A laser beam can move matter tens of centimetres and in two directions.
Such tractor beams have been used to shift small objects very short distances. To scale this up, Wieslaw Krolikowski at the Australian National University in Canberra and his team fired a laser beam at gold-coated hollow glass spheres in air. The photons heated up the spheres, creating a temperature difference between their far and near surfaces. This generated a force that pushed the shells in the opposite direction to the beam. By changing the beam's polarization state, the team was able to stop the spheres or reverse their direction.
The authors say that the technique could be used to gather samples remotely and for other applications.
Nature Photonics http://doi.org/wft (2014)