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Introduction is of quite general nature. It contains basic terminological definitions used throughout the book. The term secondary radiation is introduced. The difference between ‘luminescence’ (cold light) and ‘incandescence’ is explained. Specific kinds of luminescence are defined (photoluminescence, electroluminescence, chemiluminescence, bioluminescence, cathodoluminescence, thermoluminescence etc.). Distinctions between fluorescence and phosphorescence, between mechanisms of luminescence in organic and inorganic materials and between intrinsic and extrinsic origins of luminescence are stressed. The terms phosphor, Stokes’ law, thermal quenching and edge emission are explained. The basic terms and definitions are elucidated via using representative examples of luminescence emission spectra taken in various semiconductors.

The problem of the “body”, apophatically speaking, is perspectival and linguistic. It is a problem of language, a language whose nature petitions a discourse that gives quality without concretizing that value in an object. What may be needed is an apophatic (nonliteral) manner in which to speak of bodies in order that the discourse itself be apophatically “speaking away” without being less expressive. An example of this kind of discourse can be seen in the writing of Wallace Stevens, for whom poetry is such an apophatic “speaking away”. So it is with the apophatic body that is no body. It is an embodying perspective that can give valence to life and meaning, a vertical dimension in which ordinariness incandesces, flaming and flowering. The body that is no body is incandescence.

This chapter addresses the scientific underpinnings of several of Greg Egan's novels. It first considers the “subjective cosmology” of the universes depicted in Quarantine, Permutation City, and Distress, with their attendant quantum mechanical weirdness. Next, it tackles theories about how our own universe works as seen in the novels Diaspora, Schild's Ladder, and Incandescence. Finally, the chapter provides a rough overview of the alternate-world physics shown in the Orthogonal trilogy, with a particular focus on Clockwork Rocket and Eternal Flame, the two volumes published at the time of writing. It concludes with a section on Egan's use of scientific principles as metaphors for larger philosophical points.

Burning, more formally combustion, denotes burning in oxygen and more commonly in air (which is 20 per cent oxygen). Combustion is a special case of a more general term, ‘oxidation’, which originally meant reaction with oxygen, not necessarily accompanied by a flame. The rusting of iron is also an oxidation, but we don’t normally think of it as a combustion because no flame is involved. Oxidation now has a much broader meaning than reaction with oxygen, as I shall unfold in Reaction 5. For now, I shall stick to combustion itself. To achieve combustion, we take a fuel, which might be the methane, CH4, 1, of natural gas or one of the heavier hydrocarbons, such as octane, C8H18, 2, that we use in internal combustion engines, mix it with air, and ignite it. The outcome of the complete combustion of any hydro-carbon is carbon dioxide and water but incomplete combustion can result in carbon monoxide and various fragments of the original hydrocarbon molecule. All combustions are ‘exothermic’, meaning that they release a lot of energy as heat into the surroundings. We use that energy for warmth or for driving machinery. Another example of an exothermic combustion is provided by the metal magnesium, which gives an intense white light as well as heat when it burns in air. A part of the vigour of this reaction is due to the fact that magnesium reacts not only with oxygen but also with nitrogen, the major component of air. You should be getting a glimpse of the broader significance of the term ‘oxidation’ in the sense that the reaction need not involve oxygen; in magnesium’s case, nitrogen can replace oxygen in the reaction. Magnesium foil was used in old-fashioned photographic flashes and in fireworks. The latter now mostly use finely powdered aluminium, which is much cheaper than magnesium and reacts in much the same way. In what follows you could easily replace aluminium with magnesium if you want to think fireworks. For the whole of the following discussion you need to be familiar with oxygen, O2, 3, a peculiar molecule in several respects.

Probes are generated using laboratory sources, or in large user facilities. Photon sources include incandescence and plasma discharge lamps. Electron beams are generated using thermionic or field-emission sources. RF plasma sources generate ions that are accelerated and used for scattering experiments. Specimens should be probed first with light, as it causes the least damage. Electron interaction with matter causes beam broadening, atomic displacements, sputtering, or radiolysis leading to mass loss and local contamination. Neutrons are heavier than electrons, penetrate more deeply in materials, and require more sample for analysis. Protons (positive charge, heavier than electrons) go a longer way in the specimen without significant broadening. Ions in solids undergo kinematic collisions with conservation of energy and momentum; they also lose energy continuously as they propagate. In the back-scattering geometry, they form important methods of Rutherford backscattering spectroscopy (RBS) and low-energy ion scattering spectroscopy (LEISS). Medium energy ions generate secondary ions by sputtering that can be analyzed by mass spectrometers to determine specimen composition (SIMS). Alternatively, its composition is analyzed (ICP-MS), by creating an aqueous dispersion and converting it to a plasma. Finally, interaction of high-energy ions with core electrons can lead to inner shell ionization and characteristic X-ray emission (PIXE).