Snape and DADA

[persephone_kore]

No: HPFGUIDX 112282

> PK responded: 
> > Well, I don't see why, if you can go back in time at all, you'd be
> > restricted to times you'd actually been to previously unless you 
> > were actually stuck sharing your own consciousness at the time -- 
> > which isn't the case.
> > 
> > Whether he could perform an action which changes events is quite
> > irrelevant, as if Harry saved Snape he would of course *always* have
> > been the one who saved Snape, just as he was of course *always* the
> > one who cast the Patronus that chased the Dementors away. JKR 
> > doesn't actually do the changing-events variety of time travel -- 
> > it might look that way, but only because the reader and characters 
> > didn't have all the facts the first time around.
> 
> 
> SSSusan again:
> Hey, PK, thanks for answering this.  But, see?  I just DON'T get it!  
> If a person wasn't alive in, say, 1800, then why *should* he be able 
> to go to 1800, do something which impacted the course of events, then 
> return to the present?  It seems like such a cop-out in telling a 
> story!  
> 
> If a person was born in 1970 and returned from 2004 to 1974, then I 
> could see that happening--he really WAS alive in 1974, so it 
> makes "sense" that he could *always* have been the one to have done 
> X or Y.  But if he travels back to 1800, it *doesn't* make sense to 
> me that he was *always* the one to have done X or Y.  

PK: 
I think time travel just isn't your thing, is it? 

The thing is, why should it make a difference? Take your "If a person
was born in 1970 and returned from 2004 to 1974" scenario. If X or Y
is something he did *at the age of four*, there's no need for time
travel. If it's something he went back in time to do at the age of 34,
I can't see why having his four-year-old self existing simultaneously
would somehow make this more possible. 

If you don't like the idea of time travel at all, then I rather doubt
I can convince you it's a cop-out. But I don't think it's any more of
one than any other plot device, and it can be worked into things quite
intricately.

Perhaps you can think of it this way. Picture a timeline. Mark off, in
your mind, the years, centuries, even go down to hours, minutes, and
seconds. Well, don't really go to all that trouble; just take it that
you have a line, or a ribbon, and as you go along it in one direction
you are looking at earlier or later times. 

Now picture each individual person as having a thread of their own,
starting at the point on the overall timeline when they come into
existence and ending at their death. I think you should be fine so
far. Something kind of like the Fates and their life-threads, perhaps.

All right. In order to perform time travel, there has to be some means
-- technological, magical, mental, whatever -- that can take an
individual's *personal* timeline and rearrange it with respect to the
main one. So, for example, when your hypothetical person reaches 2004
and goes back in time, it might look as if their thread has been
severed and the end just "later" than the cut slid back to 1974 -- or
1800. In either case, it will proceed normally from there until the
individual dies or moves in time again. Keep in mind that to the
*person*, however, their own thread is continuous. Subjectively, they
are going through 1974 or 1800 *after* they went through 2004. If they
go to 1974, their thread will be running temporarily alongside itself,
but the two sections will still be independent. If they go to 1800,
the 34-year-old no more requires another section of their life to be
taking place simultaneously than if they'd stayed put and continued
proceeding through 2004, 2005, etc. 

If you step back and look at the overall timeline, assuming you're
using the single-timeline theory, you see that as of 2004, whatever
the time-traveling person did in 1974 (or 1800) *had already happened
in 2004*. The individual simply had not, from their own personal,
subjective point of view, *done* it yet. (Keep in mind that as an
alternative, you can look at the individual's personal timeline --
which is not actually *broken*, just displaced with respect to the
main one -- and see things go 1974, 1975, 1976... 2004, 1974.... and
so on.) The things they do that influence events *aren't changes*,
which is why I say they "had always done them" and that they are not
actually going back and doing things that change events. But if they
go back at age 34 to a time in which they were also four years old,
what they do depends on the four-year-old's existence only to the
degree that if they go back to a time before they were born, what they
do depends on the existence of the atoms that eventually make them up.

Now, if you take the theory that going back in time DOES change
things, producing alternate timelines, you would have one ribbon going
along normally, and then when someone went back in time to do
something that *had not been done*, the ribbon would split in two. One
would be the timeline he came from, where the thing had not happened.
The new one would be the same up to the point he did it, and then it
would branch off. (Then there are further concerns such as whether or
not you can actually get back to your 'home' timeline -- which, it
should be noted, you have not altered.) 

There is the third possibility, employed in "Back to the Future," in
which you go back in time and actually do change your own past, which
is what leads to such paradoxes as "I went back in time... and
corrected this problem... so I never had occasion to go back in
time..." etc. 

JKR, perhaps realizing that her audience would not necessarily be
familiar with the conventions of time travel or perhaps simply
preferring this version, chose the option where if you go back in
time, whatever you do there (or then) has already been taken into
account in your own past. This is made clear by the fact that Harry
and Hermione go through a particular time period twice, and the second
time through, several different things they noticed during the first
time are specifically referred to -- they just know what those things
mean this time, whereas before they didn't, or misinterpreted them.
But the same things happened in that time period. They just lived it
twice.

This is why I think the people who say "But why don't they use a Time
Turner to go back and rescue Sirius?" and other such things do not
make sense. JKR does not appear to be writing a universe in which you
can actually change the past. 

PK