Based on the latest Planck surveys, the universe is close to being remarkably flat, and yet, within observational error, there is still room for a slight curvature. If the curvature is positive, then this would lead t...Based on the latest Planck surveys, the universe is close to being remarkably flat, and yet, within observational error, there is still room for a slight curvature. If the curvature is positive, then this would lead to a closed universe, as well as allow for a big bounce scenario. Working within these assumptions, and using a simple model, we predict that the cosmos may have a positive curvature in the amount, <span style="white-space:nowrap;"><span style="white-space:nowrap;">Ω<sub>0</sub>=1.001802</span></span>, a value within current observational bounds. For the scaling laws associated with the density parameters in Friedmann’s equations, we will assume a susceptibility model for space, where, <img src="Edit_18751d6f-dbfa-47ba-be7c-8298073a34fd.png" alt="" style="white-space:normal;" />, equals the smeared cosmic susceptibility. If we allow the <img src="Edit_18751d6f-dbfa-47ba-be7c-8298073a34fd.png" alt="" /> to <em>decrease with increasing</em> cosmic scale parameter, “<em>a</em>”, then we can predict a maximum Hubble volume, with minimum CMB temperature for the voids, before contraction begins, as well as a minimum volume, with maximum CMB temperature, when expansion starts. A specific heat engine model for the cosmos is also entertained for this model of a closed universe.展开更多
Instead of the hypothesis of the dark matter and dark energy, curvature of a four dimensional Lorentzian manifold can be used to explain the accelerating expansion of the universe today and the shrink of that in the f...Instead of the hypothesis of the dark matter and dark energy, curvature of a four dimensional Lorentzian manifold can be used to explain the accelerating expansion of the universe today and the shrink of that in the future, as well as two critical points for each period life of the universe.Therefore, the Big Bang can be treated as the beginning point of the process that the total energy changes to total mass along the positive direction of entropy on the cosmic scales,where the curvature is positive and, conversely, the Big Crunch can be treated as the beginning point of the process that total mass changes to total energy along the negative direction of entropy, where the curvature is negative.By derivative, sinusoidal functions obtained to describe the change rate of the scale and that of the curvature along the periodic life of the universe.展开更多
We study the constraint on deceleration parameter q from the recent SNela Gold dataset and observational Hubble data by using a model-independent deceleration parameter q（z） = 1/2 - a/（1 ＋ z）^b under the flve-dim...We study the constraint on deceleration parameter q from the recent SNela Gold dataset and observational Hubble data by using a model-independent deceleration parameter q（z） = 1/2 - a/（1 ＋ z）^b under the flve-dimensional bounce cosmological model. For the cases of SNeIa Gold dataset, Hubble data, and their combination, the present results show that the constraints on transition redshift ZT are 0.35-0.07^＋0.14,0.68-0.58^＋1.47,and 0.55-0.09^＋0.18 with 1σ errors,respectively.展开更多
文摘Based on the latest Planck surveys, the universe is close to being remarkably flat, and yet, within observational error, there is still room for a slight curvature. If the curvature is positive, then this would lead to a closed universe, as well as allow for a big bounce scenario. Working within these assumptions, and using a simple model, we predict that the cosmos may have a positive curvature in the amount, <span style="white-space:nowrap;"><span style="white-space:nowrap;">Ω<sub>0</sub>=1.001802</span></span>, a value within current observational bounds. For the scaling laws associated with the density parameters in Friedmann’s equations, we will assume a susceptibility model for space, where, <img src="Edit_18751d6f-dbfa-47ba-be7c-8298073a34fd.png" alt="" style="white-space:normal;" />, equals the smeared cosmic susceptibility. If we allow the <img src="Edit_18751d6f-dbfa-47ba-be7c-8298073a34fd.png" alt="" /> to <em>decrease with increasing</em> cosmic scale parameter, “<em>a</em>”, then we can predict a maximum Hubble volume, with minimum CMB temperature for the voids, before contraction begins, as well as a minimum volume, with maximum CMB temperature, when expansion starts. A specific heat engine model for the cosmos is also entertained for this model of a closed universe.
文摘Instead of the hypothesis of the dark matter and dark energy, curvature of a four dimensional Lorentzian manifold can be used to explain the accelerating expansion of the universe today and the shrink of that in the future, as well as two critical points for each period life of the universe.Therefore, the Big Bang can be treated as the beginning point of the process that the total energy changes to total mass along the positive direction of entropy on the cosmic scales,where the curvature is positive and, conversely, the Big Crunch can be treated as the beginning point of the process that total mass changes to total energy along the negative direction of entropy, where the curvature is negative.By derivative, sinusoidal functions obtained to describe the change rate of the scale and that of the curvature along the periodic life of the universe.
基金Supported by the National Natural Science Foundation of China under Grant Nos 10573003, 10647110, 10703001 and 10747113 DUT （893326）, and the National Basic Research Programme of China under Grant No 2003CB716300.
文摘We study the constraint on deceleration parameter q from the recent SNela Gold dataset and observational Hubble data by using a model-independent deceleration parameter q（z） = 1/2 - a/（1 ＋ z）^b under the flve-dimensional bounce cosmological model. For the cases of SNeIa Gold dataset, Hubble data, and their combination, the present results show that the constraints on transition redshift ZT are 0.35-0.07^＋0.14,0.68-0.58^＋1.47,and 0.55-0.09^＋0.18 with 1σ errors,respectively.
