Scientists detect smallest force ever measured

Written by PTI | Washington | Updated: Jun 28 2014, 00:19am hrs
Scientists have detected the smallest force ever measured - equal to approximately 42 yoctonewtons.

Using a combination of lasers and a unique optical trapping system that provides a cloud of ultracold atoms, the researchers from the Lawrence Berkeley National Laboratory (Berkeley Lab) and the University of California (UC) Berkeley measured the tinniest force.

A yoctonewton is one septillionth of a newton and there are approximately 3 x 1023 yoctonewtons in one ounce of force.

"We applied an external force to the centre-of-mass motion of an ultra-cold atom cloud in a high-finesse optical cavity and measured the resulting motion optically," said Dan Stamper-Kurn.

"When the driving force was resonant with the cloud's oscillation frequency, we achieved a sensitivity that is consistent with theoretical predictions and only a factor of four above the Standard Quantum Limit, the most sensitive measurement that can be made," said Stamper-Kurn.

If you want to confirm the existence of gravitational waves, space-time ripples predicted by Einstein, or want to determine to what extent the law of gravity on the macroscopic scale, as described by Newton, continues to apply at the microscopic scale, you need to detect and measure forces and motions that are incomprehensively tiny, researchers said.

For example, at the Laser Interferometer Gravitational-Wave Observatory (LIGO), scientists are attempting to record motions as small as one thousandth the diameter of a proton.

The finding was published in the journal Science.