From: william@cs.arizona.edu (William E. Hertling)
Newsgroups: rec.arts.startrek.misc
Subject: Re: Modern THEORIES and Reality (was RE: S.O.S. signal!)
Summary: Time travel could be possible
Date: 4 Oct 92 20:50:34 GMT
Organization: U of Arizona CS Dept, Tucson

In article <1992Oct3.235620.756@altair.selu.edu> scsd1005@altair.selu.edu (Terry Cooper) writes:

[lots of stuff deleted]

>Now, having said all that, I still assert that backward time
>travel is impossible. Can I prove it?  YES!

[more stuff deleted]

>I cannot both exist and not exist. I can never go back into the
>past and kill an earlier ME. Therein lies the proof that backward
>time travel is impossible.

>contradiction. Likewise, I ASSUME that time travel backward is
>possible and show that the ASSUMPTION leads to a contradiction.
>There is NO physics involved!  As in the preceeding paragraph, if
>I go back and kill the younger ME, then there will be no ME in
>the present to go back. If that's the case, the earlier ME was
>not killed so that there *is* a ME in the present which means
>that I CAN go back and kill the earlier ME which means that I
>don't exist in the present so that I can't go back ...  It's a
>damn contradiction.  I cannot both exist and not exist.  Since
>assuming backward time travel to be possible leads to a
>contradiction, we have PROVED mathematically and scientifically
>that backward time travel is NOT possible.

I have to totally disagree with your statement. Having discussed this
personally with others, I know there are at least a few people who agree 
with my theory on the subject, so it is not merely "MHO", but rather
the opinion of quite a few people.

Your assumption is that events must follow some sort of logical pattern
over great periods of time. It is your belief that, if I were to travel
back 20 years, and kill myself, we would be left with a contradiction of
some type. There would be no logical pattern to connect events, and hence an
impossibility would have occured.

I think we would all agree that events/history do follow some sort of logical
pattern. However, I do not think these are long term patterns. Rather, I
think of life/events, as being governed by a finite state machine. As you
might know, there are a large number of people in various scientifi fields
that also agree with this idea. Anyway, the point of a FSM is this.
At any single moment in time, the universe is in a specific state. The state
that it is in governs what will occur when there is some input to the FSM.
In the case of the universe, the input would be the natural occurance of
events that take place in that moment - a cell starts to process a molecule,
a person's neurons start to fire as they think about something, gravity
interacts with various masses, etc. So this state and the input determine 
what will be the next state of the FSM. Notice that nowhere does it say
what will occur 40 years down the road. We do not see, of course, any way
that this view of the universe can differ from your view, since things
must still follow on a logical set of rules...your rules just happen to
span years, while the rules of my system span one instant of time.

Here is the crucial part. If I were to travel backward in time, my sudden
presence would be input to some state in the past. That state, in a rather
uncaring manner, is going to process me like any other input. I am simply
there suddenly. Now that I am there, can I interact with the past? Sure...
everything I willfully do will be input to the state that I am in, and thus
I would effect the next state. If I kill my earlier self, then that self is
dead. I will not simply disappear...as a thing encoded in the current
state, it will be illogical for me to just disappear. In general, a FSM does
not care that logic may not follow through indefinately. It is like someone
fiddling with the circuits of a real FSM, turning on this line, or 
off that state, etc. The overall effects may not be logical, but from state
to state, things do follow logically, and that is all that is required.

Of course, this whole FSM theory of the universe fits in very well with
Plank time, which basically says that in the interval of 10^-43 seconds
(10 to the minus 43), the laws of physics don't apply - the universe is
basically chaos in this interval and anything can happen. This period of
time can be compared to the transition interval of a FSM. If any new/
unexpected input occurs, the next state will not be what you expect.

Granted, this occurs very rarely. In fact, we have no proof that anything like
that has ever occured. But this can be for two reasons. 1. There is no
superbeing out there playing with our FSM, and 2. No one has ever
discovered a way to travel back in time.

Well, hope you all enjoy my theories on time travel!

william@cs.arizona.edu

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