100 years after Einstein's theory for gravitational waves, Laser Interferometer Gravitational Wave Observatory (LIGO) has successfully detected the gravitational waves. The signal came from a binary black hole coalescence 1.3 billion years ago. The monumental discovery opens a new era for gravitational waves astronomy. In this casual chat, Tsing Hua alumni Prof. Chao of the EE Department and Photonic Technologies Institute, will introduce the background and basic principle for he detection.
