It's like something out of science fiction.

It's like something out of science fiction. In China, they've built a 35-meter plexiglass sphere 700 meters underground. It holds 20,000 tonnes of a strange liquid, surrounded by 43,200 photomultiplier tubes that can detect tiny flashes of light. It's deliberately built 50 kilometers from a nuclear reactor. It will start operation soon.

The goal? To measure some numbers in a 3×3 matrix.

It's called the Pontecorvo–Maki–Nakagawa–Sakata matrix. Unless we are seriously confused — which is always possible — this matrix controls the behavior of the 3 kinds of neutrinos. Neutrinos of the first kind are produced as a byproduct of nuclear fission. But they can turn into the other kinds as they shoot along. The rate at which they do is in part described by this matrix. (It also depends on the masses of the 3 neutrinos.)

What's the use of this? Easy: one goal of any prosperous civilization has always been to better understand the universe. It's just a tiny part of the grand scheme. It usually comes well after the goal of eating lots of tasty foods, or watching people run around playing with spheres. But sometimes it has huge effects, and some of us find it very exciting.

To see more on this amazing device, which should start running this fall, read on....

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