Dynamic Spacetime: Key to the Mysteries of Dark Matter and Dark Energy

Physics is a branch of science to study matter and its motion in space and time. Development of physics usually upgrades human perspective and understanding of the space and time. Einstein successfully developed special and general theories of relativity and creatively promoted our perspective of spacetime from Newton’s absolute space and time to his relative spacetime. Based on redshift and distance measurements of galaxies and distant type Ia supernovae, cosmologists have suggested that our universe is expanding at an ever-increasing rate driven by a mysterious dark energy. Recently, the author has proposed that spacetime is dynamic. Spacetime is said to be absolute if it is independent of matter and motion, relative if it is affected by matter and motion, and dynamic if it mutually interacts with matter and motion. In dynamic spacetime, not only do matter and motion distort spacetime, but they are also affected by the distorted spacetime. Spacetime to be dynamic is a consequence of a deep insight to Mach’s principle, which tells us that the inertia of an object results from the gravitational interaction by the rest of the universe. Reaction of dynamic spacetime on a traveling light causes light redshift. Reaction of dynamic spacetime on a fast moving neutrino slows down the neutrino. The derived redshift-distance relation perfectly explained the measurements of distant type Ia supernovae and gamma ray bursts (GRBs) and also naturally obtained Hubble’s law as an approximate relation at small redshift. This explanation of cosmological redshift as the opposition of dynamic spacetime does not mandate the universe to be expanding and accelerating, so that it does not need the universe to be initiated from a Big Bang and driven out mainly by a mysterious dark energy. Extremely slowed down neutrinos in dynamic spacetime, when they are gravitationally trapped around clusters, galaxies, and any celestial objects, would play the role of dark matter in explaining the velocity-radius relations of galaxy’s or cluster’s rotations.

Constraining Neutrino Mass in Dynamical Dark Energy Cosmologies with the Logarithm Parametrization and the Oscillating Parametrization

We constrain two dynamical dark energy models that are parametrized by the logarithm form of and the oscillating form of . Comparing with the Chevallier-Polarski-Linder (CPL) model, the two parametrizations for dark energy can explore the whole evolution history of the universe properly. Using the current mainstream observational data including the cosmic microwave background data and the baryon acoustic oscillation data as well as the type Ia supernovae data, we perform the X2 statistic analysis to global fit these models, finding that the logarithm parametrization and the oscillating parameterization are almost as well as the CPL scenario in fitting these data. We make a comparison for the impacts of the dynamical dark energy on the cosmological constraints on the total mass of active neutrinos. We find that the logarithm parametrization and the oscillating parameterization can increase the fitting values of Σmv. Looser constraints on Σmv are obtained in the logarithm and oscillating models than those derived in the CPL model. Consideration of the possible mass ordering of neutrinos reveals that the most stringent constraint on Σmv appears in the degenerate hierarchy case.

Effects of dark energy interacting with massive neutrinos and dark matter on universe evolution

In this paper we investigate the evolution of the cosmology model with dark energy interacting with massive neutrinos and dark matter. Using the numerical method to investigate the dynamical system, we find that the stronger the interaction between dark energy and dark matter, the lower the ratio of dark matter in the universe is; also, the stronger the interaction between dark energy and massive neutrinos, the lower the ratio of massive neutrinos in the universe is. On the other hand, the interaction between dark energy and dark matter or massive neutrinos has an effect on disturbing the universe＇s acceleration; we also find that our universe is still accelerating.

Planetary Heating by Neutrinos: Long-Term Habitats for Aquatic Life if Dark Energy Decays Favourably

The potential cosmological and astrobiological implications of neutrinos are considered. Dark energy drives the current phase of accelerating cosmic expansion. Like inflation, it may decay in time to matter and radiation. However, since its energy density is minuscule in comparison, decay would be unlikely to inject such a rich variety of particles into the universe, and may instead be limited to the lowest energy fermions. Nonrelativistic neutrinos have the capacity to form stable, galaxy-engulfing haloes supported by degeneracy pressure, much like white dwarves and neutron stars. Conversely, bodies of mass can indefinitely rely on Coulomb forces for weight support. Opportunities for the mutual annihilation of electron neutrinos are largely confined to planets containing iron in the hcp phase. If dark energy decays primarily to neutrinos in 40 ~ 100 Gyr, then oceanic planets orbiting within the resulting haloes could provide long-term habitats for aquatic life with only lax constraints on the neutrino mass, . Various considerations now favour the possibility that neutrinos are Majorana particles with an inverted mass hierarchy and an electron neutrino mass in the vicinity of 50 meV. Sterile neutrinos of eV-mass may already be a significant component of dark matter, and could enhance planetary heating when active neutrino haloes become heavily depleted. An intriguing mechanism capable of regulating oceanic heat flux over a wide range of planetary masses is also described.

Detecting dark energy in long baseline neutrino oscillations

In this paper, we discuss a possibility of studying properties of dark energy in long baseline neutrino oscillation experiments. We consider two types of models of neutrino dark energy. For one type of models the scalar field is taken to be quintessence-like and for the other phantom-like. In these models the scalar fields couple to the neutrinos to give rise to spatially varying neutrino masses. We will show that the two types of models predict different behaviors of the spatial variation of the neutrino masses inside the Earth and consequently result in different signals in long baseline neutrino oscillation experiments.

Oscillating Flat FRW Dark Energy Dominated Cosmology from Periodic Functional Approach

I discuss the modification of Einstein＇s Theory of General Relativity based on a periodic functional approach. In this new approach, a corrected periodic gravitational coupling constant arises and plays the role of periodic damping term acting on the theory. It is found that it is achievable to have an oscillating universe dominated by dark energy and expanding aceeleratedly in time.

Speed of Gravitation and Electromagnetic Waves through the Dark Energy of Intergalactic Space and Its Implications of a Unified Theory

The recent finding that gravitational waves (GW170817) traveled at the same speed as electromagnetic (EM) waves (GRB 170817A) from a binary neutron star merger does not necessarily mean that they traveled throughout their journey at speed c. Some recent works by the author (2015) Journal of Modern Physics, 6, 78-87, and 1360-1370;(2016), 7, 1829-1844;(2017), 8, 622-635 show that the diminished brightness of Type Ia supernovae (SNe Ia) can be explained by assuming that dark energy, instead of having a negative pressure, has an index of refraction n, causing the speed of light through intergalactic space (IGS) to be reduced to c/n, with? n≈1.5. It follows that GWs (not considered in the previous works) would also travel with speed c/n through IGS. However, speed of GWs and EMWs within galaxies themselves is c. A brief review of the model is given, together with other predictions, e.g., new values for the Hubble constant and age of the universe, and necessary absence of correlation of neutrinos with gamma ray bursts (GRBs), in agreement with numerous searches. In the previous works, there were implications of a unified theory. If the model holds, since GWs would experience the same speed reduction as EMWs, this would further support unification. An improved falsification methodology for a previously proposed astronomical test based on discordant redshifts is given.

An Analogy between the Properties of “Dark Energy” and Physical Vacuum Consisting of Quantum Harmonic Oscillators Characterized by Zero-Point Energy

In quantum field theory, the physical vacuum, free from magnetic and electric fields (without regard to gravitational energy), is defined not as an empty space but as the ground state of the field consisting of quantum harmonic oscillators (QHOs) characterized by zero-point energy. The aim of this work is to show that such physical vacuum may possess the properties similar to the properties of dark energy: the positive density, the negative pressure, and the possibility of so-called accelerated expansion. In the model discussed, the mass of QHOs determines the positive density of dark energy. The observed electric polarization of physical vacuum in an electric field means the existence of electric dipole moment of QHO, which, in turn, suggests the existence inside the QHO of a repulsive force between unlike charges compensating the attractive Coulomb force between the charges. The existence of such repulsive force may be treated as the existence of omniradial tensions inside every QHO. In terms of hydrodynamics, it means that the vacuum with this property may be regarded as a medium with negative pressure. The electric dipole-dipole interaction of QHOs under some condition may result in the expansion of physical vacuum consisting of QHOs. It is shown also that the physical vacuum consisting of QHOs is a luminiferous medium, and based on this concept the conditions are discussed for the emergence of invisiblity of any objects (in particular, dark matter). The existence of luminiferous medium does not contradict the second postulate of special relativity (the principle of constancy of the velocity of light in inertial systems), if to take into account the interaction of photons with QHOs and with virtual photons (the virtual particles pairs) created by quantum entities that constitute the inertial systems.

Look at Neutrino Oscillations in Space-Like Continuum

Based on the special theory of relativity in space-like continuum, the pre-sent author points that if there exist tachyons in nature, they should be neutral point-like particles with lepton appearance, which are very much like our early understanding about neutrinos before. The author also points that an alternative explanation for neutrino oscillations may be the conversion between mass-less neutrinos with different flavors expressed in different “lowest limited momentum” during their flight journey, which originates from that the argument in the squared sine function of the probability of neutrino oscillation may be less than zero, which is mathematical foresight and may not be ignored.

Prospects for weighing neutrinos in interacting dark energy models using joint observations of gravitational waves andγ-ray bursts

Cosmological observations can be used to weigh neutrinos,but this method is model-dependent,with results relying on the cosmological model considered.If we consider interactions between dark energy and dark matter,the neutrino mass constraints differ from those derived under the standard model.On the contrary,gravitational wave(GW)standard siren observations can measure absolute cosmological distances,helping to break parameter degeneracies inherent in traditional cosmological observations,thereby improving constraints on neutrino mass.This paper examines the constraints on neutrino mass within interacting dark energy(IDE)models and explores how future GW standard siren observations could enhance these results.For multi-messenger GW observations,we consider the joint observations of binary neutron star mergers by third-generation ground-based GW detectors and shortγ-ray burst observations by missions similar to the THESEUS satellite project.Using current cosmological observations(CMB+BAO+SN),we obtain an upper limit on the neutrino mass in the IDE models of 0.15(or 0.16)eV.With the inclusion of GW data,the upper limit on the neutrino mass improves to 0.14 eV.This indicates that in the context of IDE models,the improvement in neutrino mass constraints from GW observations is relatively limited.However,GW observations significantly enhance the constraints on other cosmological parameters,such as matter density parameter,the Hubble constant,and coupling strength between dark energy and dark matter.

Exploring neutrino mass and mass hierarchy in interacting dark energy models

We investigate how the dark energy properties impact the constraints on the total neutrino mass in interacting dark energy（IDE）models. In this study, we focus on two typical interacting dynamical dark energy models, i.e., the interacting w cold dark matter（IwCDM） model and the interacting holographic dark energy（IHDE） model. To avoid the large-scale instability problem in IDE models, we apply the parameterized post-Friedmann approach to calculate the perturbation of dark energy. We employ the Planck 2015 cosmic microwave background temperature and polarization data, combined with low-redshift measurements on baryon acoustic oscillation distance scales, type Ia supernovae, and the Hubble constant, to constrain the cosmological parameters. We find that the dark energy properties could influence the constraint limits on the total neutrino mass. Once dynamical dark energy is considered in the IDE models, the upper bounds of ∑mν will be changed. By considering the values of χmin2 , we find that in these IDE models the normal hierarchy case is slightly preferred over the inverted hierarchy case; for example, ?χ2= 2.720 is given in the IHDE+∑mν model. In addition, we also find that in the Iw CDM+∑mν model β = 0 is consistent with current observational data inside the 1σ range, and in the IHDE+∑mν model β > 0 is favored at more than 2σ level.

Searching for sterile neutrinos in dynamical dark energy cosmologies

We investigate how the dark energy properties change the cosmological limits on sterile neutrino parameters by using recent cosmological observations. We consider the simplest dynamical dark energy models, the wCDM model and the holographic dark energy（HDE） model, to make an analysis. The cosmological observations used in this work include the Planck 2015 CMB temperature and polarization data, the baryon acoustic oscillation data, the type Ia supernova data, the Hubble constant direct measurement data, and the Planck CMB lensing data. We find that, mν,sterileff〈 0.2675 eV and Neff〈 3.5718 for ΛCDM cosmology, mν,sterileff〈 0.5313 eV and Neff〈 3.5008 for wCDM cosmology, and mν,sterileff〈 0.1989 eV and Neff〈 3.6701 for HDE cosmology, from the constraints of the combination of these data. Thus, without the addition of measurements of growth of structure, only upper limits on both mν,sterileff and Neff can be derived, indicating that no evidence of the existence of a sterile neutrino species with e V-scale mass is found in this analysis. Moreover, compared to the ΛCDM model, in the wCDM model the limit on mν,sterileff becomes much looser, but in the HDE model the limit becomes much tighter. Therefore, the dark energy properties could significantly influence the constraint limits of sterile neutrino parameters.

Constraints on active and sterile neutrinos in an interacting dark energy cosmology

We investigate the impacts of dark energy on constraining massive(active/sterile)neutrinos in interacting dark energy(IDE)models by using the current observations.We employ two typical IDE models,the interacting w cold dark matter(IwCDM)model and the interacting holographic dark energy(IHDE)model,to make an analysis.To avoid large-scale instability,we use the parameterized post-Friedmann approach to calculate the cosmological perturbations in the IDE models.The cosmological observational data used in this work include the Planck cosmic microwave background(CMB)anisotropies data,the baryon acoustic oscillation data,the type Ia supernovae data,the direct measurement of the Hubble constant,the weak lensing data,the redshift-space distortion data,and the CMB lensing data.We find that the dark energy properties could influence the constraint limits of active neutrino mass and sterile neutrino parameters in the IDE models.We also find that the dark energy properties could influence the constraints on the coupling strength parameterβ,and a positive coupling constant,β>0,can be detected at the 2.5σstatistical significance for the IHDE+νs model by using the all-data combination.In addition,we also discuss the"Hubble tension"issue in these scenarios.We find that the H0 tension can be effectively relieved by considering massive sterile neutrinos,and in particular in the IHDE+νsmodel the H0 tension can be reduced to be at the 1.28σlevel.

Impacts of dark energy on constraining neutrino mass after Planck 2018

Considering the mass splittings of three active neutrinos,we investigate how the properties of dark energy affect the cosmological constraints on the total neutrino mass∑mv using the latest cosmological observations.In this paper,several typical dark energy models,including ACDM,wCDM,CPL,and HDE models,are discussed.In the analysis,we also consider the effects from the neutrino mass hierarchies,i.e.the degenerate hierarchy(DH),the normal hierarchy(NH),and the inverted hierarchy(IH).We employ the current cosmological observations to do the analysis,including the Planck 2018 temperature and polarization power spectra,the baryon acoustic oscillations(BAO),the type Ia supernovae(SNe),and the Hubble constant H0 measurement.In the ACDM+∑mv model,we obtain the upper limits of the neutrino mass∑mv<0.123 eV(DH),∑mv<0.156 eV(NH),and∑mv<0.185 eV(IH)at the 95%C.L.,using the Planck+BAO+SNe data combination.For the wCDM+∑mv model and the CPL+∑mv model,larger upper limits of∑mv are obtained compared to those of the ACDM+∑mv model.The most stringent constraint on the neutrino mass,∑mv<0.080 eV(DH),is derived in the HDE+∑mv model.In addition,we find that the inclusion of the local measurement of the Hubble constant in the data combination leads to tighter constraints on the total neutrino mass in all these dark energy models.

Impacts of gravitational-wave standard siren observations from Einstein Telescope and Cosmic Explorer on weighing neutrinos in interacting dark energy models

Multi-messenger gravitational wave(GW)observation for binary neutron star merger events could provide a rather useful tool to explore the evolution of the Universe.In particular,for the third-generation GW detectors,i.e.the Einstein Telescope(ET)and the Cosmic Explorer(CE),proposed to be built in Europe and the U.S.,respectively,lots of GW standard sirens with known redshifts could be obtained,which would exert great impacts on the cosmological parameter estimation.The total neutrino mass could be measured by cosmological observations,but such a measurement is model-dependent and currently only gives an upper limit.In this work,we wish to investigate whether the GW standard sirens observed by ET and CE could help improve the constraint on the neutrino mass,in particular in the interacting dark energy(IDE)models.We find that the GW standard siren observations from ET and CE can only slightly improve the constraint on the neutrino mass in the IDE models,compared to the current limit.The improvements in the IDE models are weaker than those in the standard cosmological model.Although the limit on neutrino mass can only be slightly updated,the constraints on other cosmological parameters can be significantly improved by using the GW observations.

Dark energy versus modified gravity: Impacts on measuring neutrino mass

In this paper,we make a comparison for the impacts of smooth dynamical dark energy,modified gravity,and interacting dark energy on the cosmological constraints on the total mass of active neutrinos.For definiteness,we consider theΛCDM model,the w CDM model,the f(R)model,and two typical interacting vacuum energy models,i.e.,the IΛCDM1 model with Q=βHρc and the IΛCDM2 model with Q=βHρΛ.In the cosmological fits,we use the Planck 2015 temperature and polarization data,in combination with other low-redshift observations including the baryon acoustic oscillations,the type Ia supernovae,the Hubble constant measurement,and the large-scale structure observations,such as the weak lensing as well as the redshift-space distortions.Besides,the Planck lensing measurement is also employed in this work.We find that,the w CDM model favors a higher upper limit on the neutrino mass compared to theΛCDM model,while the upper limit in the f(R)model is similar with that in theΛCDM model.For the interacting vacuum energy models,the IΛCDM1 model favors a higher upper limit on neutrino mass,while the IΛCDM2 model favors an identical neutrino mass with the case ofΛCDM.

Ultra Low Energy Results and Their Impact to Dark Matter and Low Energy Neutrino Physics

We present ultra low energy results taken with the novel Spherical Proportional Counter. The energy threshold has been pushed down to about 25 eV and single electrons are clearly collected and detected. To reach such a performance two low energy calibration systems have been successfully developed: a pulsed UV lamp extracting photoelectrons from the inner surface of the detector and various radioactive sources allowing low energy peaks through fluorescence processes. The bench mark result is the observation of a well resolved peak at 270 eV due to carbon fluorescence, which is a unique performance for such large massive detector. It opens up a new window in dark matter and low energy neutrino searches and it may allow the detection of neutrinos from a nuclear reactor or from supernova via neutrino-nucleus elastic scattering.

Cosmological test of dark energy parametrizations within the framework of Horava-Lifshitz gravity via baryon acoustic oscillation

We conduct an investigation to explore late-time cosmic acceleration through various dark energy parametrizations(Wettrich,Efstathiou,and Ma-Zhang)within the Horava-Lifshitz gravity framework.As an alternative to general relativity,this theory introduces anisotropic scaling at ultraviolet scales.Our primary objective is to constrain the key cosmic parameters and baryon acoustic oscillation(BAO)scale,specifically the sound horizon(rd),by utilizing 24 uncorrelated measurements of BAOs derived from recent galaxy surveys spanning a redshift range from z=0.106 to z=2.33.Additionally,we integrate the most recent Hubble constant measurement by Riess in 2022(denoted as R22)as an extra prior.For the parametrizations of Wettrich,Efstathiou,and Ma-Zhang,our analysis of BAO data yields sound horizon results of r_(d)=148.1560±2.7688 Mpc,r_(d)=148.6168±10.2469 Mpc,and r_(d)=147.9737±10.6096 Mpc,respectively.Incorporating the R22 prior into the BAO dataset results in r_(d)=139.5806±3.8522 Mpc,r_(d)=139.728025±2.7858 Mpc,and r_(d)=139.6001±2.7441 Mpc.These outcomes highlight a distinct inconsistency between early and late observational measurements,analogous to the H_(0) tension.A notable observation is that,when we do not include the R22 prior,the outcomes for rd tend to be in agreement with Planck and SDSS results.Following this,we conducted a cosmography test and comparative study of each parametrization within the Lambda Cold Dark Matter paradigm.Our diagnostic analyses demonstrate that all models fit seamlessly within the phantom region.All dark energy parametrizations predict an equation of state parameter close ω=-1,indicating a behavior similar to that of a cosmological constant.The statistical analysis indicates that neither of the two models can be ruled out based on the latest observational measurements.

Remarkable Predictions of Classical Electrodynamics on Elementary Charge and the Energy Density of Vacuum

In a recent paper, we have studied the nature of the electromagnetic energy radiated over a single period of oscillation by an antenna working in frequency domain under ideal conditions and without losses when the oscillating charge in the antenna is reduced to the elementary charge. Here we extend and expand that study. The energy radiated by an oscillating current in an antenna occurs in bursts of duration T/2, where T is the period of oscillation. The results obtained here, based purely on classical electrodynamics, can be summarized by the inequality U ≥hv→q0 ≥e where U is the energy radiated in a single burst of duration T/2, h is the Planck constant, ν is the frequency of oscillation and q0 is the magnitude of the oscillating charge associated with the current. The condition U=hv→q0=e is obtained when the length of the antenna is equal to the ultimate Hubble radius of the universe (i.e. the maximum value of the antenna length allowed by nature) and the wavelength is equal to the Bohr radius (resulting from the smallest possible radius of the conductor allowed by nature). The ultimate Hubble radius is directly related to the vacuum energy density. The inequality obtained here is in general agreement with the one obtained in the previous study. One novel feature of this extended analysis is the discovery of an expression, in terms of the elementary charge and other atomic constants, for the vacuum energy density of the universe. This expression predicts the vacuum energy density to be about 4×10-10?J/m3 which is in reasonable agreement with the measured value of 6×10-10 J/m3.

Study of Baryon Acoustic Oscillations with SDSS DR13 Data and Measurements of &Omega;_kand &Omega;_DE(a)

We measure the baryon acoustic oscillation (BAO) observables , , and as a function of red shift z in the range 0.1 to 0.7 with Sloan Digital Sky Survey (SDSS) data release DR13. These observables are independent and satisfy a consistency relation that provides discrimination against miss-fits due to background fluctuations. From these measurements and the correlation angle of fluctuations of the Cosmic Microwave Background (CMB), we obtain , and for dark energy density allowed to vary as . We present measurements of at six values of the expansion parameter a. Fits with several scenarios and data sets are presented. The data is consistent with space curvature parameter? and constant.