'Negative time' confirmed: Mind-bending experiment shows light can exit a cloud of atoms before it enters, thanks to quantum physics quirk

When a beam of light passes through a cloud of atoms, photons (particles of light) sometimes appear to spend a negative amount of time there, with light seeming to exit the cloud before it even enters. Now, physicists have confirmed this quantum quirk by asking the atoms themselves.

'Negative time' confirmed: Mind-bending experiment shows light can exit a cloud of atoms before it enters, thanks to quantum physics quirk. When a beam of light passes through a cloud of atoms, photons (particles of light) sometimes appear to spend a negative amount of time there, with light seeming to exit the cloud before it even enters. Now, physicists have confirmed this quantum quirk by asking the atoms themselves. "This doesn't mean that we're on the verge of building a time machine or anything like that," study co-author Howard Wiseman , a theoretical quantum physicist at Griffith University in Australia, told Live Science. "It can all be understood with standard physics, but it's yet one more weird property of quantum physics that people hadn't suspected." Photons that pass through an atomic cloud can be temporarily absorbed. They...