"A photon has a small momentum which it can impart to anything it hits, as Arthur Compton and Peter Lebedev discovered at the beginning of the last century. We now know that photons can be used to push anything from electrons to solar sails.
"Today, Jun Chen from Fudan University in China and a few pals demonstrate the counterintuitive result that photons can pull things too. In other words, they've worked out how to generate a backward pulling force from a forward propagating beam.
"This must not be confused with various 'optical tweezer' type mechanisms in which particles trapped in a beam follow the intensity gradient of the light...This must not be confused with various 'optical tweezer' type mechanisms in which particles trapped in a beam follow the intensity gradient of the light."
This is a theory paper. The excitement [will be] when they actually build such a device and apply it to nanoscience.
Physics ArXiv: Backward Pulling Force From A Forward Propagating Beam
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