<i>CMB</i>—A Geometric, Lorentz Invariant Model in Non-Expanding Lobachevskian Universe with a Black Body Spectral Distribution Function

In the present paper, based on Lobachevskian (hyperbolic) static geometry, we present (as an alternative to the existing Big Bang model of CMB) a geometric model of CMB in a Lobachevskian static universe as a homogeneous space of horospheres. It is shown that from the point of view of physics, a horosphere is an electromagnetic wavefront in Lobachevskian space. The presented model of CMB is an Lorentz invariant object, possesses observable properties of isotropy and homogeneity for all observers scattered across the Lobachevskian universe, and has a black body spectrum. The Lorentz invariance of CMB implies a mathematical equation for cosmological redshift for all z. The global picture of CMB, described solely in terms of the Lorentz group—SL(2C), is an infinite union of double sided quotient spaces (double fibration of the Lorentz group) taken over all parabolic stabilizers P&sub;SL(2C). The local picture of CMB (as seen by us from Earth) is a Grassmannian space of an infinite union all horospheres containing origin o&isin;L3, equivalent to a projective plane RP2. The space of electromagnetic wavefronts has a natural identification with the boundary at infinity (an absolute) of Lobachevskian universe. In this way, it is possible to regard the CMB as a reference at infinity (an absolute reference) and consequently to define an absolute motion and absolute rest with respect to CMB, viewed as an infinitely remote reference.

New Cosmology: The Global Dynamics of the Higgs Quantum Space and the Accelerated Expansion of the Universe

This work investigates the nature of the empty space and of the energy accelerating expansion of the universe, within the context of the Higgs theory. It is consensus among the cosmologists that dark energy, accelerating the expansion of the universe, is energy of the empty space (vacuum) itself. According to the Higgs theory, empty space (vacuum) is filled up by a real quantum fluid medium, closely analogous to the superconducting condensate, giving mass to the elementary particles by the Higgs mechanism. This spatial medium is the holder of the vacuum energy. Current theories describe the empty space (vacuum) in terms of the stress-energy tensor of a perfect fluid and estimate the vacuum energy density in terms of zero-point energies of the various force fields. They come to the scandalous conclusion that the vacuum energy density is 120 decimal orders of magnitude larger than shown by the observations. In the context of the Higgs theory, empty space, far from a perfect fluid, is a very strongly correlated boson condensate, a perfect quantum fluid ruled by the principles of quantum physics and governed by a powerful order parameter. This order parameter is stabilized by a huge energy gap that, according to the Glashow-Weinberg-Salam electroweak model, achieves more than 200 GeV. This huge energy gap very strongly suppresses the quantum fluctuations and the zero-point energies. This lets clear that estimating the vacuum energy density in terms of the zero-point energies cannot be correct. The expanding universe does not create more and more vacuum energy and does not expand against a negative pressure. The universe is an adiabatic system that conserves the total mass-energy and expansion only reduces the vacuum energy density. Calculations within this context show that the vacuum energy density converges closely to the observed value.

Mass of the Universe and the Redshift

Cosmological redshift is commonly attributed to the continuous expansion of the universe starting from the Big-Bang. However, expansion models require simplifying assumptions and multiple parameters to get acceptable fit to the observed data. Here we consider the redshift to be a hybrid of two effects: recession of distant galaxies due to expansion of the universe, and resistance to light propagation due to cosmic drag. The weight factor determining the contribution of the two effects is the only parameter that is needed to fit the observed data. The cosmic drag considered phenomenologically yields mass of the universe &asymp;?2 × 1053 kg. This implicitly suggests that the mass of the whole universe is causing the cosmic drag. The databases of extragalactic objects containing redshift z and distance modulus &mu;of galaxies up to z = 8.26 resulted in an excellent fit to the model. Also, the weight factor wD for expansion effect contribution to &mu;obtained from the data sets containing progressively higher values of &mu;?can be nicely fitted with .

The Spring of the Earth, the Sun and the Universe

A spring term is added into Newton’s law of gravitation. The spring k of the earth is found to be 1.21 × 10-8/sec2. The PPN gamma is a dependence of distance r from the sun. The expanding universe is due to the cosmological constant. The Hubble constant is found to be the square root of the cosmological constant. The query of the missing dark matter in the galaxies is clarified.

Gravitational Energy and No Big Bang Starts the Universe

Gravitation in flat space-time is described as field and studied in several articles. In addition to the flat space-time metric a quadratic form formally similar to that of general relativity defines the proper-time. The field equations for the gravitational field are non-linear differential equations of second order in divergence form and have as source the total energy-momentum tensor (inclusive that of gravitation). The total energy-momentum is conserved. It implies the equations of motion for matter in this field. The application of the theory gives for weak fields to measurable accuracy the same results as general relativity. The results of cosmological models are quite different from those of general relativity. The beginning of the universe starts from uniformly distributed gravitational energy without matter and radiation which is generated in the course of time. The solution is given in the pseudo-Euclidean metric, i.e. space is flat and non-expanding. There are non-singular solutions, i.e. no big bang. The redshift is a gravitational effect and not a Doppler effect. Gravitation is explained as field with attractive property and the condensed gravitational field converts to matter, radiation, etc. in the universe whereas the total energy is conserved. There is no contraction and no expansion of the universe.

Space Drive Propulsion Principle from the Aspect of Cosmology

This paper describes the propulsion principle using the concept of space drive and the pressure of the field induced by local rapid expansion of space based on the latest cosmology. Assuming that space vacuum is an infinite continuum, the propulsion principle utilizes the pressure field derived from the geometrical structure of space, by applying both continuum mechanics and general relativity to space. The propulsive force is a pressure thrust that arises from the interaction of space-time around the spaceship external environment and the spaceship itself; the spaceship is propelled by the pressure used against the space-time structure. As is well known in cosmology, the expansion rule of the universe is governed by the Friedman＇s equations and the Robertson-Walker metric. In this time, the propulsion principle of space drive 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.

A Space Propulsion Principle Brought about by Locally-Expanded Space

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.

Cosmology with Bounce by Flat Space-Time Theory of Gravitation and a New Interpretation

General relativity predicts a singularity in the beginning of the universe being called big bang. Recent developments in loop quantum cosmology avoid the singularity and the big bang is replaced by a big bounce. A classical theory of gravitation in flat space-time also avoids the singularity under natural conditions on the density parameters. The universe contracts to a positive minimum and then it expands during all times. It is not symmetric with regard to its minimum implying a finite age measured with proper time of the universe. The space of the universe is flat and the total energy is conserved. Under the assumption that the sum of the density parameters is a little bit bigger than one the universe is very hot in early times. Later on, the cosmological model agrees with the one of general relativity. A new interpretation of a non-expanding universe may be given by virtue of flat space-time theory of gravitation.

《量子力学》自学辅导之十──散射

《量子力学》自学辅导之十──散射宋宇辰，曾心愉，裴文杰（复旦大学理论物理骨干教师班；复旦大学物理系，上海２００４３３）具有确定动量的粒子从远处而来，通过另一个粒子（称为散射中心）附近，相互作用后而发生偏转，又向远处而去，这就是散射。量子力学中，散射又...

坚持《理论力学》课程建设不断提高教学质量

坚持《理论力学》课程建设不断提高教学质量孙习方，李廷孝，汪厚礼，毛益麟，边翠英（武汉水利电力大学理论力学教研室，武汉４３００７２）《理论力学》是高等院校许多专业的一门主要基础课，开展理论力学课程建设，对于提高本课程的教学水平以及后续课程的教学质量，具...

设置《综合物理》课程的实践与体会

本文介绍了设置《综合物理》课程的情况、该课程的内容和教学方法，以及它在完善基础物理教学、提高物理人才素质中的作用和实践的初步效果．

试论弗里德曼对演化宇宙学的贡献

从历史角度，依据史实论述了本世纪２０年代初前苏联数学家弗里德曼在爱因斯坦广义相对论的基础上，建立时空为动态的宇宙模型，提出宇宙不稳膨胀的理论，发展并完善了相对论对宇宙的解释，以及对现代演化宇宙学作出的重要贡献。

非平宇宙中的全息精质模型

提出了非平宇宙中的全息精质模型,构造出精质标量场,对全息暗能量的宇宙学演化进行有效描述.推导了全息暗能量在非平宇宙中的演化方程,进一步通过与正则标量场建立对应,构造出全息精质标量场模型,并讨论了空间曲率对模型的影响.结果表明,空间曲率对标量场演化的影响主要表现在高红移区域,而对于重构出的标量场势函数,在标量场值越小的区域空间曲率的影响越大.

A New Solution for the Friedmann Equations

Assuming a flat universe expanding under a constant pressure and combining the first and the second Friedmann equations, a new equation, describing the evolution of the scale factor, is derived. The equation is a general kinematic equation. It includes all the ingredients composing the universe. An exact closed form solution for this equation is presented. The solution shows remarkable agreement with available observational data for redshifts from a low of z = 0.0152 to as high as z = 8.68. As such, this solution provides an alternative way of describing the expansion of space without involving the controversial dark energy.

Galaxy formation in the reionization epoch as hinted by WideField Camera 3 observations of the Hubble Ultra Deep Field

We present a large sample of candidate galaxies at z ≈ 7 - 10, selected in the Hubble Ultra Deep Field using the new observations of the Wide Field Camera 3 that was recently installed on the Hubble Space Telescope. Our sample is composed of 20 z850-dropouts （four new discoveries）, 15 Y105-dropouts （nine new discoveries） and 20 J125-dropouts （all new discoveries）. The surface densities of the Z850-dropouts are close to what was predicted by earlier studies, however, those of the Y105- and J125-dropouts are quite unexpected. While no Y105- or J125-dropouts have been found at AB ≤ 28.0 mag, their surface densities seem to increase sharply at fainter levels. While some of these candidates seem to be close to foreground galaxies and thus could possibly be gravitationally lensed, the overall surface densities after excluding such cases are still much higher than what would be expected if the luminosity function does not evolve from z ～ 7 to 10. Motivated by such steep increases, we tentatively propose a set of Schechter function parameters to describe the luminosity functions at z ≈8 and 10. As compared to their counterpart at z ≈ 7, here L^＊ decreases by a factor of ～ 6.5 and Ф^＊ increases by a factor of 17-90. Although such parameters are not yet demanded by the existing observations, they are allowed and seem to agree with the data better than other alternatives. If these luminosity functions are still valid beyond our current detection limit, this would imply a sudden emergence of a large number of low-luminosity galaxies when looking back in time to z ≈ 10, which, while seemingly exotic, would naturally fit in the picture of the cosmic hydrogen reionization. These early galaxies could easily account for the ionizing photon budget required by the reionization, and they would imply that the global star formation rate density might start from a very high value at z ≈ 10, rapidly reach the minimum at z≈ 7, and start to rise again towards z ≈ 6. In this scenario, the majority of the stellar mass that the universe assembled through the reionization epoch seems still undetected by current observations at z ≈ 6.

Alignment between satellite and central galaxies in the EAGLE simulation:dependence on the large-scale environments

The alignment between satellite and central galaxies serves as a proxy for addressing the issue of galaxy formation and evolution, and has been investigated abundantly in observations and theoretical works.Most scenarios indicate that the satellites preferentially are located along the major axis of their central galaxy. Recent work shows that the strength of alignment signals depends on the large-scale environment in observations. We use the publicly-released data from EAGLE to figure out whether the same effect can be found in the associated hydrodynamic simulation. We found much stronger environmental dependency of alignment signals in the simulation. We also explore change of alignments to address the formation of this effect.

Comparing Gravitation in Flat Space-Time with General Relativity

General relativity (GR) and gravitation in flat space-time (GFST) are covariant theories to describe gravitation. The metric of GR is given by the form of proper-time and the metric of GFST is the flat space-time form different from that of proper-time. GR has as source the matter tensor and the Einstein tensor describes the gravitational field whereas the source of GFST is the total energy-momentum including gravitation and the field is described by a non-linear differential operator of order two in divergence form. The results of the two theories agree for weak gravitational fields to the order of measurable accuracy. It is well-known that homogeneous, isotropic, cosmological models of GR start from a point singularity of the universe, the so called big bang. The density of matter is infinite. Therefore, our observable universe implies an expansion of space, in particular an inflationary expansion in the beginning. This is the presently most accepted model of the universe although doubts exist because infinities don’t exist in physics. GFST starts in the beginning from a homogeneous, isotropic universe with uniformly distributed energy and no matter. In the course of time, matter is created out of energy where the total energy is conserved. There is no singularity. The space is flat and the space may be non-expanding.

Galaxy Interactions in Filaments and Sheets:Insights from EAGLE Simulations

We study the color and star formation rates of paired galaxies in filaments and sheets using the EAGLE simulations.We find that the major pairs with pair separation<50 kpc are bluer and more star-forming in filamentary environments compared to those hosted in sheet-like environments.This trend reverses beyond a pair separation of~50 kpc.The interacting pairs with larger separations(>50 kpc)in filaments are on average redder and low-star-forming compared to those embedded in sheets.The galaxies in filaments and sheets may have different stellar mass and cold gas mass distributions.Using a KS test,we find that for paired galaxies with pair separation<50 kpc,there are no significant differences in these properties in sheets and filaments.The filaments transport gas toward the cluster of galaxies.Some earlier studies find preferential alignment of galaxy pairs with the filament axis.Such alignment of galaxy pairs may lead to different gas accretion efficiency in galaxies residing in filaments and sheets.We propose that the enhancement of star formation rate at smaller pair separation in filaments is caused by the alignment of galaxy pairs.A recent study with SDSS data reports the same findings.The confirmation of these results by the EAGLE simulations suggests that the hydrodynamical simulations are powerful theoretical tools for studying galaxy formation and evolution in the cosmic web.

Hubble’s Constant and Flat Rotation Curves of Stars: Are Dark Matter and Energy Needed?

Although dark energy and dark matter have not yet been detected, they are believed to comprise the majority of the universe. Observations of the flat rotation curve of galaxies may be explained by dark matter and dark energy. This article, using Newton’s laws and Einstein’s theory of gravitation, shows that it is possible to define a new term, called E0, variable in time and space, of which one of its limits is the Hubble constant H0. I show that E0?is strongly linked to an explanation of the flat rotation curve of galaxies. This strong correlation between Hubble’s constant H0?and E0 enables us to solve the mystery of the surplus of gravity that is stabilizing the universe.

Gravitation as Geometry or as Field

General relativity (GR) and gravitation in flat space-time (GFST) are covariant theories to describe gravitation. The metric of GR is given by the form of proper-time and the metric of GFST is a flat space-time form different from that of proper-time. The source of GR is the matter tensor and the Einstein tensor describes the gravitational field. The source of GFST is the total energymomentum including gravitation. The field is described by a non-linear differential operator of order two in divergence form. The results of the two theories agree for weak gravitational fields to the order of measurable accuracy. It is well-known that homogeneous, isotropic, cosmological models of GR start from a point singularity of the universe, the so called big bang. The density of matter is infinite. Therefore, our observable big universe implies an expansion of space, in particular an inflationary expansion in the beginning. Doubts are stated because infinities don’t exist in physics. An explanation to the present, controversial discussion of expanding accelerating or non-accelerating universe as well as non-expanding universe is given. GFST starts in the beginning from a homogeneous, isotropic universe with uniformly distributed energy and no matter. In the course of time matter is created out of energy where the total energy is conserved. There is no singularity, i.e. no big bang. The space is flat and non-expanding.