Lasers work by emitting light that is “coherent” in that it doesn’t spread out in a disorganized way like light from most sources does. This makes extremely focused beams possible that can do things ...

Narrow beams from high-power radars, both scientific and military, which are used to monitor objects throughout the inner solar system and in Earth orbit respectively. The constant-frequency carrier ...

A research team at City University of Hong Kong (CityU) has discovered a new type of sound wave: the airborne sound wave vibrates transversely and carries both rotation and orbital angular momentum ...