Date:1 February 2011
Physicists since Albert Einstein have calculated that people age faster when they stand a couple of steps higher on a staircase, due to the difference in their distance from the Earth’s centre, but the phenomenon has been too small to measure in everyday life.
Now researchers at the USA’s National Institute of Standards and Technology have put numbers to the theory, with two of the most accurate clocks in the world. The clocks tick a quadrillion times per second, using the vibration of a single aluminium ion instead of a pendulum or electronic oscillations. When the two clocks were subjected to unequal gravitational forces, only 30 cm apart, the higher clock ran faster, just as Einstein and others predicted. Over the course of an 80-year lifespan, the difference would total only 90 billionths of a second. Researchers hope the ultra-precise measurements will help map the Earth’s gravitational field, assisting scientists in predicting the behavioural changes of oceans.
By Alex Hutchinson