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Can gravitational waves be detected on Earth, and if so, how?

Kalene Vaughan

Yes, gravitational waves can be detected on Earth! But it's not an easy task. To understand how we detect these mysterious waves, let's take a quick trip down memory lane.

Gravitational waves were first predicted by Albert Einstein in 1916, but it would take nearly a century for scientists to finally observe them directly. The first detection was made in 2015 by the Laser Interferometer Gravitational-Wave Observatory (LIGO) in the United States. Since then, several more gravitational wave detections have been made, including by the Virgo detector in Italy and the GEO600 detector in Germany.

So, how do these detectors work? Well, they use incredibly sensitive instruments to detect the subtle stretching and squeezing of space caused by passing gravitational waves. The two LIGO detectors, for example, each consist of two four-kilometer-long arms arranged in an L shape. A laser beam is split and sent down each arm, where it bounces off a mirror and returns to a detector. If a gravitational wave passes by, it will cause one arm to lengthen and the other to shorten, slightly shifting the position of the mirrors and causing a change in the laser light that can be detected by the instrument.

But while the concept is simple, the execution is anything but. Detecting gravitational waves requires incredibly precise measurements, as the waves are incredibly weak by the time they reach Earth. In fact, the stretching and squeezing caused by a passing gravitational wave is typically measured in fractions of the diameter of an atomic nucleus!

To achieve this level of precision, the detectors must be carefully isolated from vibrations and other sources of noise. This means they are typically located far from cities and other sources of human activity, often in remote locations like deserts or mountaintops. For example, the LIGO detectors are located in Louisiana and Washington State, while the Virgo detector is located near Pisa in Italy.

Despite the incredible technical challenges involved, the detection of gravitational waves marks a major breakthrough in our understanding of the universe. These waves are created by some of the most violent events in the cosmos, like the collision of two black holes or the explosion of a supernova. By studying these waves, scientists can learn more about the physics of these events and test some of the fundamental predictions of general relativity.

So while detecting gravitational waves is no easy feat, the potential rewards are huge. As more detectors come online and more detections are made, we can expect to learn even more about these mysterious waves and the universe as a whole.