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A Note on friedmann equation of FRW Universe in Deformed Hoava-Lifshitz Gravity from Entropic Force

Communications in Theoretical Physics 2011年第9期56卷 455-458页

作者：魏少文刘玉孝王永强 Institute of Theoretical Physics Lanzhou University

With entropic interpretation of gravity proposed by Verlinde, we obtain the friedmann equation of the friedmann Robertson-Walker universe for the deformed Hofava-Lifshitz gravity. It is shown that, when the parameter of Hofava-Lifshitz gravity ω →∞, the modified friedmann equation will go back to the one in Einstein gravity. This results may imply that the entropic interpretation of gravity is effective for the deformed Hofava-Lifshitz gravity.

关键词： entropic force Horava-Lifshitz gravity friedmann equation

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Does Space Have a Gravitational Susceptibility? A Model for the ΛCDM Density Parameters in the friedmann equation

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Journal of High Energy Physics, Gravitation and Cosmology 2021年第2期7卷 478-507页

作者： Christopher Pilot Physics Maine Maritime Academy Castine ME USA (Retired)

We propose a model for gravity based on the gravitational polarization of space. With this model, we can relate the density parameters within the friedmann model, and show that dark matter is bound mass formed from massive dipoles set up within the vacuum surrounding ordinary matter. Aggregate matter induces a gravitational field within the surrounding space, which reinforces the original field. Dark energy, on the other hand, is the energy density associated with gravitational fields both for ordinary matter, and bound, or induced dipole matter. At high CBR temperatures, the cosmic susceptibility, induced by ordinary matter vanishes, as it is a smeared or average value for the cosmos as a whole. Even though gravitational dipoles do exist, no large-scale alignment or ordering is possible. Our model assumes that space, i.e., the vacuum, is filled with a vast assembly (sea) of positive and negative mass particles having Planck mass, called planckions, which is based on extensive work by Winterberg. These original particles form a very stiff two-component superfluid, where positive and negative mass species neutralize one another already at the submicroscopic level, leading to zero net mass, zero net gravitational pressure, and zero net entropy, for the undisturbed medium. It is theorized that the gravitational dipoles form from such material positive and negative particles, and moreover, this causes an intrinsic polarization of the vacuum for the universe as a whole. We calculate that in the present epoch, the smeared or average susceptibility of the cosmos equals, , and the overall resulting polarization equals, =2.396kg/m2. Moreover, due to all the ordinary mass in the universe, made up of quarks and leptons, we calculate a net gravitational field having magnitude,

关键词： Extended Gravitational Model friedmann equation Dark Matter Dark Energy Vacuum Energy Winterberg Model Gravitational Polarization Model Planck Mass Model

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De Broglie–Bohm Interpretation of Canonical Quantum Cosmology Implies Early Stages of the Universe Dominated by Radiation

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Communications in Theoretical Physics 2013年第12期60卷 691-694页

作者： Ch’ng Han Siong Shahidan Radiman School of Applied Physics Faculty of Science and Technology Universiti Kebangsaan Malaysia

The Einstein＇s genera/relativity is formulated in the Hamiltonian form for a spatia/ly Bat, isotropic and homogeneous universe. Subsequently, we perform the canonical quantization procedure to the Hamiltonian to obtain the Wheeler-DeWitt equation. Solving the Wheeler-DeWitt equation and employing the de Broglie-Bohm interpretation to the wave function of the universe, we obtain a new version of spatia/ly fiat friedmann equation for the early universe where the scale factor of the universe is taken to be sufilcientlv small.

关键词： de Broglie-Bohm interpretation canonical quantum cosmology friedmann equation Wheeler-DeWitt equation

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The Speed of Light Is Not Constant in Basic Big Bang Theory

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Journal of Modern Physics 2023年第3期14卷 287-310页

作者： Jef Van Royen Edegem Belgium

Starting from the basic assumptions and equations of Big Bang theory, we present a simple mathematical proof that this theory implies a varying (decreasing) speed of light, contrary to what is generally accepted. We consider General Relativity, the first friedmann equation and the friedmann-Lema?tre- Robertson-Walker (FLRW) metric for a Comoving Observer. It is shown explicitly that the Horizon and Flatness Problems are solved, taking away an important argument for the need of Cosmic Inflation. A decrease of 2.1 cm/s per year of the present-day speed of light is predicted. This is consistent with the observed acceleration of the expansion of the Universe, as determined from high-redshift supernova data. The calculation does not use any quantum processes, and no adjustable parameters or fine tuning are introduced. It is argued that more precise laboratory measurements of the present-day speed of light (and its evolution) should be carried out. Also it is argued that the combination of the FLRW metric and Einstein’s field equations of General Relativity is inconsistent, because the FLRW metric implies a variable speed of light, and Einstein’s field equations use a constant speed of light. If we accept standard Big Bang theory (and thus the combination of General Relativity and the FLRW metric), a variable speed of light must be allowed in the friedmann equation, and therefore also, more generally, in Einstein’s field equations of General Relativity. The explicit form of this time dependence will then be determined by the specific problem.

关键词： General Relativity friedmann equation Big Bang Cosmic Microwave Background CMB Varying Speed of Light Flatness Problem Horizon Problem Cosmic Inflation

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A Space Propulsion Principle Brought about by Locally-Expanded Space

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Journal of Earth Science and Engineering 2014年第8期4卷 490-499页

作者： Yoshinari Minami Advanced Science-Technology Research Organization (Formerly NEC Space Development Division) Nishi-Ku Yokohama 220-0062Japan

As is well known in cosmology, inflationary universe which shows rapid expansion of space is based on the phase transition of the vacuum exhibited by the Weinberg-Salam model of the electroweak interaction. The vacuum has the property of a phase transition, just like water may become ice and vice versa. This shows that a vacuum possesses a substantial physical structure. The expansion rule of the universe is governed by the friedmann equations and the Robertson-Walker metric. We explored another possibility of a space propulsion principle where the locally rapid expanding space generates the thrust, using the cosmology. In this paper, space propulsion principle is introduced from another angle （cosmology）, that is, the pressure of the field induced by local expansion of space is completely considered in the propulsion principle.

关键词： Space drive propulsion cosmology expanding universe friedmann equation Robertson-Walker metric de Sitteruniverse inflation.

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