i will be bold and disagree. if i may take your example. if hitler was assassinated as a child im sure that WW2 would have taken a different path which may have impacted on the cold war after that. I wont disagree that the situation in Germany was very unstable but if you travelled back in time and killed hitler i would like to think that things would have been different. my main point is that if you went back in time and decided to take the last newspaper off a stand, the effects though not major in terms of global crisis would occur for that person and the countless others who interact with him and those after him. Like the way water ripples in a pond, small stone makes waves in a quiet pond.
Then he hurries to work and goes without a newspaper until lunch. So far his day hasn't changed much.
Either way there is one less paper in the world because you (the traveller who isn't supposed to be there) took it. He could go to the next stand, take a paper from there, and now someone who would have gotten a paper from stand #2, must go on to stand #3 to get their fix, thereby depriving someone else. It's an endless cycle of paper-less mornings. And let's not even consider all that could happen in-between: he may get hit by a truck on the way to stand #2 or he may see the most beautiful woman in the world, fall in love, and end up marrying her. They may have kids someday. All because you took a paper... By time travelling, you become an unaccounted-for variable in an equation that has already been completed. 1+1 doesn't equal 2 anymore, now that you're here. You can take steps to minimize your presence, but 2.000000001 still isn't the same as what it once was and/or should be.
That only works if the number of newspapers equals the number of customers. Eventually it's going to average out because a stand carries more papers than are bought, and that will probably be on the very next stand. Most people are always in the same spot at the same time on a given day. They have their routines. If the woman is there on that day she'll be there on the next day, so chances are he'll meet her anyways. These things have a way of averaging out. Yes, there will be some differences, but the farther down the line you get the smaller effect those differences have because of the amount of play that is built into the system. The examples you give are at the far end of the bell curve of probability, and so while one of them may happen they almost certianly won't all happen. They make for good stories, but all good stories bend the law of averages.
I agree with soujiroseta on this one. Any small changes will lead to a much different outcome in the future.
Chaos theory, which developed from meteorology, postulates that there are stable and unstable points in spacetime. on a large scale, most macroevents are relatively stable. quantum fluctuations have little effect on planetary orbist and stellar lifetimes. Weather prediction has always had an uncertainty factor associated with it. No matter how fast the computers get, or how many varaiables you track, it is inherently impossible to predict certain weather trends, because small variations magnify changes. On the other hand, other weather patterns can be predicted with a high degree of accuracy. This observation led to the initial introduction of chaos theory, and has also given rise to some of the mathematics of fractal geometry as well. By chaois theory, it's very reasonable to suppose that most major trends in spacetime are relatively stable. Wars are driven by social, religious, and economic factors that are resistant to diversion by minor events, although some events could indeed be volatile, and vulnerable to small changes in random fluctuations. But from what I have seen of history, the majority of major events are not all that random. Scientific discoveries are made by several independent workers within days or weekas of one another,, because the foundations have been laid down and the relevant questions have been asked. Policies are written by one politician who is very much like the ones who ran against him, and others were already pushing similar bills. Truly accidental, out of the blue events are actually pretty rare.
Sorry, I forgot to elaborate on this. I actually had chaos theory in mind when I said this. In chaos theory, if you deviate slightly from the initial condition, then as time grows, the solutions will start looking very different. This is why if we were to do something only slightly different, it could greatly alter history. Of course, there is no way of proving this, but it seems to me that this is the best way of explaining what effects a slight change could have on history.
On the other hand, though...sometime little things like that make all the difference. Like, when you're driving and some guy runs a red light right in front of you. And you think, "God damn, if I hadn't dropped my keys on my way to my car, I might have been a second ahead and that guy would've hit me!" Maybe in an alternate universe, you didn't drop your keys, and that guy totally T-boned you. And now you're in a neck brace with your jaw wired shut, sipping pureed squash through a straw.
My point exactly. I was simply trying to illustrate that the difference between "this" and "that" can be very small and these things all have the potential to either magnify or dilute as time goes on.
That's only true if you are at an unstable node. Stable nodes tend to converge, at least on a macroscopic scale. Unstable nodes tend to diverge with only small perturbations. A saddle point tends the be stabble along one axis, but unstable along another. Larger scale phenomena are more likely to be stable, but at finer scales the local instabilities increase. This fits well with the behavior of quantum mechanics.
Nodes, saddle points, etc are only applicable to 2d models whereas chaos deals with 3d or higher models. So, I don't see how this is applicable to perturbing history.
They apply in three or more dimensions also. They are just harder to visualize. A revolution would be a macroscopically stable node, for example. There are very few events that could deflect the revolution from occurring,even if you prevebted individual precipitating incidents. The social forces driving the revolution are much greater than any single preciptating event, or even a collection of such events. I remember an episode of Tru Calling, in which she kept resetting on the sane day. Every time she prevented one person from getting killed, the events would play out similarly, but someone else would die instead. It turned out she could not prevent the original death, but what she had to do was prevent it from leading indirectly to another death. The violence surrounding the original death was a stable node.
The parallell universe should be created the moment the time traveller enters the time stream, since the mere fact that she is there makes the new timeline different from the old. Unless your dad was yourself all along, even before you decided to take a time trip and found out about it. Also remember, it doesn't matter if your time travel theory actually works in real life, it only has to be logically consistent and sound plausible to the reader. Let's say we find out that the real universe we live in allows time-travel, but has a single, unchangeable time line. Would it make science fiction stories about branching or iterating time lines any less interesting?
I didn't mind that, since I viewed it as a horror movie, not a science fiction movie, and didn't expect it to be realistic in a scientific sense. And in popular accounts, chaos theory is usually misinterpreted as saying that ANY miniscule change will cause huge deviations in ANY variable as time goes on. Asimov uses a self-stabilising time line in The End of Eternity, but the researchers in the novel are puzzled by it; they believe that, logically, any small change would cause larger and larger deviations. But as you say, this was before chaos theory.
Sorry, I wasn't clear about the parallel universe part. I'm not talking about just time travel incidents. The theory states that other decisions you face also create a parallel universe. For example, right or left? Given that choice, the universe will split regardless of whatever you choose since you could have chosen the other. But I think this is false approach since there is no clear distinction as to what constitutes a decision. Also, how can you be your own father? There is no way that could happen. First of all, that goes against biology. Second, in order to be your own father, you would have to be born first, then travel back in time. And in order to be born you'd have to be the father first. So, there is a big circle which means this isn't possible.
