Cosmos A Spacetime Odyssey S01E04 - A Sky Full of Ghosts
An exploration of how light, time and gravity combine to distort our perceptions of the universe. We eavesdrop on a series of walks along a beach in the year 1809. William Herschel, whose many discoveries include the insight that telescopes are time machines, tells bedtime stories to his son, who will grow up to make some rather profound discoveries of his own. A stranger lurks nearby. All three of them figure into the fun house reality of tricks that light plays with time and gravity.