On the meaning of a non-renormalizable theory of gravitation

The renormalizability of quantum gravity remains an open question while it has been established recently that quantum gravity in the presence of standard sources is non-renormalizable. In view of traditional confusion and ambiguities surrounding non-renormalizable quantum field theories, it has been felt that physical theories must be renormalizable. Recently a new, nonperturbative view of non-renormalizable theories has been suggested that may have relevance for various interactions including gravity and various sources. In a path integral approach to quantum field theory such a view attributes ‘hard cores’ in the space of field histories to non-renormalizable interactions. Just as with more familiar ‘hard cores’, turning off the interaction does not completely remove all effects of the potential. Consequently the interacting theory is not even continuously connected to the usual free theory, but rather to an alternative ‘pseudo-free’ theory that incorporates the vestiges of the ‘hard cores’. Some insight into what is the significance and interpretation of non-renormalizable interactions can be gleaned from exactly soluble models. Application of this philosophy of non-renormalizable interactions is discussed for the gravitational field in interaction with some standard sources.     

Plasmas meet plasmonics

The term ‘plasmon’ was first coined in 1956 to describe collective electronic oscillations in solids which were very similar to electronic oscillations/surface waves in a plasma discharge (effectively the same formulae can be used to describe the frequencies of these physical phenomena). Surface waves originating in a plasma were initially considered to be just a tool for basic research, until they were successfully used for the generation of large-area plasmas for nanoscale materials synthesis and processing. To demonstrate the synergies between ‘plasmons’ and ‘plasmas’, these large-area plasmas can be used to make plasmonic nanostructures which functionally enhance a range of emerging devices. The incorporation of plasma-fabricated metal-based nanostructures into plasmonic devices is the missing link needed to bridge not only surface waves from traditional plasma physics and surface plasmons from optics, but also, more topically, macroscopic gaseous and nanoscale metal plasmas. This article first presents a brief review of surface waves and surface plasmons, then describe how these areas of research may be linked through Plasma Nanoscience showing, by closely looking at the essential physics as well as current and future applications, how everything old, is new, once again.     

‘Planetodiversity’: the variety of planets and planetary systems in the Universe

‘Planetodiversity’ is a composite word from planetary diversity. This denomination wants to parallel the common use of the term biodiversity employed in biology but translated here to the context of planetary sciences due to the proliferating variety of planets discovered outside the Solar System and theoretically proposed to exist. There are two properties that allow us a classification of a body as a planet or more generally as a ‘planetary mass object’: the orbital configuration and the physical structure (mass, energy and chemical composition). This leads respectively to the concepts that we term the ‘orbital planetodiversity’ and the ‘physical planetodiversity’. We present in a comparative way the basic planetary types observed or expected to exist within the framework of these two concepts.     

Acoustics on an international level

This paper emphasises the multidisciplinary character of acoustic science, which itself is a branch of physics. A distinction must be made between ‘acoustics’ as a science and ‘noise abatement’ which has become a much-used expression in recent years. A survey is given of the specific activity of various institutions and organisations involved in acoustics and noise control. It is the task of the ICA to give enough prominence to physical acoustics at its Congresses.     

A synapse memristor model with forgetting effect

In this Letter we improved the ion diffusion term proposed in literature [13] and redesigned the previous model as a dynamical model with two more internal state variables ‘forgetting rate’ and ‘retention’ besides the original variable ‘conductance’. The new model can not only describe the basic memory ability of memristor but also be able to capture the new finding forgetting behavior in memristor. And different from the previous model, the transition from short term memory to long term memory is also defined by the new model. Besides, the new model is better matched with the physical memristor (Pd/WOx/W) than the previous one.     

On the dressing method for the generalised Zakharov–Shabat system

The dressing procedure for the generalised Zakharov–Shabat system is well known for systems, related to sl(N) algebras. We extend the method, constructing explicitly the dressing factors for some systems, related to orthogonal and symplectic Lie algebras. We consider ‘dressed’ fundamental analytical solutions with simple poles at the prescribed eigenvalue points and obtain the corresponding Lax potentials, representing the soliton solutions for some important nonlinear evolution equations.     

Erzwingt die Quantenmechanik eine drastische Änderung unseres Weltbilds? Gedanken und Experimente nach Einstein,Podolsky und Rosen

Do Quantum Mechanics Force us to Drastically Change our View of the World? Thoughts and Experiments after Einstein, Podolsky and Rosen Since the advent of quantum mechanics there have been attempts of its interpretation in terms of statistical theory concerning individual ‘classical’ systems. The very conditions necessary to consider hidden variable theories describing these individual systems as ‘classical’ had been pointed out by Einstein, Podolsky and Rosen in 1935: 1. Physical systems are in principle separable. 2. If it is possible to predict with certainty the value of a physical quantity without disturbing the system under consideration, then there exists an element of physical reality corresponding to this physical quantity. Together they are, as was shown by Bell in 1964, incompatible in principle with quantum mechanics and no more tenable in view of recent experiments. These experiments once more corroborate quantum theory. In order to understand their results we are forced either to drop the assumption of separability of physical systems (taken for self-evident in classical physics) or to change our concept of physical reality. After investigating the notion of separability and connecting the ‘EPR-correlations’ to the measurement problem we, conclude that a change of the concept of physical reality is indispensable. The revised concept should be compatible with both classical and quantum physics in order to allow a uniform view of the physical world.     

Elastic scattering and the K matrix: (II). Phase shifts,resonances and few-level approximations

The K-matrix expansions given in part I are applied to the scattering by a square-well potential. Their convergence proves very satisfactory from a physical point of view since few-level approximations allow very good approximations to the phase shifts and cross sections. It also appears that all the complex poles of K_l and the real ones with positive residue should undoubtedly be associated with physical resonances. As for the real ones with negative residue, i.e. the echo poles, they are obviously unrelated to resonances, but they provide a very good parametrization of the background part of the scattering. The time delay is given a major role in the argument. The possibility of having double poles is also discussed and sum rules are given for the energies and residues of the poles.     

Consciousness,crosstalk, and the mereological fallacy: An evolutionary perspective

The cross-sectional decontextualization afflicting contemporary neuroscience – attributing to ‘the brain’ what is the province of the whole organism – is mirrored by an evolutionary decontextualization exceptionalizing consciousness. The living state is characterized by cognitive processes at all scales and levels of organization. Many can be associated with dual information sources that ‘speak’ a ‘language’ of behavior-in-context. Shifting global broadcasts analogous to consciousness, albeit far slower – wound healing, tumor control, immune function, gene expression, etc. – have emerged through repeated evolutionary exaptation of the crosstalk and noise inherent to all information transmission. These recruit ‘unconscious’ cognitive modules into tunable arrays as needed to meet threats and opportunities across multiple frames of reference. The development is straightforward, based on the powerful necessary conditions imposed by the asymptotic limit theorems of communication theory, in the same sense that the Central Limit Theorem constrains sums of stochastic variates. Recognition of information as a form of free energy instantiated by physical processes that consume free energy permits analogs to phase transition and nonequilibrium thermodynamic arguments, leading to ‘dynamic regression models’ useful for data analysis.     

‘Majorana Mass’ Fermions as Untrue Majorana Particles,Rather Endowed with Pseudoscalar-Type Charges than Genuinely Neutral

The idea of a ‘Majorana mass’ to make a chiral neutrino really neutral is here reconsidered. It is pointed out that such an approach, unlike Majorana’s (non-chiral) old one, does not strictly lead, in general, to a true self-conjugate particle. This can be seen on directly using the basic definition (or fundamental representation) of charge conjugation C in Quantum Field Theory, as an operation just acting on annihilation and creation operators and just expressing particle–antiparticle interchange. It is found, indeed, that the ‘active’ and ‘sterile’ whole fields which can be obtained from mixing the chiral components of two mutually charge-conjugate Dirac fields are themselves ‘charge conjugate’ to each other (rather than individually self-conjugate). These fields, taken as mass eigenfields (as in the ‘Majorana mass’ case), are shown to describe particles carrying pseudoscalar-type charges and being neutral relative to scalar-type charges only. For them, ‘CP symmetry’ would be nothing but pure mirror symmetry, and C violation (already implied in their respective ‘active’ and ‘sterile’ behaviors) should then involve time-reversal violation as well. The new (no longer strictly chargeless) ‘Majorana mass’ neutrino model still proves, however, neither to affect the usual expectation for a neutrinoless double β-decay, nor to prevent ‘active’ and ‘sterile’ neutrino varieties from generally taking different mass values. One has, on the other hand, that any fermion being just a genuine (i.e. really self-conjugate) Majorana particle cannot truly exist in two distinct—‘active’ and ‘sterile’—versions, and it can further bear only a unified mass kind which may at once be said to be either a ‘Majorana-like’ or a ‘Dirac-like’ mass kind.     

Recent theories of glasses as out of equilibrium systems

We discuss a theoretical approach to structural glasses as they happen in real situations. Older ideas based on ‘configurational entropy’, on ‘fictive temperatures’ and on Edwards' ‘compactivity’ are sharpened and unified in an out of equilibrium context. The picture is such that it may be supported or disproved by an experimental test, which we describe.     

Path algebras,wave-particle duality,and quantization of phase space

Semigroup algebras admit certain ‘coherent’ deformations which, in the special case of a path algebra, may associate a periodic function to an evolving path; for a particle moving freely on a straight line after an initial impulse, the wave length is that hypothesized by de Broglie’s wave-particle duality. This theory leads to a model of “physical” phase space of which mathematical phase space, the cotangent bundle of configuration space, is a projection. This space is singular, quantized at the Planck level, its structure implies the existence of spin, and the spread of a packet can be described as a random walk. The wavelength associated to a particle moving in this space need not be constant and its phase can change discontinuously.     

An automatic frequency domain modal parameter estimation algorithm

In this article, a frequency-domain modal parameter estimation method is proposed. The algorithm automatically separates physical poles from mathematical ones. An important issue in the automatization of the algorithm is the inclusion of noise information to estimate the standard deviations of the poles. These standard deviations are used (together with other features) as the inputs of a fuzzy clustering algorithm. The clustering algorithm then classifies the poles into the mathematical and physical ones. The method requires no user interaction, and a parameter is available quantifying the success of the classification.     

Nature’s optics and our understanding of light

Optical phenomena visible to everyone have been central to the development of, and abundantly illustrate, important concepts in science and mathematics. The phenomena considered from this viewpoint are rainbows, sparkling reflections on water, mirages, green flashes, earthlight on the moon, glories, daylight, crystals and the squint moon. And the concepts involved include refraction, caustics (focal singularities of ray optics), wave interference, numerical experiments, mathematical asymptotics, dispersion, complex angular momentum (Regge poles), polarisation singularities, Hamilton’s conical intersections of eigenvalues (‘Dirac points’), geometric phases and visual illusions.     

Fractional Stochastic Differential Equations Satisfying Fluctuation-Dissipation Theorem

We propose in this work a fractional stochastic differential equation (FSDE) model consistent with the over-damped limit of the generalized Langevin equation model. As a result of the ‘fluctuation-dissipation theorem’, the differential equations driven by fractional Brownian noise to model memory effects should be paired with Caputo derivatives, and this FSDE model should be understood in an integral form. We establish the existence of strong solutions for such equations and discuss the ergodicity and convergence to Gibbs measure. In the linear forcing regime, we show rigorously the algebraic convergence to Gibbs measure when the ‘fluctuation-dissipation theorem’ is satisfied, and this verifies that satisfying ‘fluctuation-dissipation theorem’ indeed leads to the correct physical behavior. We further discuss possible approaches to analyze the ergodicity and convergence to Gibbs measure in the nonlinear forcing regime, while leave the rigorous analysis for future works. The FSDE model proposed is suitable for systems in contact with heat bath with power-law kernel and subdiffusion behaviors.     

Addendum to the Elementary Process Theory

Recently, the Elementary Process Theory has been introduced as an axiomatic system with a potential application as a foundational framework for physics. This addendum clarifies the primitive concepts ‘phase quantum’ and ‘monad’ that play a central role in the physical picture that arises from the axiomatic system.     

Symmetry and invariance

The concept of invariance relates to both the intrinsic symmetries of physical systems and the symmetry of the set of equivalent reference frames used to observe them. Standard algebraic expressions for electrostatic potentials and crystal-field effective operators display both types of invariance. The concept of a reference frame is generalized to that of an ‘observing system’, which can, for example, be the basis states of a quantum system. This idea is related to Racah’s mathematical machinery for evaluating the matrix elements of many-electron 4f open-shell states in lanthanide ions. It is argued, on the basis of computational flexibility and ease of interpretation, that all equations that represent physical processes be expressible in terms of invariants of the set of observing systems. This ‘Principle of Invariance’ is then applied to special relativity, leading to a simple geometrical interpretation of Maxwell’s electromagnetic field equations. The close relationship between Dirac’s relativistic wave equation and Maxwell’s equations is then exposed. This leads to the concept of an inner structure of space-time and the reinterpretation of particle spin. Finally, it is shown that the use of invariants in relativity theory identifies a set of observing systems with a higher symmetry than that of Minkowski space-time.     

A Critical Examination to the Unitarized IJ ＝ 20 ππ Scattering Chiral Amplitude

We discuss the Padé approximation to the ππ scattering amplitudes in one-loop chiral perturbation theory.The approximation restores unitarity and can reproduce the correct resonance poles,but the approximation violates crossing symmetry and produces spurious poles on the complex s plane and therefore plagues its predictions in some cases.However we find that one virtual state in the IJ = 20 channel may have physical relevance.