Gravitational waves as a way to observe the cosmos

Abstract

This thesis aims to provide a literature review of gravitational-wave astronomy, serving as a bachelor-level introduction to the subject. Gravitational waves are wave-like disturbances of space-time. Those are like waves in the ocean. Gravitational waves are an implication of the theory of general relativity by Albert Einstein. In this theory, gravity is a curvature of space-time that is caused by a mass-energy, so two objects orbiting each other emit disturbance through space-time because of the nature of gravity. Because mass-energy curves space-time also the gravitational waves must be a form of mass-energy as well as light and by observing the energy, we can study the energy source. Gravitational waves are a good way to study phenomena where a lot of light is not emitted. A good example of such a phenomenon is the collapse of a binary black hole. Black holes are difficult to observe because they do not emit light like normal stars. The first directly observed gravitational waves were from such an event. This observation happened on the 14th of September 2015. Gravitational-wave astronomy is a new field of astronomy in the empirical perspective. There are about 100 so-called events where gravitational waves are observed. But from the theoretical point of view, one may think gravitational wave astronomy is a roughly one-hundred-year-old field in astronomy starting from the publication of the theory of general relativity.