Deductive Logic on the subject of Time Travel.

[Mentat]

When I say "Time Travel" in the title, I'm referring to traveling into the past. I just wanted to see if I could establish deductive validity for my assumption that it is not just impossible, but non-sensical, to travel backward in time.

("P" stands for "Proposition" and "C" stands for "Conclusion")

Here we go:
P1: I did not exist in 1776.
P2: I exist now in a reality that includes P1 as being true.
P3: I go back in time (using whatever means) to 1776.
C: I did exist in 1776! ...

But, then, I have invalidated P1 and P2, and even (by extension) P3, so my conclusion violates all the propositions...is this logically sound?

Any and all helpful criticism is appreciated.

 

[MathematicalPhysicist]

Originally posted by Mentat
When I say "Time Travel" in the title, I'm referring to traveling into the past. I just wanted to see if I could establish deductive validity for my assumption that it is not just impossible, but non-sensical, to travel backward in time.

("P" stands for "Proposition" and "C" stands for "Conclusion")

Here we go:
P1: I did not exist in 1776.
P2: I exist now in a reality that includes P1 as being true.
P3: I go back in time (using whatever means) to 1776.
C: I did exist in 1776! ...

But, then, I have invalidated P1 and P2, and even (by extension) P3, so my conclusion violates all the propositions...is this logically sound?

Any and all helpful criticism is appreciated.

from c it can be concluded that you no more life in the present time therefor p1 isn't right anymore and so is p2, instead of them you can propse the premises which come from the conclusion (the first conclusion becomes a premise):
p1:I exist in 1776
p2: i don't exist in 2003.
c: i must have gone back in time (-;

 

[Mentat]

Originally posted by loop quantum gravity
from c it can be concluded that you no more life in the present time therefor p1 isn't right anymore and so is p2, instead of them you can propse the premises which come from the conclusion (the first conclusion becomes a premise):
p1:I exist in 1776
p2: i don't exist in 2003.
c: i must have gone back in time (-;

I'm sure you already know that this doesn't follow, lqg. Ben Franklin existed in 1776, but he didn't go back in time.

No, I seriously need a criticism of my reasoning on the matter, since it is supposed to be "possible" to travel back in time.

BTW, I always "exist in the present time" (as you put it), since the very term "exist" is in the present tense. I don't think P1 can be invalidated.

 

[MathematicalPhysicist]

Originally posted by Mentat
I'm sure you already know that this doesn't follow, lqg. Ben Franklin existed in 1776, but he didn't go back in time.

No, I seriously need a criticism of my reasoning on the matter, since it is supposed to be "possible" to travel back in time.

BTW, I always "exist in the present time" (as you put it), since the very term "exist" is in the present tense. I don't think P1 can be invalidated.

but the present time is changing for you when youre traveling in time, if you travell in time the present is ofcourse subjective the past becomes your present and the present becomes your future which you already know it (so you can say the future is forseeable).

i think your reasoning is true the conclusion contradicts the premise.

 

[Mentat]

Originally posted by loop quantum gravity
but the present time is changing for you when youre traveling in time, if you travell in time the present is ofcourse subjective the past becomes your present and the present becomes your future which you already know it (so you can say the future is forseeable).

Yes, this is all true, and it is the reason why P2 is phrased as it is. I exist now, in a reality that is contingent with P1.

i think your reasoning is true the conclusion contradicts the premise.

Thanks for the support, I can't seem to find a flaw either...I hope someone else can.

 

[hypnagogue]

Originally posted by Mentat
When I say "Time Travel" in the title, I'm referring to traveling into the past. I just wanted to see if I could establish deductive validity for my assumption that it is not just impossible, but non-sensical, to travel backward in time.

("P" stands for "Proposition" and "C" stands for "Conclusion")

Here we go:
P1: I did not exist in 1776.
P2: I exist now in a reality that includes P1 as being true.
P3: I go back in time (using whatever means) to 1776.
C: I did exist in 1776! ...

But, then, I have invalidated P1 and P2, and even (by extension) P3, so my conclusion violates all the propositions...is this logically sound?

Any and all helpful criticism is appreciated.

We can circumvent this contradiction if we assume parallel universes (which is the standard way to get around most time travel paradoxes, such as the matricide paradox). If we assume parallel universes, then we get something like this:

P1: I did not exist in 1776 in universe A.
P2: I exist now in a reality that includes P1 as being true (although I think this one is a little redundant, if we are already assuming P1 to be true).
P3: I go back in time (using whatever means) to 1776.
C: It is logically inconsistent for me to still be in universe A; therefore I must be in a different universe, call it B, with a history/timeline very similar to A's.

 

[diverz]

You guys ever heard of this theory ----> Present conditions affects past

Sounds illogical isn't it? Its always a forward motion of ------> the present conditions affect the future.

Your thoughts?

 

[Mentat]

Originally posted by hypnagogue
We can circumvent this contradiction if we assume parallel universes (which is the standard way to get around most time travel paradoxes, such as the matricide paradox). If we assume parallel universes, then we get something like this:

P1: I did not exist in 1776 in universe A.
P2: I exist now in a reality that includes P1 as being true (although I think this one is a little redundant, if we are already assuming P1 to be true).
P3: I go back in time (using whatever means) to 1776.
C: It is logically inconsistent for me to still be in universe A; therefore I must be in a different universe, call it B, with a history/timeline very similar to A's.

Hmm...I suppose this could work, but wouldn't adding an extra Universe violate Occam's Razor?

Also, Stephen Jay Gould (along with many others) is in favor of the idea (the name of which I've forgotten...temporary brain fart) that changing even the smallest thing in history can dramatically change the series of events that happen afterward. He believes that the course of history is occurance acting on the otherwise probabilistic/chance-governed nature of reality. I (currently) agree with him on this point, since the alternative seems like determinism.

Oh yeah, the phrasing of P2 could seem redundant, I suppose, but I couldn't think of a better way to phrase it at the time.

 

[Mentat]

Originally posted by diverz
You guys ever heard of this theory ----> Present conditions affects past

Sounds illogical isn't it? Its always a forward motion of ------> the present conditions affect the future.

Your thoughts?

I guess it's not unscientific, but I do think it may be illogical...my first attempt at a proof:

P1: I exist in the present (slightly redundant in itself, since "exist" is in the present tense).
P2: P1 is true only because of the previous occurances which lead up to my having been born and living as I've lived.
P3: Because of P1 and P2, any change in the past, caused by me, stops me from existing, which stops me from changing the past, which allows me to exist again...which will go on in circles.
C: The idea of my changing the past is self-contradictory/paradoxical.

 

[physicskid]

I find time travel an indeed very stupid idea
because, wouldn't your memory of what you have perceived
now and in the past flow back to the
surroundings through your five senses
when you travel to the past?!
So you would not even know that you had traveled
back in time becasue you can't bring
your present consciousness to the past.

Sounds logical right?

For example:
Imagine that you are living in negative time zone
(equivilant to traveling back in time)
and you are gliding at a speed of 10m/s for -10s
(because you are in negative space-time).

So the distance travelled= (10m/s)*(-10s)= -100m
Conclusion: If you are traveling back in time,
everything that you did or possesses would act
in the reverse manner! (including your brain!)

 

[Mentat]

Originally posted by physicskid
I find time travel an indeed very stupid idea
because, wouldn't your memory of what you have perceived
now and in the past flow back to the
surroundings through your five senses
when you travel to the past?!
So you would not even know that you had traveled
back in time becasue you can't bring
your present consciousness to the past.

Sounds logical right?

For example:
Imagine that you are living in negative time zone
(equivilant to traveling back in time)
and you are gliding at a speed of 10m/s for -10s
(because you are in negative space-time).

So the distance travelled= (10m/s)*(-10s)= -100m
Conclusion: If you are traveling back in time,
everything that you did or possesses would act
in the reverse manner! (including your brain!)

Ok, so you're talking about regressive backward time travel. Yeah, I agree, it is completely illogical.

 

[Royce]

Originally posted by Mentat
When I say "Time Travel" in the title, I'm referring to traveling into the past. I just wanted to see if I could establish deductive validity for my assumption that it is not just impossible, but non-sensical, to travel backward in time.

("P" stands for "Proposition" and "C" stands for "Conclusion")

Here we go:
P1: I did not exist in 1776.
P2: I exist now in a reality that includes P1 as being true.
P3: I go back in time (using whatever means) to 1776.
C: I did exist in 1776! ...

But, then, I have invalidated P1 and P2, and even (by extension) P3, so my conclusion violates all the propositions...is this logically sound?

Any and all helpful criticism is appreciated.

Isn't this where I came in, Mentat?

If you went back in time to 1776 (P3) then that would invalidate P1. The rest would still be valid except the inclusion in P2 that P1 is true. It would also be true that in the present time of P2 the fact that you went back to 1776 (P3); (C) would already be in your history which would again make P1 invalid. P1 can never be true if you ever go back in time to 1776. P1 and P2 are true only if you never go back in time to 1776. It isn't a paradox as P1 and P3 are mutally exclusive. One or the other but not both can be true.

 

[Anti-Jesus]

Originally posted by physicskid
I find time travel an indeed very stupid idea
because, wouldn't your memory of what you have perceived
now and in the past flow back to the
surroundings through your five senses
when you travel to the past?!
So you would not even know that you had traveled
back in time becasue you can't bring
your present consciousness to the past.

Sounds logical right?

For example:
Imagine that you are living in negative time zone
(equivilant to traveling back in time)
and you are gliding at a speed of 10m/s for -10s
(because you are in negative space-time).

So the distance travelled= (10m/s)*(-10s)= -100m
Conclusion: If you are traveling back in time,
everything that you did or possesses would act
in the reverse manner! (including your brain!)

Okay I am only 15 but i question your idea. Because isn't your memory just chemicals in your brain which your brain reconize as memorys? if that's right when you travel back in time then those chemicals would be the same therefore your memory would be the same? right? Anyways maybe we shouldn't go back in time unless the idea of multiple (and i mean lots!) realitys or timeflow(brain just went dead) right? or we might do one of those weird paradox things where we **** up the universe:D

 

[hypnagogue]

Originally posted by Mentat
Hmm...I suppose this could work, but wouldn't adding an extra Universe violate Occam's Razor?

Maybe, maybe not. From where we currently stand, it seems to violate Occam's Razor. But suppose one day we find that time travel into the past is possible. Well, if this occurs, we know that the traditional paradoxes that are associated with time travel must be false, otherwise we would have a logically inconsistent system (much like the one you created). At this point, then, it would be more reasonable to assume parallel universes to explain how time travel into the past is possible without raising all those paradoxes.

Also, Stephen Jay Gould (along with many others) is in favor of the idea (the name of which I've forgotten...temporary brain fart) that changing even the smallest thing in history can dramatically change the series of events that happen afterward. He believes that the course of history is occurance acting on the otherwise probabilistic/chance-governed nature of reality. I (currently) agree with him on this point, since the alternative seems like determinism.

That sounds more like he is describing history as chaotic, as opposed to non-deterministic. In any case, I agree that history probably works like that. No doubt that going back to 1776 would greatly change the future course of history. But the important idea is that that greatly changed future happens to another universe, and thus is not in contradiction with the history we have observed in our own universe.

 

[Royce]

Hypna,
That line of thought ignores the fact that if some one were to go back in time and do something that would alter history and thus the present and future history, it would already be in our history that that had happened.
Going back in time may or not be possible in one universe, I think not; but, changing past history is logically impossible. As I said, any change would already be part of our history and not a change at all. What has happened in the past happened and that would include someone going back and effecting what was then happening.
Multiverses is another thing. If some one where to go back and do something that would start another universe in which his doing whatever he did would already be in its history. That doesn't make any sense at all to me; but then I don't believe in multi-universes.
Here I agree with Mentat, that that would violate Occam's Razor. Not tha Occam's Razor is an inviolate Law; but, that it is not necessary, elegant or beautiful but messy, redundant and over complicated.

 

[hypnagogue]

Originally posted by Royce
That line of thought ignores the fact that if some one were to go back in time and do something that would alter history and thus the present and future history, it would already be in our history that that had happened.

Well, I see what you are saying about the "already would have happened" part. I agree with that. Sometimes it is easier to say "change," however, to draw attention to how things in our respective universes are similar (or identical) up until the point when a time traveler from one enters the other at a certain point in time.

But say someone traveled back to 1776. It would not have already happened in our universe, since in our universe A no one did go back to 1776. That happened in universe B.

Here I agree with Mentat, that that would violate Occam's Razor. Not tha Occam's Razor is an inviolate Law; but, that it is not necessary, elegant or beautiful but messy, redundant and over complicated.

Then again, Occam's Razor is not really relevant here. We aren't talking about whether time travel is actually possible, only if it could be logically possible. Thus, it suffices to create a logically consistent scenario where time travel is logically possible. Whether that logical possibility is then a physical actuality is a question of empirical investigation, which is a separate issue.

 

[Royce]

Originally posted by hypnagogue

But say someone traveled back to 1776. It would not have already happened in our universe, since in our universe A no one did go back to 1776. That happened in universe B.

Then again "logically" speaking in a multiverse scenario, it would have already happened in B's history. We can't get around it. No matter which history or which unverse's past we go to, It had to have already happened, been recorded and experienced in that universe's history. It is either that or a split occurs in which one universe's past was not visited and changed and ther other was visited and changed but no one would know it because that universe's history would already contain and record the visit and "change" but for them it would not be a change in there history because their history already includes the "change". Only some supra spatial being outside of space and time would be able to see the change by noticing the split.
Simply put, logic will not allow the future to effect any change in the past as it would have already been included in its history and thus is not a change. No way around it. I hate to be a bubble buster because I have always loved sci-fi time travel stories but logically it can't happen.
We can't go back and save Lincoln or assassinate Hitler because if we do it would already be part of our history and it would be imperitive
that we do go back and save or assassinate. This would make the universe's present determined by it past, eliminating free will.
So instead of going back and killing your grandfather to change history all you have to do is not go back and save lincoln in a universe where you did go back and save lincoln; but in that universe you would not have that option or ability. No matter what you tried or tried not to do you would be forced to go back and save lincoln because that is already your history. And on and on and on ad nausium.

Then again, Occam's Razor is not really relevant here. We aren't talking about whether time travel is actually possible, only if it could be logically possible. Thus, it suffices to create a logically consistent scenario where time travel is logically possible. Whether that logical possibility is then a physical actuality is a question of empirical investigation, which is a separate issue.

Okay, I'll go along with that but then I have shown how it is logically impossible. Logic will not only not allow a paradox but it won't allow a messy, ugly, redundant multiverse either.
It is not a Law of logic that can't be violated as a physical law but that if it were violated then it wouldn't be logical. Our universe has so far as we know is logical. It is cosmos not chaos.

 

[Mentat]

Originally posted by Royce
Isn't this where I came in, Mentat?

If you went back in time to 1776 (P3) then that would invalidate P1. The rest would still be valid except the inclusion in P2 that P1 is true. It would also be true that in the present time of P2 the fact that you went back to 1776 (P3); (C) would already be in your history which would again make P1 invalid. P1 can never be true if you ever go back in time to 1776. P1 and P2 are true only if you never go back in time to 1776. It isn't a paradox as P1 and P3 are mutally exclusive. One or the other but not both can be true.

I don't understand what you are saying. If P3 is true, then both P1 and P2 also have to be true (since my existence is kind of required for "me" to travel back in time ).

Besides, my point is that I can establish P1 and P2 as being true (by scientific and other such proofs) but they would invalidate P3, and thus I can never travel back in time...does that mean that it is illogical to postulate time travel?

 

[Mentat]

Originally posted by hypnagogue
Maybe, maybe not. From where we currently stand, it seems to violate Occam's Razor. But suppose one day we find that time travel into the past is possible. Well, if this occurs, we know that the traditional paradoxes that are associated with time travel must be false, otherwise we would have a logically inconsistent system (much like the one you created). At this point, then, it would be more reasonable to assume parallel universes to explain how time travel into the past is possible without raising all those paradoxes.

"At that point it would be reasonable"? Does that mean that at this point it is not reasonable? Are the "extra" postulates really "extra", since there is no indication (now) that other Universes exist?

That sounds more like he is describing history as chaotic, as opposed to non-deterministic. In any case, I agree that history probably works like that. No doubt that going back to 1776 would greatly change the future course of history. But the important idea is that that greatly changed future happens to another universe, and thus is not in contradiction with the history we have observed in our own universe.

Here's a question for you, with regard to that "extra Universe" idea: How can one ever get to another Universe? This is not an irrelevant question of possibility in practice, I'm talking about possibility in principle. If there is another Universe*[/size], then there is nothing seperating that Universe from ours (not space, not time, not anything), and thus there is (logically) also nothing connecting us, which precludes our ever traveling there, doesn't it?


*[/size]In these contexts, I will deign to refer to "Universe" in the common sense of what astronomers refer to as "local universes", and not in the "set of all that exists" sense.

 

[Mentat]

Originally posted by hypnagogue
Then again, Occam's Razor is not really relevant here. We aren't talking about whether time travel is actually possible, only if it could be logically possible. Thus, it suffices to create a logically consistent scenario where time travel is logically possible. Whether that logical possibility is then a physical actuality is a question of empirical investigation, which is a separate issue.

On the one hand, I agree with you that you are just constructing a possible-in-principle framework, in response to my request for all possibilities to be presented.

On the other hand, the problem with Occam's Razor is a real one, in this case, since yours could (note: "could", not necessarily "will") become an ad hoc argument, since you would first add the postulate of an extra Universe. Then postulates of how (even in principle) a connection could be established between Universes, and so on.

 

[Mentat]

Originally posted by Anti-Jesus
Okay I am only 15 but i question your idea. Because isn't your memory just chemicals in your brain which your brain reconize as memorys? if that's right when you travel back in time then those chemicals would be the same therefore your memory would be the same? right? Anyways maybe we shouldn't go back in time unless the idea of multiple (and i mean lots!) realitys or timeflow(brain just went dead) right? or we might do one of those weird paradox things where we **** up the universe:D

Welcome to the PFs, Anti-Jesus.

I, too, am 15 years old. It makes me feel good to know that there are others, around my age, that are interested in science or philosophy as I am.

Anyway, I don't think your counter-argument works, because physicskid was referring to regressive time-travel (wherein everything starts going backward, until the point in time that is your destination). As it is, everything going backward requires that you too go backward, since you are part of "everything". Ergo, you would get younger and younger, until you ceased to exist.

 

[hypnagogue]

Originally posted by Royce
Then again "logically" speaking in a multiverse scenario, it would have already happened in B's history. We can't get around it.

Yes, I acknowledged this in my previous post.

Okay, I'll go along with that but then I have shown how it is logically impossible. Logic will not only not allow a paradox but it won't allow a messy, ugly, redundant multiverse either.
It is not a Law of logic that can't be violated as a physical law but that if it were violated then it wouldn't be logical. Our universe has so far as we know is logical. It is cosmos not chaos.

You are confusing aesthetics with logic. For something to be logically possible, it does not have to be beautiful or elegant or orderly. It just has to not contradict itself.

 

[hypnagogue]

Originally posted by Mentat
"At that point it would be reasonable"? Does that mean that at this point it is not reasonable? Are the "extra" postulates really "extra", since there is no indication (now) that other Universes exist?

Well, you have raised questions as to its reasonableness due to OR, which I can accept. There is indeed no indication of multiple universes as of yet. It is just a theory, but again, that is all that this thread has asked for.

Here's a question for you, with regard to that "extra Universe" idea: How can one ever get to another Universe? This is not an irrelevant question of possibility in practice, I'm talking about possibility in principle. If there is another Universe*[/size], then there is nothing seperating that Universe from ours (not space, not time, not anything), and thus there is (logically) also nothing connecting us, which precludes our ever traveling there, doesn't it?

The traditional answer to a question like this is simply "wormholes." I believe it is consistent with current theory that a region of spacetime could become "pinched off" from our own universe and be connected via a wormhole. How to create or travel through such a wormhole is obviously problematic, but I don't think it has yet been shown to be logically impossible.

 

[Mr. Robin Parsons]

In order for your logic to work, P1 P2 and C must all exist at the same time.

When you leave the present time, travel back, the present time does not disappear to everyone else, hence it would be required that both Now, and 1776, exist at the same time, all the time!

That would infer that all time exists in all space all of the time, which invalidates the very notion of time itself.

It is not wrong to postulate time travel but prefferable that you do not become obsessed with something that cannot exist, as time itself does not 'exist', substantively, merely idealogically.

 

[Royce]

P1: I did not exist in 1776.
P2: I exist now in a reality that includes P1 as being true.
P3: I go back in time (using whatever means) to 1776.
C: I did exist in 1776! ...

P1 is true only if P3 is false; because, if P3 is true at any time in your life, that event would always be true in your history. The only way that P1 can ever be true is if P3 is always false.

P2 is a conditional statement, i.e. it requires that P1 be true for P2 to be true thus it is not a proposition. However if P1 is true then P2 is true if and only if P3 is false.

If P3 ever becomes true then it makes P1 false. P2 is also false then because of the inclusion of P1 and also because you cannot exist in both states at the same time. Your are either in the present or in 1776.

C is only true if P3 is true and P1 and P2 are false.

In other words your entire set of statements is illogical reguardless of whether time travel is logical or not.

 

[hypnagogue]

The set of statements is not illogical if revised as I have outlined. If in universe A I exist in 2003 but did not exist in 1776, this is not inconsistent with saying that I existed in 1776 in universe B. (Assuming the multiverse version of time travel, of course-- but again-- we are only looking for logical consistency here.)

 

[Royce]

I agree, Hypna, as revised in a multverse scenerio your set would be logically valide so long as you make reference to which universe you are speaking of when.
It is perfectly logical to be both not in 1776 in universe A and be in 1776 in universe B; but that must be stipulated before hand.

Mentat was making a logical statement including time travel to show that time travel is not logical. He has done this before. If fact back in March when I first joined PF it was one of the first discussions that I got involved in. We have been buddies ever science.
which is why I said that this is where I came in.
I don't think time travel in a single universe is logically possible at least yet. It may be possible to go back and observe but not to interact with or be detected by the past. If we ever detect or are contacted by someone or thing from the future then it would be possible. I go along with Hawking on this. He does not believe that time travel is possible but he would never bet against it with anyone because that person may be from the future.

 

[Mr. Robin Parsons]

Sticking to the one universe we know exists, try a simple excersize, prove to me (using logic) that we are traveling forward in time, at this very moment.

See, time is the application of an Ideology (an ideological system) upon a reality, and fooling ourselves into somehow believing that that makes it a real thing, it ain't!

 

[phoenixthoth]

perhaps by showing that the total entropy is increasing? but why that should be called forward in time i don't know. whatever forward means, backward means the opposite of that so it doesn't make any difference if we're moving forward or backward in time or what we call what we're doing. seems as though if the total entropy was decreasing, some thermodynamics laws might be invalidated.

 

[einsteinian77]

I would also like to add that if you were to travel back to 1776 wouldn't you be nullifying all the events that lead up to your existence and therefore making it impossible for you to exist. Thats only if there is one past of course.

 

[Mentat]

Originally posted by Mr. Robin Parsons
Sticking to the one universe we know exists, try a simple excersize, prove to me (using logic) that we are traveling forward in time, at this very moment.

P1: If I were going backward in time, I would not being responding to this post, since reading precedes responding.
P2: I am responding to this post, after having read it.
C: Therefore, I am not going backward in time.

 

[Mr. Robin Parsons]

Originally posted by Mentat
P1: If I were going backward in time, I would not being responding to this post, since reading precedes responding.
P2: I am responding to this post, after having read it.
C: Therefore, I am not going backward in time.

It has the arbitrary nature of "up and down", (when we know it is away from the Earth and towards) as the simple reality is that you only see your life as it has passed you.

Intuitively you could construe that as you traveling backwards through time, as if while traveling through this, "you only look backwards", as you can only see the parts of your life as they have passed, you travel with your back towards the futur, you are traveling backwards?

Backwards and forward in time is arbitrary in nature, impossible in reality...there is no time, just an ideological (ergo Very useful) perception of (a BIG hint) Movement/Motion!

Otherwise, you are fooling yourself, and this can be proven(?)!

 

[Mentat]

Originally posted by Mr. Robin Parsons
It has the arbitrary nature of "up and down", (when we know it is away from the Earth and towards) as the simple reality is that you only see your life as it has passed you.

Intuitively you could construe that as you traveling backwards through time, as if while traveling through this, "you only look backwards", as you can only see the parts of your life as they have passed, you travel with your back towards the futur, you are traveling backwards?

Backwards and forward in time is arbitrary in nature, impossible in reality...there is no time, just an ideological (ergo Very useful) perception of (a BIG hint) Movement/Motion!

Otherwise, you are fooling yourself, and this can be proven(?)!

Was this designed to confuse me? Seriously, if you are looking "backward" at the future, that you are coming from, then the future is the past, and the past is your future, and 1776 would have to be in the "future", since I'm moving farther and farther away from it, right?

 

[Mr. Robin Parsons]

Originally posted by Mentat
Was this designed to confuse me? No, but it obviously did.[/color] Seriously, if you are looking "backward" at the future, that you are coming from, then the future is the past, and the past is your future, and 1776 would have to Have[/color] been[/color] in the "future", since I'm moving farther and farther away from it, right?

As I tried to help you to realize, they are arbitrarily interchangable words, "forwards in time" and "backwards in time" nothing establishes which "direction" truly is the one we "move" in, other then human convention.

 

[Mentat]

Originally posted by Mr. Robin Parsons
As I tried to help you to realize, they are arbitrarily interchangable words, "forwards in time" and "backwards in time" nothing establishes which "direction" truly is the one we "move" in, other then human convention.

I understood this part of it, but I don't understand how it changes anything, since I am moving away from 1776, regardless of whether it happened in my "future" or "past", right?

 

[Mr. Robin Parsons]

Originally posted by Mentat
I understood this part of it, but I don't understand how it changes anything, since I am moving away from 1776, regardless of whether it happened in my "future" or "past", right?

Yes, but it also tells you that the universe cannot exist in the same state twice, ergo it is a singularity of sorts inasmuch as the state of the universe at any given time is the only point in any time that it will exist that way, hence if you are existent NOW, then the past is NOT available to you as time travel is impossible, as you cannot travel through that which doesn't actually exist. (You cannot travel through an "Idea"...'cept in your mind hee-hEE!)

 

[Mentat]

Originally posted by Mr. Robin Parsons
Yes, but it also tells you that the universe cannot exist in the same state twice, ergo it is a singularity of sorts inasmuch as the state of the universe at any given time is the only point in any time that it will exist that way, hence if you are existent NOW, then the past is NOT available to you as time travel is impossible, as you cannot travel through that which doesn't actually exist. (You cannot travel through an "Idea"...'cept in your mind hee-hEE!)

Sooooo...you're agreeing that we can't travel through time, right?

 

[phoenixthoth]

i think i know what you mean by "the past doesn't exist" but i may not. either way, how do you know that?

 

[Mr. Robin Parsons]

Originally posted by Mentat
Sooooo...you're agreeing that we can't travel through time, right?

Agreeing?? with whom??

 

[Mentat]

Originally posted by Mr. Robin Parsons
Agreeing?? with whom??

With...me?

 

[Jeebus]

Originally posted by Mentat
When I say "Time Travel" in the title, I'm referring to traveling into the past. I just wanted to see if I could establish deductive validity for my assumption that it is not just impossible, but non-sensical, to travel backward in time.

("P" stands for "Proposition" and "C" stands for "Conclusion")

Here we go:
P1: I did not exist in 1776.
P2: I exist now in a reality that includes P1 as being true.
P3: I go back in time (using whatever means) to 1776.
C: I did exist in 1776! ...

But, then, I have invalidated P1 and P2, and even (by extension) P3, so my conclusion violates all the propositions...is this logically sound?

When you say you are referring time travel into the past your argument could fail right then before you even propose the P1 standard. All you would have to say is:

(i) "Time present and time past
Are both perhaps present in time future."

Counterresponse (1) - However, time travel is quite strange to begin with, and it does not appear to be a terribly strong additional argument against time travel that it has strange consequences.

(ii) But in order for time travel to occur the event has to take place. Thus the strange consequences of structure imposes constraints on states on space-like surfaces. However, space-time and matter interact. Suppose that one is in a space-time with closed time-like lines, such that certain counterfactual distributions of matter on some neighborhood of a point p are ruled out if one holds that space-time structure fixed.

Either way you come back to that "Time present and time past
are both perhaps present in time future" statement continuum of Time Travel.

 

[Mentat]

Originally posted by Jeebus
When you say you are referring time travel into the past your argument could fail right then before you even propose the P1 standard. All you would have to say is:

(i) "Time present and time past
Are both perhaps present in time future."

Counterresponse (1) - However, time travel is quite strange to begin with, and it does not appear to be a terribly strong additional argument against time travel that it has strange consequences.

(ii) But in order for time travel to occur the event has to take place. Thus the strange consequences of structure imposes constraints on states on space-like surfaces. However, space-time and matter interact. Suppose that one is in a space-time with closed time-like lines, such that certain counterfactual distributions of matter on some neighborhood of a point p are ruled out if one holds that space-time structure fixed.

Either way you come back to that "Time present and time past
are both perhaps present in time future" statement continuum of Time Travel.

I don't understand what "time present and time past are both time present in the future" means...that's just completely losing me. Please explain further.

 

[Jeebus]

Originally posted by Mentat
I don't understand what "time present and time past are both time present in the future" means...that's just completely losing me. Please explain further.

Alright, let me see here.

"The time present and time past are both time present in the future" basically means that even if you are in the past, which you concluded in your example, you technically never left the present or the future. Since you inevitably are in the past - you can still hop in between the present and the future because your origin started from the present.

 

[Sniper__1]

all time past present and future coexist right now but the only way to travel through time is through quantum teleportation which would have you stuck in different realities forever no matter how small the difference or how big the difference. (like if you went to 1950 the nazis might have won the war in the reality you would then exist in and the world would be different) and you however would still exist in the time you started because you didnt really leave you created another of your self and he left to a time and reality where you didnt already exist thus quantum mechanics explains that time travel is possible and impossible in one single bound



confusing huh

 

[Iacchus32]

If time travel were ever possible, then we are already living in the past, because it would already have occurred.

Or, would we then be living in the future, as a future event, of whoever traveled backwards in the past?

So, has anyone yet to hear of such things? Remember, if it were possible, it would have already happened, and continue to happen, even as we speak.

Or, could this be a possible means by which to account for some of our alien and UFO sightings?

 

[Mr. Robin Parsons]

Originally posted by Mentat
(SNIP)[/color] With...me? (SNoP)[/color]

Are you sure you don't mean the British Scientist who was promoting that Idea, back in the early ninties, he was called 'Radical' for it apparently, although I suspect he won greater acceptance, if to only the question of it, "time" that is, the question of the "existence" (or Non-existence) of time

 

[Sniper__1]

but Iacchus as i explained when you traveled you would be in a different reality so chances are we wouldn't hear about until they found a way to control which reality they went to which i believe would be impossible. oh and yes we are the past present and future all in one right now.

And mr robin parsons i think time does not exist as again i have stated before.

 

[Mentat]

Originally posted by Jeebus
Alright, let me see here.

"The time present and time past are both time present in the future" basically means that even if you are in the past, which you concluded in your example, you technically never left the present or the future. Since you inevitably are in the past - you can still hop in between the present and the future because your origin started from the present.

Still don't got it...sorry, but I don't understand what you're trying to say.

We can travel throughout the past, because it's all "the past" to "the future"?

 

[Mentat]

Originally posted by Sniper__1
all time past present and future coexist right now but the only way to travel through time is through quantum teleportation which would have you stuck in different realities forever no matter how small the difference or how big the difference. (like if you went to 1950 the nazis might have won the war in the reality you would then exist in and the world would be different) and you however would still exist in the time you started because you didnt really leave you created another of your self and he left to a time and reality where you didnt already exist thus quantum mechanics explains that time travel is possible and impossible in one single bound



confusing huh

Sniper, your very first sentence contained a huge semantic error, and I think that error is corrupting your later ideas. You said that past, present, and future are coexisting right now. The term "now" refers only to the present. I'm not both here and there at the same time, otherwise the purpose of the terms "here" and "there" would lose their meaning. In like manner, I'm not both "then" and "now" otherwise this distinction would be completely meaningless, and everything would be happening in the present (the sinking of the Titanic, both World Wars, even the Big Bang itself).

 

[Royce]

Mentat, remember way back in March when I first joined PF, you and I got in a discussion about time being a dimension, a real dimension?
I said that there is only one time and one time dimention that exists. The past, present and furture all exist along this dimension; but, as we are only 3 dimensional beings we cannot see or experience other than now; and we are compeled to travel along that dimention at whatever speed it is we are traveling and at whatever direction we are traveling.
Einstein showed that time is relative to the observer and interestingly time showed up negative in his relativity equations. If this has any significance or not I don't know; but, everybody including Einstein himself just ignored that fact.
In order for time travel to be possible in one universe then there must be one time in one (the 4th) dimension and all of time must exist at all times along that dimension. Time travel would then be traveling along that dimension; or, jumping out or off of our time line and jumping back in or on at another location. If this were possible then it would already be in our historic past whether known or not, or if would already be in our future history. Another facet of this one time idea is that to me it would make the universe determinate as our future already exists and we would be compelled to live it as it happens; but, others who believe this say that it doesn't, that we have, can and do exercise free will. This is illogical to me unless the future already includes our choices but then are we really choosing freely?
In one very real way we are all time travelers, traveling along our time line from our past to our future but always experiencing it as our present.