New technology can measure the tiniest changes in how the Earth spins. 

Earth's seemingly unwavering spin is not as constant as it appears, exhibiting subtle shifts that slightly alter the length of days. 

Normally, tracking these minute changes has required elaborate methods using data from scattered radio telescopes or signals from various Earth-orbiting satellites. 

But now, a team of Kiwi and German scientists has unveiled a laser gyroscope capable of pinpointing these minuscule fluctuations in Earth's rotation with astonishing precision – to within mere milliseconds over four months of observations. 

The breakthrough may revolutionise how day length variations are monitored.

The gyroscope features a 16-metre laser cavity through which two laser beams traverse in opposite directions. 

This interaction generates distinct interference patterns, a characteristic of laser beams. As the Earth twirls and oscillates through space, the apparatus mimics these motions, causing the distance covered by light in opposite directions inside the cavity to diverge, affecting the interference pattern. 

By closely monitoring this interference pattern over time, the researchers have achieved the ability to measure day length variations every three hours with pinpoint accuracy, over a span of four months. 

This stands in stark contrast to conventional methods, which yield just one measurement per day.

The team suggests their advancement could prove instrumental in refining our comprehension of global transport phenomena and enhancing geophysical models.

More details are accessible here.