Jannes, Gil

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Universidad Complutense de Madrid
Faculty / Institute
Ciencias Económicas y Empresariales
Economía Financiera, Actuarial y Estadística
Estadística e Investigación Operativa
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Now showing 1 - 10 of 11
  • Publication
    Hawking versus Unruh effects, or the difficulty of slowly crossing a black hole horizon
    (Springer, 2016-10-28) Barbado, Luis C.; Barceló, Carlos; Garay Elizondo, Luis Javier; Jannes, Gil
    When analyzing the perception of Hawking radiation by different observers, the Hawking effect becomes mixed with the Unruh effect. The separation of both effects is not always clear in the literature. Here we propose an inconsistency-free interpretation of what constitutes a Hawking effect and what an Unruh effect. An appropriate interpretation is important in order to elucidate what sort of effects a detector might experience depending on its trajectory and the state of the quantum field. Under simplifying assumptions we introduce an analytic formula that separates these two effects. Armed with the previous interpretation we argue that for a free-falling detector to cross the horizon without experiencing high-energy effects, it is necessary that the horizon crossing is not attempted at low velocities.
  • Publication
    Influence of Service Valuation and Package Cost on Market Segmentation: The Case of Online Demand for Spanish and Andorra Ski Resorts
    (MPDI, 2021-02-24) Barreal, Jesús; Ferrer-Rosell, Berta; Cristobal-Fransi, Eduard; Jannes, Gil
    Ski resorts are important tourist resources in mountain areas. They have a high impact on the environment but also on the development of the territory. Corporate social responsibility management plays an important role in influencing consumer purchasing behavior. This research seeks to understand the behavior of ski tourists and to classify them. Approximately 50,000 online purchases of tourist packages to ski resorts in Spain and Andorra are analyzed in order to describe the different segments of demand in these resorts through a latent class model. The tourists’ age and previous experience, the type of accommodation, and the season—among other variables—are considered to clarify the different classes. Six different segments were found. Some relevant results for the online ski-package market are highlighted, such as the influence of skier’s expenditure on service valuation. Managerial implications, limitations of this study and recommendations for future research are also discussed.
  • Publication
    Emergent gravity: the BEC paradigm
    (Universidad Complutense de Madrid, Servicio de Publicaciones, 2009-12-10) Jannes, Gil; Barceló Serón, Carlos; Garay Elizondo, Luis. J.
    We study selected aspects of quantum gravity phenomenology inspired by the gravitational analogy in Bose–Einstein condensates (BECs). We first review the basic ideas and formalism of analogue gravity in BECs, with particular emphasis on the possibility of simulating black holes. We stress that the dispersion relation in a BEC has a relativistic form in the hydrodynamic limit, and acquires non-relativistic, ‘superluminal’ modifications at high frequencies. This makes it a particularly interesting model for many scenarios of quantum gravity phenomenology which consider a possible violation of local Lorentz invariance at high energies. In particular, it allows the study of kinematical corrections that such quantum gravity scenarios could impose on general relativity.
  • Publication
    Quantum non-gravity and stellar collapse
    (Springer, 2011-09) Barceló, Carlos; Garay Elizondo, Luis Javier; Jannes, Gil
    Observational indications combined with analyses of analogue and emergent gravity in condensed matter systems support the possibility that there might be two distinct energy scales related to quantum gravity: the scale that sets the onset of quantum gravitational effects E-B ( related to the Planck scale) and the much higher scale E-L signalling the breaking of Lorentz symmetry. We suggest a natural interpretation for these two scales: E-L is the energy scale below which a special relativistic spacetime emerges, E-B is the scale below which this spacetime geometry becomes curved. This implies that the first 'quantum' gravitational effect around E-B could simply be that gravity is progressively switched off, leaving an effective Minkowski quantum field theory up to much higher energies of the order of E-L. This scenario may have important consequences for gravitational collapse, inasmuch as it opens up new possibilities for the final state of stellar collapse other than an evaporating black hole.
  • Publication
    Estrategia de gamificación aplicada a métodos estadísticos en el proceso de aprendizaje en enseñanzas turísticas
    (2020-01-23) Barreal Pernas, Jesús; Jannes, Gil; Albert García, Carlos; Vela Pérez, María; Gutiérrez Salinero, María Ángeles; López Fernández, Angel Luis; Arroyo Barrigüete, José Luis; Montiel Ben Allal, Nora; Agustín Herrera, Alma; Suarez-Varela Marti, Olga; Krak, Darya; González Gutiérrez, Nebiur; Ferrando Aguirre, Daniel; López Domingo, Belén; Lluna Taverner, Francisco José; Cisneros Martínez, José David
  • Publication
    The trans-Planckian problem as a guiding principle
    (Int School Advanced Studies, 2011-11) Barbado, L. C.; Barceló, C.; Garay Elizondo, Luis Javier; Jannes, Gil
    We use the avoidance of the trans-Planckian problem of Hawking radiation as a guiding principle in searching for a compelling scenario for the evaporation of black holes or black-hole-like objects. We argue that there exist only three possible scenarios, depending on whether the classical notion of long-lived horizon is preserved by high-energy physics and on whether the dark and compact astrophysical objects that we observe have long-lived horizons in the first place. Along the way, we find that i) a theory with high-energy superluminal signalling and a long-lived trapping horizon would be extremely unstable in astrophysical terms and that i i) stellar pulsations of objects hovering right outside but extremely close to their gravitational radius can result in a mechanism for Hawking-like emission.
  • Publication
    Spatial and Temporal Wildfire Decomposition as a Tool for Assessment and Planning of an Efficient Forest Policy in Galicia (Spain)
    (MDPI, 2020-07-27) Barreal Pernas, Jesús; Jannes, Gil
    Wildfires in Galicia have various temporal and spatial trends. This temporal and spatial behavior must therefore be studied and taken into account in order to design more efficient forest policies. Since both factors are inhomogeneous, it was proposed to study them using a Gini index decomposition. The number of fires and the affected forest area were studied in terms of the months and the forest districts, which serve as basic temporal and spatial elements. The objective of this methodology is to know the months in which the fires are most concentrated throughout the administrative geographical districts of the various provinces of Galicia, and the elasticity of each month with respect to the global concentration. It is also used to know the temporal inequality in each forest district of Galicia and its contribution to the global index. To apply this methodology, monthly data are taken from 2006 to 2015 for each of the Galician forest districts. It is found that there is a high spatial concentration of fires in the autumn and winter months, and a much lower one in the remaining months. On the other hand, most districts register a great temporal inequality in the occurrence of fires. Tentative suggestions of how the forest policy in Galicia could be improved by taking into account both these spatial and temporal patterns are discussed.
  • Publication
    Chronology protection implementation in analogue gravity
    (Springer, 2022-04-06) Barceló, Carlos; Eguia Sánchez, Jokin; García Moreno, Gerardo; Jannes, Gil
    Analogue gravity systems offer many insights into gravitational phenomena, both at the classical and at the semiclassical level. The existence of an underlying Minkowskian structure (or Galilean in the non-relativistic limit) in the laboratory has been argued to directly forbid the simulation of geometries with Closed Timelike Curves (CTCs) within analogue systems. We will show that this is not strictly the case. In principle, it is possible to simulate spacetimes with CTCs whenever this does not entail the presence of a chronological horizon separating regions with CTCs from regions that do not have CTCs. We find an Analogue-gravity Chronology protection mechanism very similar in spirit to Hawking’s Chronology Protection hypothesis. We identify the universal behaviour of analogue systems near the formation of such horizons and discuss the further implications that this analysis has from an emergent gravity perspective. Furthermore, we build explicit geometries containing CTCs, for instance spacetimes constructed from two warp-drive configurations, that might be useful for future analysis, both from a theoretical and an experimental point of view.
  • Publication
    Conceptual Challenges on the Road to the Multiverse
    (MDPI, 2019) Alonso Serrano, Ana; Jannes, Gil
    The current debate about a possible change of paradigm from a single universe to a multiverse scenario could have deep implications on our view of cosmology and of science in general. These implications therefore deserve to be analyzed from a fundamental conceptual level. We briefly review the different multiverse ideas, both historically and within contemporary physics. We then discuss several positions within philosophy of science with regard to scientific progress, and apply these to the multiverse debate. Finally, we construct some key concepts for a physical multiverse scenario and discuss the challenges this scenario has to deal with in order to provide a solid, testable theory.
  • Publication
    Experiential Learning: Interpretación socioeconómica del Covid-19 desde el aula a la práctica empírica
    (2021-08) Jannes, Gil; Amundaray Carmona, Samai; Encabo Herrera, Víctor; Ferrer Caja, José María; Morales Chinea, Ainhoa; Ribes Rossiñol De Zagranada, Juan; Riego Miedes, Enrique; Usar Artiles, Alejandro; Veintemillas Fernández, Víctor
    Memoria final del proyecto de Innovación Docente nº 416