Simplify the following text for a Grade 12 native English-speaking person.
Original: Thus , the coordinates differences ( Î '' x , Î '' y , Î '' z ) and ( Î '' Î 3\/4 , Î '' Î , Î '' Î ) are not intrinsic to the rod , but merely reflect the reference frame used to describe it ; by contrast , the length L is an intrinsic property of the rod .
Simplified: The most common term for `` Universe '' among the ancient Greek philosophers from Pythagoras onwards was Ï Î Ï Î Î 1\/2 ( The All ) , defined as all matter ( Ï Î Î Î '' Î Î 1\/2 ) and all space ( Ï Î Î Î Î 1\/2 Î Î 1\/2 ) .