We present several quantum mechanical experiments involving photons that strain the notions of space, time and causality. One for these experiments gives rise to the "quantum liar paradox," where Nature seems to contradict herself within a single experiment. In the last section we propose an outline for a theory that aspires to integrate GR and QM. In this outline, i) "Becoming," the creation of every instant anew from nothingness, is real. ii) Force-carrying particles, such as photons, do not merely mediate the interaction by propagating in some pre-existing, empty spacetime; rather, they are the very progenitors of the spacetime segment within which the interaction takes place.

This paper considers the amount of information in a photon. It is argued that a photon in a pure state also carries information, which is contrary to established opinion based on von Neumann entropy.

Our starting platform is the staggering and pervasive successes of the Huygens-Fresnel principle (HFP) from macro to nano photonics fields, which model the propagation as if each point on the wave front serves as a secondary point source. Summation of the complex amplitudes of these secondary wave fronts with proper inclination factor gives us remarkably accurate results for every possible realistic situation. Therefore, we take the concept of secondary point source of "energy" as a reality in all of cosmic space, irrespective of whether the space is "empty" or filled with "materials" as we understand them. It amounts to accepting the existence of an all pervading cosmic tension field (CTF). We justify our platform by comparing and contrasting with the various "material" based propagating waves that we can generate and experience, which always require the existence of uniform tension field energy at every point. Then we show that two of the key motivations behind Dirac's quantization of the EM field can easily be accommodated by semi-classical model a la Jaynes (quantized atoms and classical EM wave packet). They are: (i) Photo electric effects that require photon to be indivisible packets of energy; and (ii) QM transition rule requiring the emission of a unique frequency ν would violate "monochromaticity" rule implied by Fourier's time-frequency theorem and "coherence theory" if photons were to be time-finite classical wave packets.

Comparing the radio and the light wave detection processes, this paper clarifies that what we normally call "interference" of EM waves, is actually the summation of the field induced signals carried out by the detectors. We have also presented a generalized definition of the superposition effects as measured (SEM) due to multiple physical steps behind any detection process. Thus the manipulation of the various physical properties of the detectors to various parameters of the EM waves can yield different "interference" effects for the same set of superposed waves. If EM waves interfered by themselves, such manipulation would not have been possible. We also give simple examples of visibility degradations due to rotation of the states of polarization and underscore that such degradation should not be assigned to degradation of coherence properties of the EM waves. It is due to the change in the stimulating amplitude, reduced by Malus'cosθ law, which is accessible to the uniaxial dipole like response of the detecting molecules.

The postulated 2^nd quantization creation-annihilation operators a^t and a in the radiation-photon Hamiltonian comprise some of the many unexplained assumptions of mainstream Standard Model physics. But we show here that these operators do not have to be 'postulated'. The uncertainty principle must apply to both the sine wave photon source and its receiver allowing different source frequencies ω and ω'even for a plane wave. Thus the prosthaphaeresis formula cosω't + cosωt = 2cos(½(ω'+ω)t)cos(½(ω-ω')t) then gives this beat frequency as Δω= ½(ω-ω'). These beat frequency envelopes, or lobes, are then the 'photons' which provides the motivation for the use of a^t and a. Thus the 'photon' does not have to be postulated and we have explained its origin.

Based on the quantum field theory and classical electromagnetic field theory, the behaviors of the electromagnetic field in the boundary of the classical environment and the quantum environment were studied, and three dead-points and five paradoxes, like Lorentz-Compton paradox, non-conservation of the energy of the electromagnetic field before and after quantization due to a number of zero-point energy, the non-self-consistence of the wave-particle duality, etc, were discovered. Through analyzing these dead-points and paradoxes, we found that these paradoxes are related to each other, and all wrapped together. The core problem is the non-self-consistence in the theoretical system and the ambiguity in the mechanism of the wave-particle duality. Based on resolving the classical electromagnetic field into the electromagnetic element-waves according to the photons, a third kind of wave-particle duality, the particle-like characteristics of the classical electromagnetic field in structure, was put forward, and the structure of &pgr;-shape of three kinds of wave-particle duality was revealed. So, in wave-particle duality, the wave and the particle are staggered in existing time, or in existing form, either in imagination or in reality, and the third kind of wave-particle duality will be combined into a unit with the first kind of wave-particle duality, Einstein's wave-particle duality of light, and the second kind of wave-particle duality, de Broglie's wave-particle duality of matter particle. Hence, a self-consistent picture of wave-particle duality of light was set up, and three dead-points and five paradoxes of the electromagnetic field in the boundary of the classical environment and the quantum environment were dispelled. In the last, a crucial experiment was designed for testing this picture.

We have recently constructed a photon position operator with commuting components. This was long thought to be impossible, but our position eigenvectors have a vortex structure like twisted light. Thus they are not spherically symmetric and the position operator does not transform as a vector, so that previous non-existence arguments do not apply. We find two classes of position eigenvectors and obtain photon wave functions by projection onto the bases of position eigenkets that they define, following the usual rules of quantum mechanics. The hermitian position operator, r⁁⁽⁰⁾, leads to a Landau-Peierls wave function, while field-like eigenvectors of the nonhermitian position operator and its adjoint lead to a biorthonormal basis. These two bases are equivalent in the sense that they are related by a similarity transformation. The eigenvectors of the nonhermitian operators r⁁^(±½) lead to a field-potential wave function pair. These field-like positive frequency wave functions satisfy Maxwell's equations, and thus justify the supposition that MEs describe single photon wave mechanics. The expectation value of the number operator is photon density with undetected photons integrated over, consistent with Feynman's conclusion that the density of non-interacting particles can be interpreted as probability density.

We show that (in contrast to rather common opinion) QM might be not a complete theory. We present a prequantum model with the infinite dimensional phase space such that QM can be considered as an algorithm for approximation of averages with respect to prequantum fluctuations. Such an approximation is based on the asymptotic expansion of classical statistical averages with respect to a small parameter &kgr;. Therefore statistical predictions of QM are only approximative and a better precision of measurements would induce deviations of experimental averages from quantum mechanical ones. In this paper we present a natural physical interpretation of &kgr; as the time scaling parameter (between quantum and prequantum times). We analyse consequences of various choices of the prequantum time scale. Possible connections with attophysics and Grand Unification model are discussed.

We show in this paper that the quantized energies of light in vacuum can be derived directly from the classical electromagnetic theory through the consideration of statistics based on classical physics, which are just a series of expectation values corresponding to relatively stable statistic distributions of electromagnetic harmonic oscillators. Therefore, the quantization of energy is an intrinsic property of light as a classical electromagnetic wave and has no need of being related to particles. The theory developed in this paper is also used to derive the energy equipartition theorem and the discrete levels of hydrogen atom from classical mechanics.

Throughout the development and confirmation of the photon concept, "Gedankenexperiments" have been invoked where a light source is attenuated until "only one photon is in the apparatus." Such a statement requires, however, knowledge on details of the light generation process, which were not known until the advent of true single-photon light sources such as isolated single atoms or molecules. Here, starting from a two atom light source, it is shown that probably multi-atom or multi-molecule light sources do not generate, even not in small fractions, antibunching photons and that attenuation down to one photon per time unit is not reliably possible. Thus, one of the strongest arguments in favour of the existence of single "photons" in free space, the accumulation time argument, which discusses the absorption of a single photon by a single atom or molecule, becomes questionable.

Experiments done with single photons in the early 1990's produced a surprising result: that single photons pass through a photonic tunnel barrier with a group velocity faster than the vacuum speed of light. This result has stimulated intense discussions related to causality, the speed of information transfer, the nature of barrier tunneling and the meaning of group velocity. The superluminality of tunneling photons is now textbook material, although the authors note that controversy still remains. Another paradoxical result, known as the Hartman effect, is that the tunneling time of the photons becomes independent of barrier length in the limit of opaque barriers. In this paper we examine the meaning of group velocity in the context of barrier tunneling. We ask whether a single tunneling photon can be described by a group velocity and whether the short group delays imply superluminal group velocity. We resolve the paradox of the Hartman effect and show that the predicted and measured group delays are not transit times but photon lifetimes.

In the 1970s, Jones demonstrated a photon drag by showing that the translation of a window caused a slight displacement of a transmitted light beam. Similarly he showed that a spinning medium slightly rotated the polarization state. Rather than translating the medium, the speed of which is limited by mechanical considerations, we translate the image and measure its lateral delay with respect to a similar image that has not passed through the window. The equivalence, or lack of it, of the two frames is subtle and great care needs to be taken in determining whether or not similar results are to be obtained.

We present an experimental realization of a "sudden mirror replacement" thought experiment, in which a mirror that is inhibiting spontaneous emission is quickly replaced by a photodetector. The question is, can photons be counted immediately, or only after a retardation time that allows the emitter to couple to the changed modes of the cavity, and for light to propagate to the detector? Our results, obtained with a parametric downconverter, are consistent with the cavity QED prediction that photons can be counted immediately, and are in conflict with the retardation time prediction.

In the emerging field of quantum information technology the two basic subfields are quantum communication and quantum computation. Photonic qubits are considered as most promising information carriers for this new technology due to the immense advantage of suffering negligible decoherence. Additionally, the very small photon-photon interactions can be replaced by inducing effective nonlinearities via measurements which allow for the implementation of crucial two-qubit gate operations. Although the spontaneous parametric down-conversion gives access to the generation of highly entangled few-photon states, such as four-qubit cluster states which allow to demonstrate the new concept of the one-way quantum computer, its applicability is highly limited due to the poor scaling of the simultaneous emission of more than one-entangled photon pair. Therefore of particular interest is the reversible mapping of qubits from photon states to atomic states. This might allow the implementation of photonic quantum repeaters for long-distance quantum communication or the generation of arbitrary multi-photon states as required for linear-optics quantum computing. Thus for the realization of such a quantum network several approaches for achieving the required quantum control between matter and photons have been studied during the past few years. Recent experiments demonstrating the generation of narrow-bandwidth single photons using a room-temperature ensemble of ⁸⁷Rb atoms and electromagnetically induced transparency should emphasize the progress towards such a quantum network.

Finding a model or paradigm to capture the essence of light, is an enterprise of historic legend. The two main contenders, particle beams and waves have alternated in acceptance, with each ultimately proving unsatisfactory. Currently, the particle variant is predominant, but with strong caveats encompassed in Bohr's Principle of Complementarity. Herein a study of correlated pairs of photons is presented. It reveals additional challenges for the particle paradigm. Finally, it is suggested that as neither of these two paradigms is optimal, the direct-interaction paradigm as originally introduced by Schwarzschild deserves further consideration.

We have previously shown that the use of the fair sampling assumption in EPR experiments could be questioned on the basis of experimental data. We continue our analysis of the data from the optical EPR experimental performed by Weihs et al. in Innsbruck 1997-1998, and we discuss whether a non-rotationally invariant source can account for the experimental results.

Theoretical estimates and correlations, based upon the Electro-Gravi-Magnetics (EGM) Photon radiation method, are presented for the Root-Mean-Square (RMS) charge radius and massenergy of many well established subatomic particles. The EGM method is a set of engineering equations and techniques derived from the purely mathematical construct known as Buckingham's "&Pgr;" (Pi) Theory. The estimates and correlations coincide to astonishing precision with experimental data presented by the Particle Data Group (PDG), CDF, D0, L3, SELEX and ZEUS Collaborations. Our tabulated results clearly demonstrate a possible natural harmonic pattern representing all fundamental subatomic particles. In addition, our method predicts the possible existence of several other subatomic particles not contained within the Standard Model (SM). The accuracy and simplicity of our computational estimates demonstrate that EGM is a useful tool to gain insight into the domain of subatomic particles.

The paper reports the positive results obtained with a stationary Michelson-Morley interferometer operating during two consecutive years (2003-2005) in Bogota, Colombia. After subtracting the environmental periodical effects, there is still a periodic residual that is no longer correlated to the environmental variables. There is, however, a significant correlation between the daily fringe-shift residuals for each month and the velocity of motion of the earth relative to the center of our galaxy at that particular time. This hints to a possible dependence of the velocity of light in our terrestrial laboratory and the velocity of the earth. This result is contrary to the current model for the photon that postulates a constant speed of light. From our data we have calculated the solar velocity consistent with our observations: 500 km/s, right ascension 16h-40 min, declination -75°.

It is known from measurements of beat frequencies of beam pairs extracted from single mode dual polarized ring lasers that the optical cavity can support four different phase velocities depending on left or right polarization and on clockwise or anticlockwise direction of travel. The topological theory of singular solutions to Maxwell's equations has demonstrated that these four modes are due to different Spinor pairs. Moreover, the theory demonstrates that the Lorentz Vacuum and the Chiral Vacuum can be formally indistinguishable, except for the impedance of free space (which can related to the determinant of a dynamic constitutive tensor and therefore to the chiral polarization and expansion coefficients involving Optical Activity and Faraday rotation). It is suggested that modifications of the dual polarized Sagnac ring laser with its resonance Q of 10⁺¹⁸ might permit the experimental detection of any chiral properties of space-time induced by intransitive motions (those with fixed points of rotation and expansion) that are not induced by transitive motions (translations).

Under the paraxial approximation for the propagation of vectorial coherence function, we made a theoretical investigation into the mechanism of the orbital angular coherence momentum associated with a coherence vortex. By controlling the irradiance distribution of an extended quasi-monochromatic spatially incoherent source with a spatial light modulator, we examined the phase structure of coherence function and investigated the birth and evolution of the orbital angular coherence momentum. Some properties related to the fractional coherence vortex, such as a wave particle-like duality of coherence function, are also investigated both theoretically and experimentally for the first time.

The linear mathematics of Fourier composition and decomposition of monochromatic electromagnetic fields is supposed to have a direct realization in the physical world in the sense that we assume complete equivalence of reality as well as of physical effects when an arbitrary electromagnetic field is substituted physically with its Fourier components, and vice versa, in the same spatial region. In the simplest cases, two superposed light fields at frequencies &ohgr;₁ and &ohgr;₂ are supposed to be identical in their physical effects to a single field at the average frequency, amplitude modulated at half the difference frequency, in spite of the significant differences in the experimental arrangements needed to produce the two cases. This equivalence has been questioned and recently Lee and Roychoudhury¹ cited experimental results on atomic resonance and Fabry-Perot filters to assert that there is no such equivalence. Considering the importance of such assertions for the foundations of physics in general, we have conducted a detailed analysis of the issue, and have conducted tests in which amplitude modulated field at resonant frequency, corresponding mathematically to a superposition of two monochromatic fields detuned equally away from the resonance, is applied to Rb atomic vapor, and also passed through a Fabry-Perot cavity. We conclude from the results of these experiments that there is complete physical equivalence, corresponding to the mathematical equivalence. We clarify several conceptual issues that have been raised about the superposition of light in this context.

In an analysis of the Afshar experiment R.E. Kastner points out that the selection system used in this experiment randomly separates the photons that go to the detectors, and therefore no which-way information is obtained. In this paper we present a modified but equivalent version of the Afshar experiment that does not contain a selection device. The double-slit is replaced by two separate coherent laser beams that overlap under a small angle. At the intersection of the beams an interference pattern can be inferred in a non-perturbative manner, which confirms the existence of a superposition state. In the far field the beams separate without the use of a lens system. Momentum conservation warranties that which-way information is preserved. We also propose an alternative sequence of Stern-Gerlach devices that represents a close analogue to the Afshar experimental set up.

The question "What is a photon?" motivates an analysis of the interface between quantum field theory and non-relativistic quantum mechanics (QM). Despite the predictive success of quantum field theory, it retains many non-relativistic concepts while throwing out the one aspect of QM that might give a spatially-well-defined answer to the original question. A novel approach to quantizing relativistic wavefunctions is then discussed, leading to an identification of the electromagnetic vector potential as a possible single-photon wavefunction. The key missing ingredient is a relativistically-correct measurement theory, in which a photon can be partially constrained/measured everywhere along a closed 3-D hypersurface in 4-D space-time.

As optical scientists and engineers we have an educational paradigm that stresses passing knowledge from teacher to student. We are also taught to use inductive reasoning to solve problems. Yet many of the fundamental questions in optics such as the topic of this conference "What are photons?" require that we use retroductive reasoning to deduce the possible and probable cause of the observations and measurements we make. We can agree that we don't have all the answers for many fundamental questions in optics. The retroductive reasoning process requires a different way of thinking from our traditional classroom setting. Most of us learned to do this through working in a research lab or industry. With the amount of information and new discoveries to consider, it makes it difficult to cover everything in the classroom. This paper looks at transformational learning techniques and how they have been applied in science and engineering. These techniques show promise to prepare our students to learn how to learn and develop skills they can directly apply to research and industry.

The origin and elaboration of our fundamental theories like quantum theory, the theory of relativity and the quantum field theories can be traced to the study of light and its properties. While developing these theories, several notions on the behaviour of light have been hypothesized as well as asserted, sometimes without any direct or compelling empirical evidence. In the context of quantum physics, there is a widespread belief that experiments on quantum correlations establish nonlocality as an essential aspect of nature. Another unshakable belief without direct empirical support is the absolute constancy of the speed of light relative to moving observers. In this paper, I argue that no experiment on quantum correlations of spatially separated photons necessitates the concept of nonlocality, and that there is no direct empirical proof of nonlocality. I also comment on the need to modify established notions on quantum light, in the context of a clear conflict between cosmology and the zero point energy of quantum electrodynamics. Then I describe the first experiments on the measurement of the true one-way speed light relative to a reference platform that is in inertial motion. The results are at variance with the belief that the speed of light is independent of the velocity of the observer.

Any superposition effect as measured (SEM) by us is the summation of simultaneous stimulations experienced by a detector due to the presence of multiple copies of a detectee each carrying different values of the same parameter. We discus the cases with light beams carrying same frequency for both diffraction and multiple beam Fabry-Perot interferometer and also a case where the two superposed light beams carry different frequencies. Our key argument is that if light really consists of indivisible elementary particle, photon, then it cannot by itself create superposition effect since the state vector of an elementary particle cannot carry more than one values of any parameter at the same time. Fortunately, semiclassical model explains all light induced interactions using quantized atoms and classical EM wave packet. Classical physics, with its deeper commitment to Reality Ontology, was better prepared to nurture the emergence of Quantum Mechanics and still can provide guidance to explore nature deeper if we pay careful attention to successful classical formulations like Huygens-Fresnel diffraction integral.

On the basis of comparing Maxwell equation for a light wave to Schroedinger equation for a photon, we conclude that the former solution that must be a real function is the real part of the latter solution that must be a complex function. Using the state-vector function that is the general solution of Schroedinger equation for a photon, we solve some true but strange optical problems including the simple demonstration of Malus's Law and the orthogonal decomposition of a natural light.

Here we postulate a geometrical 2D closed path invariant ds=ds_t+ds_Φ (geometrical interpretation) with the observer's own 2D ds=ds_t+ds_Φ then giving a total direct sum 2⊕2=4 degrees of freedom for the resulting (observer translation) Dirac equation pde and its ψ. There are several, more or less technical, ways of stating the consequences of that new "observer interpretation" Dirac equation pde. Two such ways are "wave function collapse," and in a more common sense vein "Bertlmann's socks." Note that wavefunction collapse to ψ then (and experimental nonlocality implications) is the "observables translation" of that fundamental postulate and so not itself postulated. Also that geometrical postulate does not allow a Bohmian hidden variable interpretation because of its fundamental nature (i.e., we cannot go any deeper). For example that postulate states no x or p that we would be certain of in some hidden variable context. Thus we can ignore here the straw man arguments of J.S. Bell that are in response to Bohmian hidden variable theories only. Thus there cannot result Bell's kink at θ=0 in the correlation function between the polarization measurements on the two ends of an EPR experimental apparatus (Bell, 1987). Recall this kink required correlating in a hidden variable, classical statistical mechanical context, with resulting superluminal implications. Also note here the "observer interpretation" boundary condition conservation of angular momentum of the initial singlet state for our 4D Dirac pde results in this being a time independent solution to this pde. Thus wave function collapse to the measured value in no way implies superluminal communication. In laymen terms it is just the Bertlmann's socks common sense fact that we knew before hand about the original singlet state of the central emitter, no superluminal communication between the left and right ends of the Aspect apparatus was required to know about this. Thus our new observer representation Dirac equation pde (the below equation 3.7), and the geometrical postulate it originated from, solves the nonlocality problem which has been an enigma to physics ever since that original EPR paper of many decades ago. This is relevant to the origin of the photon since this wave function collapse is also a basic behavior of light and photons.

The experiment results show that human consciousness can change photoelectric signals such as Voc and Isc of solar cell at isolation air. First in the world, consciousness signal is able to be recorded through the experiment. (It succeed in 10,22,2002) Consciousness augment or reduce the Voc to the slow wave like the ERP of the brain wave. Photoelectrical signal converts to slow fluctuation signal without characteristics of sine fluctuation, Which proves that there is a "cause and effect" relationship between alterations of consciousness (active) and photoelectrical signal (passive); Under the standard limit optical source (AM1.5), consciousness changes a normal photoelectric signal above threshold value of I-V tester. The experiment proves that consciousness signal is a kind of unknown physical signal. With a characteristic of slow fluctuation, mass wave of the light is different from the Einstein's light quantum (energy wave). Frequency interaction principle of it and its photoelectric conversion equation are being put forward. It is rife hold true. Consequently, it is discovered that consciousness signal with a slow weak wave has such high power. Mass energy space and time system theory and Quantum microcosmics space and time are being put forward. It give a support to new Mass wave. Consciousness can produces the consciousness signal with the mass wave and use it to act on photoelectric system. The system magnifies it. Consciousness is independent and self-determined while brain signal is passive and driven. Consciousness is spiritual and Intelligence while brain signal is physical, corporality and mechanic.

The fact that an orbiting electron does not collapse into the nucleus of its parent atom has thus far been considered a major obstacle to a classical interpretation of the stable states of orbiting electrons. Quantum mechanics avoids the very problem by discussing the probability of finding it, a method that confessedly has been very fruitful in the exploring the behaviour of elementary particles. Nonetheless, why should necessarily those two approaches be regarded as each others' enemies? In this paper it is shown that the classical mechanistic approach is still capable of explaining the eternal, circular movement of an electron around a nucleus. It is possible if reformulating the laws of action involved, returning to the simple electrostatic model, based upon Coulomb's law (1785, 1771). Further, in this paper it is also discussed, how electromagnetic radiation due to the de-excitation of excited electrons, orbiting around a positive nucleus, can be explained classically, as a sudden peak in the otherwise zero electric field, due to the inwards spiralling movement connected to the de-excitation. The concept of a distinct particle, the 'photon' is thereby rejected.

In quantum mechanics, light cannot be described in terms of waves and particles at the same time. However, the question about light "as it really is" implies a description that is independent from the constraints of measurement. It is rather preferable to incorporate both aspects in a causal ontological theory, especially if it simplifies explanation and improves predictions. Hence, the photon can be described as an extended longitudinal association of discrete indivisible constituents, which are held together by the effect of their own waves on each other. The same waves can then be used to interpret the force of interactions between different pulses of light, or between light and matter. The concept of wavemediated interaction between sub-photonic entities is entirely consistent with the observations of quantum mechanics. The key is to assume that elementary sources of waves never collide, and that they have constant parameters. Novel experimental implications follow from this approach. For example, the speed of propagation of changes within magnetic or electrostatic fields may not be equal to the speed of light. Also, interference fringes should be detectable beyond the volume of overlap of two non-entangled beams, but only in special experimental settings.