147,069 research outputs found
LHCb prospects for full energy and beyond (incl. upgrades)
The LHCb experiment is running at the Large Hadron Collider to study CP
violation and rare decays in the beauty and charm sectors. The physics
potential is given for five key observables sensitive to new physics in nominal
conditions. The motivation and the strategy of the upgrade envisaged for 2016
is presented with the expected performance for an integrated luminosity of 50
1/fb.Comment: 5 pages, 2 figures, Proceeding of the HCP2010 conferenc
Missing Elements and Missing Premises: A Combinatorial Argument for the Ontological Reduction of Chemistry
Does chemistry reduce to physics? If this means Can we derive the laws of chemistry from the laws of physics?', recent discussions suggest that the answer is no'. But sup posing that kind of reduction-- epistemological reduction'--to be impossible, the thesis of ontological reduction may still be true: that chemical properties are determined by more fundamental properties. However, even this thesis is threatened by some objections to the physicalist programme in the philosophy of mind, objections that generalize to the chemical case. Two objections are discussed: that physicalism is vacuous, and that nothing grounds the asymmetry of dependence which reductionism requires. Although it might seem rather surprising that the philosophy of chemistry is affected by shock waves from debates in the philosophy of mind, these objections show that there is an argumentative gap between, on the one hand, the theoretical connection linking chemical properties with properties at the sub-atomic level, and, on the other, the philosophical thesis of ontological reduction. The aim of this paper is to identify the missing premises (among them a theory of physical possibility) that would bridge this gap. Introduction: missing elements and the mystery of discreteness The refutation of physicalism A combinatorial theory of physical possibilia Combinatorialism and the Bohr model Objections The missing premises and a disanalogy with min
Space, supervenience and substantivalism
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Consider a straight line on a flat surface running from point A to C and passing though B. Suppose the distance AB to be four inches, and the distance BC to be six inches. We can infer that the distance AC is ten inches. Of all geometrical inferences, this is surely one of the simplest. Of course, things are a little more complicated if the surface is not flat. If A, B and C are points on a sphere, then the shortest distance between A and C may be smaller (it may even be zero). We can make our inference immune from concerns about non-Euclidean spaces, however, by qualifying it as follows: if AB = n, and BC = m, then, in the direction A⇒B⇒C, the distance AC is n + m. This is apparently entirely trivial. But trivial truths can hide significant ontological ones. Let us translate our mathematical example to the physical world, and suppose A, B and C to be points, still in a straight line, but now at the centre of gravity of three physical objects
Time, and the static image
Photographs, paintings, rigid sculptures: all these provide examples of static images. It is true that they change-photographs fade,paintings darken and sculptures crumble-but what change they undergo (unless very damaging) is irrelevant to their representational
content. A static image is one that represents by virtue of
properties which remain largely unchanged throughout its existence. Because of this defining feature, according to a long tradition in aesthetics, a static image can only represent an instantaneous moment, or to be more exact the state of affairs obtaining at that moment'. It cannot represent movement and the passage of time.
This traditional vieu- mirrors a much older one in metaphysics: that change is to be conceived of as a series of instantaneous states and hence that an interval of time is composed of extensionless moments. The metaphysical view has been involved in more controversy than its aesthetic counterpart. Aristotle identified it as one
of the premises of Zeno's arrow paradoxZ and Augustine employed it in his proof of the unreality of time. The aesthetic view, for its part, was subjected to a blistering attack in Ernst Gombrich's brilliant
essay 'Moment and movement in Art'", uhich persuasively
argues, not only against the doctrine that the changeless cannot represent change, but also against the very idea of an instant of time.
Still, Gombrich overstates his case. Is the idea of an instant simply a philosophers' fiction? And if we allow such an idea into our conception of the world, are we thereby committed to a mistaken view of pictorial representation? Implicit in Gombrich's argument
is a link between depiction and perception. But what is this link, and what role does it play in the argument? I propose in this essay to take another look at the question of what time-span is represented by the static image, and consider whether answering this question presupposes a view of time and change. I shall begin with a brief resume of Gombrich's discussion
Commutant Lifting for Commuting Row Contractions
If is a row contraction with commuting entries,
and the Arveson dilation is ,
then any operator commuting with each dilates to an operator of
the same norm which commutes with each .Comment: one section and references were adde
Spectroscopic reassignment and ground state dissociation energy of molecular iodine
Spectroscopic reassignment and ground state dissociation energy of molecular iodin
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