Light needs a surface to bounce off, otherwise light cannot be detected,   
   for example when in a dark room, a light bulb or cfl is switched on then   
   we can see the furniture, walls in that room because the light is   
   bouncing/reflecting of those objects/surfaces. When a laser pointer is   
   pointed at a screen or at a target that spot can be detected because the   
   laser beam falls on the target and bounces back and then is detected by   
   a photosensor.   
      
   But, what if it was possible to detect a spot or point of light in just   
   air, without the need of a surface for that spot/point to bounce of.   
   What would be the practical applications of such an invention?   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)