Sökning: "Cosmology: theory"

Visar resultat 1 - 5 av 65 avhandlingar innehållade orden Cosmology: theory.

1. 1. String Theory at the Horizon : Quantum Aspects of Black Holes and Cosmology

   Författare :Martin Olsson; Ulf Danielsson; Lárus Thorlacius; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Theoretical physics; theoretical physics; string theory; black holes; cosmology; de Sitter space; c=1 matrix models; 2D string theory; topological string theory; conifolds; 4D BPS black holes; Gödel universe; closed time-like curves; Teoretisk fysik; Physics; Fysik;

   Sammanfattning : String theory is a unified framework for general relativity and quantum mechanics, thus being a theory of quantum gravity. In this thesis we discuss various aspects of quantum gravity for particular systems, having in common the existence of horizons. LÄS MER

3. 2. Gravitational perturbations in plasmas and cosmology

   Författare :Mats Forsberg; Gert Brodin; Michael Bradley; Christopher Clarkson; Umeå universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; general relativity; cosmology; gravitational waves; plasma; electromagnetic waves; nonlinear waves; Plasma physics; Plasmafysik; Theory of relativity; gravitation; Relativitetsteori; gravitation; Cosmology; Kosmologi; teoretisk fysik; Theoretical Physics;

   Sammanfattning : Gravitational perturbations can be in the form of scalars, vectors or tensors. This thesis focuses on the evolution of scalar perturbations in cosmology, and interactions between tensor perturbations, in the form of gravitational waves, and plasma waves. LÄS MER

4. 3. Cosmoparticle Physics and String Theory

   Författare :Stefan Sjörs; Marcus Berg; Joseph Conlon; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Supersymmetry; dark matter; cosmology; inflation; modifications of gravity; string theory; flux compactifications; perturbative string theory; teoretisk fysik; Theoretical Physics;

   Sammanfattning : This thesis deals with phenomenological and theoretical aspects of cosmoparticle physics and string theory. There are many open questions in these topics. In connection with cosmology we would like to understand the detailed properties of dark matter, dark energy, generation of primordial perturbations, etc. LÄS MER

5. 4. Vacua in String Theory : de Sitter Space and Stability in Flux Compactifications

   Författare :Sergio C. Vargas; Ulf Danielsson; Alessandro Tomasiello; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; String theory; Cosmology; Flux Compactifications; Landscape; Swampland;

   Sammanfattning : Our understanding of cosmology has evolved radically in the last decades. Current models demand the presence of dark energy in our universe and the most favored candidate behind this component is a small positive cosmological constant that characterizes a de Sitter (dS) spacetime. LÄS MER

7. 5. Core-collapse Supernovae : Theory vs. Observations

   Författare :Dennis Alp; Josefin Larsson; Sergey Tsygankov; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Astrophysics; Supernovae; Fysik; Physics;

   Sammanfattning : A core-collapse supernova (CCSN) is an astronomical explosion that indicates the death of a massive star. The iron core of the star collapses into either a neutron star or a black hole while the rest of the material is expelled at high velocities. LÄS MER