@Griffyn--son of a (expletive expletive expletive). You're right. About 2 seconds after I got the reasoning of your argument about the energy at DR being an interaction with its wards I forgot it when replying to Hollorr. Since I do not currently have dementia, my only excuse is that the temporal echoes thing from an altered timeline makes so much intuitive sense to me it creeps back in when it shouldnt. My bad.

It all just seems so convoluted for the result.  Lea bargains with the Reds to not interfere in their war; Lea gets Infected; Mab has to cure Lea, but has to fulfill Lea's promises while she's incapacitated, so she can't act out against the Reds; so she has Molly learn dark magic, to screw with her friend's minds, so the GK detects dark magic, and out of courtesy tells Harry, so Harry has to go looking for the dark magic, so that Maeve can manipulate him into thinking its a heavy duty practitioner summoning phages, so he has to send it back on them, only to have it be Fetches, who can take Molly to Arctis Tor because Harry sent them to her, so Harry will follow them to AT to retrieve her, so that Lily can give him summer fire to fire into the wellspring, to then cause a natural reaction among winter Fae to draw everyone back to home base, allowing Maeve to slow time, keeping Winter near Arctic Tor long enough to allow Summer to then move against the Reds.

Aren't all the theories on PG and SmF complicated like this though? They ALL seem to involve 11 dimensional chess.

Not really.  I am positing that a universe (real or fictional) could exist such that some modes of time travel, or behaviours while travelling in time, lead to a closed loop, and other modes of time travel, or behaviour while time-travelling lead to changing the past.

 

Ahh, there. This makes sense. It seems exceedingly obvious now that you’ve said it, but it wasn’t at all obvious to me before. Not all time travel has to be the same kind of time travel. We could have Tardis-y time travel, and the ribbon time folding-y thing Griffyn612 mentioned and any number of other models, some of which could lead to the closed time loops, others possibly allowing the past to be rewritten. This latter version would be the one which Odin was talking about, and the only one, for sure, that we know about which causes temporal echoes. As a matter of fact, if we incorporate Ms Duck’s point that not every being engaging in time travel will have the same skill or power level, it could be that the differences in such is what results in the ability to change time versus getting stuck in a closed loop.

So to the original question I asked—whether the lack of temporal echoes means that we know Time Travel Harry did not fix Little Chicago—the answer, in my opinion, is no, it does not prove anything because we do not yet know enough about time travel in TDF to know that temporal echoes occur in every situation or what type of time travel would be involved in that particular journey.

I think JB was using that opportunity to establish the idea of parallel alternate timelines in the Dresdenverse.  My guess is that someone will use time-travel to change something, or they already have, and JB is going to go the parallel-time-line route rather than the traditional time-travel route.  I don't see JB doing both a TT-back story and a TT-parallel story in the remaining 6 books before the BAT.  And since he's already shown enthusiasm for a Mirror Mirror story, the TT-back plot is probably out.

And I seriously doubt that Harry will time-travel back to PG to do anything, even if a TT-back plot were introduced.  But my point is that he could, and it would explain some things.  Pretty much all the other theories are easier, and infintely more likely.  But that doesn't mean that it couldn't happen.

Put simply, the TTH theory doesn't offer any solutions that can't be reached by other theories; it simply opens the door for another layer to the pre-existing story of PG, making it more complex.

Agreed. That’s nice to be able to say.

But then why did Odin tell Harry about the temporal echoes from changing the past at all? If the echoes from Maeve and Lily at DR werent from them changing the past, then when did Odin give Harry that part of the explanation, which was both useless and wrong? I could see Odin giving Harry info he would also need for a different situation later on, but the way you've theorized time travel, none of the potential examples we have in the books are actually changing time, so no temporal echoes, and Odin's info again applies to nothing. I dont think Odin or Jim gave us the explanation of the way those echoes work not to have it apply somewhere in TDF.

The time at which the attack commenced was the night of December 31st.  From that place and time, Maeve and Lily created a time-distortion field.  Their attack then branched out through time, attacking from multiple times.  That's how Bob describes the attack early in CD.  In doing so, it impacted the wards at DR, which then caused the ripples which everyone sensed.

Ok, I think I'm pretty much with you. But if Maeve/Lily's time-dilation spell, which only slowed time down for a few seconds or a few minutes or distorted it right where they were casting, created enough feedback to echo for at least a day before the event in question, I still find it hard to believe that Merlin or Harry folding time wouldn't create any temporal disturbance at all.

And I don't think the echoes from what Maeve and Lily were doing had anything to do with Demonreach's wards, mainly because Odin's description of the temporal echoes didn't specify that it would only occur at special places or special circumstances; the echoes seemed pretty universal.

Cold Days Incident
I'm one of the biggest TTH theory supporters around.  At least, I talk about it the most.  So understand that as I analyze your observation, I do so in a slightly biased fashion. 

First, my interpretation of what caused the build-up is different from what yours is.  You seem to think that the energy build-up felt on the island was due to someone messing with time.  My interpretation was that it was a build-up of energy by the attack that had already commenced.

See, Maeve and Lily both hit DR with a lot of power within a time-dilation field.  Harry and the Hunt were caught in the time-dilation field, and Odin Claus had to break them through it to get them there on time.  Once there, they battled the Outsiders first, and then went after the Ladies.

The Ladies had a good amount of time to attack DR.  Their attack was designed to hit DR not only in one place at one time, but at one place from multiple times.  That's the other purpose of the time-dilation they cast; it allowed their attack to happen simultaneously with other times.  That energy attack is what set off the build-up of energy felt by DR.  The build-up wasn't from the explosion of the island, or the time-stream trying to be changed; it was from the attack.  Bob himself showed a movie about it, where the attack was represented as a dissonance against the protection spells on the island.  It was that dissonance build-up that caused the flares which were felt on the island.

Since there's no time-dilating attack in PG, there wouldn't have to be a build-up like the one we saw on DR. 

Well, to be honest, as I was writing the OP, I realized that I didn’t really understand/recall enough about what the heck all was going on with time and energy at Demonreach.  But I kinda figured that for purposes of this post, I didn’t need to have the intricacies of what was happening there down pat, because I was relying on what Odin explained about how time travel wherein you change the past means that you cause temporal echoes. For the Little Chicago example, we are talking about changing the past (aside from the arguments against whether this is really changing the past or merely assuring it, as Elegast and wyltok were noting) and THAT would cause the temporal echoes Odin described, regardless of whether time travel was involved with DR.  So I guess I was hoping to skirt my non-understanding of the precise nature of what was happening at Demonreach.

But let’s talk about it for a second. You are saying the energy buildup which was going to cause the explosion Molly was talking to Harry when he first gets to Chicago is NOT due to someone futzing with time but is a result of the spell Maeve and Lily were performing, if I understand you correctly. But how is it that the energy buildup had already started before Harry even met with Molly? Remember Molly had already been talking to Lea about it, so not necessarily days or anything, but people were noticing the energy backlash definitely some time before that night at Demonreach. I noticed that you said their (Maeve/Lily’s) attack was happening simultaneously with other times. I could see that. But it couldn’t have been happening as early as when Molly noticed the energy building up, because didn’t Harry met with both Maeve and Lilly at the Botanical Gardens after that?   

You're making the assumption that Future Dresden traveled to the past to change it, rather than Future Dresden traveled to the past to ensure everything happened the way it was meant to. Think Harry Potter and the Prisioner of Azkaban, where Potter makes the Stag Patronus that saves himself and Sirius from the Dementors.

If the situation here is like the one in Harry Potter, then the time travel is aligned with the temporal inertia, rather than against it, so there would be no temporal echoes in the past. Instead, the temporal echoes would occur near the time in the future where Dresden travels to the past, with the echoes being a result of the timeline changing if Dresden fails to do what he already did.

Ugh, this is why I LOATHE time travel. I am admittedly horrible at reasoning this out. But let me try...

Ok, only one of two people could have changed LC in our example. Now Harry or Future Harry. We know Now Harry did not do it because Now Harry has no memory of doing so and we don’t watch him do so (though I guess he has “forgotten” things like ordering his own death and his blasting rod, so this may not be a safe assumption, but let’s table that for now).  Therefore, it is Future Harry which takes the actions changing LC (like in the example you used, it is Future Potter). If Future Harry does not act, then LC blows up.

If you say, well, Future Harry always was going to fix LC, so he is not changing the past, he is making it happen the way it was always supposed to, then there would be no such thing as changing the past because every action Future Person takes is always the action they would have taken and the past is never altered [/u]. Yet we know from Odin’s speech that such a thing is possible, though difficult.

         We learned from Odin that there are laws that govern the progression of time in relation to space. Altering the future is easier than changing one’s past, which is more than mildly difficult. Overcoming the inertia of an event to remain as it originally occurred requires tremendous energy, will and a measure of simple luck.

         The larger, more significant or more energy in the event, the more inertia it has to stay the same and the echoes caused by a temporal event are proportionately greater than the span of time that was bridged. If centuries are bridged, echoes begin far, far in advance. We see that the energy echoes happening in the day before the events at Demonreach allowed Harry to determine that the spell was being cast that same day or hours around that time.

         Now consider Little Chicago. If it had not been fixed, it would have exploded with tremendous energy. It would have killed Harry, so it was a significant event in his timeline. Therefore, it is a large, significant, energetic event with an equal amount of inertia working to keep it happening the same way. Therefore, if a time-traveling Harry went back into his own past to fix Little Chicago, which occurred 6 years ago in the Dresden Files timeline, at the very least we should have been seeing echoes 6 years before Proven Guilty, right? And the further in time we get from the fixing of LC to when we see TT Harry make the trip, the early the echoes should have started.

        In Cold Days, the echoes we saw from the events at Demonreach included an energy building up, like a steam boiler, that was going to explode and take out the midwest. I'm not sure what kind of echoes to look for from TT Harry stopping the explosion of LC and his own death, but I can't think of anything that would fit the bill.

       Does this sound a death knell for the idea that Time Travel Harry fixed Little Chicago? Can anyone think of potential echoes which prove that Harry did travel back in time and avert his own death??