From: Ross A. Finlayson (raf@tiki-lounge.com)
Date: Sun May 20 2001 - 11:31:47 MDT
Lee Corbin wrote:
> Mitch, Hal, and Eugene keep coming dangerously close to a full
> discussion of SF level time travel, paradoxes and all.
>
> Is there anyone on this list who has not at some time or other
> personally tried to work out a theory of time travel that
> would resolve, or escape from, the paradoxes?
>
> One idea I had turns out (so I like to think) isomorphic to
> what David Deutsch suggests! First, DD wrote an article in
> Scientific American five or six years back that purported to
> describe how time travel would really work. You can't imagine
> my anticipation of reading that, only to be rather disappointed.
> It seemed that DD was saying that --- well, you know how anything
> can happen in the multiverse? E.g., your keyboard could suddenly
> turn into a brown rabbit, because there is a small amplitude in
> QM for just such a transformation? --- he was saying, or so it
> seemed to to me, that the appearance of a time traveler from
> the future was exactly such a miraculous transformation. How
> dull.
>
> But I always have to read Deutsch twice to appreciate him. In
> "The Fabric of Reality" he devotes an entire chapter to time
> travel! And he's right on the money (as we Americans say),
> merely fleshing out his earlier SA article.
>
> But here was my idea from many years ago: suppose (to make
> the paradox simpler) we have a Contrarian. This person will
> always say "Yes" if he is supposed to say "No" and vice-verse.
> The Contrarian receives information from the future that he
> is about to say "Yes", so naturally he says "No". Well, then
> after he writes down his answer somewhere, and some time travel
> apparatus gets hold of it, it's now the "No" answer that flies
> backwards in time. This time, the past Contrarian is presented
> with the "He said No" information, and so says "Yes". Then,
> later, when **his** information is written down and then used
> by the time travel apparatus, the cycle repeats.
>
> As you have already probably guessed, this picture involves
> a sort of meta-time. (You should properly have gagged at a
> number of the "this time's" and "later's" that I used in
> that paragraph.) Now then, we mark the "nth" instance of the
> information going backwards in time, and then the "n+1th"
> instance and so on, where n and n+1 are elements of a non-
> well-ordered set (so that there is no starting element).
> But it gives rise to an ensemble-type picture: you look
> at these two paths and see them both happening infinitely
> many times, but identically each time, which really amounts
> to them just happening once each (under a certain interpretation).
>
> The more elaborate paradoxes are handled similarly. You kill
> your grandfather, and then aren't born in the next "run", but
> then history is different, someone else gets the time machine,
> then kills his grandfather (or sends the 1937 Electrical
> Engineering Handbook back to 1837), and a different history
> happens, and then a different history happens, and then...
> some large but finite number of times, until you are born
> once more, and the entire cycle repeats.
>
> But so far as I can make out, this is what David Deutsch is
> in effect saying. If you "go back in time" you are going to
> a different branch of the multiverse, that's all. (The
> multiverse is a continuum, so it would lack my finite recursion
> property that I used for illustration above, but that isn't
> essential.)
>
> Eugene wrote
>
> > ...you've got a loop of Final Cause (the Antipode of the First
>
> > Cause) keeping reaching back, and restructuring the timeline.
> > Iteratively. Not only is this bootstrap, this is autofeedback.
> > The capabilities are nudged backwards with each increment. The
> > initial kinetics dynamics is limited, but I have no idea how
> > limited. Even if you're getting back "only" information, you
> > might be very surprised what you might be getting back from
> > scant few hours into the future.
>
> It's not completely clear to me what he's saying, but the idea
> I get out of this is as follows. Suppose that you are climbing
> a hill at a certain angle theta. Then information from the
> future arrives which enables you to climb at theta+iota. But
> then since you are now on *that* slope, so to speak, you are
> going to be receiving information from a more advanced future.
> The effect of that information will be to now place you on a
> theta+iota+iota slope, and so on, as long as you keep your machine
> receiving from the tangential future. (The tangent space, for
> those who know differential geometry, is a good metaphor here.)
>
> For the metaverse, this would have the following implication.
> Intelligent life (i.e. life that is capable of devising and
> profiting from the use of time travel devices) almost always
> goes off on an indescribable tangent (to badly mix metaphors).
> That is, a Singularity is achieved in a way that we have not
> so far discussed very much.
>
> Anyway, so much for paradoxes: they can be dealt with in the
> manner that I have suggested, namely by an appeal to the
> multiverse which (I think!) is indistinguishable from the
> meta-time idea above. (My reference to the 1937 Electrical
> Handbook is taken from the marvelous old time travel short
> story "Other Tracks", which has inspired almost all my time
> travel ideas.)
>
> Lee Corbin
I think if you consider all the possible events that might occur, then
there are graphs of the probabilities and their realities. For example,
consider sports betting where each week all the teams except for a
couple play. For each of those games for each week, then, there are
simple charts of points scored and games won, although it is less
significant who had any given number of points or some other statistic,
because at the end of a season, each of those teams would have a
win-loss record.
If you could rewind time to the start of the season, considering some
regular league, then with the schedules already set the teams would play
as they did in the first sampling of the season, where it could be
expected to see very similar results for this repeated season, because
the initial conditions are the same except for you having found some way
to rewind time. The more dedicated are all of the players, the more
likely it is to see similar results.
Thus, at the end of this second sampled season, the graph or chart of
outcomes of the events would likely be very similar. Then there are
questions about what happened to the first season, and the third,
fourth, etc. Here what this leads to is probabilistic representations
of the conditions at the points where time travel took place.
So the multiverse is one way to examine the concept, yet it might also
be the closed loops system, where any change in time resonates back to
real time. It could be a hybrid system, where insignificant events only
minisculely change the probabilistic state and caught and pulled by the
current of that local spacetime back into the primary or main line of
time, where significant events to the spacetime might have enough weight
to fall into the next current of spacetime.
This is reminiscent of "Groundhog Day", where the premise is that the
protagonist repeats a day over and over again, consciously, where no
scientific explanation is offered. The protagonist uses this long time
to become skilled in many things, and knowledgeable of the initial
conditions of that day which keeps repeating, where he eventually
escapes with a happy ending, having gained character.
In analysis, with Minkowskian or super-Euclidean spacetime, where
Euclidean space is a state of what we see as 3-D, a snapshot, the
non-Euclidean space is measured by what are called time-like or
light-like vectors, where the light measure vectors are zeroed and the
time-like vectors imaginary with respect to Euclidean space, and one
axis of the time dimensions, for us as observers, plods ever from time
negative infinity to time infinity, with it always being zero.
About paradoxes, I think there are none.
Ross
-- Ross Andrew Finlayson Finlayson Consulting Ross at Tiki-Lounge: http://www.tiki-lounge.com/~raf/ "It's always one more." - Internet multi-player computer game player
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