Ontological aspects of the Casimir Effect

The role of the vacuum, in the Casimir Effect, is a matter of some dispute: the Casimir force has been variously described as a phenomenon resulting "from the alteration, by the boundaries, of the zero-point electromagnetic energy", or a "Van der Waals force between the metal plates" that can be "computed without reference to zero point energies". Neither of these descriptions are grounded in a consistently quantum mechanical treatment of matter interacting with the electromagnetic field. However, the Casimir Effect has been canonically described within the framework of macroscopic quantum electrodynamics. On this account, the force is seen to arise due to the coupling of fluctuating currents to the zero-point radiation, and it is in this restricted sense that the phenomenon requires the existence of zero-point fields. The conflicting descriptions of the Casimir Effect, on the other hand, appear to arise from inadequate ontologies in which an unwarranted metaphysical priority is assigned either to the matter or the fields. Such ontological errors may have a direct bearing on the problem of the cosmological constant and the correct prediction of the Casimir force in a state of thermal equilibrium.Comment: 6 page

The paradox of the Casimir force in inhomogeneous transformation media

It has recently been argued that Casimir-Lifshitz forces depend in detail on the microphysics of a system; calculations of the Casimir force in inhomogeneous media yield results that are cutoff-dependent. This result has been shown to hold generally. But suppose we introduce an inhomogeneous metamaterial into a cavity that effectively implements a simple distortion of the coordinate system. Considered in its 'virtual space', the optical properties of such a material are homogeneous and consequently free from the cutoff-dependency associated with inhomogeneous media. This conclusion should be reconciled with recent advances in our understanding of Casimir-Lifshitz forces. We consider an example of such a system here and demonstrate that, whilst the size of the Casimir force is modified by the inhomogeneous medium, the force is cutoff-independent and can be stated exactly. The apparent paradox dissolves when we recognise that an idealised metamaterial that could implement a virtual geometry for all frequencies would be devoid of internal scattering, and would not give rise to a cutoff-dependency in the Casimir force for that reason.Comment: 7 page

Colored filters improve exclusion of perceptual noise in visually symptomatic dyslexics

Dyslexic individuals have deficits in detecting visual stimuli embedded in high levels of perceptual noise. Here we show that visually symptomatic dyslexics, who otherwise had elevated contrast thresholds for discriminating symbols in visual noise, had thresholds similar to non-dyslexics when wearing colored filters. These findings provide evidence that colored filters, which minimize the visual distortions and discomfort of dyslexics when reading, improve dyslexics' noise exclusion to normal levels

Not the Last Word

English and American Literature and Languag

Subjects of Triumph and Literary History: Dido and Petrarch in Petrarch's Africa and Trionfi

English and American Literature and Languag