Vedran Brdar

The speed of light in a vacuum is physics' metronome: it sets the rhythm for all processes. If it falters, the familiar harmony collapses. Neutrinos, ubiquitous but almost intangible particles from space, can check if this rhythm ever stumbles under extreme conditions.

Three rain gauges are set up across a big city. Two of them record rare but very intense downpours, while the third, the most sensitive, stays dry. That's roughly the puzzle posed by neutrino detectors: those nearly elusive particles that arrive from the depths of space. The ANITA-IV balloon-borne experiment, floating over Antarctica, reported four suspicious signals.