knowlEDGE has no EDGE



LIGHT

 IF ANY OBJECT(LIKE BALL) IS THROWN AT RIGHT ANGLES ON

THE WALL,IT WILL RETURN ALONG THE SAME PATH TO SOME DISTANCE  (i.e.IT WOULD RETRACE ITS PATH).

EVEN IF ANY OBJECT IS THROWN
AT 90 DEGREE TOWARDS YOU
(i.e.ALONG THE LINE OF SIGHT
) THAT OBJECT WOULD APPEAR
TO BE AT REST FOR SOME SECONDS.ACTUALLY IT IS MOVING TOWARDS YOU.

THIS IS THE REASON SOMETIMES AEROPLANE APPEARS TO BE STATIONARY TO OUR EYES. IT MEANS THAT WE ARE VIEWING IT AT THE LINE OF SIGHT (i.e.AT RIGHT ANGLES).
ALSO ANOTHER FACT IS THAT, THIS LINE OF SIGHT IS PARALLEL TO THE GROUND OR EARTH'S SURFACE.

LIGHT RAYS WHICH IS INCIDENT AT RIGHT ANGLES TO THE WALL, WOULD RETACE ITS  PATH.