Search results for "Einstein"

Seeing reality through Einstein's eyes: a teaching proposal for special relativity

2021

The teaching of Special Relativity is still a critical issue not only for students but also for teachers. In this paper, we describe the trial of a learning unit on the Special Relativity topic based on Minkowski's approach through spacetime diagrams, following the results in pedagogical researches in this field. The main innovation of our project consists of a mechanical instrument: it allows to physically and mechanically represent Lorentz’s transformations by hands, exploring the effects of a change of the reference frame. Teachers and students can deal “by eye” with unusual phenomena as the loss of simultaneity, time dilation, length contraction, relativistic addition of velocities and …

Paul Strand y las paradojas de la modernidad americana

2006

Entre Manhatta (1920), pionera sinfonía urbana co-realizada con Charles Sheeler, y Native Land (1942), pasando por Redes(1934), la obra del fotógrafo Paul Strand en el cinematógrafo fue fundamental, no sólo en su calidad de realizador, sino también de activista ante los conflictos sociales. Una parte sustancial de la historia de la historia de la izquierda norteamericana entre comienzos de los años treinta y la Segunda Guerra Mundial tiene su índice privilegiado en los avatares estéticos, técnicos, políticos, asociativos y de producción de Paul Strand. El presente texto analiza los tres films citados en relación con los movimientos estéticos y sociales de cada coyuntura norteamericana, trat…

Applications of light-matter interaction in nanosciences

2009

In this thesis, light matter interaction in nanoscale has been studied from various aspects. The interaction between surface plasmon polaritons (SPPs) and optically active organic molecules (Rhodamine 6G, Sulforhodamine 101 and Coumarine 30) and semiconducting nanocrystals (quantum dots) is studied in the weak coupling regime. In particular, a photon-SPP-photon conversion with spatially separated inand outcoupling was demonstrated by using molecules. Also, a frequency downconversion for propagating SPPs was presented by utilization of vibrational relaxation of organic molecules. A strong coupling regime was reached for Rhodamine 6G (R6G) and SPP despite the broad absorption linewidth of R6G…

Ricci Tensors on Some Infinite Dimensional Lie Algebras

1999

Abstract The Ricci tensor has been computed in several infinite dimensional situations. In this work, we shall be interested in the case of the central extension of loop groups and in the asymptotic behaviour of the Ricci tensor on free loop groups as the Riemannian metric varies.

Three-dimensional splitting dynamics of giant vortices in Bose-Einstein condensates

2018

We study the splitting dynamics of giant vortices in dilute Bose-Einstein condensates by numerically integrating the three-dimensional Gross-Pitaevskii equation in time. By taking advantage of tetrahedral tiling in the spatial discretization, we decrease the error and increase the reliability of the numerical method. An extensive survey of vortex splitting symmetries is presented for different aspect ratios of the harmonic trapping potential. The symmetries of the splitting patterns observed in the simulated dynamics are found to be in good agreement with predictions obtained by solving the dominant dynamical instabilities from the corresponding Bogoliubov equations. Furthermore, we observe…

On Einstein bilinear form

2012

From physical motivations and from geometrical interpretations of the Einstein equations, we give a justi cation of the non-triviality and non-degeneracy of Einstein bilinear form introduced in [1].

Landau‐Zener transition for association of an atomic Bose‐Einstein condensate with interparticle elastic interactions included.

2008

Airy-function approach to binary black hole merger waveforms: The fold-caustic diffraction model

2022

From numerical simulations of the Einstein equations, and also from gravitational wave observations, the gravitational wave signal from a binary black hole merger is seen to be simple and to possess certain universal features. The simplicity is somewhat surprising given that non-linearities of general relativity are thought to play an important role at the merger. The universal features include an increasing amplitude as we approach the merger, where transition from an oscillatory to a damped regime occurs in a pattern apparently oblivious to the initial conditions. We propose an Airy-function pattern to model the binary black hole (BBH) merger waveform, focusing on accounting for its simpl…

Time as an Empirical Concept in Special Relativity

2019

According to a widespread view, Einstein’s definition of time in his special relativity is founded on the positivist verification principle. The present paper challenges this received outlook. It argues that Einstein’s position on the concept of time, to wit, simultaneity, is best understood as a mitigated version of concept empiricism. He contrasts his position to Newton’s absolutist and Kant’s transcendental arguments, and in part sides with Hume’s and Mach’s empiricist arguments. Nevertheless, Einstein worked out a concept empiricism that is considerably more moderate than what we find in the preceding empiricist tradition and early logical positivism. He did not think that the origin of…

Freeze-out radii extracted from three-pion cumulants in pp, p–Pb and Pb–Pb collisions at the LHC

2014

In high-energy collisions, the spatio-temporal size of the particle production region can be measured using the Bose-Einstein correlations of identical bosons at low relative momentum. The source radii are typically extracted using two-pion correlations, and characterize the system at the last stage of interaction, called kinetic freeze-out. In low-multiplicity collisions, unlike in high-multiplicity collisions, two-pion correlations are substantially altered by background correlations, e.g. mini-jets. Such correlations can be suppressed using three-pion cumulant correlations. We present the first measurements of the size of the system at freeze-out extracted from three-pion cumulant correl…