Horizon Season 2015 Episode 2 Aftershock: The Hunt for Gravitational Waves

Aftershock: The Hunt for Gravitational Waves is an episode of the science documentary series Horizon, aired in 2015. This episode explores the groundbreaking discovery of gravitational waves, which are ripples in the fabric of space-time caused by violent cosmic events such as the collision of black holes.

The episode starts by introducing the LIGO (Laser Interferometer Gravitational-Wave Observatory) project, which involves the construction of two identical detectors in the United States to detect gravitational waves. The detectors work by using laser beams to measure incredibly small changes in the length of the arms of their enormous L-shaped structures, caused by the passing of a gravitational wave. The episode covers the background of LIGO, including the initial construction of the sites and the funding issues that cropped up over the years.

The episode further examines the challenges of detecting gravitational waves and the quest to make the detectors more sensitive. The researchers face the challenge of filtering out natural vibrations, and so must construct LIGO in such a way that it's totally isolated from its environment. This isolation is necessary since any vibrations or interference could disturb the incredibly precise measurement needed to detect gravity waves.

The episode also delves into the history of gravitational waves research, starting with Einstein's prediction of their existence in his theory of general relativity. Einstein believed that the waves were so weak that they'd be impossible to detect. Other physicists over the years tried to pick up gravitational signals without any success, so many researchers believed that the phenomenon didn’t exist at all.

However, this all changed in 2015, when LIGO detected a gravitational wave for the first time. Thanks to a new, upgraded system, LIGO captured the collision of two black holes over a billion light-years away. This historic discovery is widely viewed as the birth of a new era of astronomy, where scientists will be able to see the universe in an entirely new way.

The episode highlights the moment of the discovery and the excitement it created among the researchers involved in the project. The programme speaks to some of the scientists who have spent decades working on the project and captures their emotional reactions to the actual discovery of the gravitational waves. The discovery confirmed the existence of gravitational waves and validated Einstein's theory of general relativity.

The programme also explains how the discovery can be used to further study the universe, such as exploring the violent formation of some of the universe's most mysterious objects and testing alternative theories to relativity.

The Aftershock: The Hunt for Gravitational Waves episode is a fascinating and informative look into a remarkable discovery and the many researchers who worked tirelessly to make it happen. It shows the remarkable efforts and ingenuity it took to construct the detectors, and explains why the discovery of gravitational waves is so essential to our understanding of the universe. The future implications of this groundbreaking discovery in physics, astrophysics, and astronomy are sure to be staggering.