Researchers at the Lawrence Berkeley National Laboratory (Berkeley Lab) and the University of California (UC) Berkeley have detected the smallest force ever measured – approximately 42 yoctonewtons – by employing a unique combination of lasers and optical tracking system that provides a cloud of ultra-cold atoms. To the uninitiated, a yoctonewton is one septillionth of a newton and there exist nearly 3 x 1023 yoctonewtons in one ounce of force.
Dan Stamper-Kurn, a physicist associated with the project and corresponding author of a paper in Science that details these results, stated – “We applied an external force to the center-of-mass motion of an ultra-cold atom cloud in a high-finesse optical cavity and measured the resulting motion optically. 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.” The researchers added that in order to confirm the existence of gravitational waves, space-time ripples as predicted by Sir Albert Einstein in his theory of general relativity, or to determine the extent to which the law of gravity acts on the macroscopic scale, one needed to detect and measure forces and motions that are almost incomprehensively tiny. Scientists at the Laser Interferometer Gravitational-Wave Observatory (LIGO) are attempting to record motions as small as one-thousandth the diameter of a proton.
Read more : Lawrence Berkeley National Laboratory