Gravitational Waves: Principles, Detection, and Recent Discoveries

In 1915, Einstein formulated his theory of general relativity. Among its many applications, gravitational waves have provided us with a unique window to observe the Universe. From the famous quadrupole formula—characterizing the radiation emitted by accelerating masses—to experimental advances such as Weber bars, interferometric detectors, and finally the first detection in 2015, our understanding of compact objects like black holes and neutron stars has evolved over the past decade.

In this talk, I will first introduce the basic theory behind the generation of gravitational waves. After arriving at the quadrupole formula, we will explore gravitational waveforms and the data-analysis techniques used to transform a trigger in the detector into a confident observable detection.

Finally, I will conclude by highlighting a few important signals from the Observation Run 3 (O3) and Observation Run 4 (O4) catalogues, and explain why these observations are transforming our understanding of compact objects, astrophysical populations, and fundamental physics.