what is the reason !?
409083
It has nothing to do with the two halves of the lens anyway. The way I can explain it is spherical abberation, i.e due to the difference in the foci for the edge of the lens and the middle of the lens. But that would form a blurred image and not two images.
881748
Read the link below, it explains it quite nicely.\nAnd bravo to you for being curious and wanting to know the REAL reasons for things!  Keep being inquisitive and asking questions!!
1100771
What is there to explain???
217313
because they spell "why" with a "Y"!!!
58530
what is the question?
55658
What was the question???
390996
there's got to be a reason why right..im in the same situation right now, and asked myself why does it have to be that way...becoz there's a reason behind it....
833150
Simply because we asked it to.\n\nPeace!
909958
WHat - I dont understand !
468750
I was wondering that... why ARE you here?
113500
Why would you want to know!!!!!\nAre you hard up for a question?
99421
why are you asking this question?
519045
Rewrite your question! It makes no sense...
534444
dont understand the question!
483165
who? where? what? why? when? how?
1116326
Why were we here? So that we can ask why we are here. And why should we ask why we are here? Because we are here and can ask why we are here.\nPretty absurd actually.
1172743
There are a variety of reasons.\n\nBut you have to ask yourself - who is teh girl cheeting on?