A Weasel Shut Down the $13 Billion Large Hadron Collider

The Large Hadron Collider at CERN, near Geneva, is the most complex and expensive scientific instrument ever built. It cost approximately $13.25 billion. It smashes particles together at nearly the speed of light to explore the fundamental nature of the universe.

On April 29, 2016, at approximately 5:30 AM, it was shut down by a weasel.

The Incident

A beech marten, a small weasel-like mammal common in the Swiss countryside, found its way into an outdoor transformer connected to the LHC's electrical infrastructure. The animal caused a short circuit that damaged high-voltage connections and cut power to part of the collider.

The LHC went into standby. Experiments were halted. Engineers were called in to assess the damage.

The Aftermath

CERN spokesperson Arnaud Marsollier confirmed the incident, noting that the animal had caused "a severe electrical perturbation." The marten did not survive the encounter.

Repairs took several days. The collider was brought back online the following week. CERN subsequently improved its wildlife barriers around electrical installations, though they acknowledged this was not the first time an animal had disrupted operations.

The most expensive machine in human history, designed to unlock the secrets of the universe, was temporarily defeated by an animal weighing less than two kilograms.