As gravitational waves pass through the Earth, space itself is stretched in one direction and compressed in the other, so the detector’s two “arms” actually stretch and contract slightly. This means that each ray travels a slightly different distance. This shows up in the recombined laser light pattern as spikes in frequency called “cosmic chirps.” This is the gravitational wave signal.
To measure it, Virgo relies on state-of-the-art equipment. The mirrors at the end of each tunnel are made of fused silica, so they absorb only 1 in 3,000,000 of the photons that hit them. Polished down to the atomic level, it’s smooth enough to scatter light very little. And because it is coated with a thin layer of highly reflective material, he loses less than 0.0001% of the laser light on contact.
Each mirror is suspended under a super dampener to protect it from seismic vibrations. They consist of a series of seismic filters that work like a pendulum encased in a vacuum chamber within a 10-meter-tall tower. This setup is designed to counteract the Earth’s motion, which he is nine orders of magnitude stronger than the gravitational waves that Virgo is trying to detect. Superattenuators are so effective that mirrors behave as if they are floating in space, at least horizontally.
A more recent innovation is the Virgo “squeeze” system. This counteracts the effects of Heisenberg’s uncertainty principle. This is a peculiar feature of the elementary particle world that certain pairs of properties of quantum particles cannot be measured accurately at the same time. For example, both the position and momentum of a photon cannot be measured with absolute accuracy. The more precisely we know its position, the less we know its momentum, and vice versa.
Inside Virgo, the uncertainty principle manifests itself as quantum noise, masking the gravitational wave signal. However, by injecting a special state of light into a pipe that runs parallel to the main vacuum tube and overlaps the main laser field with a beam splitter, researchers can “squeeze” or It can be reduced, it can be reduced quantum. Improved Virgo sensitivity to noise and gravitational wave signals.
Since 2015, nearly 100 gravitational wave events have been recorded in the constellation Virgo and its corresponding three observations by LIGO in the United States. With both facility upgrades and his KAGRA participation, the next observational run, starting in March 2023, promises much more. Researchers hope to gain a deeper understanding of black holes and neutron stars, and the sheer volume of expected events offers an intriguing prospect of building a picture of the evolution of the universe with gravitational waves. Offers. “This is just the beginning of new ways of understanding the universe,” says Rothrund. “A lot will happen in the next few years.”
This article originally appeared in the January/February 2023 issue of WIRED UK Magazine.
