Matching Boundary Conditions for Scalar Waves in Body-Centered-Cubic Lattices

Matching boundary conditions(MBC’s)are proposed to treat scalar waves in the body-centered-cubic lattices.By matching the dispersion relation,we construct MBC’s for normal incidence and incidence with an angle a.Multiplication of MBC operators then leads to multi-directional absorbing boundary conditions.The effectiveness are illustrated by the reflection coefficient analysis and wave packet tests.In particular,the designed M1M1 treats the scalar waves in a satisfactory manner.

Absorption of a massless scalar wave from a Schwarzschild black hole surrounded by quintessence

By using the partial wave method, we investigate the absorption of a massless scalar wave from a Schwarzschild black hole surrounded by quintessence. We obtained the expression of absorption cross sectionσabs（ω）=π/ω^2 ∑ t=0^∞ （2l＋1）｜Tωl（ω）｜^2=π/ω^2∑ t=0^∞（2l＋1）Гωl（ω）.Then we numerically carry out the absorption cross section and we find that the larger the angular momentum quantum number 1 is, the smaller the corresponding maximum value of the partial absorption cross section is, and that the total absorption cross section tends to the geometric-optical limit σhfabs≈ bc^2. We also find that higher value of ωq （state abs parameter of quintessence） corresponds to the higher value of absorption cross section gabs.

On Scalar Planck Waves

The sound of space-time at the large scale is observed in the form of gravitational waves, which are disturbances in space-time produced by wavelike distortions (or kinks) in the gravitational field of an accelerating parcel or distribution of energy. In this study, we investigate a hypothetical wave mode of quantum space-time, which suggests the existence of scalar Planck waves. According to this hypothesis, the sound of quantum space-time corresponds to kinks propagating in the gravitational displacement field of an oscillating energy density. In evaluating the emission of scalar Planck waves and their effect on the geometry of space-time, one finds that they not only transport a vanishingly small amount of energy but can also be used to simulate gravity.

Scattering of Scalar Wave by Extended Black Hole in f(R) Gravity

We analyze the Sehrodinger-type scalar wave equation of an extended black hole in f（R） gravity, and numerically investigate its absorption/scattering cross sections using the partial wave method. It is found that the dimension of length a makes the peak value of the effective scattering potential fall down, and the absorption cross section oscillates around the geometric optical value in the high frequency regime. We can also see that the scattering flux becomes stronger and its angle width becomes narrower in the forward direction, the glory peak becomes lower and the glory width becomes narrower along the backward direction when the coupling parameter α increases.

On the gauge dependence of scalar induced secondary gravitational waves during radiation and matter domination eras

We revisit the vital issue of gauge dependence in the scalar-induced secondary gravitational waves(SIGWs), focusing on the radiation domination(RD) and matter domination(MD) eras. The energy density spectrum is the main physical observable in such induced gravitational waves. For various gauge choices, there has been a divergence in the energy density, ?GW, of SIGWs.We calculate SIGWs in diferent gauges to quantify this divergence to address the gauge-dependent problem. In our previous studies, we had found that the energy density diverges in the polynomial power of conformal time(e.g., η^(6) in uniform density gauge). We try to fix this discrepancy by adding a counter-term that removes the fictitious terms in secondary tensor perturbations. We graphically compare the calculations in various gauges and also comment on the physical origin of the observed gauge dependence.

Primordial black holes and third order scalar induced gravitational waves

The process of primordial black hole(PBH)formation is inevitably accompanied by scalar induced gravitational waves(SIGWs).The strong correlation between PBH and SIGW signals may offer a promising approach to detecting PBHs in upcoming gravitational wave experiments,such as the Laser Interferometer Space Antenna(LISA).We investigate third order SIGWs during a radiation-dominated era in the case of the monochromatic primordial power spectrum Pζ=Aζkσ(k-k*).For LISA observations,the relationships between the signal-to-noise ratio(SNR)and monochromatic primordial power spectrum are studied systematically,revealing that the effects of third order SIGWs extend the cutoff frequency from 2f+to 3f and lead to an approximately 200%increase in the SNR for the frequency band from 10^(-5)Hz to 1.6×10^(-3)Hz,corresponding to PBHs with masses in the range 4×10^(-12)M⊙~10^(-7)M⊙.We find that there is a critical value,A×=1.76×10^(-2),for the amplitude of the monochromatic primordial power spectra,such that when Aζ>A*,the energy density of third order SIGWs is larger than that of second order SIGWs.

Theoretical Analysis and Calculation for Rotatory Optic Fiber

Using electromagnetic field theory of dielectric in a cylindrical coordinates system,the theoretical analysis and calculation for a rotatory optic fiber are presented in this paper.

Absorption cross section of black holes with global monopole

We study the absorption problem for a massless scalar field propagating in general static spherically-symmetric black holes with a global monopole. The absorption cross section expression is provided using a partial-wave method, which permits us to make an elegant and powerful resummation of the absorption cross section, and to extract the physical information encoded in the sum over the partial-wave contributions.

Deductions from the Quaternion Form of Maxwell’s Electromagnetic Equations

It is often claimed that Maxwell’s electromagnetic equations were originally written in terms of quaternions. Once returned to that form and treated with left and right hand operators as in the mathematics of P. M. Jack, a new seventh scalar electromagnetic field component emerges with possible relations to clean energy extraction and gravitation. It is the purpose here to examine this approach afresh and see how it might link up with other fairly recent, but little known, work in the field. Again, as with the usual form of Maxwell’s equations, a new scalar wave equation is derived but, on this occasion, due to the presence of the scalar component of the quaternion, that equation exhibits a wave speed greater than the speed of light. Historical and present uses within military and humanitarian contexts are considered briefly.