115,901 research outputs found
About quantum fluctuations and holographic principle in (4+n)-dimensional spacetime
In the article we present explicit expressions for quantum fluctuations of
spacetime in the case of -dimensional spacetimes, and consider their
holographic properties and some implications for clocks, black holes and
computation. We also consider quantum fluctuations and their holographic
properties in ADD model and estimate the typical size and mass of the clock to
be used in precise measurements of spacetime fluctuations. Numerical
estimations of phase incoherence of light from extra-galactic sources in ADD
model are also presented.Comment: 5 page
Towards a holographic theory of cosmology -- threads in a tapestry
In this Essay we address several fundamental issues in cosmology: What is the
nature of dark energy and dark matter? Why is the dark sector so different from
ordinary matter? Why is the effective cosmological constant non-zero but so
incredibly small? What is the reason behind the emergence of a critical
acceleration parameter of magnitude in galactic dynamics? We
suggest that the holographic principle is the linchpin in a unified scheme to
understand these various issues.Comment: 8 pages, LaTeX; This Essay, dedicated to the memory of Hendrik van
Dam, received Honorable Mention in the 2013 Essay Competition of the Gravity
Research Foundatio
Critique of proposed limit to space--time measurement, based on Wigner's clocks and mirrors
Based on a relation between inertial time intervals and the Riemannian
curvature, we show that space--time uncertainty derived by Ng and van Dam
implies absurd uncertainties of the Riemannian curvature.Comment: 5 pages, LaTex, field "Author:" correcte
Solid state morphology and band gap studies of ETS-10 supported CdS nanoparticles
Engelhard titanosilicate (ETS-10) supported cadmium sulphide (CdS) nanoparticles were synthesized and characterized by various solid state techniques including: XRD, DR UV-Vis, TEM and FESEM. The effect of different synthesis routes of CdS nanoparticles on its physicochemical character was studied. It was observed that CdS nanoparticles prepared by both in situ sulphur reduction (CdS-IS) and reverse micelle (CdS-RM) methods showed similar properties. However, CdS-IS nanoparticles are more feasible and economically practical. The reflectance measurements of the as-synthesized CdS nanoparticles are apparently blue-shifted compared to bulk CdS. This phenomenon of blue-shifted absorption edge has been ascribed to an increase in bandgap energy with a decrease in particle sizes. The bandgap of the as-synthesized CdS samples was calculated from the linear correlation of [F(R) h?]2 and h?. The bandgap of CdS in ETS-10 was noticeably slightly reduced when compared with the as-synthesized CdS (8 nm) due to the formation of cluster arrays on the pores of ETS-10
Spacetime Foam, Holographic Principle, and Black Hole Quantum Computers
Spacetime foam, also known as quantum foam, has its origin in quantum
fluctuations of spacetime. Arguably it is the source of the holographic
principle, which severely limits how densely information can be packed in
space. Its physics is also intimately linked to that of black holes and
computation. In particular, the same underlying physics is shown to govern the
computational power of black hole quantum computers.Comment: 8 pages, LaTeX; Talk given by Jack Ng, in celebration of Paul
Frampton's 60th birthday, at the Coral Gables Conference (in Fort Lauderdale,
Florida on December 17, 2003). To appear in the Proceedings of the 2003 Coral
Gables Conferenc
Analyse contextuelle pour un projet de numérisation des archives du Service du développement territorial de l'Etat de Vaud
La Division Hors zone Ă bĂątir arrive actuellement Ă saturation des espaces de stockage de ses archives. De plus, en 2018, tout le service va ĂȘtre dĂ©mĂ©nagĂ©. LâimplĂ©mentation dâun rĂ©fĂ©rentiel documentaire pour la gestion et le stockage des documents Ă©lectroniques est prĂ©vue pour 2020. Durant cette pĂ©riode transitoire, la division a rapidement besoin de numĂ©riser ses documents et de passer Ă la dĂ©matĂ©rialisation de ses processus mĂ©tiers. Ces dossiers doivent pouvoir ĂȘtre stockĂ©s dans un environnement facile dâaccĂšs et sĂ©curisĂ©. Relatifs aux demandes de construction et dâinstallations sur des terrains hors des zones Ă bĂątir, ils doivent ĂȘtre conservĂ©s depuis 1972. Le tout doit ĂȘtre en adĂ©quation avec la lĂ©gislation pour que les documents numĂ©riques aient la mĂȘme valeur de preuve que les documents papier. A noter Ă©galement que le secrĂ©tariat de la division fait face Ă une rĂ©organisation de ses tĂąches. Ainsi un Ă©tat de lâart a Ă©tĂ© fait en interne et auprĂšs des autres organisations cantonales concernant les demandes de permis de construire. Cette Ă©tude a permis de mettre en lumiĂšre les diffĂ©rentes pratiques en vigueur au sein de ces institutions, ainsi que leurs lacunes. Etudier la lĂ©gislation et les normes en vigueur est une partie importante du travail. De plus, un processus de base de la numĂ©risation a Ă©tĂ© exposĂ© avec les diffĂ©rents scĂ©narios qui sâoffrent Ă la division. Tous les outils nĂ©cessaires Ă la gestion, la numĂ©risation et la dĂ©matĂ©rialisation sont dĂ©crits. De ce fait, un scĂ©nario en particulier se distingue afin de procĂ©der Ă une numĂ©risation des documents dâarchives de la division. Cela pourra se faire au fur et Ă mesure selon les besoins des collaborateurs de la Division HZB. Ce processus est conforme aux exigences de la conservation Ă valeur de preuve sur le long terme en lien avec la dĂ©matĂ©rialisation. Cela est possible grĂące Ă lâintĂ©gration dâun certain nombre dâoutils, de matĂ©riel et de logiciels adĂ©quats. De plus, pour la phase transitoire, sâajoute le fait de pouvoir sâassurer, auprĂšs de la Direction des systĂšmes dâinformations de lâEtat de Vaud, que les documents numĂ©riques soient en sĂ©curitĂ©. Tous ces Ă©lĂ©ments assurent un stockage des documents Ă©lectroniques sur le long terme, pour prĂ©server leur intĂ©gritĂ© et leur conformitĂ© aux originaux papiers. Ils permettent dâĂȘtre en adĂ©quation avec le futur systĂšme de gestion et de stockage des documents Ă©lectroniques de la Direction des systĂšmes dâinformation prĂ©vu pour 2020, ainsi que le systĂšme dâarchivage Ă©lectronique Ă venir des Archives cantonales vaudoises
Physics of computation and light sheet concept in the measurement of (4+n)-dimensional spacetime geometry
We analyze the limits that quantum mechanics imposes on the accuracy to which
-dimensional spacetime geometry can be measured. Using physics of
computation and light sheet concept we derive explicit expressions for quantum
fluctuations and explore their cumulative effects for various spacetime foam
models.Comment: 5 page
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