A clock so precise it would lose one second since the Big Bang

Technology · Published 30 October 2026 Swipe more like this →

In short: Current atomic clocks are the gold standard for our global infrastructure, but a new generation of optical clocks is pushing the boundaries of physics. By probing electron transitions with light rather than microwaves, these devices offer a level of precision that could reveal if the universe's fundamental constants are actually changing.

The current definition of a second relies on caesium atomic clocks, which measure time using microwave frequencies to track quantum vibrations in electrons. However, optical clocks represent a significant leap forward because they use visible light. Since visible light has a frequency five orders of magnitude higher than microwaves, these new timekeepers are approximately 100 times more accurate than the current standard. These devices represent a new kid on the block in timekeeping technology. They are designed to probe electron transitions using light waves. This shift allows for much higher resolution than previous methods.

This extreme precision allows scientists to probe the very fabric of reality. For instance, at the National Physical Laboratory (NPL), researchers use an optical clock featuring a single trapped ytterbium ion. This specific setup is highly sensitive to variations in the fine structure constant—the value governing the strength of electromagnetism between particles. Because some theories suggest these fundamental constants might not be truly constant over time, such high-accuracy clocks serve as essential tools for testing the limits of modern physics. The ytterbium ion is kept trapped at the core of this specific device. It serves as a primary tool for testing fundamental physics. These measurements could potentially confirm if universal constants fluctuate.

Beyond theoretical science, optical clocks are becoming a matter of national security. Our global infrastructure—including banking, shipping, and energy grids—depends on perfectly synchronized time signals. In regions experiencing warfare, such as Russia, Ukraine, and the Middle East, these transmissions face growing risks of interference or seizure. NPL aims to build a robust, secure future timescale by establishing a wide-reaching optical clock system linked through varied transmission techniques. Leon Lobo leads the National Timing Centre programme overseeing these efforts. The new network will be geographically distributed across the UK. This design ensures security is embedded into the next generation of timescales from the very beginning.

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