'Negative Time' Really Does Exist, New Experiments Suggest

Researchers sent photons through a cloud of rubidium atoms and found the transmitted photons arrived earlier than expected.

The timing results suggest a negative dwell time inside the cloud, echoing an effect seen in earlier work.

The team also measured the atoms themselves to test whether the result reflects a real quantum phenomenon rather than a scattering artifact.

The study, led by Aephraim Steinberg's group at the University of Toronto, was published in Physical Review Letters.