Ok, so lets start a serious discussion on the theory that Harry used time-travelling to fix LC (no mentioning of "Mab explains this better" please - lets discuss the merits of the theory on its own).
Here are some points to start with:
The nature of time travel in the DV:The first thing we need to work out is how time travel works in the Dresdenverse. I'm sure we all have seen various ways of dealing with the problems inherent in time travel, and while we do not yet know how exactly Jim will address the issue, we have a clue (coincidentally?) in PG.
According to Bob, a big problem with Time Travel is paradoxageddon. To be perfectly accurate, Bob's example doesn't necessarily use time travel, but merely future prediction. His example is "if you warn someone that something will happen, he will avoid it, so how did you warn him in the first place".
To me this suggests the following interpretation of "normal" time travel in the DV:
1) You
cannot change the past. Doing anything else will risk paradoxeggedon.
2) As such, the only thing you can actually accomplish with time travel is
something that already happened. If you kill someone in the past, then historically (your timeline), he must have been killed by you as well.
ImplicationsIf we believe this is the way that time travel works, then you are really very limited in what you can do. For example, no going back in time to save someone's life -- you'll destroy the universe if you do so.
Thus, if you want to change something in the past (like save a life), you need:
1) You must know that person's life had actually been saved.
2) You must not know in advance who saved the person (i.e. if you do know that you will save that person in the future, then what if you suddenly choose not to do so? --- paradoxeggdon).
3) You probably also need to know the "Rules" of time travel. Otherwise you are probably going to break something.
Little ChicagoInterestingly enough, if Harry does go back in time to fix LC, these three points are very conveniently covered in PG.
1) Harry knows LC got fixed. Therefore he knows that he can fix it without causing paradox.
2) Bob makes sure to point out to Harry that LC, but not who fixed it. If Bob was aware that Harry fixed LC using time travel, this is the
exact amount of information he is supposed to pass on to Harry in order to avoid paradox.
3) Bob also makes sure to explain to Harry the rules of time travel.
Other corroborating pointsObviously we won't find much - this is very much a WAG, but here goes:
1) There is a WoJ that a future book will deal with time travel. If we believe the theory of how time travel works in the DV, we need to find an event
that already happened that will be dealt with. Of course, the book could always take us back to Sue or something like that (which city vanished for a few hours?). However, if Jim really wants to show us the implications of time travel, it would really need to be an event where Harry must tread carefully around events he remembers to avoid paradox .
Among all the events seen in the course of the series so far, fixing LC seems most likely.
2) Serack did a very interesting Doyle analysis
here of PG. Specifically, he points out that Jim inserted a detour and seemingly superfluous encounter with Thomas into the narrative without any "implication". Since Jim is an admitted "Lazy Writer", we have to ask ourselves why he needed to write those paragraphs. If we assume that a future time travel book will take place around PG time, this creates a perfect "obstacle" for Harry to avoid.
That's all I have for now.