This may sound stupid, but I saw Star Trek: First Contact recently, and on the
way home, I had an hour long discussion on the paradoxes and other problems
with time travel. I'm not going to list them all here, but they were all very
odd and bizare, and thought this crowd could beat them to death a little more.

50 responses total.

Time Travel, Hm... I think the medium being what it is will not support our
bodies to either travel backwards (or) forward in time.  I will accept it if
someone says we could go back  or forth in our mind but then what of vital
inputs like sight, smell, touch, taste and hearing ??? Not at all stupid Snafu
but then you always start like that!

Uh huh.. our argument basically inged on the fact that you could travel back,
but you couldn't travel forward. Mainly because the past is already written,
but the furture all depends on what you do, therefore you couldn't travel
forward to a specific point in the future.. So you travel back, but as soon
as you go back, the future becomes variable, therefore you can't travel back
to the place you started from..

Well, I know of people that do travel in time, but it isn't what most people
think it is. Going back in time is like reading a book. Everything that has
been done has left an impression back there...you can go back and look at what
has happened, but you can't change it in any way. It is a record....Now the
future is a different story...it is like your hand...there are many possible
futures and one probable future, which would be your middle finger...the
future hasn't happened yet, so it is fluid and yet there is a probable future.
The motion that things are moving is the probable future, the inertia of
events.  This is called crossing the veil, and has been done for thousands
of years by indeginous cutures through the world.

well.... I guess... not exactly what I meant by time travel. I meant more of 
travel back (or forward) and CHANGING things.

I think that one day it may be possible.  Imagine telling a cave man that he
would one day fly.  He would probably say ugh scratch his head and walk off
to kill some buffalo.  but the idea of time travel and changing the past is
really scary to me.  t hese things should not be messed with.  If someone were
to go back and kill hitler at birth <please no-one take offence from this.
I'm not saying what hitler said is good>  but the world would be massively
overpopulated.  And good or evil could have come form any of those who died
the possibilities are endlessit's just scary what could happen if time travel
got into the wrong hands.

        Well, relax, you can't change the past...at least that is what I have
been told by those that go there....

Right... A suggestion... make conversation and discusion, as opposed to saying
"I AM GOD, WHAT I SAY IS RIGHT!!" don't just discount others' beliefs.... you
won't get far  here like that...

Discount another's belief's? No not at all, just trying to ease the worry of
someone who has anxiety. Relax.

Yeah... Ease worries... some of our discussions stem from worries, and without
them, we have notheing..

Who's worried/ not like it's going to happen within the next few centuires
anyway

BRAVO!! I'm just trying to do a little soap-box kicking...

snafu--the fact is, if at some point we can't just say "it is this way just
because this is the way it is", there is no point to logic.  
hokshila--what do you mean by "those who go there"
snafu again--How do you find time travel worrying?

Food for thought. I read a book recently where the Heroine goes back in time 
and takes part in history. She doesn't change anyrthing per se, because history
refects her journey.

Right.. I don't find time travel worrisome... It's just that he said his thing
about "setting at ease the worriers.." or something like that, here, so I
responded here...

Eldrich--If your'e going to belive that is possible, you have to give up the
idea of cause and effect.  THe standard idea of cause and effect is that it
only moves forwards in time, but if time were to reflect her journey, then
her travelling back in time would cause the events of history, which would
cause her travelling back in time, which would casue the events of history,
etc.

Exsactly! She isn't changing anything because her journey already has
happened. I don't think I'm exsplaining this right... oh well.

I think it's called a "predestination paradox".  You have to go back, 
because if you didn't the future would be changed.

OK. I've got a wee bit more... Time Travel may be a possibility since time
itself is relative. We are looking at this from being very human and
maintaining that this is not possible. maybe so. But if we break out of those
restrictive parameters ... it may be a definite yes.  Think about flying. when
we got to the idea of flying in an aircraft, the idea just took off. But there
were maiden attempts like leaping off a cliff - for instance. I've been
thinking about this for quite sometime. Keeps getting better by the day. Guys,
Gals! dont be chintzy with your ideas. We'll put them down and the fw can
delete the previous ones (can you tell me who I can print - say - the 15th
response ).

<I'm getting sick of being the resident skeptic--someone else argue with this
guy>

I could argue with myself, but that would be odd.. 

Go ahead...we don't mind

Well, it would depend:  Is your temporal theory linear or other?  What is
time (i.e. is it a quantifiable "energy", or is it merely a label we apply
to our perception of decay and entropy which are the inevitable results
of conservation of energy and matter)? 

whoa...lost me there, de.  If I understand the first part of the question...
Yes, I'm talking about linear time, because if time is not linear than cause
and effect goes out the window.  And I'm not willing to throw away the
foundation of much of our logical understanding of the world unless you give
me a damn good reason.  As for the second part, how can time be an 'energy'?
And how can decay exist without time?  Maybe I'm misunderstandinn the
question.  
And incidentally, welcome to thezone, de.

De, we were taking about linear time all right! Progressive and linear. Time
- an energy ? I've lost you on that one. I'm willing to look at non linear
concept of time. But then, people who talk about it arent quite sure and tend
to get lost somewhere along the way. If you can clarify, please. 

Nistel:
Most ideas about nonlinear time that I have heard run somewhat like this--
Time is an illusion, as are cause and effect, and change.  The universe is
merely an 'object', rather than a succesion of events.
Note that I don't agree with those theories, but just want to clarify what
we are talking about.  Perhaps de, if he returns, can explain better.

Hmm.. Dunno... What is everyones opinion of linear time? IMHO, Time is linear,
(one path) in the past, since it's already happened.. The future is completly
scattered, like the end of an unraveled rope... the point where the rope
transitions from a single cord to a fuzzy mess is the present.. The rope
itself is the past, and the fuzz is the future... The past is set, unles you
found a way to go back and change it.. The future is immensely variable...
Soemthing as trivial as that last misspelling of something could have a small,
minor, or massive impact on my future... Or yours, or some guy named Boris
in northern siberia... Get my point?

Orin, Thanks on that one. Snaf this one's for you :
Pardon Impossible, To be sent to Siberia.
Pardon, Impossible to be sent to siberia.
eh snaf ?

<orin doesn't get it>

Nither do I... Extrpolate please?
er... extrapolate...

I suppose what I meant when I referred to time being an "energy" was that
that is how many people who discuss time travel, in my experience, seem
to regard it.  That time is something to be manipulated and quantified by
instruments other than a clock.  Others liken it to a river that can be 
traversed and exited from to re=enter at another point (i.e. the past or
the future).  A better word, rather than energy, would have been "force"
I suppose.  And there, I think, lies the root of the problem of time travel.
First, we must discover whether it is something that can be manipulated, or
if it is a label we affix to the perception of change in our environment.

Sorry for the lack of definition.

You are saying in other words, that there are two possible ways to look at
time:
1--time is just how our minds explain change, and so time travel is really
just reversing changes.
2--time is a force that causes change, and time travel is really counteracting
that force.
Am I understanding you correctly now?

Yes.  Thank you for being concise when that ability failed me :)

Yikes... I think I've dove in WAY over my head...

The problem with theory #1 is that 'change' assumes the existence of time.
You cannot have change without time...or at least I can't see how you can.
Explain?

Hi everyone, I'm new here and find this topic very interesting. I have a lot
of doubts about time, and going back. 
Firstly, what exactly is "going back in time"? When you go back in time, say,
2yrs from now, what is it going to be like? Is it :
1. you as well as the space (surroundings of you) go back 2yrs?
2. Only the space goes back two yrs but you will be what you are now, except,
in the space that is two yrs younger.

In all the fictions which talk of time-travelling, the 2nd case applies. You
go back to pre-historic age, being yourself amoung pre-historic people.
Its like seeing the history live. You will still be what you are. Is it
posible, when you go back, everything changes to what it was, except you?
This is not posible! If you want to look at in in another angle, say, it is
posible. If not we, someone in 10001st yr or 20001st yr will invent the time
machine. Then, he should have come back to some year before 1997 Feb 18th,,
to see what it was like! But till now we don't have any evidence of it.
SO, in my opinion, case 2 is wrong.

If you come to case 1, lets assume that its posible. Time as such is a
physical dimention. I'm 27yrs old now. If I want to go back 28yrs from
now, is it posible? I physically do not exist in the space at that time!
If you pull in some more variables into this theory, even this looks
illogical. Yet, if this is posible, the time you can trevel back is limited
on the scale.

pkk--I agree with you that, if your mental and physical state reverted as well
as your 'position' in time, time travel would be a lot more 'possible', and
pose much fewer paradoxes.  But, it also would not be something we would
recognize as unusual or out-of-the-ordinary.  We could well be blinking
forwards and backwards in time thousands of times a second and not notice it
under this theory:
Suppose that I were to travel 10 years forwards in time, and then back to the
present, spontaneously.  When I travelled 10 years forwards, 'memories' of
10 years worth of life, 10 years of accumulated knowledge, etcetera, would
be given to me, and when I travelled back, my mental state would return to
what it is now.  Meaning, on the trip forwards in time, I wouldn't notice any
break in continuity, because I would 'remember' the 10 years between now and
then; and on the trip backwards, I wouldn't notice any break in continuity
because my mental state would be 'reset', and I would forget the trip
entirely.
So, while your theory #1 is interesting, there is no way to prove it, and time
travel, under it, would be essentially meaningless.  Which is unfortunate,
because it does circumvent a lot of the paradoxes inherent in time travel...

More food for thought: As I see it the above theory one implies that there
is a predestined sequence of events (hence allowing travel forward). Something
else: give theory one is true and you could go back, would events run the same
way or could they be changed?

Theoretically, it depends (That made a lot of sense, didn't It?) It depends
on which theory you use... If you believe that you can go back, avoid contact,
and do nothing, change nothing, etc, then you should be able to go back
forward... however, as a firm believer of the idea that you can't observe or
study anything without causing subtle, or not-so-subtle changes in it, no,
I don't believe that you could.... 

- Backtalk version 1.3.30 - Copyright 1996-2006, Jan Wolter and Steve Weiss