Verlinde has suggested that the gravity has an entropic origin, and a gravitational system could be regarded as a thermodynarnical system. It is well-known that the equipartition law of energy is invalid at very low t...Verlinde has suggested that the gravity has an entropic origin, and a gravitational system could be regarded as a thermodynarnical system. It is well-known that the equipartition law of energy is invalid at very low temperature. Therefore, entropic force should be modified while the temperature of the holographic screen is very low. It is shown that the modified entropic force is proportional to the square of the acceleration, while the temperature of the holographic screen is much lower than the Debye temperature TD. The modified entropic force returns to the Newton＇s law of gravitation while the temperature of the holographic screen is much higher than the Debye temperature. The modified entropic force is connected with modified Newtonian dynamics （MOND）. The constant ao involved in MOND is linear in the Debye frequency WD, which can be regarded as the largest frequency of the bits in screen. We find that there do have a strong connection between MOND and cosmology in the framework of Verlinde＇s entropic force, if the holographic screen is taken to be bound of the Universe. The Debye frequency is linear in the Hubble constant Ho.展开更多
We probe the universality of acceleration scale a_(0) in Milgrom's modified Newtonian dynamics(MOND)using the recently released rotation curve data from SPARC galaxies.We divide the SPARC data into different subsa...We probe the universality of acceleration scale a_(0) in Milgrom's modified Newtonian dynamics(MOND)using the recently released rotation curve data from SPARC galaxies.We divide the SPARC data into different subsamples according to the morphological types of galaxies,and fit the rotation curve data of each subsample with the theoretical prediction of MOND.MOND involves an arbitrary interpolation function which connects the Newtonian region and the MOND region.Here we consider five different interpolation functions that are widely discussed in the literature.It is shown that the best-fitting a_(0) significantly depends on the interpolation functions.For a specific interpolation function, a_(0) also depends on the morphological types of galaxies,implying that a_(0) may be not a universal constant.Introducing a dipole correction to a_(0) can significantly improve the fits.The dipole directions for four of the five interpolation functions point towards an approximately consistent direction,but a_(0) still varies for different interpolation functions.展开更多
A new model of the modified Newtonian gravity called Compacted & Collapsing Gravity (CCG) is proposed. Similar to the Milgrom’s MOND, it allows explaining the flattening of rotation curve in spiral galaxies, thus...A new model of the modified Newtonian gravity called Compacted & Collapsing Gravity (CCG) is proposed. Similar to the Milgrom’s MOND, it allows explaining the flattening of rotation curve in spiral galaxies, thus eliminates the need for dark matter at this level. However, in contrast to MOND, it puts a distinct limit on effective gravity;thereby constraints the sizes of single galaxies in connection to their masses, which complies with observations. In the bigger than single galaxies structures such as galaxy clusters, CCG rather complements than replaces interpretations of the observational data based on dark matter. Besides, the new model provides a plausible explanation to the hierarchical structure of the universe.展开更多
In contemporary physics, there is an observed discrepancy in the mass calculations used to determine the strength of celestial gravitational fields. Therefore, physics is searching for dark matter candidate particles,...In contemporary physics, there is an observed discrepancy in the mass calculations used to determine the strength of celestial gravitational fields. Therefore, physics is searching for dark matter candidate particles, such as weakly interacting massive particles (WIMPs) and axions, while attempting to modify Newtonian dynamics and the law of universal gravitation. Inspired by the classical theories of electric and magnetic field mass-energy calculations, the present work proposes a new theoretical attempt to explore the dark matter in the universe and challenge theories that modify Newtonian dynamics and the law of universal gravitation. Like the formulas for calculating the mass-energy density of electric and magnetic fields, Newtonian static gravitational fields also have a mass-energy density. The matter in the gravitational field will also generate a new gravitational field and thus derive the formula for calculating the mass-energy of matter in the gravitational field. In this way, the gravitational mass-energy of celestial bodies should consider the ordinary visible matter and invisible matter of the gravitational field. The strength of a gravitational field is a vector, and the mass-energy density of a gravitational field is proportional to the square of its strength. The greater the strength of the gravitational field, the greater the mass-energy density of the gravitational field at that location. Assuming that ordinary matter is distributed uniformly within a sphere, it deduces that the mass-energy of the celestial body is not only related to that of ordinary matter but also to its structure. The higher the celestial structure factor of that body, the greater the mass-energy density of matter in the gravitational field inside and outside the body.展开更多
In a previous article entitled: “Evidences for varying speed of light with time” [1], a series of observational evidence was presented in favor of the hypothesis that the speed of light varies with time according to...In a previous article entitled: “Evidences for varying speed of light with time” [1], a series of observational evidence was presented in favor of the hypothesis that the speed of light varies with time according to the relationship d<i>c</i>/d<i>t</i> = -<i>Hc</i>, where <i>H</i> is the Hubble constant which is considered a universal constant. In this paper we propose to elaborate on the observational evidence supporting the hypothesis, and to probe the consequences of this relationship on General Relativity. Also we will provide a theoretical justification of the previous relationship and we will show how from it we can deduce galactic velocity curves. We can deduce the important empirical Tully-Fisher relation linking these curves to the baryonic mass of the galaxy and we can justify the apparent accelerated expansion of the universe without intervening elusive entities such as dark matter and dark energy.展开更多
We test and explore a Modified Universe Dynamics (MOUND) formula recently proposed by the author. We show that, similarly to Milgrom’s Modified Newtonian Dynamics (MOND), it is successful in accounting for the mass d...We test and explore a Modified Universe Dynamics (MOUND) formula recently proposed by the author. We show that, similarly to Milgrom’s Modified Newtonian Dynamics (MOND), it is successful in accounting for the mass discrepancy in spiral galaxies, and it predicts the Baryonic Tully-Fisher Relation (BTFR) and the Radial Acceleration Relation (RAR). Contrary to Milgrom’s MOND, MOUND also explains the dynamics of galaxy clusters and does not rely on an empirical interpolating function or an ad hoc acceleration parameter.展开更多
基金Supported by the National Natural Science Foundation of China under Grant Nos.10525522 and 10875129
文摘Verlinde has suggested that the gravity has an entropic origin, and a gravitational system could be regarded as a thermodynarnical system. It is well-known that the equipartition law of energy is invalid at very low temperature. Therefore, entropic force should be modified while the temperature of the holographic screen is very low. It is shown that the modified entropic force is proportional to the square of the acceleration, while the temperature of the holographic screen is much lower than the Debye temperature TD. The modified entropic force returns to the Newton＇s law of gravitation while the temperature of the holographic screen is much higher than the Debye temperature. The modified entropic force is connected with modified Newtonian dynamics （MOND）. The constant ao involved in MOND is linear in the Debye frequency WD, which can be regarded as the largest frequency of the bits in screen. We find that there do have a strong connection between MOND and cosmology in the framework of Verlinde＇s entropic force, if the holographic screen is taken to be bound of the Universe. The Debye frequency is linear in the Hubble constant Ho.
基金Supported by the National Natural Science Fund of China(11603005,11775038,11947406),Fundamental Research Funds for the Central Universities(2020CQJQY-Z003)。
文摘We probe the universality of acceleration scale a_(0) in Milgrom's modified Newtonian dynamics(MOND)using the recently released rotation curve data from SPARC galaxies.We divide the SPARC data into different subsamples according to the morphological types of galaxies,and fit the rotation curve data of each subsample with the theoretical prediction of MOND.MOND involves an arbitrary interpolation function which connects the Newtonian region and the MOND region.Here we consider five different interpolation functions that are widely discussed in the literature.It is shown that the best-fitting a_(0) significantly depends on the interpolation functions.For a specific interpolation function, a_(0) also depends on the morphological types of galaxies,implying that a_(0) may be not a universal constant.Introducing a dipole correction to a_(0) can significantly improve the fits.The dipole directions for four of the five interpolation functions point towards an approximately consistent direction,but a_(0) still varies for different interpolation functions.
文摘A new model of the modified Newtonian gravity called Compacted & Collapsing Gravity (CCG) is proposed. Similar to the Milgrom’s MOND, it allows explaining the flattening of rotation curve in spiral galaxies, thus eliminates the need for dark matter at this level. However, in contrast to MOND, it puts a distinct limit on effective gravity;thereby constraints the sizes of single galaxies in connection to their masses, which complies with observations. In the bigger than single galaxies structures such as galaxy clusters, CCG rather complements than replaces interpretations of the observational data based on dark matter. Besides, the new model provides a plausible explanation to the hierarchical structure of the universe.
文摘In contemporary physics, there is an observed discrepancy in the mass calculations used to determine the strength of celestial gravitational fields. Therefore, physics is searching for dark matter candidate particles, such as weakly interacting massive particles (WIMPs) and axions, while attempting to modify Newtonian dynamics and the law of universal gravitation. Inspired by the classical theories of electric and magnetic field mass-energy calculations, the present work proposes a new theoretical attempt to explore the dark matter in the universe and challenge theories that modify Newtonian dynamics and the law of universal gravitation. Like the formulas for calculating the mass-energy density of electric and magnetic fields, Newtonian static gravitational fields also have a mass-energy density. The matter in the gravitational field will also generate a new gravitational field and thus derive the formula for calculating the mass-energy of matter in the gravitational field. In this way, the gravitational mass-energy of celestial bodies should consider the ordinary visible matter and invisible matter of the gravitational field. The strength of a gravitational field is a vector, and the mass-energy density of a gravitational field is proportional to the square of its strength. The greater the strength of the gravitational field, the greater the mass-energy density of the gravitational field at that location. Assuming that ordinary matter is distributed uniformly within a sphere, it deduces that the mass-energy of the celestial body is not only related to that of ordinary matter but also to its structure. The higher the celestial structure factor of that body, the greater the mass-energy density of matter in the gravitational field inside and outside the body.
文摘In a previous article entitled: “Evidences for varying speed of light with time” [1], a series of observational evidence was presented in favor of the hypothesis that the speed of light varies with time according to the relationship d<i>c</i>/d<i>t</i> = -<i>Hc</i>, where <i>H</i> is the Hubble constant which is considered a universal constant. In this paper we propose to elaborate on the observational evidence supporting the hypothesis, and to probe the consequences of this relationship on General Relativity. Also we will provide a theoretical justification of the previous relationship and we will show how from it we can deduce galactic velocity curves. We can deduce the important empirical Tully-Fisher relation linking these curves to the baryonic mass of the galaxy and we can justify the apparent accelerated expansion of the universe without intervening elusive entities such as dark matter and dark energy.
文摘We test and explore a Modified Universe Dynamics (MOUND) formula recently proposed by the author. We show that, similarly to Milgrom’s Modified Newtonian Dynamics (MOND), it is successful in accounting for the mass discrepancy in spiral galaxies, and it predicts the Baryonic Tully-Fisher Relation (BTFR) and the Radial Acceleration Relation (RAR). Contrary to Milgrom’s MOND, MOUND also explains the dynamics of galaxy clusters and does not rely on an empirical interpolating function or an ad hoc acceleration parameter.
