Particle horizon

About: Particle horizon is a research topic. Over the lifetime, 2096 publications have been published within this topic receiving 69137 citations.

The thermodynamic evolution of the cosmological event horizon

Abstract: By manipulating the integral expression for the proper radius $R_e$ of the cosmological event horizon (CEH) in a Friedmann-Robertson-Walker (FRW) universe, we obtain an analytical expression for the change $\dd R_e$ in response to a uniform fluctuation $\dd\rho$ in the average cosmic background density $\rho$. We stipulate that the fluctuation arises within a vanishing interval of proper time, during which the CEH is approximately stationary, and evolves subsequently such that $\dd\rho/\rho$ is constant. The respective variations $2\pi R_e \dd R_e$ and $\dd E_e$ in the horizon entropy $S_e$ and enclosed energy $E_e$ should be therefore related through the cosmological Clausius relation. In that manner we find that the temperature $T_e$ of the CEH at an arbitrary time in a flat FRW universe is $E_e/S_e$, which recovers asymptotically the usual static de Sitter temperature. Furthermore, it is proven that during radiation-dominance and in late times the CEH conforms to the fully dynamical First Law $T_e \drv S_e = P\drv V_e - \drv E_e$, where $V_e$ is the enclosed volume and $P$ is the average cosmic pressure.

Expansion Speeds and Accelerations of the Universe in Five General Cosmic Models

Abstract: Four new cosmological quantities were introduced which are the horizon expansion speed, horizon expansion acceleration, horizon volume speed and horizon volume acceleration of the universe expansion. These quantities have been investigated in five general cosmic models. The distributions of the space expansion speed of the universe in these models decrease up to minimum values, then they increase slowly until t = 20.9524 Gyr, and hence rise appreciably faster. In the observed general model the minimum space expansion speed is at t = 7.3562 Gyr. However, the distributions of the horizon expansion speed of the universe in the general models continuously descend with cosmic time. At the present time in the observed general model dh (t0) = 300024.5 km s-1 . On the other hand, the distributions of the horizon volume speed of the universe expansion surge slowly until t = 41142.0298yr, afterwards they ascend more rapidly up to maximum values, and hence they decrease gradually towards zero. At the present time in the observed general model Vh (t0) = 50.4425 (10kpc)3 s-1, while the maximum horizon volume speed is at t = 2.7454 Gyr. The distributions of the speed expansion acceleration of the universe in the general models exhibit steep rise towards ä (t) = 0 and remain very close to this value, then they increase very slowly up to t = 85.3846Gyr, then they rise more rapidly, however after t = 100.3846 Gyr they surge substantially faster. Nevertheless, the distributions of the horizon expansion acceleration of the universe in the general models display sharp ascension towards \(\ddot{d}\)h (t ) = 0 and stay so adjacent to this value hence after t = 10.2857 Gyr. Finally, the distributions of the horizon volume acceleration of the universe expansion in the general models decline with time unit t = 2.1951Gyr, where they remain close to \(\ddot{V}\)h (t0) . At the present time in the observed general model \(\ddot{d}\)h (t0) = -0.0007 \(\times\)10-9 km s -2, \(\ddot{V}\)h (t0) = -0.0456 \(\times\)10-3pc3 s -2 . It is found that the four new cosmological quantities are strongly related to the distribution of the total pressure of the universe.

Universe: the dynamics of the minimum and maximum expansion states (Time: the collateral dimension)

Abstract: Abstract Two hypotheses stand out in describing the evolution of the Universe. The predominant one predicts that the present expansion began at a certain instant and will not preserve any variation of energy that performs work; apparent flat Universe (Ω = 1) is advocated by relativistic calculations and observational data, with an end at its maximum expansion (3D Space). The other hypothesis considers that the Universe is cyclical, always alternating phases of expansion and contraction. This proposal aims to demonstrate that both hypotheses can be correct by not being distinct, but complementary. Supported by the immutability of physical laws, analyses of concepts define an exclusive presence of 1D Space in static states of minimum and maximum expansion of the Universe. With our 3D Space Universe created and existing between these extreme states, the Friedmann-Lemaître-Robertson-Walker (FLRW) metric, becomes inadequate for this analysis; therefore, the concept of absolute rest energy (1D Space) is applied, demonstrating that the complete evolution of the Universe is spatially dynamic in a perpetual time dimension, always recreating our Universe, and making possible a relative maintenance of any existence.

Universe: the dynamics of the minimum and maximum expansion states (Time: the collateral dimension)

Abstract: Abstract Two hypotheses stand out in describing the evolution of the Universe. The predominant one predicts that the present expansion began at a certain instant and will not preserve any variation of energy that performs work; apparent flat Universe (Ω = 1) is advocated by relativistic calculations and observational data, with an end at its maximum expansion (3D Space). The other hypothesis considers that the Universe is cyclical, always alternating phases of expansion and contraction. This proposal aims to demonstrate that both hypotheses can be correct by not being distinct, but complementary. Supported by the immutability of physical laws, analyses of concepts define an exclusive presence of 1D Space in static states of minimum and maximum expansion of the Universe. With our Universe (3D Space) created and existing between these extreme states, the Friedmann-Lemaître-Robertson-Walker (FLRW) metric, becomes inadequate for this analysis; therefore, the concept of absolute rest energy (1D Space) is applied, demonstrating that the complete evolution of the Universe is spatially dynamic in a perpetual time dimension, always recreating our Universe, and making possible a relative maintenance of any existence.

The Center and Spin of the Universe

Abstract: It is generally believed that the universe emerged from the Big Bang, before which space and time did not exist. However, Penrose proposed his theory of conformal cyclic cosmology, in which an aeon existed preceding this universe. Based on the cosmological principle, the universe is homogeneous and isotropic, expanding without center, but recently more and more deviations have been observed. By studying the fundamental particles and reactions of nature, we initiated a model that the Big Bang is the result of the collapse of a neutrino star within a black hole. We therefore re-analyze the cosmic microwave background (CMB) and find that the Center of the universe where the Big Bang occurred was at 0.66 +0.03 -0.01 times the radius of the surface of last scattering away from the Local Supercluster (LS) and at Galactic coordinates (l, b) = (286o +/- 10o, -43o +7 -6). If we look from the LS to the Center, the universe is spinning clockwise. Our findings are supported by Penrose’s conformal cyclic cosmology, low-variance circle sets in the CMB, and many other independent observational evidence of cosmic inhomogeneities, spatial anisotropies, and time variations.