://dx.doi.org/10.1142/s0217751x17501743.

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We calculate new corrections to the braneworld dynamics, lying in a 5D Schwarzschild–de Sitter black hole, generalizing the result of Nojiri, Odintsov and Ogushi (NOO). The NOO entropy effect is based on the logarithmic correction to the bulk entropy firstly calculated by Mukherji and Pal. We calculate higher order contributions to the brane worldsheet. The extra terms obtained lead to interesting implications in brane cosmology. In particular, new entropic terms rapidly disappear in the late Universe while exploding in the very early Universe. In particular, we show that they may trigger a cosmological bounce in the very early Universe. On the other hand, they contribute to the cosmological expansion in the late Universe. We also discuss a scenario in which the BLK anisotropies are washed out, toward a new ekpyrotic brane cosmology.

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38

Kragh, Helge. "Early dynamical world models: A historical review." Proceedings of the International Astronomical Union 5, S260 (January 2009): 182–88. http://dx.doi.org/10.1017/s1743921311002262.

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AbstractModels of the universe, in the sense of solutions to the cosmological field equations, took their start in 1917 with Einstein's closed universe. During the next two decades they were developed to comprise evolving models, some of them cyclic and some of them with a definite age. The history of this development, as it occurred up to the mid 1930s, is reviewed. It is argued that in 1930-31, cosmology experienced a kind of paradigm shift.

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39

Horn, Bart. "The Higgs Field and Early Universe Cosmology: A (Brief) Review." Physics 2, no. 3 (September 21, 2020): 503–20. http://dx.doi.org/10.3390/physics2030028.

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We review and discuss recent work exploring the implications of the Higgs field for early universe cosmology, and vice versa. Depending on the model under consideration, the Higgs may be one of a few scalar fields determining the evolution and fate of the Universe, or the Higgs field may be connected to a rich sector of scalar moduli with complicated dynamics. In particular, we look at the potential consequences of the Higgs field for inflation and its predictions, for the (meta)stability of the Standard Model vacuum, and for the existence of dynamical selection mechanisms in the landscape.

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40

BRANDENBERGER, ROBERT H. "ALTERNATIVES TO THE INFLATIONARY PARADIGM OF STRUCTURE FORMATION." International Journal of Modern Physics: Conference Series 01 (January 2011): 67–79. http://dx.doi.org/10.1142/s2010194511000109.

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The inflationary paradigm, although very successful phenomenologically, suffers from several conceptual problems which motivate the search for alternative scenarios of early universe cosmology. Here, two possible alternatives will be reviewed. - "string gas cosmology" and the "matter bounce". Their successes and problems will be pointed out.

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41

BUETTNER, DOUGLAS J., P. D. MORLEY, and IVAN SCHMIDT. "SEARCHING FOR EXTRA DIMENSIONS IN THE EARLY UNIVERSE." International Journal of Modern Physics A 19, no. 25 (October 10, 2004): 4201–5. http://dx.doi.org/10.1142/s0217751x04019925.

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We investigate extra spatial dimensions (D=3+∊) in the early universe using very high resolution molecular rotational spectroscopic data derived from a large molecular cloud containing moderately cold carbon monoxide gas at Z≈6.42. It turns out that the ∊-dependent quantum mechanical wavelength transitions are solvable for a linear molecule and we present the solution here. The CO microwave data allows a very precise determination of <∊>=-0.00000657±0.10003032. The probability that <∊>≠0 is one in 7794, only 850 million years (using the standard cosmology) after the Big Bang.

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42

PERCIVAL, WILL J. "COSMOLOGY FROM GALAXY SURVEYS." International Journal of Modern Physics D 20, no. 10 (September 2011): 2115–19. http://dx.doi.org/10.1142/s0218271811020275.

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Galaxy Redshift surveys provide a three-dimensional map of the Universe. Three distinct processes that encode cosmological information in these maps, are commonly used to constrain models: (i) the comoving power spectrum shape depends on the physical properties of the early Universe, including the physical matter, baryon and neutrino densities, the inflation power spectrum and the degree of Gaussianity of density fluctuations; (ii) we can use the statistical clustering of galaxies as a standard ruler by matching it, or parts of it at different redshifts, and to the Cosmic Microwave Background (CMB); (iii) redshift-space distortions, anisotropic patterns caused by peculiar galaxy velocities, reveal structure growth. Following the design of my talk at the 1st Galileo–Xu Guangqi Meeting, I will use these proceedings to briefly review these experiments.

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43

PAUL, B. C., D. P. DATTA, and S. MUKHERJEE. "CHAOTIC INFLATIONARY SCENARIO IN AN ANISOTROPIC UNIVERSE." Modern Physics Letters A 01, no. 02 (May 1986): 149–55. http://dx.doi.org/10.1142/s021773238600021x.

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The chaotic inflationary model of the early universe, proposed by Linde is studied within the framework of an anisotropic Kantowski-Sachs cosmology. It is shown that the chaotic model naturally leads to an inflationary phase which also helps in the isotropization of the universe.

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44

Nesic, Ljubisa, and Stojan Obradovic. "On space and time in quantum cosmology." Facta universitatis - series: Physics, Chemistry and Technology 2, no. 4 (2002): 173–82. http://dx.doi.org/10.2298/fupct0204173n.

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The paper considers the properties of space and time in quantum cosmology. It presented the basic ideas of the substantial and relational conceptions of space and time, as well the basic ideas of the continuity and discreteness of space and time. The basics of standard quantum cosmology, i.e. quantum cosmology formulated over the field of real numbers R, have also been presented. Quantum cosmology is the application of the quantum theory to the universe as a whole in the early phases of its evolution, when the universe was very small so that all the four interactions were practically unified. In order to obtain the maximum possible information from quantum cosmology it is necessary that it be "complete". The concept "complete" refers here to the formulation of the theory over the field of real numbers and the field of p-adic numbers Qp. Since p-adic numbers are generally not well-known, the idea of their introduction has carefully been considered. Within the p-adic quantum cosmology representing quantum cosmology over the field of p-adic numbers Qp, the main results concerning the de Sitter model have been presented. The consequence of this (complete) formulation of the de Sitter model is the radius discreteness of the universe.

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45

Bahcall, Neta A. "Dark matter universe." Proceedings of the National Academy of Sciences 112, no. 40 (September 28, 2015): 12243–45. http://dx.doi.org/10.1073/pnas.1516944112.

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Most of the mass in the universe is in the form of dark matter—a new type of nonbaryonic particle not yet detected in the laboratory or in other detection experiments. The evidence for the existence of dark matter through its gravitational impact is clear in astronomical observations—from the early observations of the large motions of galaxies in clusters and the motions of stars and gas in galaxies, to observations of the large-scale structure in the universe, gravitational lensing, and the cosmic microwave background. The extensive data consistently show the dominance of dark matter and quantify its amount and distribution, assuming general relativity is valid. The data inform us that the dark matter is nonbaryonic, is “cold” (i.e., moves nonrelativistically in the early universe), and interacts only weakly with matter other than by gravity. The current Lambda cold dark matter cosmology—a simple (but strange) flat cold dark matter model dominated by a cosmological constant Lambda, with only six basic parameters (including the density of matter and of baryons, the initial mass fluctuations amplitude and its scale dependence, and the age of the universe and of the first stars)—fits remarkably well all the accumulated data. However, what is the dark matter? This is one of the most fundamental open questions in cosmology and particle physics. Its existence requires an extension of our current understanding of particle physics or otherwise point to a modification of gravity on cosmological scales. The exploration and ultimate detection of dark matter are led by experiments for direct and indirect detection of this yet mysterious particle.

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46

Loeb, Abraham. "The habitable epoch of the early Universe." International Journal of Astrobiology 13, no. 4 (September 9, 2014): 337–39. http://dx.doi.org/10.1017/s1473550414000196.

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AbstractIn the redshift range 100≲(1+z)≲137, the cosmic microwave background (CMB) had a temperature of 273–373 K (0–100°C), allowing early rocky planets (if any existed) to have liquid water chemistry on their surface and be habitable, irrespective of their distance from a star. In the standard ΛCDM cosmology, the first star-forming halos within our Hubble volume started collapsing at these redshifts, allowing the chemistry of life to possibly begin when the Universe was merely 10–17 million years old. The possibility of life starting when the average matter density was a million times bigger than it is today is not in agreement with the anthropic explanation for the low value of the cosmological constant.

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47

Ng, Yee Jack. "Holographic Foam Cosmology: From the Late to the Early Universe." Symmetry 13, no. 3 (March 8, 2021): 435. http://dx.doi.org/10.3390/sym13030435.

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Quantum fluctuations endow spacetime with a foamy texture. The degree of foaminess is dictated by black hole physics to be of the holographic type. Applied to cosmology, the holographic foam model predicts the existence of dark energy with critical energy density in the current (late) universe, the quanta of which obey infinite statistics. Furthermore, we use the deep similarities between turbulence and the spacetime foam phase of strong quantum gravity to argue that the early universe was in a turbulent regime when it underwent a brief cosmic inflation with a “graceful” transition to a laminar regime. In this scenario, both the late and the early cosmic accelerations have their origins in spacetime foam.

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48

VAKILI, BABAK. "COSMOLOGY WITH MINIMAL LENGTH UNCERTAINTY RELATIONS." International Journal of Modern Physics D 18, no. 07 (July 2009): 1059–71. http://dx.doi.org/10.1142/s0218271809014935.

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We study the effects of the existence of a minimal observable length in the phase space of classical and quantum de Sitter (dS) and anti-de Sitter (AdS) cosmology. Since this length has been suggested in quantum gravity and string theory, its effects in the early universe might be expected. Adopting the existence of such a minimum length results in the generalized uncertainty principle (GUP), which is a deformed Heisenberg algebra between minisuperspace variables and their momenta operators. We extend these deformed commutating relations to the corresponding deformed Poisson algebra in the classical limit. Using the resulting Poisson and Heisenberg relations, we then construct the classical and quantum cosmology of dS and AdS models in a canonical framework. We show that in classical dS cosmology this effect yields an inflationary universe in which the rate of expansion is larger than that of the usual dS universe. Also, for the AdS model it is shown that the GUP might change the oscillatory nature of the corresponding cosmology. We also study the effects of the GUP in quantized models through approximate analytical solutions to the Wheeler–DeWitt (WD) equation, in the limit of a small scale factor for the universe, and compare the results with the ordinary quantum cosmology in each case.

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49

MONIZ, PAULO VARGAS. "QUANTUM COSMOLOGY: SUSY'S STAGE." International Journal of Modern Physics D 22, no. 04 (March 2013): 1330006. http://dx.doi.org/10.1142/s0218271813300061.

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This report comprises two parts. On the one hand, I will, based on the talks at the CM4 parallel session "Quantum Cosmology and Quantum Effects in the Early Universe" which I chaired, point to interesting recent developments in quantum cosmology. On the other hand, some of the basics of supersymmetric quantum cosmology are briefly reviewed, pointing to promising lines of research to explore. I will start with the latter, finishing the report with the former.

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50

Calcagni, Gianluca, and Golam Mortuza Hossain. "Loop Quantum Cosmology and Tensor Perturbations in the Early Universe." Advanced Science Letters 2, no. 2 (June 1, 2009): 184–93. http://dx.doi.org/10.1166/asl.2009.1025.

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