PHYS1160 Lecture Notes - Lecture 1: Cern, Dark Energy, Weakly Interacting Massive Particles
Document Summary
The subject of dark matter is still quite unknown. It is evident that midway between 1 and 15 billion years ago (7. 5 billion years), the universe experienced a change in its rate of expansion. It is theorised that this increase in rate of expansion, indicated by the marked flattening of the curvature in diagram 1, is caused by the presence of dark matter [1]. Diagram 1: change in rate of universe expansion over time [1] Historically, evidence shows that the velocity of orbiting stars was much faster than what should be expected if only visible matter was considered as contributing to the gravitational force. Thus, it is believed that there must be a large quantity of unknown material, called dark matter, to explain the incongruous gravitational attraction observed in astronomical structures, such as galaxies [2]. As explained above, the detection of dark matter is primarily based on observational evidence, i. e. its gravitational influence.
