Dark points within a changing wave pattern can shift faster than light, even while the waves carrying energy move far more slowly. An electron microscopy experiment has tracked that counterintuitive behavior in a thin material sample.

The moving features are locations where a measured wave field cancels to zero. Their motion describes an evolving pattern, so it does not provide a way to send information faster than light.

The study, published in Nature, was led by researchers at the Technion-Israel Institute of Technology. Tomer Bucher and Alexey Gorlach worked with Ido Kaminer’s team and an international collaboration to map these optical phase singularities.