From: aberigan@nde.unl.edu (A. Berigan)
Subject: Re: Feedback, Boundary Conditions, and Time Travel (long....)
Organization: Ord High School, Ord, NE
Date: Mon, 28 Sep 1992 19:29:44 GMT

ingles@engin.umich.edu (Ray Ingles) writes:
>aberigan@nde.unl.edu (A. Berigan) writes:
>>ingles@engin.umich.edu (Ray Ingles) writes:
>>>tbmg9061@uxa.cso.uiuc.edu (Thomas B MacIukenas) writes:
>>>>ingles@engin.umich.edu (Ray Ingles) writes:

>>>>> Knowing something about the future or the past is like setting a
>>>>>boundary condition. It constrains the possible timeline into a set of
>>>>>timelines that contain that element.

>>Sorry, I'm firmly in the belief that knowledge has little to do with
>>time travel and jelly doughnuts.  And if it does, then everyone has a
>>passive knowledge about the wholeness of time.  Displace a little air in
>>the past, and the tornado that hit your house as a child never happened.

> Purely out of curiosity, did you jump into this thread or have you been
>reading it for a while? My money's on #1....

Guilty as charged. :-)

>>> In the worldview under discussion, I *already* appeared back then. In
>>>fact, part of the reason history turned out the way it did is because I
>>>was there to "change the positions of air molecules, block and reflect
>>>photons, etc."

>>Your putting your effects before your causes in a single Universe.  No

> Isn't "putting effects before causes" the *definition* of time travel?

Technically yes, but there is a way to view it so that the effects are
still after your causes.

>>changes have been made until you do them.  Sure you can travel back to
>                        ^^^^^

> Define "until" in the context of time travel. How do you measure "when"
>something occurred?

By the order in which the traveller experiences them.  (Don't make me
use phrases like "wioll haven be retrowhen", please.)

>>the "present" and see the effects of your changes, but they weren't
>>there in the first place.  Indeed, that is not your Universe.

> As has been pointed out in previous articles, this requires at least five
>dimensions, three of space, one of normal time, and one perpendicualar to
>normal time.

Myself, I go with 3 of time, just because it is easier for me to think
about it than just 2 of time.

>Mind you, this doens't make it impossible, but it's not the
>multiverse I was talking about.

This Universe is a single-dimension Universe, and will continue to be
one, until time travel is done.  At that point, Time will expand itself
to handle the problem instantaneously.  But only the traveller can tell
of such expansion.  Indeed, because of this limited ability to perceive
it by those that do not travel, it is quite possible that what we
perceive to be a single-dimension Universe is really multi-dimensional,
and that our perceived instantaneous expansion always existed.

>>> History in this view is a static sculpture in four dimensions. Past,
>>>present, and future all 'already' exist, just in directions we can't
>>>normally perceive or gain access to. Whether this view conflicts with
>>>free will is another topic.

>>In such a universe, time travel is an impossibility.
>                     ^^^^ ^^^^^^ ^^ ^^ ^^^^^^^^^^^^^
> Not if the travellings are 'already' built into the structure of that
>universe.

Then boundary conditions still make no difference whether you knew about
them or you didn't.  If you don't know what you will do in the past, you
will seem to have free will (it is an inseperable topic).  If you do
know, you will then realize that you never did have free will, and will
be forced to do whatever it was you did.

In effect, in such a Universe, boundary conditions are always in
existence.  You only notice them when you try to work against them.

>>If it is possible,
>>you throw quantum theory out the window.  Indeed, quantum theory is
>>already out the window.

> Explain this in detail, please.

Sorry, my mind is currently blank about that.  I may have been thinking
about things like Shroedinger's Cat.

>(BTW, have you ever seen "The Terminator?")

No.  I have seen "The Terminator" though. :-)

I see why you mention it.  Looking only at that movie, ignoring the
sequel, it depicts both the fated birth of John Connor, the fated
failure of the CSM-101-T-800, and the fated taking of the picture of
Sarah fated to fall into the hands of the fated father.  It is full of
fate, while still John says (via Reese), "The future is not set."

Had not the bit about the picture been depicted, I could explain it away
with a multiverse.  Instead I have to say it is complete fiction, and
that is even ignoring technical inconsistencies such as the T-800 having
the commented assembly source code for an Apple II RWTS utility
built-in.

>Ray Ingles                  || The above opinions are probably
>ingles@engin.umich.edu      || Michigan. Yet.

With slight changes, what we saw would be of a third artificially-created
universe, and that is if they could track the T-800's chronal position
in the second artificially-created universe from the first universe
where the time machine is.  If not, there would be no T-800 in the
universe in which Reese found himself.  However there would be a T-800
in a universe where there would be no Reese anyway.

-- 
aberigan@nde.unl.edu (Greg Berigan)
Newsgroups: rec.arts.sf.science