A classical spinor approach to the quantum/classical interface

2008 ◽  
Vol 86 (4) ◽  
pp. 629-634
Author(s):  
W E Baylis ◽  
J D Keselica
Keyword(s):  
Clifford Algebra ◽  
Classical Mechanics ◽  
Physical Space ◽  
Classical Electrodynamics ◽  
Algebra Of Physical Space ◽  
Insight Into

A promising approach to the quantum/classical interface is described. It is based on a formulation of relativistic classical mechanics in the Clifford algebra of physical space. Spinors and projectors arise naturally and provide powerful tools for solving problems in classical electrodynamics. They also reproduce many quantum results, allowing insight into quantum processes.PACS Nos.: 03.65.Ca, 03.65.Ta, 04.20.Gz, 02.10.Xm

scholarly journals Relativistic quantum mechanics

1932 ◽  
Vol 136 (829) ◽  
pp. 453-464 ◽  
Keyword(s):  
Quantum Mechanics ◽  
Quantum Theory ◽  
Classical Theory ◽  
Correspondence Principle ◽  
Relativistic Quantum ◽  
Classical Mechanics ◽  
Hamiltonian Function ◽  
Relativistic Quantum Mechanics ◽  
Classical Electrodynamics ◽  
Quantum Phenomena

The steady development of the quantum theory that has taken place during the present century was made possible only by continual reference to the Correspondence Principle of Bohr, according to which, classical theory can give valuable information about quantum phenomena in spite of the essential differences in the fundamental ideas of the two theories. A masterful advance was made by Heisenberg in 1925, who showed how equations of classical physics could be taken over in a formal way and made to apply to quantities of importance in quantum theory, thereby establishing the Correspondence Principle on a quantitative basis and laying the foundations of the new Quantum Mechanics. Heisenberg’s scheme was found to fit wonderfully well with the Hamiltonian theory of classical mechanics and enabled one to apply to quantum theory all the information that classical theory supplies, in so far as this information is consistent with the Hamiltonian form. Thus one was able to build up a satisfactory quantum mechanics for dealing with any dynamical system composed of interacting particles, provided the interaction could be expressed by means of an energy term to be added to the Hamiltonian function. This does not exhaust the sphere of usefulness of the classical theory. Classical electrodynamics, in its accurate (restricted) relativistic form, teaches us that the idea of an interaction energy between particles is only an approxi­mation and should be replaced by the idea of each particle emitting waves which travel outward with a finite velocity and influence the other particles in passing over them. We must find a way of taking over this new information into the quantum theory and must set up a relativistic quantum mechanics, before we can dispense with the Correspondence Principle.

scholarly journals Revealing topology with transformation optics

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Lizhen Lu ◽  
Kun Ding ◽  
Emanuele Galiffi ◽  
Xikui Ma ◽  
Tianyu Dong ◽  
...  
Keyword(s):  
Physical Space ◽  
Real Space ◽  
Virtual Space ◽  
Transformation Optics ◽  
Coordinate Space ◽  
Dimensional System ◽  
Edge States ◽  
And Topology ◽  
Higher Dimensional ◽  
Insight Into

AbstractSymmetry deepens our insight into a physical system and its interplay with topology enables the discovery of topological phases. Symmetry analysis is conventionally performed either in the physical space of interest, or in the corresponding reciprocal space. Here we borrow the concept of virtual space from transformation optics to demonstrate how a certain class of symmetries can be visualised in a transformed, spectrally related coordinate space, illuminating the underlying topological transitions. By projecting a plasmonic system in a higher-dimensional virtual space onto a lower-dimensional system in real space, we show how transformation optics allows us to construct a topologically non-trivial system by inspecting its modes in the virtual space. Interestingly, we find that the topological invariant can be controlled via the singularities in the conformal mapping, enabling the intuitive engineering of edge states. The confluence of transformation optics and topology here can be generalized to other wave realms beyond photonics.

Access to Research Online

2021 ◽  
pp. 571-589
Author(s):  
Kristina Symes
Keyword(s):  
Open Access ◽  
Physical Space ◽  
Content Delivery ◽  
Remote Access ◽  
Digital Content ◽  
Future Developments ◽  
Current Trends ◽  
The World ◽  
Insight Into

The world is hungry for knowledge and quickly-producing researchers of varying caliber who are less dependent on the physical space than ever before. This presents a number of challenges to librarians, out of which issues related to technology stand out prominently. How can the library pave roads to curated digital content and make it easily accessible from any location? How does it remain relevant in the age of Google, sophisticated piracy and the open access movement? The chapter begins with an overview of IP-based and federated access technologies, touching on less-used methods as well. Personally-conducted interviews with library industry experts aim to determine current trends in order to provide a collective insight into future developments. These include the widespread migration towards cloud-based services, the global RA21 initiative, the open access movement, the need for better statistics, and new ways of content delivery, all of which affect libraries' demands for remote access in different ways.

The Kitchen

2017 ◽  
Author(s):  
Nicole Tarulevicz
Keyword(s):  
Physical Space ◽  
The State ◽  
Food Preparation ◽  
Intimate Association ◽  
Insight Into ◽  
The Way

This chapter looks at the marginalized Singaporean kitchen. Although they think hard about where and what they eat, very few Singaporeans spend time thinking about where their food is prepared. The chapter thus considers the physical space of the kitchen, with reference to domestic architectural sources, and the sociological meaning of the kitchen in the colonial and the post-independence periods. Because of the intimate association between the state and housing, Singaporean kitchens provide a unique insight into the way in which food preparation is conceptualized by the state. Moreover, discussions of kitchens and their relationship to Singaporean society requires a different understanding of the categories of gender and domesticity.

SYMMETRY PROPERTIES OF THE EXACT EM RADIATION-REACTION EQUATION FOR CLASSICAL EXTENDED PARTICLES AND ANTIPARTICLES

2013 ◽  
Vol 28 (18) ◽  
pp. 1350086 ◽  
Author(s):  
CLAUDIO CREMASCHINI ◽  
MASSIMO TESSAROTTO
Keyword(s):  
Conservation Laws ◽  
Classical Mechanics ◽  
Finite Size ◽  
Radiation Reaction ◽  
Classical Electrodynamics ◽  
Qualitative Properties ◽  
Hamilton Variational Principle ◽  
Electromagnetic Interactions ◽  
Symmetry Properties ◽  
Self Force

Based on recent theoretical developments (Cremaschini and Tessarotto, 2011–2013), in this paper the issue is addressed of the first-principle construction of the nonlocal relativistic radiation-reaction (RR) equation for classical spherical-shell, finite-size particles and antiparticles. This is achieved invoking the axioms of Classical Electrodynamics by means of the Hamilton variational principle. In connection with this, the Lagrangian conservation laws, together with the possible existence of adiabatic invariants, and the transformation laws of the RR equation with respect to CPT and time-reversal transformations are investigated. The latter properties make possible the parametrization of the RR equations, holding respectively for particles and antiparticles of this type, in terms of the same coordinate time t and the investigation of the qualitative properties of their solutions. In particular, in both cases the RR self-force is found to have the same signature, which implies that the dynamics of classical finite-size antiparticles is equivalent to that of classical extended particles of opposite charge. Therefore, in the framework of Classical Mechanics, a distinction between particles and antiparticles cannot be made based solely on the electromagnetic interactions associated with electromagnetic RR phenomena. As a basic application of the theory, the Lagrangian conservation laws and symmetry properties for the Hamiltonian asymptotic approximations of the exact RR equation are also addressed.

Into the NICU

2019 ◽  
pp. 59-88
Author(s):  
Dána-Ain Davis
Keyword(s):  
Intensive Care Unit ◽  
Intensive Care ◽  
General Population ◽  
Neonatal Intensive Care Unit ◽  
Birth Outcomes ◽  
Neonatal Intensive Care ◽  
Newborn Infants ◽  
Physical Space ◽  
Premature Births ◽  
Insight Into

This chapter offers ethnographic insight into the neonatal intensive care unit (NICU), a space that is largely inaccessible to the general population. The chapter describes the physical space of the NICU. Parents reveal how they felt about having their newborn infants admitted to the NICU and the varying degrees of racism that saturated the experiences of some, but not all, parents. Most parents interpret their experience through the lens of medical racism. At the very least they understand that if it were not for a particular mediating factor, such as having a connection to the medical field, they likely would have been subjected to racist medical encounters. This chapter also examines how mostly white neonatologists respond to questions related to race and adverse birth outcomes and finds that, for most, class replaces race as the explanatory factor for understanding premature births.

Low-gain Free Electron Lasers

2010 ◽  
Vol 03 (01) ◽  
pp. 77-91 ◽  
Author(s):  
Nikolay Vinokurov
Keyword(s):  
Traveling Wave ◽  
Free Electron ◽  
Electronic Devices ◽  
Classical Mechanics ◽  
Classical Electrodynamics ◽  
Free Electron Lasers ◽  
Undulator Radiation ◽  
The Family ◽  
Vacuum Electronic Devices ◽  
Traveling Wave Tubes

Free electron lasers (FELs) are lasers which utilize the phenomenon of stimulated undulator radiation. Contrary to most lasers, the motion of an electron in the FEL may be described by classical mechanics and classical electrodynamics. Therefore, FELs belong to the family of vacuum electronic devices, such as traveling wave tubes or klystrons. In this article, basics of the low-gain FEL physics are discussed and general considerations are clarified through some examples.

Mechanics of Herbert Pendulum Hardness Tester and its Application

2017 ◽  
Vol 741 ◽  
pp. 122-127 ◽  
Author(s):  
Radim Halama ◽  
Jiří Podešva ◽  
Ryosuke Suzuki ◽  
Masaaki Matsubara ◽  
Rostislav Čech
Keyword(s):  
Classical Mechanics ◽  
Rolling Resistance ◽  
Resistance Coefficient ◽  
Metallic Materials ◽  
Low Friction ◽  
Hardness Tester ◽  
Swing Angle ◽  
Simplified Solution ◽  
Resistance Coefficients ◽  
Insight Into

The knowledge of classical mechanics gives deeper insight into the Herbert hardness tester applicability for material testing. Elastic materials with low friction presence between contact surfaces are supposed to be investigated in this study. Firstly the dynamics approach is used to obtain simplified solution of swing angle. Then a new solution of the problem is gained by means of an energy approach. Slight decrease of the swing angle is predicted by the new solution as also shown in experiments. After comparison of both solutions a new formulae useful for evaluation of rolling resistance coefficient is applied for measurements performed on some metallic materials and artificial sapphire. Rolling resistance coefficients obtained by the way are always less than maximal estimated value.

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