Muons can travel faster than the local speed of light in ice

Simple English Wikipedia: Antares Telescope. https://simple.wikipedia.org/wiki/Antares_Telescope

Antares Telescope The ANTARES Experiment is a telescope that is built at the bottom of the Mediterranean Sea. But it is not a normal telescope that uses light to see distant objects. Instead, it uses neutrinos, very small and light particles that can fly through the earth. The name comes from Astronomy with a Neutrino Telescope and Abyss environmental RESearch project. There is also a star called Antares. Functions It uses 900 light sensors attached to 12 strings that float in the sea to detect neutrinos. The strings are held onto the sea floor by an anchor and straight up by a buoy floating in the sea. Although the neutrinos are invisible, they can create a different particle, a muon, in water. The muon then gives off light by the Cherenkov effect because it travels faster than light in water. The sensors are so sensitive that they need only very little light and can even detect single photons. This is necessary because the muons produce only very little light. Location The detector is located in the Mediterranean, about 40 kilometres off Toulon in southern France. There the sea is 2500 metres deep. It is built by a group of physicists from 12 European countries.