Introduction to LIGO

LIGO (Laser Interferometer Gravitational-Wave Observatory) is a scientific collaboration of over a thousand physicists and engineers from around the world to detect gravitational waves. Gravitational waves are ripples in the fabric of space-time caused by violent cosmic events such as colliding black holes or neutron stars. LIGO has two identical detectors located in Hanford, Washington, and Livingston, Louisiana, in the United States. The detectors use laser interferometry to measure the infinitesimal strains caused by gravitational waves.

How LIGO detects gravitational waves

LIGO consists of two perpendicular arms, each about 4 kilometers long, with mirrors at the end of each arm. A laser beam is split into two and travels down the arms, bouncing off the mirrors and returning to the central splitter. If both beams return in phase, they interfere constructively and produce a bright fringe. If the phases are shifted by even a fraction of a wavelength, the beams interfere destructively and produce a dark fringe. When a gravitational wave passes through the detector, it causes the arms to stretch and squeeze by a tiny amount, changing the relative lengths of the two beams. This causes a phase shift that can be detected by the interference pattern. By analyzing the interference pattern, scientists can determine the frequency and amplitude of the gravitational waves.

The impact of LIGO’s discoveries

LIGO’s first detection of gravitational waves in 2015 confirmed a prediction made by Albert Einstein exactly 100 years earlier. This discovery earned three LIGO pioneers the Nobel Prize in Physics in 2017. LIGO has since detected several other gravitational waves, providing unprecedented insights into the universe’s most extreme events, such as the merger of two black holes or neutron stars. Gravitational wave astronomy has opened up a new window to the universe, allowing scientists to observe events that were previously invisible to traditional telescopes.

Future developments for LIGO and gravitational wave research

LIGO is currently undergoing an upgrade to increase its sensitivity and detection capabilities. This upgrade, called Advanced LIGO, is expected to be completed in 2022. LIGO also plans to expand its network of detectors worldwide, including the construction of a new detector in India called LIGO-India. The expansion of LIGO’s network will help localize the sources of gravitational waves more precisely and provide more accurate measurements of their properties. The future of gravitational wave astronomy is promising, with the potential for new discoveries that could revolutionize our understanding of the universe.