nanohertz gravitational waves

Nanohertz gravitational waves are extremely low-frequency ripples in spacetime caused by massive cosmic events, such as supermassive black holes merging billions of light-years away. These waves wiggle spacetime gradually, over periods of years or decades, making their detection challenging. To observe them, scientists use networks of precise atomic clocks and monitor timing variations in signals from pulsars—rapidly rotating neutron stars—acting like cosmic metronomes. Detecting nanohertz gravitational waves helps us understand the universe's most massive objects and the evolution of cosmic structures across vast timescales.