Why Does LIGO Splits the Laser into Two Arms Instead of Three?

LIGO is a colossal interferometer at the forefront of gravitational wave detection. The decision to split the laser into two arms instead of three is a result of careful consideration and practical constraints. This article delves into the reasons behind this choice and explores the implications for the field of gravitational wave astronomy.

The Role of Interferometers in Gravitational Wave Detection

Understanding Interferometers: Interferometers, like LIGO, are sophisticated scientific instruments designed to measure minute changes in distance. They work by splitting a laser beam into two arms, which travel to mirrors and then recombine to form an interference pattern. Any small change in the distance between the mirrors due to gravitational waves can be detected.

The Benefits of Splitting the Laser into Two Arms

Enhanced Sensitivity and Multiple Detection Points: By splitting the laser into two arms, LIGO significantly enhances its sensitivity. Each arm can detect gravitational waves independently, providing redundancy and increasing the chances of accurate detection. This dual-armed setup ensures that any signal detected is robust and reliable.

The Challenges of Adding a Third Arm

Theoretical Versus Practical Considerations: In principle, adding a third arm perpendicular to the first two could provide additional coverage, filling in some gaps in the antenna pattern. However, this idea faces significant practical challenges. The construction of a 4 km tower with the necessary rigidity would be highly complex and costly, making it impractical.

Global Distribution of LIGO Detectors

The Optimal Solution: A Worldwide Network: Instead of constructing a third arm, LIGO has adopted a more practical approach by deploying multiple two-arm interferometers around the world. This global network increases the overall coverage and sensitivity, providing a more comprehensive detection capability.

Implementing LIGO in Japan and India

Collaborative Efforts: LIGO is currently active in Japan, with ongoing work and plans to establish the third LIGO detector in that country. India is also seriously considering installing a LIGO detector, which would complement the existing facilities and further enhance the global network.

Conclusion

While the idea of a third arm in LIGO seems appealing, the practical limitations make it unfeasible. Instead, the choice to split the laser into two arms and distribute detectors globally has proven to be the most effective strategy for gravitational wave detection. This approach ensures robust and reliable data collection, paving the way for significant scientific breakthroughs in the field of astronomy.

Keywords

LIGO, Interferometer, Laser Splitting