Sökning: "EINSTEIN"

Visar resultat 1 - 5 av 85 avhandlingar innehållade ordet EINSTEIN.

1. 1. Was Einstein Wrong? : Theoretical and observational constraints on massive gravity

   Författare :Marcus Högås; Edvard Mörtsell; David Mota; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Gravity; Massive gravity; Bimetric gravity; Cosmology; Gravitational collapse; Gravitational waves; Observational constraints; Theoretical Physics; teoretisk fysik;

   Sammanfattning : For more than a century, Einstein's theory of general relativity has described gravitational phenomena with astonishing precision. However, for the theory to fit observations we need to add two elusive substances: dark energy and dark matter. Together they add up to 95% of the energy budget of the Universe. LÄS MER

3. 2. The Chevreton Superenergy Tensor in Einstein-Maxwell Spacetimes

   Författare :Ingemar Eriksson; Göran Bergqvist; Paul Todd; Linköpings universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Einstein-Maxwell; graviational energy; superenergy; Bel tensor; Chevreton tensor; conservation laws; Conformal Einstein space; Theory of relativity; gravitation; Relativitetsteori; gravitation;

   Sammanfattning : In this thesis we investigate the superenergy tensor that was introduced by Chevreton in 1964 as an electromagnetic counterpart to the Bel-Robinson tensor for the gravitational feld.We show that in Einstein-Maxwell spacetimes with a source-free electromagnetic feld, the Chevreton superenergy tensor has many interesting properties. LÄS MER

4. 3. On the Einstein-Vlasov system

   Författare :Mikael Fjällborg; Alexander Bobylev; Markus Kunze; Karlstads universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Einstein-Vlasov system; finite extension; monotone functions; MATHEMATICS; MATEMATIK; Matematik; Mathematics;

   Sammanfattning : In this thesis we consider the Einstein-Vlasov system, which models a system of particles within the framework of general relativity, and where collisions between the particles are assumed to be sufficiently rare to be neglected. Here the particles are stars, galaxies or even clusters of galaxies, which interact by the gravitational field generated collectively by the particles. LÄS MER

5. 4. On the Einstein-Vlasov system: Stationary Solutions and Small Data Solutions with Charged and Massless Particles

   Författare :Maximilian Thaller; Chalmers tekniska högskola; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Static Solutions; Vector Field Method; non-linear wave equation; massless Einstein-Vlasov system; General Relativity; Conformal Einstein Field Equations; Minkowski stability; Vlasov matter; symmetric hyperbolic system; Einstein-Vlasov-Maxwell system;

   Sammanfattning : The Vlasov matter model describes an ensemble of collisionless particles moving through space-time. These particles interact via the gravitational field which they create collectively. In the framework of General Relativity this gravitational field is described by space-time curvature. LÄS MER

7. 5. Bose-Einstein Condensation of Magnetic Excitons in Semiconductor Quantum Wells

   Författare :Vitalie Boţan; Lars Nordström; Sveatoslav Moskalenko; Pavlos Lagoudakis; Uppsala universitet; []
   Nyckelord :Physics; Bose-Einstein condensation; magnetic excitons; electron-hole pairs; electron-hole liquid; magnetorotons; magnetoplasmons; superfluidity; Fysik;

   Sammanfattning : In this thesis regimes of quantum degeneracy of electrons and holes in semiconductor quantum wells in a strong magnetic field are studied theoretically. The coherent pairing of electrons and holes results in the formation of Bose-Einstein condensate of magnetic excitons in a single-particle state with wave vector K. LÄS MER