Stars:   Michael Hordern ,  John Perry Barlow  and  Gareth Edwards Original Air Date:  29 April 1991 Horizon  is a current and long-running  BBC  popular  science  and  philosophy   documentary  programme. http://en.wikipedia.org/wiki/Horizon_(BBC_TV_series)   ◀ ▶ LINK EMBED POPOUT Share Tweet DOC - Robert Ashley Robert Ashley is a contemporary American composer,