Researchers have detected the smallest force ever measured. Using lasers and an optical trapping system, they recorded a force of just 42 yoctonewtons. A yoctonewton is one septillion of a newton, and there are about 3x1023 yoctonewtons in just one ounce of force. The measured level of sensitivity is only a factor of four above the quantum limit.
Actually I think this is bigger news than it first appears. And here's why:
Gravity is a notoriously weak force in comparison to the three other fundamental forces. It takes something the size of the Earth to hold you down with the weight you feel every day. By comparison, electromagnetism about 10^40 times more powerful.
Because gravity is so weak, it's difficult for us to make instruments that can detect and measure gravitational forces on a microscopic scale. And, arguably, this might be one of the reasons why we had such a hard time understanding gravity in a quantum mechanical way. We have not yet detected gravitons. To detect gravity waves accurately requires gigantic apparatus. And because it's so hard to get good measurements and data about gravity, general relativity and quantum mechanics have remained poorly unified for about 90 years.
In the last twenty years some formulations of string theory have predicted that one of the reasons why gravity is so weak is that is that some of its energy is "leaking" away into higher dimensions on the microscopic scale. The prediction is we should be able to measure the effects of this leakage on a scale of a centimeter. At this range electromagnetic effects are quite easy to see and measure very accurately. Gravity? Not so much.
The problem is to make instruments to detect gravitational effects even at that scale is quite difficult.
So perhaps the apparatus described in the article above can somehow be adapted to test the string theory prediction. Or at least let us measure the effects of gravity on tiny scales, like weighing tiny samples of antimatter for example.