[HPforGrownups] Re: Paradox of Time Travel in PoA (long!)

[Troels Forchhammer]

No: HPFGUIDX 135816

At 23:02 29-07-05 +0000, you wrote:
>smilingator:
>
>I was so excited to see a post that wasn't about HBP... turned out to
>be in reference to a post I made about 3 weeks ago on time traveling
>in POA (see post #132073)
>
> >davenclaw:
> > If time can't be changed, then why would Dumbledore need to send the
> > kids back in time at all?  Everything had already worked itself out,
> > right?
>
>Ahhh, the beauty of DD's statement and Hermione's understanding of
>"more time". Harry and Hermione did have a choice as to whether or not
>they should go back in time. Since H/Hr did go back in time, Buckbeak
>and Sirius were saved. The reason that everything worked itself out
>was BECAUSE the two went back in time, not IN SPITE of the fact that
>they went back in time. Had H/Hr not gone back, Buckbeak would be dead
>and probably more people than Sirius would have been *kissed* by the
>dementors.

Precisely!

That their choice, at the objective time that they made it, was
already known (before they were, at that same moment, racing from
the top of the tower to reach the hospital in time), is irrelevant
to that issue.

Only by choosing to go back in time could Harry and Hermione ensure
that the past that they had just lived through happened as it did.
The outcome of their choice had already been known for three hours
when they went back (albeit not to themselves) -- but seriously: isn't
the outcome of Harry's choice of whether to fight Voldemort or not
just as certain before its time? Or if you like, isn't the outcome
of my choice to walk, unaided, on the ceiling just as determined by
the basic forces that govern our universe?

> > This theory requires that the impact of having gone back in
> > time is seen before the point in time at which the time travelers
> > actually go back in time.  It means that you would make the decision
> > to go back in time with the understanding that the impact of this
> > decision had already been experienced, but that the traveling itself
> > was required in order to fulfill what had already happened.

Precisely!

When you do go back to yesterday at noon, you will not come back
to a 'new' yesterday, but rathe at the same yesterday as you lived
through yesterday.

That means that when we (the whole world -- objective time) reached
yesterday at noon, there was suddenly two of you walking about and
doing things. The one that appeared at noon (whom I shall call you*)
may even be tailing the younger one (you-), but unless you actually
(when preparing to travel back) recall seeing yourself, it will be
impossible for you* to be seen by you- -- if it didn't happen for
you-, then it never did happen.

That, at least, is the basis of Igor Novikov's theory of the Self-
Consistent Histories.

We cannot, obviously, know if that the model Rowling uses for
Potterverse (let's face it -- she's unlikely to have been studying
physical journals to learn about these things <G>), and that model
is, indeed, inconsistent with Hermione's statement implying that
McGonagall told her of wizards who had killed their /past/ selves
(a variant of the Grandfather Paradox: if the wizard kills his past
self, then he doesn't live on to travel back, in which case he
cannot kill his past self, so that he actually can travel back and
kill . . .)

Paradoxes are messy ;-)

<snip>

>As I explained in my previous post, there are a number of time
>travelling theories out there, but most stem from two main beliefs...
>that time can be changed and in doing so, alternate universes are
>created OR that time can not be changed. My interpretation of the
>canon is that JKR is operating under Theory 2. I mean, she explains
>observations from the first perspective while we are experiencing the
>second perspective. If she was not operating under this theory, then
>what would be her point in discussing things, such as the footsteps in
>the corridor, the falling of the axe when we thought Buckbeak was
>killed, or Harry saving himself with the patronus? The important
>thing: NOTHING CHANGED during the dual telling of the events but our
>perspective of them. I'm not sure what canon evidence you have for
>believing that there was some other sequence of events that was
>altered, but I'd love to hear about it  :)

Well . . .

The change in the sequence that the characters emerge from the
Whomping Willow when going back to the castle is generally held
to be an error (I've never really seen anyone seriously wishing
to claim otherwise), and it seems to me quite plain that Rowling
intends us to understand that she is describing the exact same
events from two different viewpoints (in particular when the
older Harry and Hermione observe the events behind Hagrid's hut:

    And then came the howling, and this time they could hear
    Hagrid's words through his sobs.

/this time/ -- so this is the same howling they heard earlier,
but when they hear it again, when they hear it 'this time', they
are able of actually understanding what is going on instead of
misinterpreting.

There appears to be no serious opposition to the interpretation
that nothing did change, and that we saw the exact same events
and exact same period of time from two different viewpoints,
which just incidentally happens to be both those of Harry Potter . . .

The main challenge to the idea that time in Potterverse works as
in Novikov's Self-consistent Histories is still Hermione's
paraphrasing of McGonagall's information.

In order to allow for that statement to express factual truth in
Potterverse, and yet still prevent that messy possibility of
paradoxes crushing the very logical firmament of this fictional
universe, we have to turn to the Alternative Universes theory.

It isn't difficult to find good arguments why Hermione's statement
/might/ be untrue, but it is far more difficult to find any arguments
of why it /must/ be so. Personally I'd be more happy accepting her
statement as a statement of fact (at least for the time being -- a
canonical statement that the past cannot be changed would be deeply
appreciated . . . pleeease Jo? <G>)

I cannot, however, (it is the physicist within me) accept a universe
where paradoxes are allowed (it's a failing, I know, and I can only
hope -- pray for, really -- that Rowling recognises the literary
problems inherent in allowing a universe that can

The theory of Alternative Universes does appear strangely attractive
to me -- in particular if we can allow certain special properties
to hold true in such a universe:

1) The universe seeks to avoid creation of alternative histories
    (branchings of time).
2) The universe will seek to repair any branchings, bringing the
    time-lines back together.
('seek' in the above should be understood in the same way as when we
say that a quantum-mechanical system 'seeks' a state with a lower
energy).

A universe as that would be perfectly suited to explain everything
in PoA -- we can even, if we should desire to do so, explain the
change in the order of emerging from the Whomping Willow: something
(obviously something we don't see) created a small difference, and
at this point we have a little branching, but obviously the two
histories are quickly brought back together as Peter escapes and
Lupin changes . . .

We can also explain Hermione's statement (obviously killing your
past self creates a new history), and we can also explain why
nothing (more) was changed -- the universe acted to prevent that.

The real test, however, of any such model is literary. How would
it work, and would that be consistent with the known evidence?

For a particularly playful author the model offers a lot of
possibility to play around with minor changes of events -- bringing
all the branches together again etc.

For more cautious authors, the model offers an explanation and
'excuse' (if you will) of why there is only one time line, but at
the same time it allows the author to leave a real threat of
terrible temporal consequences hanging over the heads of their
characters if they embark on journeys backwards in time.

Using the creation of alternative histories to resolve major plot
points would, however, be quite problematic. Suppose that Harry
were to go back in time to change certain events as they took
place. Then his original history would be split off and he would
end up in the new history with no possibility of getting back
(you can't just pick which universe you want to be in). That would,
unfortunately leave the original history without a Harry Potter.

All in all I think this modified use of the theory of Alternative
Universes offer the explanation that satisfies me best -- the one
that I would prefer to see in effect for Potterverse. In that lies,
obviously, the recognition that I have no clue whatsoever, as to
what Rowling will prefer -- or would prefer if she had thought it
out at all (in all honesty I don't think there actually is a well-
defined model for time in Potterverse because I don't think Rowling
will have considered that -- math and physics: her mind doesn't work
that way).

/Troels Forchhammer