Yet Another Time Turner Q

[tex23236]

No: HPFGUIDX 33169

Science Fiction has many ways of dealing with time travel.  The one
JKR seems to have selected is the idea that the time traveler can't
change history. In fact, in this solution, the time traveler often 
causes the events that happen.  For example, if Neville breaks 
something, he can't go back in time and prevent the accident.  In 
many time travel stories of this sort, the time traveler causes the 
thing he was trying to prevent. Harry saw himself, then went back 
and conjured the big patronus.  His time travel caused the final 
state of the reality.  I suspect Dumbledore's admonition that they 
not be seen had more to do with witnesses seeing them when they 
were supposed to be elsewhere, but that's just me.

tex23236