ช่วยแปลหน่อยครับ มันแปลว่าไงอะ ฟังแล้วงงง

if a photon is directed through a plane with two slits in it and either is observed   it will not go through both.
if unobserved,it will.   however if it's observed after it left the plane, before it hits its target   it will not have gone through both slits.