The Doppler shift of sound or light waves from a moving source is familiar to physicists and non-physicists alike. Now, researchers in China and Australia have seen the more exotic inverse Doppler ...

Scientists have demonstrated for the first time how 'twisted' sound waves from a rotating source can produce negative frequencies—akin to turning back time. A team of international researchers, ...

Experimental physicist Prof. Thomas Zentgraf and his two colleagues from the University of Birmingham, Dr. Guixin Li and Prof. Shuang Zhang, have for the first time proved experimentally the nonlinear ...

Can't see the video? Download an mp4 [10.4 MB] version of this video. Smart phones are expensive so please take care not to swing yours too close to a wall or a person or inside a sock that's almost ...

Twist and shift: Incident beams with opposite orbital angular momentum (green spiral) reflect from a spinning surface: some of the light in the reflected beam has been red-shifted after reflection and ...

At the time of its construction in the 1950s, the Dwingeloo Radio Observatory was the largest rotatable telescope in the world with a dish diameter of 25 meters. It was quickly overtaken in the ...

The pitch of a blaring car horn rises as the vehicle approaches and falls as it moves away. That’s the Doppler effect, and it also occurs for electromagnetic radiation, enabling police to catch ...