A precipice below which lies absurdity? Theories without a spacetime and scientific understanding

Funder: Trinity College, University of Cambridge; doi: http://dx.doi.org/10.13039/501100000727While the relation between visualization and scientific understanding has been a topic of long-standing discussion, recent developments in physics have pushed the boundaries of this debate to new and still unexplored realms. For it is claimed that, in certain theories of quantum gravity, spacetime 'disappears': and this suggests that one may have sensible physical theories in which spacetime is completely absent. This makes the philosophical question whether such theories are intelligible, even more pressing. And if such theories are intelligible, the question then is how they manage to do so. In this paper, we adapt the contextual theory of scientific understanding, developed by one of us, to fit the novel challenges posed by physical theories without spacetime. We construe understanding as a matter of skill rather than just knowledge. The appeal is thus to understanding, rather than explanation, because we will be concerned with the tools that scientists have at their disposal for understanding these theories. Our central thesis is that such physical theories can provide scientific understanding, and that such understanding does not require spacetimes of any sort. Our argument consists of four consecutive steps: (a) We argue, from the general theory of scientific understanding, that although visualization is an oft-used tool for understanding, it is not a necessary condition for it; (b) we criticise certain metaphysical preconceptions which can stand in the way of recognising how intelligibility without spacetime can be had; (c) we catalogue tools for rendering theories without a spacetime intelligible; and (d) we give examples of cases in which understanding is attained without a spacetime, and explain what kind of understanding these examples provide

AVANAR: een ruimtelijk model voor het berekenen van vraag-aanbodverhoudingen voor recreatieve activiteiten; basisdocumentatie en gevoeligheidsanalyses

Op verzoek van het Milieu- en Natuurplanbureau levert dit rapport een beschrijving van het recreatiemodel AVANAR, inclusief enkele gevoeligheidsanalyses en suggesties voor verdere ontwikkeling. Het model berekent in hoeverre het aanbod aan groene recreatieruimte is afgestemd op de vraag naar vooral recreatieve wandel- en fietstochten. De vraag wordt afgeleid uit een deelnamepercentage van de bevolking op een maatgevende dag (hier de vijfde drukste dag van het jaar). Het aanbod bestaat uit grondgebruikklassen omgerekend naar recreatieve opvang¬capaciteiten. De afstemming vindt plaats binnen door het beleid bepaalde ‘normafstanden’. Per herkomsteenheid, bij voorkeur geaggregeerd naar bijvoorbeeld gemeenten of stadsdelen, wordt zodoende bepaald hoeveel procent van de vraag gedekt wordt, en wat het tekort (eventueel om te zetten in ruimteclaims) is. Dit rapport bevat ook een technische beschrijving van de GIS-applicatie. De gevoeligheidsanalyses laten zien dat de resultaten sterk afhankelijk zijn van de gehanteerde, deels normatieve invoerwaarden. In de verdere ontwikkeling dient er dan ook vooral aan de empirische onderbouwing van deze invoerwaarden en de ‘validatie’ van de modeluitkomsten gewerkt te worde

Analyses ten behoeve van een groene recreatiebalans voor Amsterdam; AVANAR als instrument voor het monitoren van vraag- en aanbodverhoudingen voor basale openluchtrecreatieve activiteiten

In opdracht van de dienst Ruimtelijke Ordening van Amsterdam is, in aansluiting op een eerder project, berekend hoe vraag en aanbod van groene recreatiemogelijkheden zich verhouden voor de Amsterdamse stadsdelen. Vanwege verfijning van de rekenmethode is hiervoor speciaal een applicatie ontwikkeld, genaamd AVANAR: Afstemming Vraag & Aanbod Natuur Als Recreatieruimte. Analyses zijn uitgevoerd voor wandelen, fietsen en parkbezoek. Ook is gekeken naar de gevoeligheid van de rekenmethode voor haar normatieve uitgangspunten, en naar de mogelijkheden om AVANAR in te zetten voor scenarioberekeningen en als monitorings¬instrument. Tot slot is een verkenning uitgevoerd van de relatie tussen berekende tekorten en het zich manifesteren van negatieve gevolgen die verwacht mogen worden bij een daadwerkelijk tekort aan groene recreatie¬mogelijkhede

Network analysis of the COSMOS galaxy field

The galaxy data provided by COSMOS survey for 1 by 1 degree field of sky are analysed by methods of complex networks. Three galaxy samples (slices) with redshifts ranging within intervals 0.88-0.91, 0.91-0.94 and 0.94-0.97 are studied as two-dimensional projections for the spatial distributions of galaxies. We construct networks and calculate network measures for each sample, in order to analyse the network similarity of different samples, distinguish various topological environments, and find associations between galaxy properties (colour index and stellar mass) and their topological environments. Results indicate a high level of similarity between geometry and topology for different galaxy samples and no clear evidence of evolutionary trends in network measures. The distribution of local clustering coefficient C manifests three modes which allow for discrimination between stand-alone singlets and dumbbells (0 <= C <= 0.1), intermediately (0 < C < 0.9) and clique (0.9 <= C <= 1) like galaxies. Analysing astrophysical properties of galaxies (colour index and stellar masses), we show that distributions are similar in all slices, however weak evolutionary trends can also be seen across redshift slices. To specify different topological environments we have extracted selections of galaxies from each sample according to different modes of C distribution. We have found statistically significant associations between evolutionary parameters of galaxies and selections of C: the distribution of stellar mass for galaxies with interim C differ from the corresponding distributions for stand-alone and clique galaxies, and this difference holds for all redshift slices. The colour index realises somewhat different behaviour.Comment: 12 pages, 8 figures, accepted for publication in Monthly Notices of the Royal Astronomical Societ

In defence of activities

In this paper, we examine what is to be said in defence of Machamer, Darden and Craver’s (MDC) controversial dualism about activities and entities (Machamer, Darden and Craver’s in Philos Sci 67:1–25, 2000). We explain why we believe the notion of an activity to be a novel, valuable one, and set about clearing away some initial objections that can lead to its being brushed aside unexamined. We argue that substantive debate about ontology can only be effective when desiderata for an ontology are explicitly articulated. We distinguish three such desiderata. The first is a more permissive descriptive ontology of science, the second a more reductive ontology prioritising understanding, and the third a more reductive ontology prioritising minimalism. We compare MDC’s entities-activities ontology to its closest rival, the entities-capacities ontology, and argue that the entities-activities ontology does better on all three desiderata

Shadow Places: Patterns of Spatial Concentration and Incorporation of Irregular Immigrants in the Netherlands

Summary: In Western countries, irregular immigrants constitute a sizeable segment of the population. By combining quantitative and qualitative research methods, this article describes and explains irregular immigrants’ patterns of spatial concentration and incorporation in the Netherlands. So far these spatial patterns have not been described and explained systematically, neither in the Netherlands nor elsewhere. The article shows that illegal residence is selectively embedded in the (urban) social structure in various ways. The authors argue that irregular immigrants are likely to be spatially concentrated and incorporated in similar ways in other Western countries; now and in the foreseeable future

Management system for optimizing public transport networks: GPS record

As cities continue to grow in size and population, the design of public transport networks becomes complicated, given the wide diversity in the origins and destinations of users [1], as well as the saturation of vehicle infrastructure in large cities despite their attempts to adapt it according to population distribution. This indicates that, in order to reduce users’ travel time, it is necessary to implement alternative road solutions to the use of cars, increasing investment in public transportation [2, 3] by conducting a comprehensive analysis of the state of transportation. This situation has made appear the solutions and development oriented to transportation based on Internet of Things (IoT) which allows, in a first stage, monitoring of public transport systems, in order to optimize the deployment of transport units and thus reduce the time of transfer of users through the cities [4]. These solution proposals are focused on information collected from user resources (data collected through smart phones) to create a common database [5]. The present study proposes the development of an intelligent monitoring and management system for public transportation networks using a hybrid communication architecture based on wireless node networks using IPv6 and cellular networks (LTE, LTE-M)