New Record for Smallest Force Measured
Sometimes small things can mean very big things, but before those big things can happen, you have to detect the small things. Detecting the almost infinitesimal is hardly easy though, but researchers at Berkeley Lab and the University of California, Berkeley have recently measured a force of roughly 42 yoctonewtons (yN). That would be 0.000000000000000000000042 (42*10-24) Newtons, and one ounce of force is 0.278 N (or 2.78*1023 times greater).
This ultrasensitive detector uses an optical trap to hold and cool a cloud of rubidium atoms. Two standing-wave light fields are what actually trap the atoms and isolate them from the external environment. By modulating one of the fields, the cloud's center of mass can be moved, and this movement can be picked up by another, probe beam of light. The key aspect of this detector is that it decouples the atoms from the environment, which allows the measurement to approach the Standard Quantum Limit, which is the smallest force that can be measured, according to the Uncertainty principles. The closest we have gotten to the SQL before was six to either orders of magnitude, but this got us to just four times above it.
The ability to measure such unbelievably small forces could impact Newtonian physics and General Relativity. We have to be able to measure forces, specifically gravity, at very small scales to answers some of the questions these fields present us with.
Source: Berkeley Lab