March 31, 2023

The lake is up to a mile deep and has the clearest fresh water in the world. A railway from the time of the tsar runs comfortably along the south bank. Most importantly, it is covered in a three-foot-thick layer of ice in winter: nature’s ideal platform for installing an underwater photomultiplier array.

“It’s like Baikal was made for this type of research,” said Bair Shaybonov, a researcher on the project.

Construction work began in 2015. By the time the ice melts in April, a first phase with 2,304 light-detection spheres floating in the depths should be completed. (The spheres stay in the water year-round, looking for neutrinos and sending data via underwater cables to the scientists’ lakefront base.) The telescope has been collecting data for years, but Russian Science Minister Valery N. Falkov crashed a chainsaw into the ice in the frame an opening ceremony for television this month.

The Baikal Telescope looks through the entire planet on the other side to the center of our galaxy and beyond, essentially using the earth as a giant sieve. For the most part, larger particles hitting the opposite side of the planet will eventually collide with atoms. But almost all neutrinos – 100 billion of which go through your fingertip every second – essentially proceed in a straight line.

However, when a neutrino strikes a nucleus in water extremely rarely, it creates a blue cone of light called Cherenkov radiation. The effect was discovered by the Soviet physicist Pavel A. Cherenkov, one of the former colleagues of Dr. Domogatski in the corridor of his institute in Moscow.

If you spend years monitoring a billion tons of deep water for unimaginably tiny flashes of Cherenkov light, many physicists believe, you will eventually find neutrinos attributed to cosmic conflagrations emitted billions of light years away.

The orientation of the blue cones even shows the exact direction the neutrinos came from, which caused them. Since neutrinos have no electrical charge, they are not affected by interstellar and intergalactic magnetic fields and other influences that disrupt the paths of other types of cosmic particles such as protons and electrons. Neutrinos go through the universe as directly as Einstein’s gravity allows.