M. Meier

Inside the detector, which resembles a large thermos filled with germanium, faint flashes are born. Neutrinos, tiny particles that barely interact with matter, occasionally bump into germanium nuclei. The nucleus recoils, and the detector registers the jolt. But to distinguish a real signal from noise, the instrument needs precise calibration.

Earth is a closed book for those accustomed to leafing through pages with light. But to neutrinos, the invisible particles born in cosmic rays and barely remembering the prediction of Pauli, our planet is a braille script: each kilometer of depth presses its relief into their…

For almost a century, seismology has been the planet’s chief X-ray, probing the interior through elastic waves. But neutrinos, ghost particles predicted by Wolfgang Pauli, offer a different perspective.

Deep beneath the ice of the South Pole, nearly two and a half kilometers down, an unusual telescope is at work. It is not pointed at the sky but through the Earth. Its quarry: neutrinos, nearly elusive particles that pass through planets and stars without interacting with anything.