I’ve just finished Jörg Frauendiener’s, “On the applicability of constrained symplectic integrators in general relativity”. It’s a readable paper (the necessary background is given in the paper) about numerical integration in Hamiltonian systems. The idea here is that if we have a symplectic manifold modelling the states of some system of ODE’s, along with a …
Category Archive: General Relativity
What do we really know about Dark Energy?
I refer you to Ruth Durrer’s very readable (and short) paper with the same title as above. The main point of the paper is that all evidence for Dark Energy comes from the measurement of luminosity distance as a function of redshift and that energy/matter content of the universe is then inferred from this measurement …
Analytic work on constraint quantities lacking?
The paper provides a general introduction to how to perform analysis of the attractors of some dynamical system (with specified initial conditions) and then applies this to a particular initial value formulation of Einstein’s equations.
Taking another look at gravitational fields at infinity
I’ve now read lots more about spinors and vector bundles and am feeling far more confident about understanding exactly what Friedrich is up to. I’m aiming to provide a post on each major section (and sometimes subsection) to both help me and maybe you (assuming anyone reads this!). So the introduction. It makes a lot …
Is general relativity “essential understood”?
Predictably the papers answer is no. Why? Because current numerical methods in general relativity are limited. The paper implies that these limitations are Inability to compute global solutions Inability to evolve initial data for strongly gravitating and very dynamic systems. In any case Friedrich then divides the field equations to four classes the system of …