How does Quadruple Pendulum isolate LIGO from Seismic Vibrations?

In summary: JhA4vZc9ZsIIn summary, Dr. Rainer Weiss, 2017 Nobel Prize winner for Physics, gave a lecture at the Ontario Science Centre on his work with the Laser Interferometer Gravitational-Wave Observatory (LIGO). He discussed the use of quadruple pendulums in LIGO to isolate mirrors from seismic vibrations and encouraged the audience to make their own pendulums at home. The group behind the website hotpoprobot.com took up this challenge and presented their experiment at a meeting of the Royal Astronomical Society of Canada. They also have a video available on their website demonstrating the pendulum in action.
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nvikas
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On 28 November 2018, a lecture was given by Dr. Rainer Weiss (2017 Nobel Prize Winner for Physics) at the Ontario Science Centre, Toronto. The lecture was about his work with the Laser Interferometer Gravitational-Wave Observatory (LIGO).

In his lecture talked about quadruple pendulums or four pendulums vertically stacked one below the other. LIGO uses such pendulums to isolate its mirrors from seismic vibrations. Gravitational Waves and Seismic Vibrations have overlaps in frequencies.

He encouraged the audience to make a quadruple pendulum using washers and strings to see for themselves how they worked. We took up this challenge and planned an experiment around it. The best way to learn science is by doing an experiment.

We made a quadruple pendulum and added accelerometers to it, to get change in motion data at each stage. After the experiment, it became clear to us how the quadruple pendulum works and why it is used in LIGO.

Check our experiment and data:
https://hotpoprobot.com/2019/04/07/ligo/

 
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Very nice home experiment. Do you also have some video showing the pendulum in action? I can only see still images from your homepage.
 
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Orodruin said:
Very nice home experiment. Do you also have some video showing the pendulum in action? I can only see still images from your homepage.
Thanks. At this moment, we do not have any videos. But we will record them once we run this experiment again.
 
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On 22 May 2019, we gave a presentation on our project:
How does Quadruple Pendulum isolate LIGO from Seismic Vibrations? at the meeting of the Royal Astronomical Society of Canada -Toronto at the Ontario Science Centre.

The video of the presentation: which show the pendulum in action, and live data being gathered is available at:

Complete details about the project are available at:
https://hotpoprobot.com/2019/04/07/ligo/
 
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Very nice presentation, @nvikas !

Thanks for sharing
 
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Orodruin said:
Very nice home experiment. Do you also have some video showing the pendulum in action? I can only see still images from your homepage.

Thanks. We now have the video available based on the presentation we gave at the Ontario Science Centre. It can be viewed at:
 
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1. How does a Quadruple Pendulum work?

A Quadruple Pendulum is a type of pendulum that consists of four pendulums connected together. The top pendulum is attached to a fixed point, while the other three pendulums are attached to the bottom of the previous pendulum. This design allows the pendulum to move freely in multiple directions, making it highly sensitive to vibrations.

2. How does a Quadruple Pendulum isolate LIGO from seismic vibrations?

The Quadruple Pendulum is designed to reduce the impact of seismic vibrations on the LIGO detectors. The multiple pendulum design allows the pendulum to move in a direction opposite to the vibrations, canceling out their effects. This helps to isolate the detectors from any ground vibrations, allowing them to accurately measure gravitational waves.

3. What materials are used to make the Quadruple Pendulum?

The Quadruple Pendulum is made up of high-quality materials such as steel, aluminum, and tungsten. These materials are chosen for their strength, durability, and low thermal expansion, which is crucial for the precise measurements needed in LIGO.

4. How does the Quadruple Pendulum reduce thermal noise in LIGO?

The Quadruple Pendulum is designed to reduce thermal noise in LIGO by using materials with low thermal expansion. This helps to minimize any movement caused by changes in temperature, which can affect the accuracy of the measurements. Additionally, the design of the pendulum allows it to dissipate any remaining thermal energy, further reducing thermal noise.

5. What is the role of the Quadruple Pendulum in the LIGO experiment?

The Quadruple Pendulum plays a crucial role in the LIGO experiment as it isolates the detectors from external vibrations and reduces thermal noise. This allows the detectors to accurately measure the minute gravitational waves passing through the Earth, providing valuable insights into the nature of the universe.

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