Researchers build a working tractor beam, on a very small scale

We recently saw research that suggested negative radiation pressure in light could lead to a practical tractor beam. A partnership between the Czech Republic's Institute of Scientific Instruments and Scotland's University of St. Andrews can show that it's more than just theory: the two have successfully created an optical field that flipped the usual pressure and started pulling objects toward the light. Their demo only tugged at the particle level -- sorry, no spaceships just yet -- but it exhi...