Coughing laughter echoes weakly through the room. look close, in through the glass of this bulb... the filament, a secret tungsten alloy, has twisted in a rictus grin, and is vibrating with spirit laughter. A little joke set up by ghosts who like you, but think it would be better for you if you got a little scare once in a while. Not to worry.     The receiver changed the sound to moving pictures of the dead, which could float free and alive in the air.