Superluminal and Negative Group Velocity in the Electromagnetic Wave Propagation

In this paper, a penetrating analysis is first made of the superluminal and negative group velocities that occur in the EM wave propagation. Discussed then are the superluminal and negative group velocities which are in the state of evanescent waves in the waveguide below cutoff(WBCO).Through an experiment in the coaxial photonic crystal a group velocity of 1.5-2.4 times the speed of light are observed in the stop band.

Subluminal and Superluminal Phenomena in a Four-Level Atom

In a four-level atomic system, we investigate the light pulse propagation properties interacting with only one laser field. It is shown that in the steady state, the group velocity of the light pulse can be changed from subluminal to superluminal by varying the field detuning. Meanwhile, the effects of the field intensity on the group velocity are also shown. At last, with special parameters, the analytical solution for the group index is also obtained.

Conscious Entities in Superluminal Parallel Universe

Tachyons are theoretical superluminal particles, i.e., faster than light particles. The idea of existence of tachyons comes from Arnold Sommerfeld. Bilaniuk and Sudarshan （1969） published the article ＂Particles beyond the Light Barrier＂ in Physics Today magazine where they analyze the theoretical properties of tachyons. From the tachyon idea I have hypothesized the existence of a Superluminal Parallel Universe constituted by Superluminal Conscious Entities that, like the theoretical tachyons, only can exist at speeds greater than the speed of light. This hypothesis should be subject to scientific inquiry but also to philosophical speculation or spiritual imagination. Later I imagine that the Superluminal Parallel Universe is the Spiritual World thought by theologians and idealistic philosophers. I relate the Superluminal Conscious Entities with Spirits and the Superluminal Parallel Universe comprising infinity of Superluminal Conscious Entities with God, the Universal Spirit, thus being simultaneously Unity and Infinity given that superluminal speed implies non-local, instantaneous connections. I imagine that the material Universe might have emerged from that God, assuming that many Spirits could lose superluminality generating the two classes of substances of the Universe： the class of subluminal particles of matter and the class of luminal particles, like photons. I imagine a Soul as a quasi superluminal entity dropped from a Spirit to animate material entities. The substances of both Universes would have evolved in parallel, with life arising and evolving from the subluminal substance driven by companion Souls. Let＇s also imagine that the natural way of being of Spirits and free Souls is a state similar to conscious dreaming. In this imagination, we all, Souls, would have been a part of God and we all might be again. We all are makers of the Universe. We all might get connected with the Spirits in God to beg for and to receive inspiration.

Superluminal light attenuated by strong dispersion of complex refractive index

The propagation of narrow packets of electromagnetic waves（EMWs） in frequency dispersive medium with the consideration of the complex refractive index is studied. It is shown that counting in the dispersion of the complex refractive index within the context of the conventional expression of the group velocity of narrow wave packets of EMWs propagating in a dispersive medium results in the appearance of additional constraints on the group velocity, which dictates that the physically acceptable group velocity can only be realized in the case of a negligible imaginary part of the group index. In this paper, the conditions that allow one to realize the physically acceptable group velocity are formulated and analyzed numerically for the relevant model of the refractive index of a system of two-level atoms in the optical frequency range. It is shown that in the frequency band where superluminal light propagation is expected, there is a strong dispersion of the refractive index that is accompanied with strong absorption, resulting in a strongly attenuated superluminal light.

Subluminal to superluminal light propagation in a V-type three-level atomic system interacting with squeezed vacuum

We study the light propagation properties in a V-type three-level atomic system interacting with two independent broadband squeezed baths. Using the graphic method, the dependences of the absorption and the dispersion of the system on the coupling field strength, the incoherent pumping field strength and the intensity of the squeezed vacuum are analysed. The result shows that the probe pulse propagation can be changed from subluminal to superluminal speed.

Study on the Superluminal Group Velocity in a Coaxial Photonic Crystal

In this paper, the superluminal group velocity in a coaxial photonic crystal is studied. The simulation of the effective refraction index in coaxial photonic crystal is performed. The group velocity is calculated based on the transmission line equations and compared with experimental results.

Role of incoherent pumping and Er^(3+) ion concentration on subluminal and superluminal light propagation in Er^(3+)-doped YAG crystal

We study the absorption-dispersion process and group index of weak probe field in a four-level Er^3＋：YAG crystal.We find that the Er^3＋ion concentration and incoherent pumping field can influence the absorption-dispersion process and group index of weak probe field. Moreover, our results show that Er^3＋ion concentration plays a major role in lasing without inversion and absorption with inversion.

Relativity and impossibility of superluminal motion

I prove that not only particle motion but also wave propagation cannot be faster than light according to relativity.

Superluminal Motion and Polarization in Blazars

A relativistic beaming model has been successfully used to explain the observed properties of active galactic nuclei (AGNs). In this model there are two emission components, a boosted one and an unbeamed one, shown up in the radio band as the core and lobe components. The luminosity ratio of the core to the lobe is defined as the core-dominance parameter (R = (LCore/LLobe)). The de-beamed radio luminosity (Ljetdb) in the jet is assumed to be proportional to the unbeamed luminosity (Lub) in the co-moving frame, i.e., f = (Ljetdb/Lub), and f is determined in our previous paper. We further discuss the relationship between BL Lacertae objects (BLs) and flat spectrum radio quasars (FSRQs), which are subclasses of blazars with different degrees of polarization, using the calculated values of the ratio f for a sample of superluminal blazars. We found 1) that the BLs show smaller averaged Doppler factors and Lorentz factors, larger viewing angles and higher core-dominance parameters than do the FSRQs, and 2) that in the polarization-core dominance parameter plot (P-log R) the BLs and FSRQs occupy a scattered region, but in a revised plot (log (P/c(m)) ? log R), they gather around two different lines, suggesting that they have some different intrinsic properties.

On Universal Mechanics and Superluminal Velocities

In this work we continue to set up the theory of universal space and time and derive the Euclidean form of the scaling transformations. Two types of velocities emerge, inertial and universal, with the former bound by the light velocity c whereas the latter is unbound, and may accommodate consistently particles’ velocities possibly exceeding c. The inertial velocity is the ratio of the simultaneous source’s displacement and the corresponding length of the light trip to the observer, whereas the universal velocity has its familiar meaning for motion in a synchronous inertial frame. Defining the momentum as the product of universal velocity and mass, and utilizing the already established mass-energy equivalence, the mechanics constructed on the bases of the new concepts, named universal mechanics, admits superluminal velocities but yet coincides with the relativistic mechanics in its basic dynamical components and their inter-relations. The possibility of superluminal velocities provides a straight forward explanation of the presence of the μ-meson particles abundantly at the sea level despite their generation at high altitude and their short lifetime.

SGC Switching Between Subluminal to Superluminal Propagation in V-Type Atom

For a V-type three-level atomic system with two closely spaced upper levels, we investigate the light pulse propagation properties with only one laser field. Due to spontaneously generated coherence, the group velocity of the light pulse can be changed from subluminal to superluminal. The effects of the field intensity and the two-upper level splitting on the group velocity are also shown. At last, an analytical expression for the group velocity is given in the case of a weak field.

Neutrinos as Superluminal Particles

Based on parity violation in the weak interaction and evidences from neutrino oscillation, a natural choice is that neutrinos may be superluminal particles with tiny mass. To keep causality for Superluminal particles, a kinematic time under a non-standard form of the Lorentz transformation is introduced. A Dirac-type equation for Superluminal neutrinos is further investigated, and its solution is brief discussed. This equation can be written in two spinor equations coupled together via tiny mass while respecting maximum parity violation. As a consequence, parity violation implies that the principle of relativity is violated in the weak interaction.

Superluminal Propagation in Er^(3+)-doped Fiber Bragg Grating

The method to pump the FBGT written into an Er^3＋-doped optical fiber is proposed to increase the group velocity of a probing pulse based on the facts that pump-induced process changes the refractive index and dispersion associated with the ^4I15/2-^4I12/2 transition in Er^3＋-doped optical fiber.The system equations are derived.The effects of pump power and doping concentration on the group velocity are discussed.

Superluminality and Entanglement in an Electromagnetic Quantum-Relativistic Theory

An electromagnetic theory that links quantum and relativistic phenomena in a single context is built. Wave-particle duality is the experimental proof of their common origin. In this context, Quantum Mechanics and Special Relativity are two compatible synergistic theories. The developed theory shows the existence of superluminal effects that suggest an explanation to the entanglement between pairs of particles and photons.

Measurement Method of Graviton Velocity and Thought on Correcting Lorentz Transformation——The Superluminal Neutrino’s Influence on Special Relativity and Other Physical Theories

After discovery of the superluminal particle and consideration on development of contemporary physical theory research, also on the existing errors and omissions, the principle of constant light speed is found not a necessary condition in derivation of Lorentz Transformation;instead, this thesis proposes the velocity of graviton may feature superluminal, constant velocity in different directions, and independence of inertial reference frame speeds. This is an optional thought of correction. According serial hypothesis, an equation of graviton’s motion trace, i.e., the central curve of nebula density, is established for spiral galaxy. Thus we gain the method to measure velocity of graviton. If to totally avoid problem of limit speed, we have to search for independent of inertia frames, and relevant to space-time properties. Regarding current difficulties of singular points in the Theory of Limited Universe, this thesis points out that the document [1] is the best solution to these difficulties.

Developments of Space-Time, Complete Special Relativity, and Superluminal Entangled Communication

Time and space are two very important basic concepts in philosophy and nature.In special relativity we proved that there are necessarily two symmetrical topological structures separated by the light-cone,which includes the generalized Lorentz transformation(GLT)for the spacelike interval,in which phase velocity is superluminal.Based on quantum entanglement as new fifth interaction,we research a simple superluminal entangled communication,whose key is to establish two mutually entangled particles or devices Alice(A)and Bob(B).We observe and control the information of A position,and then can know the corresponding results of the other B.This is not to send directly information each other.It may be superluminal,and should agree and test GLT.Moreover,we research some new possible developments of time and space,such as the fractal dimension extended to the complex dimension,the higher dimensional time,and the arrow of time.A generalized Noether’s theorem is proposed.In quantum theory,we search the higher dimensional complex space in supersymmetry,and the space-time operators.

Neutrino Oscillations and Superluminal Propagation,in OPERA or Otherwise

We digress on the implications of recent claims of superluminal neutrino propagation. No matter how we turn it around such behaviour is very odd and sits uncomfortably even within “far-fetched” theories. In the context of non-linear realizations of the Lorentz group (where superluminal misbehaviour is run of the mill) one has to accept rather contrived constructions to predict superluminal properties for the neutrino. The simplest explanation is to require that at least one of the mass states be tachyonic. We show that due to neutrino mixing, the flavor energy does not suffer from the usual runaway pathologies of tachyons. For non-tachyonic mass states the theories become more speculative. A neutrino specific dispersion relation is exhibited, rendering the amplitude of the effect reasonable for a standard Planck energy. This uses the fact that the beam energy is close to the geometrical average of the neutrino and Planck mass;or, seen in another way, the beam energy is unexceptional but its gamma factor is very large. A dispersion relation crossing over from a low energy bradyonic branch to a high energy tachyonic one is also considered. We comment on consistency with SN 1987Awithin these models.

No-relationship Between Impossibility of Faster-Than-Light Quantum Communication and Distinction of Ensembles with the Same Density Matrix

It has been claimed in the literature that impossibility of faster-than-light quantum communication has an origin of indistinguishability of ensembles with the same density matrix. We show that the two concepts are not related.We argue that even with an ideal single-atom-precision measurement, it is generally impossible to produce two ensembles with exactly the same density matrix; or to produce ensembles with the same density matrix, classical communication is necessary. Hence the impossibility of faster-than-light communication does not imply the indistinguishability of ensembles with the same density matrix.

Propagation of Superluminous L-O Mode Waves During Geomagnetic Activities

The effect of the azimuthal angle φ of the wave vector k on the propagation characteristics of the superluminous L-O mode waves （together with a case of the R-X mode） during different geomagnetic activities using a three-dimensional （3D） ray-tracing method is investigated. This work is primarily an extension of our previous two-dimensional study in which the wave azimuthal angle was not considered. We present numerical simulations for this mode which is generated in the source cavity along a 70° night geomagnetic field line at the specific altitude of 1.5RE （where RE is the Earth＇s radius）. It is found that, as in the two-dimensional case, the trajectory of L-O mode starting in the source meridian plane （or the wave azimuthal angle φ = 180°） can reach the lowest latitude; whereas it basically stays at relatively higher latitudes starting off the source meridian plane （or φ=180°）. The results reveal that under appropriate conditions, the superluminous L-O mode waves may exist in the radiation belts of the Earth, but this remains to be supplemented by observational data.

Forty Years Research of Faster-Than-Light——Review and Prospects

Since the early work of O.M.Bilanuik and B.C.Sudarshan in 1962 and G.Feinberg in 1967, the research work on the faster-than-light (superluminal) has been performed in the world, such as in USA, Europe and China. In this paper, the development stages of the study are presented, which include beginning stage, transitional stage and experimental stage. Based on the Einstein’s paper in 1905, the velocities greater than that of light had no possibility of existence. However, in the Einstein’s papers of 1907 it was founded that the superluminal signal speed could not be refuted absolutely. In this paper, the studies on velocities are classified. The definition of General Information Speed is suggested, which will ease the discussion. After reviewing the researches of 1962-2004, it can be concluded that the faster-than-light is a realizable scientific statement.