Indeed, and since there is no real time-travel, the realm of speculation is a big one, so, if someone can theorize and explain that theory realistically within a story, then it can be taken as fact within the fictional universe you are creating. lol. I love confusing topics.

 

You guys are all wrong. If Harry time travels and kills his grandfather then Colin Creevy becomes his new grandfather, his dad becomes his third nut, Ginny's long lost hymen becomes his new Dad, and Voldemort's tattered soul gets infused into the shrunken head from the third movie. It is so obvious you ignorant ingrates!

Seriously, we don't even know if time travel is possible, until it happens it remains fiction and so any repercussions will be completely up to the author of the fiction in question.

 

why didn't I see it before? It's all so clear to me now, thanks for saving me from my ignorant stupidity

 

As far as I'm concerned anybody can do what they want with this subject and I wouldn't get mad. Nobody really knows, I don't care, do what you want. Although it is good food for thought.

 

Aww but you are all assuming the theory of causality is in effect. Causality is basically a theory that there is an active physical force which can "follow" a time-traveler back through time. ALL paradox theories…well almost all…are based off the fact that this theory is true. If causality is ever proved or disproved then we will know wither or not I’m right or wrong but since all this time paradox theories right now are based off of that theory I’m going to keep things simple and say that for all intense and purposes causality doesn’t exist. So thus all the theories based off that theory are negated. Theories based off of theories is bad physics in my book.

 

ROFLMFAO.
You can't just assume that causality doesn't exist because it invalidates your argument. There are whole branches of physics and mathematics which are entirely theoretical, saying that theories based on other theories is bad physics is ridiculous. Nearly all physics theories are just that, theories which we assume to be true because they seem to fit with our perception of reality. There is no way t PROVE the big bang theory but there are many theories about the nature of the universe based on it. Are you calling all of these pieces of advanced scientific study worthless?

 

No, most theories are based off of laws not other theories….the whole theory of causation was started by Aristotle back in god knows how long ago (300B.C sometime), the only reason why its still around is b/c most physicists don’t even want to deal with time travel since its fundamentally a paradox in and of itself. Also you have to remember this is the same guy who thought there was only five elements and that motion was a force not a vector. I would take anything he said with a grain of salt.

EDIT-The big bang theory at least has evidence supporting it causation is a theory based off…well nothing, we have NO idea what would happen if we time travel and we can do very little physical tests to prove or disprove any theories we have. We cant even do these test b/c we would conceivably need a power source several million times larger then the sun to make about 1 gram of hydrogen travel back in time a few milliseconds. Causation in my non-expert opinion seems a little far-fetched.

 

Again, think about time as a state of being or for lack of a better word "dimension"; similar to the other two (or 3 depending on how you look at it) more easily understood dimensions.

Now we enter the arena of time travel. Since time is a state of being like the other two (or 3) it is theoretically possible to alter it... After all it is possible to alter the size of a cardboard box.

This brings us to the inevitable paradox of the question of whether or not it is indeed possible to remove yourself from time.

Because we are examining Time as a state of being your elimination of your past self will not impact your current state. It will impact your future state however.

I really can't explain this to clearly because there just isn't enough empirical evidence gathered from the study of the Black Holes for any more inferences to be made. However the current evidence backs time as a state of being because of the temporal dilations that have been mathematically proven to exist around the event horizons of black holes.

 

I'll throw out my two cents in trying to explain this in a way to make the rest of you shut up about it.

There's two distinctly different interpretations on time travel:
1). The first way is the sort of parallel alternate universe theory. You live to point A, go back to Point A -10 years, with the knowledge of the world up to Point A. Now at that new juncture, Point A -10 years, you create an entirely new world, and we can call Point A -10 years Point B. Point B never existed in the world of Point A. Everything that happens after Point B is a new world. With your knowledge of your original universe, you try and make the events after Point B turn out the way you wished life had been at Point A. But you can never reach Point A again, as it's in the original universe and timeline, a world in which you never went back in time (or disappeared from when you did split off to Point B, but that theory leaves a whole world of helpless people behind).

2). The other idea about time travel, and this is the one used in Prisoner of Azkaban, is that there are no parallel universes. If you live to Point A, and then go back to Point A -5years, then live life normally, everything you do in those five years, actually completely happened in the timeline to get you to Point A originally. The past cannot be changed. If you run into a 5 year older version of yourself, then there is nothing in the world that can prevent you from again going back five years, and then repeating that exact scenario again. And this time you're on the other side and run into that five year younger version of yourself. This theory on time travel must always account for the timeline fixing itself. Like in Prisoner of Azkaban, the cookie jar in hagrid's hut exploded when Hermione hit it with a rock (I'm going off memory of the movie here). At the first time through they didn't know what happend to the cookie jar, only for Hermione to figure out and understand she threw the rock that broke it. It was inevitable because it already happened.

----------------
If any aspect of the past or history changes, then you are creating a sort of parallel universe. If everything in the past is set, including perhaps your visits to the past, then you have a fixed timeline. If you can kill your grandfather, you're in a number 1. If you are unable to kill him, it may be because you're in a number 2. It's only those that see number 2 as the only option for time-travel, that you can dream up impossibilities and paradoxes like killing your grandfather before you're born.

I think the OP's complaint is the whiny ass stories that send Harry back who changes only the smallest things, so that the knowledge he has up to his original universe's Point A is most useful, as the events and people resemble his knowledge closely. So Harry still gets his ass beaten by Dursleys, he sits idly by letting Sirius rot in prison for just a 'couple' more years, allows wormtail to escape, just so Voldemort can be reborn and is 'most vulnerable' then. Shit bitches, he's barely alive and a bodiless wraith in first year, just capture and contain the bastard then. And for god's sake, don't get in the way of Ginny's diary fetish. It was so close in the original timeline. Just let that one slide.

 

Thank you nonjon

Have you ever looked at any of the mathematical basis' for String Theory? It really is fascinating and it explains so much.

I only ask because I think you might find them interesting

 

I completely agree with Tobang's point that stories where Harry goes back to change the past but doesn't change anything suck. I also concede the potential alternate universe point. What I can't accept is that in the canon method of time travel there is no such thing as causality, and I also can't accept the gross simplification of the issue.

 

That was my point. *If* there is causality and the history of the timeline can be changed, you're dealing with a 'potential alternate universe'. Whether the change is something incredibly tiny and minor, or massive and it's effects are immediately visible. Either one is still a different timeline from the first.

I just have no faith at all in the idea that there are limits to how far you can change a potential universe. Like you're allowed to change what color sweater you put on that morning, but you're not allowed to kill your younger self that morning. That's where the paradoxes happen. When you impose ideas on how much can be changed. Then you're trying to push a changed 'alternate universe' into the original 'universe' and unite them into a singular existence and timeline. Whereas I'm saying those two cannot be combined. Either the timeline/universe can be changed or it can't. If it can, you're dealing with an alternate universe, if it can't then it's all already happened and what happened in any moment of your past is already set. This does not take away free will nor predestine the future, only your existence up until the point you are aware and knowledgable of it. (Because I'm a subscriber to the belief that free will exists as long as you believe you have it. This allows for the memory charm just before going back, even if it is a fixed timeline. You still have free will and are doing exactly what you already did. A deviation from it would cause an alternate universe even if you're not aware of the split.)

Now in writing and fiction (or even theoretical science I suppose) you can try and devise ways to combine a universe that has changed with the original unchanged one it stems from, but to take it to this step requires a different viewpoint on time travel and not one that floats for me. That's where you can make up all the odd paradoxes you want, and question whether free will and causality really exist or not. The two versions I listed a couple posts back are the simplistic ones where you can understand and make sense of time travel without paradox or confusion.

------------

And no, I'm not familiar with String Theory. Only took a math course for about a week in college. Couldn't understand the Professor through his thick slavic accent. Tested out of enough Calculus that I never had to take it to graduate. Which puts my last math work at about 11 years ago in high school. Got a good link for String Theory?

 

oh for the love of god....

next thing I see you'll be trying to explain magic as logical manipulation at the atomic level...

props to Nonjon for the smacketh similar to what I would of posted had I been here!

 

Hey!

I was only using logic because time as a state of being is just so much easier to conceptualize *sticks tongue out*

Ok

Here is a link to a decent string theory site.

http://www.superstringtheory.com/

It doesn't have everything, but it has some pretty good explainations.