You know, that explains a lot. My subconscious is quite the asshole.
My conscious can be quite the asshole. But now I have an excuse-- I’m not really conscious at all! I can’t help myself 
JK, of course. Just as the story @DPRK posted says:
…pretend that you have free will. It’s essential that you behave as if your decisions matter…
We must all act as if we have free will and are in control of our density, whether or not it’s true.
As my son once said of his Stellaris playthrough, “As far as [his civilization] are concerned, they think they have free will.”
I’ll say this in favor of Springer-Verlag:
They’re not Elsevier.
And bringing it back to time travel, we usually start reacting to things a second or two before they actually happen, because our brains are too slow to wait to start reacting until they actually do. Which requires a lot of prediction of what’s about to happen, which is why we can be so thrown for a loop when something completely unexpected happens (or fails to happen).
Even more rare, the historical dudes don’t all speak English.
Yeah, and that’s used for humor.
There are few spontaneous decisions that people make in life. It’s called planning.
“Not to decide is to decide.”
(Harvey Cox?)
(I saw it on a poster in middle school, and it stuck with me)
.
It’s noon on a Friday, but I have to stop and raise a toast to poor Jovistus. Cut down in his prime by some fuckstick with a boomstick…
And we can certainly hide a pile of gold under a particular rock in Yellowstone which won’t be disturbed until next weekend (excuse me, I need to arrange a flight)
My point was questioning whether or not we make conscious decisions, and if all of our decisions are made unconsciously, and we only think we consciously make them, do we really have free will? That has nothing to do with spontaneous decision making vs. planning.
I am sorry for my intervention. Let’s do something else. 
Sounds like a great plan 
We’ve had discussions of this kind many times, and eventually I like to lay out some of the different possibilities. There are only a few consistent theories of time travel, and the ‘alternate timeline’ theory is one, but it is not the only one.
1/ One possibility that seems to be quite popular among physicists is the ‘consistent single timeline’ conjecture, sometimes called the Novikov Self-Consistency conjecture. In this concept there is only one timeline, and everything is pre-ordained; if you go back in time you can’t change history, and everything you do has always existed as part of the timeline.
This makes paradoxes impossible, as you literally can’t kill your grandfather before he is parent to your father, no matter how hard you try. This seems to deny free will, but free will is a problematic concept anyway.
2/ Alternately, we can consider the ‘alternate timeline conjecture’; you might go back in time and change history, but this creates a new timeline. Simple enough on the face of it, but the bifurcation of timelines means there are two possible histories to consider, and you might lose sight of the world that you grew up in.If you keep going back and changing history you could create a cat’s cradle of branching possibilities, and never be able to find your way home.
2a/ Perhaps all the alternate timelines vanish, except the one you are currently in, but that sounds suspiciously like condemning entire pre-existing universes of people to non-existence just because you want to change a few tiny details. Nasty.
2/b or maybe all the alternate timelines collapse into one, so that all your attempts to change history are ineffectual and revert to the norm after a trivial amount of time has passed. Temporal Inertia, in other words. This allows a certain amount of free will, but it is ineffectual.
3/ The most likely scenario is what I call the ‘boring universe’ scenario, where time travel simply doesn’t work. There is no evidence that any phenomenon can reverse causality in any meaningful way; perhaps this is because of some sort of chronological protection as described by Hawking or Niven, or perhaps it is just because time travel is impossible full stop.
I was about ask, “Have you read these books?”, when I noticed who was posting, and now I’m assuming you have.
For everyone else, this is pretty much the business model of The Company. They create agents in the past, who move through time with a shopping list of stuff the company wants. Things like the Library of Alexandria. We know it burned down, but we don’t know that a couple of agents posed as librarians for a few years, and made copies of every book in the library, which were hidden in a secured bunker for a couple of thousand years.
Yes, I read all of the books - and I’m pretty sad that the author died so young.
That reminds me of a scene in the time travel series Time Wars. The protagonists have just fought and defeated people from an alternate timeline who were trying to ensure the change that resulted in their timeline happened, while the protagonists were trying to preserve original history and thus their own timeline. Afterwards, they have a discussion with their boss; paraphrased from memory:
Boss: “And now that the change to history has been prevented, that alternate timeline never existed.”
Character: “But that’s ridiculous! Of course they existed. I spoke with them, fought them!”
Boss: “No, they never existed…because if they did exist, then we just killed an entire world of people. People who were just trying to preserve their own world.”
(room is silent)
Boss: "So…they never existed."
Fritz Leiber’s Change War series had that kind of thing (and so did 11/22/63 by King). In both cases, significant change was possible, with great effort and planning - though in the second case, the side effects were so bad that you were better off not doing it.
Another alternative is hard to describe - it’s kind of a meta-time approach. There’s one time line, always self-consistent, but it evolves along another time dimension. So the universe in state A has no time travel. It evolves into the universe in state A’ where a guy gets a message telling him how to build a time machine - which he uses to send a message to himself about how to build a time machine. The universe in state A’ can evolve further (back to A with no time travel) or into A’‘’‘’’ with many many more self consistent loops. A meta-observer would see the changes, but an internal observer just sees self-consistent time-travel (or lack thereof). Hogan’s Thrice Upon a Time is kind of like that
The Many-Worlds concept might be another alternative option. Every event where more than one possibility can occur creates a separate timeline for each outcome; this happens all the time no matter what we do, and we might live in a universe where timelines branch, or foliate, constantly, every nanosecond, even when no time travel is involved
Bringing time travel into a universe where there are innumerable timelines already makes little difference - every timeline will be a little bit different anyway, so a little bit of timey-wimey jiggery-pokery just adds a few more foliations to the manifold.
This explanation is why, when I first heard about the many worlds interpretation of quantum mechanics, I assumed it was something created by a sci fi or comics writer (like Stan Lee writing about Dr. Strange and his calculations of how many potential worlds could the Avengers defeat Thanos in) to troll serious physicists. It seems so far out their that the idea that this is a serious real world hypothesis boggles the mind.
Strictly speaking, Many Worlds isn’t a hypothesis, because hypotheses are testable, and it’s core to the Many Worlds idea that it’s not. It’s an interpretation. And it makes exactly the same predictions as every other interpretation of quantum mechanics.