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What Is Dark Matter? Roughly 80% of the mass of the universe is made up of material that scientists cannot directly observe. Known as dark matter, this bizarre ingredient does not emit light or energy. So why do scientists think it dominates? Since at least the 1920s, astronomers have hypothesized that the universe contains more matter than seen by the naked eye. Support for dark matter has grown since then, and although no solid direct evidence of dark matter has been detected, there have been strong possibilities in recent years. "Motions of the stars tell you how much matter there is," Pieter van Dokkum, a researcher at Yale University, said in a statement. "They don't care what form the matter is, they just tell you that it's there." Van Dokkum led a team that identified the galaxy Dragonfly 44, which is composed almost entirely of dark matter. The familiar material of the universe, known as baryonic matter, is composed of protons, neutrons and electrons...

Introduction to Quantum Field Theory in Curved Spacetime Prerequisites, Timetable, Outline, Literature, and more ... Summary and Overview The main aim of this course is to explain what are (some of) the obstacles that one faces when trying to generalise the standard formalism and procedures of Minkowski space Poincare-covariant QFT to curved spacetimes, and to illustrate the new phenomena that one encounters by some typical and important examples: particle creation by time-dependent gravitational fields, the Unruh effect, and (some elementary aspects of) Hawking black hole radiation and black hole thermodynamics. Many of the key-issues can already be understood in a purely quantum-mechanical context by studying the Heisenberg picture quantisation of a time-dependent harmonic oscillator, so I will spend some time to discuss the issue of quantisation ambiguities, Bogoliubov transformations, mode creation etc., in this setting. When moving on to field theory, we will consider the simplest...