A critique of the quantum nondemolition concept

A formal quantum theory of new types of measurement of small forces was published recently. The purpose of this note is to show that this theory suffers from a serious inconsistency which makes its conclusions invalid.     

Perspectives A critique of two metals

I argue that Anderson's identification of the conflict between the fermi-liquid and non-fermi-liquid metallic states as the central issue of cuprate superconductivity is fundamentally wrong. All experimental evidence points to adiabatic continuability of the strange metal into a conventional one, and thus to one metallic phase rather than two, and all attempts to account theoretically for the existence of a luttinger-liquid at zero temperature in spatial dimension greater than one have failed. I discuss the underlying reasons for this failure and then argue that the true higher-dimensional generalization of the luttinger-liquid behavior is a propensity of the system to order. This implies that the central issue is actually the conflict between different kinds of order, i.e. exactly the idea implicit in Zhang's paper. I then speculate about how the conflict between antiferromagnetism and superconductivity, the two principal kinds of order in this problem, might result in both the observed zero-temperature phase diagram of the cuprates and the luttinger-liquid phenomenology, i.e. the breakup of the electron into spinons and holons in certain regimes of doping and energy. The key idea is a quantum critical point regulating a first-order transition between these phases, and toward which one is first attracted under renormalization before bifurcating between the two phases. I speculate that this critical point lies on the insulating line, and that the difference between the Mott-insulator and fermi-liquid approaches to the high TC problem comes down to whether or not the superconducting states made by nand p-type doping can be continued into each other. A candidate for the second fixed point required for distinct superconducting phases is the P- and T-violating chiral spin liquid state invented by me.     

A critique of Segal's chronometric theory

The Segal Chronometric theory is examined, with particular attention given to the role of a physical measurement in the theory. A calculation of the red shift in Segal's theory in the geometrical optics limit yields the resultz=0, in contradiction to Segal's resultz=tan² (/2), and the disagreement is shown to arise from the unphysical nature of Segal's theory of measurement. An argument is also presented to show that the postulates on which Segal's theory is based are inconsistent when massive particles are introduced into the Segal universe.     

A critique on the application of infrared photodetector theory

The physical and mathematical framework underlying photodetector theory is appraised, with particular interest in those aspects relevant to practical device application. The mathematical assumptions and conventions on which signal and r.m.s. noise calculations are based are examined, together with the relationships between the characteristic parameters, responsivity and detectivity, and device spectral response, frequency response and linearity. An equivalent ramp-function spectral response based on the definition of an effective cutoff wavelength is derived and is shown to be useful for cases where device data are incomplete. The standard expressions for responsivity, detectivity, signal and noise currents, signal-to-noise ratio and noise-equivalent temperature difference are examined with particular interest in their application to device use and IR system design.     

Nuclear radii: A critique of the droplet model

Equivalent sharp radii of a number of nuclei are calculated with the droplet model, using parameters that have been determined by the Hartree-Fock (HF) method with a given force (Gogny). They are found to be systematically smaller than the sharp radii given by direct HF calculations on the nucleus in question with the same force. This is shown to be a result of nuclear matter being squeezed by the surface tension much more in the droplet model than in the HF method. Inclusion of higher-order terms in the droplet model's expansion in powers of $\text{A}{}^{\mathrm{<mtext>?</mtext><mtext>1</mtext><mtext>3</mtext>}}$ in no way helps to remove the anomaly, and in fact serious questions concerning the convergence of this expansion arise.     

A critique of Zwaan-Stueckelberg phase integral techniques

The Zwaan-Stueckelberg technique, based on semi-classical J.W.K.B. phase integrals and their analytic continuation in the complex plane, is reviewed. Stueckelberg's derivation of Jeffreys' connection formula is discussed, as are his connection formulae for strongly coupled, non-adiabatic collisions involving adiabatic crossings or diabatic non-crossings. His choice of branch cut is clarified. Avoided adiabatic crossings are described using both physical and non-physical branch cuts. Other limitations and defects of the Stueckelberg treatment are examined in detail and most are eliminated. New formulae for the general non-crossing case are presented. They describe perturbed symmetric resonance, reducing in an exactly correct manner for the Rosen-Zener model and also for exact resonance. Within a dynamical adiabatic treatment they also describe perturbed united-atom degeneracy, giving rise to strong rotational coupling in σ-π transitions. The limitation of the Landau-Zener theory to σ-σ transitions is thus avoided.     

Aharonov-Bohm效应和量子力学相位概念的一些问题——评曾谨言著《量子力学》卷Ⅱ第六次印刷第四章的物理概念

意图澄清一些对于Aharonov-Bohm效应的误解,指出一本国内流行甚广的量子力学教科书中对这一物理概念的错误解说.     

A critique of the disturbance theory of indeterminacy in quantum mechanics

Heisenberg'sgendanken experiments in quantum mechanics have given rise to a widespread belief that the indeterminacy relations holding for the variables of a quantal system can be explained quasiclassically in terms of a disturbance suffered by the system in interaction with a quantal measurement, or state preparation, agent. There are a number of criticisms of this doctrine in the literature, which are critically examined in this article and found to be ininconclusive, the chief error being the conflation of this disturbance with the projection postulate. We present a critique of the disturbance theory based on the fact that the required disturbance will in general depend on the interaction time of the system and state-preparer. This point is exploited in the construction of a spin-interaction model which acts as a counterexample to the disturbance doctrine, while remaining faithful to the spirit of Heisenberg'sgedanken experiments. Several consequences of this result are discussed.This work formed part of a thesis submitted by one of us (HRB) in partial fulfilment of the requirements for the degree of Doctor of Philosophy in the University of London.     

A critique of the unsaturable trap model of radiation damage in metals

The unsaturable trap model, which attributes the increase of the electrical resistivity of fcc metals during electron irradiation in the temperature regime of Stage-II recovery to the trapping of Stage-I_E interstitials at impurity atoms, is shown to be in serious disagreement with the experiments, contrary to opposite statements in the literature. As shown recently, the predictions of the unsaturable trap model are independent of the dimensionality of the diffusion of the Stage-I_E interstitials. Previous attempts to rule out a one-dimensional migration of the Stage-I_E interstitials (and hence the two-interstitial model) on the basis of the alleged agreement of the unsaturable trap model with Stage-II damage curves are thus meaningless. On the contrary, it is demonstrated that the two-interstitial model accounts for minute details of the measured Stage-II damage curves in a natural way.     

On the proper behavior of atoms: A comment on a critique

A recent article [S. Keen, R. Standish, Profit maximization, industry structure, and competition: a critique of neoclassical theory, Physica A 370 (2006) 81-85] suggests that the Cournot model, which is widely used in Economics, is inappropriate and the article proposes an alternative. I argue that the supporting arguments compute derivatives incorrectly which, amongst other things, have the effect of confusing the relationship between an individual actor in a market and the total mass of firms. I also indicate that the proposed alternative was considered about 20 years ago and found to be unsatisfactory. Thus, it should not be surprising when the authors fail to use their own proposal in the second half of the paper.     

氧化锌发光中心的统计力学模型

根据ZnO结构的两种空隙(四面体和多面体),提出了一种发光模型.用统计系综求得了上述两种填隙锌的数量计算公式.     

Naked singularities in spherically symmetric gravitational collapse: A critique

One of the most important questions in the physics of gravitation phenomena is whether gravitational collapse can lead to the formation of singularities which are not hidden by an event horizon. The Cosmic Censorship Conjecture (CCC) represents the hope that such a drastic event cannot happen in realistic physical situations. However, in the recent past several counter examples to the CCC were demonstrated by several researchers in situations of spherically symmetric gravitational collapse. The disturbing aspect about these counter examples is that they are strong naked singularities—they can crush matter to zero volume and can have a disastrous influence on causal physics. We examine these counter examples for their physical content by working through the dynamical collapse of inhomogeneous dust and argue that these are not physically acceptable counter examples. Our main result is that the singularities when naked are weak and when strong, strongly censored. The strong naked singularities in the counter examples do not arise from dynamical collapse; they result from the intrinsically singular nature of the initial density distributions chosen. The CCC seems to remain robust as far as spherically symmetric collapse is concerned.     

A new concept for the origin of the Schaefer-Bergmann diffraction patterns

The origin of the Schaefer-Bergmann diffraction patterns is interpreted by the concept of a diffuse acoustic field occuring in high Q-factor crystals like the sound field in large low-loss auditoriums. It is shown that the inhomogeneous illumination of the patterns obtained by crystals with high symmetry or with weak anisotropy is due to interference phenomena in the diffuse field.     

The empty ghosts of Michelson and Morley: A critique of the Marinov coupled-mirrors experiment

It is suggested that the existence of a preferred cosmological reference frame has a number of generally unrecognized implications which are by no means inconsistent with the assumptions and consequences of special relativity. Indeed, the assumption that there exists a cosmological fundamental reference frame for light propagation leads to an intelligible interpretation of relativistic effects and of the null observations of Michelson-Morley-type experiments. Hence all such experiments are impotent for the detection of any such fundamental frame, and it is shown that this applies also to the ingenious coupled-mirrors experiment proposed by S. Marinov. Only astronomical observation allied to cosmological theory can reveal the existence of this frame.     

量子力学基本概念教学探讨

用一维无限深势阱中粒子的动态量子模型讨论了态叠加原理和时间与能量的不确定关系原理的意义,指出量子隧穿效应静态模型的疑难,建立了一个隧穿效应动态模型,并讨论了隧穿效应的微观机制.     

A note on the propensity concept in quantum mechanics

It is shown that the propensity concept of Wódkiewicz is identical to the notion of the probability distribution of results of a measurement of quantum observables covariant with respect to the galilean group as is defined in the statistical model of quantum measurements.     

A model for the stabilization of atomic hydrogen centers in borate glasses

A previously proposed model describing the trapping site of the interstitial atomic hydrogen in borate glasses is analyzed. In this model the atomic hydrogen is stabilized at the centers of oxygen polygons belonging to B–O ring structures in the glass network by van der Waals forces. The previously reported atomic hydrogen isothermal decay experimental data are discussed in the light of this microscopic model. A coupled differential equation system of the observed decay kinetics was solved numerically using the Runge Kutta method. The experimental untrapping activation energy of 0.7×10⁻¹⁹ J is in good agreement with the calculated results of dispersion interaction between the stabilized atomic hydrogen and the neighboring oxygen atoms at the vertices of hexagonal ring structures.     

Concerning measurements in quantum theory: A critique of a recent proposal

Conclusion Jauch's theory of measurement, if satisfactory, would have provided an elegant and very simple solution to all of the standard difficulties found in other versions of the measurement process in quantum theory. We have examined this theory and found it to contain an important element of obscurity (that concerned with just exactly under what conditions the reductions may be performed) and ambiguity (namely concerning which reductions are to be performed), but most importantly we have concluded that it was both inconsistent and lacking in physical plausibility.I wish to acknowledge Dr. J. Bub and members of my graduate seminar, stimulating conversations with whom served to clarify many of the issues in this paper.