Search results for "theory of relativity"
showing 10 items of 61 documents
Relativistic holonomic fluids
1989
The notion of holonomic fluid in relativity is reconsidered. An intrinsic characterization of holonomic fluids, involving only the unit velocity, is given, showing that in spite of its dynamical appearance the notion of holonomic fluid is a kinematical notion. The relations between holonomic and thermodynamic perfect fluids are studied.
Introduction to Part IV
2018
When looking at the early development of relativity theory, one finds an astonishing number of contributions by mathematicians, some of which deeply influenced the work of leading theoretical physicists. Within the context of special relativity, Hermann Minkowski’s writings come immediately to mind (Walter 2008). Klein and Hilbert followed Minkowski’s ideas from their infancy, and both pursued some of their consequences after the latter’s premature death in January 1909. Two other figures with close ties to Gottingen, Max Born and Arnold Sommerfeld, were both instrumental in elaborating Minkowski’s 4-dimensional approach for physicists (Walter 2007). Born had been Minkowski’s assistant for …
Flat lightlike hypersurfaces in Lorentz–Minkowski 4-space
2009
Abstract The lightlike hypersurfaces in Lorentz–Minkowski space are of special interest in Relativity Theory. In particular, the singularities of these hypersurfaces provide good models for the study of different horizon types. We introduce the notion of flatness for these hypersurfaces and study their singularities. The classification result asserts that a generic classification of flat lightlike hypersurfaces is quite different from that of generic lightlike hypersurfaces.
Relativity and constituent quark structure in model calculations of parton distributions
2004
According to recent studies, Parton Distribution Functions (PDFs) and Generalized Parton Distributions (GPDs) can be evaluated in a Constituent Quark Model (CQM) scenario, considering the constituent quarks as composite objects. In here, a fully covariant model for a system of two particles, together with its non relativistic limit, are used to calculate PDFs and GPDs. The analysis permits to realize that by no means the effects of Relativity can be simulated taking into account the structure of the constituent particles, the two effects being independent and necessary for a proper description of available high energy data in terms of CQM.
Relativistic SU(6) wave functions as the basis of modern approaches to hadronic wave functions
1991
The connections between various models of hadrons and the relativistic SU(6) wave functions are established. In formal terms and by concrete example it is shown how the Bargman-Wigner fields of freely moving quarks and antiquarks of equal velocity form the basis of the above approaches. This places modern attempts in their historical setting and allows for a more unified analysis of the various schemes.
Radio mode feedback: Does relativity matter?
2017
Radio mode feedback, associated with the propagation of powerful outflows in active galaxies, is a crucial ingredient in galaxy evolution. Extragalactic jets are well collimated and relativistic, both in terms of thermodynamics and kinematics. They generate strong shocks in the ambient medium, associated with observed hotspots, and carve cavities that are filled with the shocked jet flow. In this Letter, we compare the pressure evolution in the hotspot and the cavity generated by relativistic and classical jets. Our results show that the classical approach underestimates the cavity pressure by a factor larger or equal to 2 for a given shocked volume during the whole active phase. The tensio…
Winteler, Jost (1846–1929)
2006
J Winteler was born in a village in the Swiss canton of Glarus. He studied philology in Jena, Germany. In his famous doctoral thesis, published in 1876, he described his native dialect of Kerenz. By analyzing the activity of the organs producing language (dialect) sounds, he was the founder of the so-called sound physiology (together with his teacher Eduard Sievers). In his prestructural approach, he noticed that there are sounds with and others without the capacity to change meaning. Purely structural terms were used already, such as Lautgegensatze (‘contrasts of sound’), (Sprach-)Bau ‘(linguistic) structure,’ and Konsonantensystem, Sprachsystem ‘system of consonants, of language.’ There w…
Electronic properties of graphene: A learning path for undergraduate students
2016
The purpose of this work is to present a learning path aimed at deepening student understanding of the fundamental concepts underlying the electronic properties of new materials, graphene in particular. To achieve this task, we propose a five-week long workshop where students may be introduced to fundamental concepts of advanced physics, rarely used in learning paths, such as the symmetry properties of the crystal lattice, the group theory , the features of the free electron wave functions and energy levels, the relativistic Dirac equation. Particular emphasis is given to the manner of introducing these concepts, since an essential knowledge of solid state physics, quantum physics and relat…
The Mathematicians’ Happy Hunting Ground: Einstein’s General Theory of Relativity
2004
There is hardly any doubt that for physics special relativity theory is of much greater consequence than the general theory. The reverse situation prevails with respect to mathematics: there special relativity theory had comparatively little, general relativity theory very considerable, influence, above all upon the development of a general scheme for differential geometry. —Hermann Weyl, “Relativity as a Stimulus to Mathematical Research,” pp. 536–537.
Ajan ja avaruuden käsitteet ovat sekä filosofiaa että fysiikkaa
2014
Tässä lehdessä on käyty kiivasta ja provokatiivistakin keskustelua suhteellisuusteoriasta. Edellisessä numerossa Juha Himanka (Tieteessä tapahtuu 3/2014) väittää, että Albert Einsteinin suhteellisuusteoria, erotuksena luonnontieteestä, on yksinomaan filosofiaa. Se ylittää hänen mukaansa luonnontieteen rajat pyrkiessään yleispätevään esitykseen todellisuudesta, ajasta ja avaruudesta. Hän myös pitää sitä fenomenologiseen tieteenkritiikkiinsä vedoten ongelmallisena. Toisaalta Kari Enqvist ja Syksy Räsänen (Tieteessä tapahtuu 3/2014) ovat korostaneet suhteellisuusteorian kiistatonta empiiristä tukea sekä siihen pohjaavan teknologian toimivuutta osoituksena teorian paikkansapitävyydestä. Esitän …