Scientists observe darkness that appears to move faster than light

Researchers at Technion reported that optical phase singularities—zero-amplitude vortices in polaritons—were observed moving with superluminal phase velocities in a slowed-light hexagonal boron nitride sample, and the team published the results in Nature.

Researchers at Technion reported laboratory observations of optical phase singularities that moved at superluminal phase velocities in a slowed-light material. The experiments used polaritons—hybrid light-matter excitations—confined in a thin flake of hexagonal boron nitride where light propagation is much slower than in free space. The team employed ultrafast, sub-wavelength microscopy to track the creation and annihilation of zero-amplitude vortices and published the work in Nature. The study tests a long-standing theoretical distinction between speed limits that apply to particles and behaviors possible for wave phenomena. Key findings: - Optical phase singularities (zero-amplitude vortices) were observed to exhibit unbounded superluminal phase velocities during creation and destruction events. - Experiments were carried out with polaritons in hexagonal boron nitride, where the effective light speed is reported to be roughly 100 times slower than in free space. - The team used ultrafast microscopy with sub-wavelength temporal and spatial resolution to image the wave dynamics and reported the results in Nature. - The researchers emphasized that these moving dark points carry no information or mass, so the observations do not violate relativity; the effect concerns phase velocity and the absence of photons. - Lead researcher Ido Kaminer described the result as revealing universal laws across wave types and as enabling study of hidden processes in other fields. Summary: The reported findings clarify a theoretical distinction between the cosmic speed limit for particles and possible behaviors of wave features such as phase singularities. The article mentions potential future uses for the experimental techniques in high-speed imaging, quantum sensors, and novel light sources, but practical applications and timelines are undetermined at this time.