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A powerful windstorm in Colorado, US, last week caused more than a dozen atomic clocks at the National Institute of Standards and Technology (NIST) in Boulder to disconnect from their system, temporarily disrupting the US official time standard.
The event led to NIST’s Coordinated Universal Time, or UTC (NIST), slowing by 4.8 microseconds when a backup generator failed, contributing to a short-lived temporal inaccuracy.
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The affected atomic clocks, mainly hydrogen masers and cesium beams, are essential for determining UTC(NIST), with 10 to 15 of them typically in active use at the Boulder laboratory.
WHAT ARE ATOMIC CLOCKS?
Atomic clocks are extremely precise devices that tell time based on vibrations in an atomic or molecular system, usually cesium-133 or rubidium-87, as its timekeeping element.
Their capability has earned them the title of being the most accurate clock in the world.
Because of the precise time telling, the clocks are used in GPS systems, telecommunications, and to inform scientific research.
Earlier in 2025, Nasa also launched atomic clocks into space with the aim of proving the theory of time given by Albert Einstein.
These clocks are now omnipresent around the world, acting like the bedrock in synchronising technology systems around the world, including things like satellite positioning and broadcasting.
WHAT REALLY HAPPENED?
Despite the outage, all atomic clocks continued operating on battery backup systems.
“All of the atomic clocks continued ticking through the power outage last week thanks to their battery backup systems,” said NIST supervisory research physicist Jeff Sherman.
“What failed was the connection between some of the clocks and NIST’s measurement and distribution systems.”
Data from these clocks is continuously measured by multi-channel measurement systems (MCMS) to detect frequency changes. The MCMS feeds information into a computer algorithm, which, with other machines, determines the precise US time standard used globally.
It may have consequences for critical infrastructure, telecommunications, GPS signals, and more, Sherman told Joe Hernandez at National Public Radio (NPR).
Power has now been restored to the NIST facility, and the team has corrected the temporary timing discrepancy.
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