Whispering-gallery wave known as surface plasmons has been demonstrated in the form of whispering-gallery waves, and likewise for exciton-polaritons in semiconductors. Galleries simultaneously containing both acoustic and optical whispering-gallery waves have also been made, exhibiting very strong mode coupling and coherent effects. Hybrid solid-fluid-optical whispering-gallery structures have been observed as well. Whispering-gallery wave Whispering-gallery waves, or whispering-gallery modes, are a type of wave that can travel around a concave surface. Originally discovered for sound waves in the whispering gallery of St Paul’s Cathedral, they can exist for light and for other waves, with important applications in nondestructive testing, lasing, cooling and sensing,
National Portrait Gallery, London National Portrait Gallery, London The National Portrait Gallery (NPG) is an art gallery in London housing a collection of portraits of historically important and famous British people. It was the first portrait gallery in the world when it opened in 1856. The gallery moved in 1896 to its current site at St Martin's Place, off Trafalgar Square, and adjoining the National Gallery. It has been expanded twice since then. The National Portrait Gallery also has regional outposts at Beningbrough Hall in Yorkshire and Montacute House in Somerset. It is unconnected to the Scottish National Portrait Gallery in Edinburgh, with which