Introduction You might have seen figure skaters spinning around quickly and then tucking their arms to spin faster—or opening them to spin more slowly. This happens, thanks to a physics concept known ...

The manoeuvre depends on the principle of conservation of angular momentum, which states that the angular momentum of a system remains constant unless external torques act on it. For example, some ...

Ultrashort measurement-time resolution is traditionally obtained in pump–probe experiments, for which two ultrashort light pulses are required; the time resolution is then determined by the pulse ...