Gnegg's Paradox

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Liet Kynes
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Gnegg's Paradox

Postby Liet Kynes » Fri Jan 02, 2009 10:24 pm UTC

Recently while I was Stumbling I came across this:
http://www.floom.com/words/lyrics_gnegg.htm

I've been thinking about this quite a bit and wanted to hear some other opinions.

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Re: Gnegg's Paradox

Postby Rentsy » Sat Jan 03, 2009 12:33 am UTC

Okay. Imagine Gnegg's life as a 4-dimensional line. Gnegg goes back one hour, and cuts off the line, destroying all possible timelines - other than the one in which he"goes back in time and kills himself".

That is so say, unless he makes it a murder-suicide, he didn't accomplish anything by killing his past self.

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Re: Gnegg's Paradox

Postby danpilon54 » Sat Jan 03, 2009 3:12 am UTC

I dont like the multiple-timeline explanation. An hour before he goes back in time, nobody came and killed him, so he doesn't go back in time and kill himself. Its like asking what if a person falls off a cliff but doesn't?
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Re: Gnegg's Paradox

Postby EdgarJPublius » Sat Jan 03, 2009 4:20 am UTC

A self consistent paradox could result (as per Novikov consistency).
I.E. the gun misfires (the laws of physics say no such thing re: bullet must be expelled when trigger is pulled. There are a myriad of ways in which a bullet could fail to be expelled, many of which are quite mundane) either spectacularly, which could kill Gnegg2, fulfilling his original intent to kill himself, albeit in an unexpected way (Gnegg2, prior to traveling to the past, remembers a spectacular noise and turning around to find himself dead on the floor clutching the remains of a gun, this may or may not cause him to contemplate suicide), or nonspectacularly, giving Gnegg2 a chance to talk with Gnegg1 (A conversation Gnegg2 remembers happening, which may cause Gnegg1 to go on and become Gnegg2, and causes gnegg2 to decide to continue living, at the end of the hour long conversation, Gnegg1 goes back in time to start the conversation from the other side, and Gnegg2 goes on living his life.)

In essence, Novikov's Self Consistency principle states that the probability of any event which would cause a non-self consistent paradox to occur (I.E., a grandfather paradox, Gnegg's paradox, or any other time travel related paradox which would have the result of stopping itself from happening) is 0. Therefore, between the time Gnegg1 decides to become Gnegg2 in order to kill Gnegg1, some event necessary to Gnegg1/2 achieving his goal will fail to happen.
This could be as simple as the time machine failing to operate correctly, or as complex as the scenarios presented above (or even more complex).
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Re: Gnegg's Paradox

Postby Charlie! » Sat Jan 03, 2009 5:20 am UTC

Yeah, there's a moderately convincing principle that says that everything fits together. The future is unknown but the past is fixed, and if you travel to the past you will only do it in a way that preserves the present because it's already happened.

At least that seems moderately plausible.
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Re: Gnegg's Paradox

Postby nolancamp2 » Sat Jan 03, 2009 6:33 am UTC

I think that Gnegg1 would be killed, but nothing would happen to Gnegg2. There would be no physical reason or force for him to suddenly wipe from existence.

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Re: Gnegg's Paradox

Postby Game_boy » Sat Jan 03, 2009 11:18 am UTC

I personally like many-worlds. Imagine a single past splitting into two futures (Gnegg not dead (called A), and Gnegg dead (called B)). Both of these futures exist in parallel, with no way to get from one to the other without going back to the junction and then going forward in the other future. Gnegg2 uses the time machine to travel back to the junction, killing Gnegg1 and sending himself into the other branch. The events that led to the intention to kill are still in future A, and the consequneces of the death are in future B.
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Re: Gnegg's Paradox

Postby ThinkerEmeritus » Sat Jan 03, 2009 4:41 pm UTC

nolancamp2 wrote:I think that Gnegg1 would be killed, but nothing would happen to Gnegg2. There would be no physical reason or force for him to suddenly wipe from existence.


Then Gnegg2 would have to go on in time as Gnegg1, cycle back to kill Gnegg1/2, go on as Gnegg3, etc. Actually, Star Trek addressed this theme more cleverly, see http://en.wikipedia.org/wiki/Time%27s_Arrow_(TNG_episode).
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Re: Gnegg's Paradox

Postby danpilon54 » Sat Jan 03, 2009 4:47 pm UTC

I have many problems with the many worlds theory. Here are a few.

1. It assumes the universe gives a crap what we do, and can give a crap at all.

2. It assumes distinct timelines, which don't exist due to relativity.

3. It violates occam's razor. Isn't it more likely that, assuming a timeline can exist, it is consistent? The creation of multiple timelines simply due to a person's actions seems like a big leap of faith over just saying that the past is fixed, or traveling back in time is impossible.

4. If traveling back in time is possible, it won't be like either case, really. Show me the math. Causality is still important, and any timeline changes still could only propagate at c, so how does it work? I thought a major part of relativity is that it is local and does not change the entire universe due to an object's actions.
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Re: Gnegg's Paradox

Postby alexh123456789 » Sat Jan 03, 2009 5:55 pm UTC

doesn't many worlds state that all waveform collapses cause a new universe to split off? so it wouldn't be the universe caring about us exactly but the universe doing what it always does.

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Re: Gnegg's Paradox

Postby Rentsy » Sun Jan 04, 2009 2:45 am UTC

That is exactly what the "many worlds" theory would say - that the 4th dimensional line that is your life has infinite 5th dimensional lines branching off it, in which everything went "the other way".

Some of the calculations a quantum computer could perform would otherwise require more atoms than there are in the universe. David Deutsch believes that this is the strongest evidence of "many worlds" theories, as all the (conventional) computing power in our universe would be insufficient, but if we used that of other universes, it would make sense and explain "where" quantum computing does everything.

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Re: Gnegg's Paradox

Postby danpilon54 » Mon Jan 05, 2009 3:49 am UTC

also, Ive always wondered about this. If the many worlds theory is true, and a new universe is created for each possible outcome, how would probabilities work? Its not like every wavefunction is an equal combination of 2 states. You usually have an infinite number of possibilities with 0 probability each. What you end up with is a range of possibilities (uncertainty) for which there is a non-zero, finite probability. So say there is an irrational probability that a wavefunction collapses to a certain state. How are the universes created? How many? Are there an infinite number created with each wavefunction collapse? None of this makes any sense to me.
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Re: Gnegg's Paradox

Postby Velifer » Mon Jan 05, 2009 3:42 pm UTC

danpilon54 wrote:What you end up with is a range of possibilities (uncertainty) for which there is a non-zero, finite probability.

(Any event that has happened has a probability of 1 of having happened.) [edit: now watch me create a framework where contradictions of this are possible. Damn.]

If we are going to assume a time machine, wouldn't it be prudent to assume a universe(s) where such a device could exist? I tend toward a many-worlds interpretation that seems (without getting all mathy) to allow for time travel a bit more readily than other models of reality.
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Re: Gnegg's Paradox

Postby danpilon54 » Mon Jan 05, 2009 8:55 pm UTC

Velifer wrote:(without getting all mathy)


Here is the problem. Has anyone "got all mathy" with many worlds? I feel like everything Ive heard about it glosses over the details. say something has a probability of 1/pi of happening and it happens. How many universes are created?
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Re: Gnegg's Paradox

Postby SmashtheVan » Mon Jan 05, 2009 9:21 pm UTC

in the hour before gnegg kills himself, he is composed of a set of atoms. an hour later, before going back in time, he is composed mostly of the same atoms. Upon going back in time, we now have 2 sets of identical atoms, existing in one spacetime. matter has been created. universe is fucked.

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Re: Gnegg's Paradox

Postby YoungStudent » Mon Jan 05, 2009 9:23 pm UTC

Exactly! You can not change the ammount of energy that is in universe...if you go back in time...you have created matter...and you also carry some extra energy with yourself...so what does that mean?
Okay, quote me - We try to explain magic, presence of spirits and supernatural with science, which only explains 'the physical world' that we observe. It's like blind earthworm declaring that there is no light.

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Re: Gnegg's Paradox

Postby SmashtheVan » Mon Jan 05, 2009 9:25 pm UTC

YoungStudent wrote:Exactly! You can not change the ammount of energy that is in universe...if you go back in time...you have created matter...and you also carry some extra energy with yourself...so what does that mean?


it means you have either created the most effective doomsday device ever, or nothing is going to happen at all because the time travel didnt happen.

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Re: Gnegg's Paradox

Postby EdgarJPublius » Tue Jan 06, 2009 6:08 am UTC

SmashtheVan wrote:in the hour before gnegg kills himself, he is composed of a set of atoms. an hour later, before going back in time, he is composed mostly of the same atoms. Upon going back in time, we now have 2 sets of identical atoms, existing in one spacetime. matter has been created. universe is fucked.


unless his time machine required an amount of energy equivalent tot he mass transported back in time (and thus 'created') plus any inefficiencies inherent to the process.
I.E., it converts energy into matter, just at a dislocation in time.
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Re: Gnegg's Paradox

Postby Velifer » Tue Jan 06, 2009 2:55 pm UTC

EdgarJPublius wrote:unless his time machine required an amount of energy equivalent tot he mass transported back in time (and thus 'created') plus any inefficiencies inherent to the process.


So if time travel is discovered in the future, it will be most important to be very careful of where you are standing in the past er... in your proximate future, or you might have to wait a few years to meet up with your bits.
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Re: Gnegg's Paradox

Postby Xanthir » Tue Jan 06, 2009 3:13 pm UTC

EdgarJPublius wrote:
SmashtheVan wrote:in the hour before gnegg kills himself, he is composed of a set of atoms. an hour later, before going back in time, he is composed mostly of the same atoms. Upon going back in time, we now have 2 sets of identical atoms, existing in one spacetime. matter has been created. universe is fucked.


unless his time machine required an amount of energy equivalent tot he mass transported back in time (and thus 'created') plus any inefficiencies inherent to the process.
I.E., it converts energy into matter, just at a dislocation in time.

As far as we currently know, that still doesn't work. I mean, you *can* do that, but only by sneaking in under the Heisenburg radar. That's vacuum energy, essentially - virtual particles popping in and out of existence for tiny fractions of time, violating conservation of energy for short enough periods that they don't cross accounting periods.
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Re: Gnegg's Paradox

Postby Rentsy » Wed Jan 07, 2009 12:38 am UTC

The problem you people are talking about is violation of the Pauli Exclusion principle.

But the two Gneggs won't be in the same physical place - and so it will be avoided.

No doomsday device.

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Re: Gnegg's Paradox

Postby Kurushimi » Wed Jan 07, 2009 1:25 am UTC

I'd say that only alternate timelines make sense in this. Otherwise, backwards time travel seems pretty unreasonable to me.

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Re: Gnegg's Paradox

Postby Mr. Smiles » Wed Jan 07, 2009 4:15 am UTC

This kind of paradox seems to be the sort that usually makes people think "Oh, so it means whatever can't happen" rather than "Oh, it has to happen in this overly complex and counter-intuitive way."

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Re: Gnegg's Paradox

Postby SmashtheVan » Wed Jan 07, 2009 4:16 am UTC

Mr. Smiles wrote:This kind of paradox seems to be the sort that usually makes people think "Oh, so it means whatever can't happen" rather than "Oh, it has to happen in this overly complex and counter-intuitive way."


which is why im calling occam's razor on this shit!

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Re: Gnegg's Paradox

Postby YoungStudent » Wed Jan 07, 2009 5:52 am UTC

I have a question...why should Universe explode when you increase the energy ammount it carry's?

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Re: Gnegg's Paradox

Postby Rentsy » Thu Jan 08, 2009 1:25 am UTC

SmashtheVan wrote:which is why im calling occam's razor on this shit!


You can't make relativity go away just because it is more complex than necessary to explain a car crash.

String theorists seem to find extra dimensions useful for making new theories. If we have two three dimensional points, seperated by time, we can draw a four dimensional line between them. We can then draw a branching, 5th dimensional line to represent something different happening. We could draw as many of these as we want. "Many worlds" opponents get hung up on how many of these. "Worlds" aren't being created so much as actualized. "How many?", you say, "Infinite." Just like how you are able to draw an infinite number of lines from a 1-d line, those lines in the 2nd dimension.

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Re: Gnegg's Paradox

Postby SmashtheVan » Thu Jan 08, 2009 1:46 am UTC

YoungStudent wrote:I have a question...why should Universe explode when you increase the energy ammount it carry's?


well not really explode, really. the logic follows that if youre breaking one of the essential laws of physics, they will all break down and the universe will be destroyed. whether it is said to explode or implode in on itself is just preference of the person saying it, since it doesnt really matter because it will never happen

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Re: Gnegg's Paradox

Postby ++$_ » Thu Jan 08, 2009 1:49 am UTC

I don't understand what the big fuss is here. The scenario as described is obviously impossible, so something went wrong at some point. After the event, historians can figure out what exactly it was that went wrong. Here are some possibilities:

1. Gnegg's past self, upon realizing that he is about to get shot, pulls out his own gun, shoots his future self, and destroys the body. Then he represses the memory.
2. Gnegg's time machine, sadly, vaporizes him rather than transporting him back in time as intended.
3. Gnegg's past self does indeed die. However, a version of Gnegg from even farther in the future arrives, knocks the original future version of Gnegg unconscious, and uses future technology to ressurect Gnegg's past self. He then returns Gnegg's unconscious future self to that future self's proper time, and returns himself to the even more distant future.
4. Gnegg forgot to load his gun. He returns to the future to reload, but is mauled by a bobcat which had been waiting several years for the proper opportunity. He has to go to the hospital, where he is mistakenly diagnosed with Parkinson's disease and treated with L-DOPA. He has an adverse reaction to the drug and becomes catatonic, preventing him from returning to the past once again to shoot his past self.

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Re: Gnegg's Paradox

Postby Rentsy » Thu Jan 08, 2009 4:52 am UTC

I don't see why people insist on silly ways of preventing the death of Gnegg.

Obviously, whatever mechanism for time travel trumps our current understanding of reality.

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Re: Gnegg's Paradox

Postby Mr. Smiles » Thu Jan 08, 2009 6:47 am UTC

OK, I'm going to play along here, just a bit. But I'm going to say some things before I do. First, it makes no sense for unbreakable and unstoppable laws of physics to be enforced through a defined change in human will. By that I mean it makes no sense for either Gnegg, or any other Gnegg, to be involved in a way as to thwart what happens. Looking at this a little more abstractly, the issue here is that a bundle of atoms cannot go back in time and cause itself not to be in the place that allowed it to go back in time. So, then, the only way for something like this to happen is to create new atoms, probably along with some new energy to keep em all moving how we like, and send that back in time. Except that matter cannot be created or destroyed. Again, this is getting overly complex and no explanation, no matter how well thought out, will be able to cover it. Time travel simply isn't possible, at least not in the sense that you can go back in time and kill yourself.

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Re: Gnegg's Paradox

Postby danpilon54 » Thu Jan 08, 2009 3:40 pm UTC

Rentsy wrote:
SmashtheVan wrote:which is why im calling occam's razor on this shit!


You can't make relativity go away just because it is more complex than necessary to explain a car crash.

String theorists seem to find extra dimensions useful for making new theories. If we have two three dimensional points, seperated by time, we can draw a four dimensional line between them. We can then draw a branching, 5th dimensional line to represent something different happening. We could draw as many of these as we want. "Many worlds" opponents get hung up on how many of these. "Worlds" aren't being created so much as actualized. "How many?", you say, "Infinite." Just like how you are able to draw an infinite number of lines from a 1-d line, those lines in the 2nd dimension.


Theres a difference between verifying that something complex is true, and making up something complex just so your theory works. Don't even get me started on string theory. I think they both fit in the same pile tho. Two things about "physics" that people just want to be true rather than have any evidence for.
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Re: Gnegg's Paradox

Postby gmalivuk » Thu Jan 08, 2009 4:48 pm UTC

SmashtheVan wrote:the logic follows that if youre breaking one of the essential laws of physics, they will all break down and the universe will be destroyed.

That logic doesn't follow at all, actually.

If you're breaking (what we thought was) one of the essential laws of physics, then obviously it simply wasn't a real law in the first place. If we find a way to travel in time, it wouldn't be by breaking physical laws. Rather, it would be proof that our previous understanding of physical laws was mistaken. (Just like how antimatter annihilation doesn't actually violate any real conservation laws, it just violates our incomplete, pre-relativity understanding of conservation.)

Now, that's not to say we couldn't do something that did end up destroying the universe, but that wouldn't be because we'd actually broken any laws of physics. It would just mean that we did something that, according to the (real) laws of physics, destroyed the universe (by changing it so fundamentally as to become unrecognizable).
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Re: Gnegg's Paradox

Postby qbg » Thu Jan 08, 2009 7:52 pm UTC

The universe is a computer scientist's wet dream (i.e. it's a computer): Gnegg's time machine traverses the links going back in time to the point of one hour ago, and creates a portal between now and a branch of then. Gnegg then uses the portal to travel to this branch with his gun, which he then uses to kill the Gnegg in that branch. He then uses the portal to travel back, and seeing how this has done nothing to him, he shuts the portal down. The branch is no longer pointed to by an active branch, and is then garbage collected by the universe.

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Re: Gnegg's Paradox

Postby drunken » Thu Jan 08, 2009 8:24 pm UTC

Please excuse the wall of text, the part between the stars ********* is my actual answer to the question

I read a book in highschool (the name and author long since forgotten sorry) which although being about robotics and cybernetics, for some reason had a chapter on evaluating time paradoxes in such a way as to eliminate paradoxes and always end up with a stable sequence of events. It also does not require alternate timelines per se, but simply proposes that a single timeline exists which is however evaluated similarly to a computer program in a series of loops with a single output.
The theory went something like this:
******************************
If you successfully achieve backwards timetravel, in the simplest case the example of a message is used. You send a message to yourself in the past, upon recieving this message, something in your life has changed, albeit in a minor way. Once time progresses to the point that you send the message you are now not the same as the person that originally sent it, and therefore the message is not exactly the same. Thus when you send the message the effect of recieving it is not exactly the same as before and then when you go to send that message it is different again. Eventually after a certain amount of iterations it would reach a stable state. Examples of stable states for the message example are that your time machine breaks and you are unable to send it, or that you do not recieve it for various reasons, or that you recieve the message, and then later on having remembered exactly the message you recieved send it in exactly the same way (improbable). While this theory would have to allow for the possibility of an endless loops it would be infinitely unlikely, as it would have to survive an infinite number of iterations without reaching a stable state.
For the Gnegg's Paradox the stable states would be: the time machine breaks down, Gnegg dies of a heart attack before time travelling, Gnegg was never born in the first place. Note that all stable states have to conform to physical laws (no stopping bullets). Situations where Gnegg goes back in time and then decides not to kill himself when he sees himself are unstable as he would then remember in his past having almost been killed and then the change of heart, and would therefore not bother going back, unless of course he was a bit dim witted and really believed that he could do it and that his past-future self was not the same as his present self... well you get the picture.
In short, Gnegg will not shoot himself, in fact it is very unlikely that he will even succeed in seeing himself in another time.
**************************
The point of this theory in the book was actually to demonstrate an component of time machine design that the author had invented. As you may notice the most likely and therefore the most common stable states involve the act of time travel not happening. This is the simplest case but if one were to build such a machine that could not be relied upon. It is possible (but hopefully unlikely) that the iterations could spiral out into something like the human race never having existed or life on earth never having existed and this is not worth risking. The author's argument was that anyone attempting to build a time machine should install waht he referred to as a "probability fuse" which is simple an electronic component which is inserted into a crucial circuit in the device, which has a significant chance of failing, preferably without the need for any discernable cause whatsoever. This would guarantee that if any time travel paradox were to result from use of the device, the simplest and most probable stable state is the failure of the probability fuse. Being able to set the fuse to specific probabilities would be useful for such a device but repeated use could have a cumulative effect, eg. the chance of a 10% probability fuse failing 100 times in a row is very small and it might be evaluated as such.
Anyway I thought it was a nice way of looking at time travel because it avoids all that tedious mucking about in alternate realities. It also allows that time travel may be possible but even if the way of doing it becomes clear it will probably never be made to work, which sounds realistic to me.
***This post is my own opinion and no claim is being made that it is in any way scientific nor intended to be construed as such by any reader***

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Re: Gnegg's Paradox

Postby YoungStudent » Thu Jan 08, 2009 8:40 pm UTC

It's easy, when i go back in time, i see second me (me2) and when i kill me2, then me2 is dead, but im not...and timeline goes on...when i go back to the future 1 hour, i see rottening me2 but im still alive. Isn't that just logical?
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Re: Gnegg's Paradox

Postby Entropy » Sun Jan 11, 2009 5:22 pm UTC

drunken wrote:...Eventually after a certain amount of iterations it would reach a stable state.


I propose attempting to send a single bit of information to yourself a minute in the past. If you received a zero a minute ago, you send a one, otherwise you send a zero. (If you didn't receive anything a minute ago you send a zero). Then, if you sent a one you go to the movies and if you sent a zero you go bowling.

How would that converge? :twisted:

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Re: Gnegg's Paradox

Postby danpilon54 » Mon Jan 12, 2009 2:19 am UTC

All this makes me think, that if the universe is paradox free, then traveling back in time is impossible, or there is an infinite number of universes. I claim the former is more likely, and therefore the solution, unless somebody has evidence of multiple universes.

And those who respond that relativity might allow for travel back in time, show me the math that describes exactly how it works.
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Re: Gnegg's Paradox

Postby drunken » Sun Jan 18, 2009 1:04 am UTC

YoungStudent wrote:It's easy, when i go back in time, i see second me (me2) and when i kill me2, then me2 is dead, but im not...and timeline goes on...when i go back to the future 1 hour, i see rottening me2 but im still alive. Isn't that just logical?

No it is highly illogical, if you get back to the present and the body is just rotting on the floor, then the body cant get in the time machine and go back to kill itself in the past. This means it isn't dead and doesnt rot on the floor. What you are talking about is the logically fallacious multiple universe theory, I will talk about that below in response to danpilon.

0xentropy wrote:I propose attempting to send a single bit of information to yourself a minute in the past. If you received a zero a minute ago, you send a one, otherwise you send a zero. (If you didn't receive anything a minute ago you send a zero). Then, if you sent a one you go to the movies and if you sent a zero you go bowling.
How would that converge? :twisted:

In my thought experiment there is no paradox here, you simply do what you described. There are some probability questions that I can't answer with it but no real paradox. Basically what you describe could be a stable sequence of temporal events.

danpilon54 wrote:All this makes me think, that if the universe is paradox free, then traveling back in time is impossible, or there is an infinite number of universes. I claim the former is more likely, and therefore the solution, unless somebody has evidence of multiple universes.

I don't agree with either of your possibilities in the context of this discussion.
Firstly, multiple universes: I think that the multiple universe explanation for time travel comes from popular media, where the writers can't be bothered coming up with a coherent time travel theory and so just don't bother resolving paradoxes. We then try and think of ways to explain what is actually just a writers trope. Not only this but the explanation is not logically consistent. I don't deny the possibility of multiple universes, but if you travel from one universe to another, that is not time travel. We can hypothesise that time passes the same in all universes, and that if you travel to another one, you arrive there at the corresponding time, then if you spend five minutes there, and then return to your own time, you will arrive back 5 minutes after you left. Great, no paradox, but also no time travel. We can hypothesise a mechanism by which time is not constant across universes, or it is but when you skip from one to the other you leave time and can enter the universe at any time in its history. This is also not time travel, you have simply travelled to a universe in which (for example) the medieval period is still happening. You could kill some important historical figure in this universe and then travel back to your own universe and nothing there would have changed. These mechanisms however imply that when you travel back to your own universe, you could also travel back to a different time in your own universe. This is normal everyday time travel and is subject to all the same paradoxes as a single universe theory, and explains none of them. If the mechanism required that you always arrived back at the same time in your own universe, there is still nothing to stop you travelling back to the previous universe, at a time earlier than your last visit, and setting a deadly trap or leaving a message for yourself. Again the same paradoxes apply. So no possible explanation of a multiple universe theory actually helps with any of the time travel paradoxes, unless strange fictional mechanisms are built in which just raise hundreds of new inconsistencies for every one they eliminate. Also the mechanisms in the last two examples are more examples of writers tropes, there is no explanation or reason why the mechanism would be so other than narrative consistency. I think fictional tropes need to stay out of reasonable discussions of time travel.

Time travel is impossible: obviously this is an option and doesn't really need to be discussed. It is also the most likely the correct option. The purpose however of Gneggs paradox and any other time travel discussions is to reconcile the hypothesis that time travel is possible, with the laws of logic. That is what I was attempting to do in my first post in this thread. I believe the theory is sound but it implies that while time travel is theoretically possible (as per the starting hypothesis), it is practically impossible or nearly infinitely improbable, that anyone will ever successfully do it. It also implies that if someone does do it they will only do so by not really changing anything in the past. The theory does allow for hollywood style time travel radically changing history, but it would have to be through the most bizzare set of circumstances that no hollywood writer could possibly wrap their head around (or their viewers for that matter).

The theory I put forward however is not what I believe personally. It is just a theory for a hypothesis. What I personally believe is that both time and space are simply artifacts of human consciousness, that they don't have any true existence in reality, but are simply constructs of our thought processes that enable us to understand the world better. Given my personal beliefs on the subject asking any question about time travel is the same as asking wether a triangle can have 4 sides, or wether blue green red purple.
The correct answer therefore in my opinion to this and other time travel questions is simply "Huh?"

I do have one further question though: Why is this thread in science, there is no science here.
***This post is my own opinion and no claim is being made that it is in any way scientific nor intended to be construed as such by any reader***

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Re: Gnegg's Paradox

Postby notallama » Sun Jan 18, 2009 2:33 am UTC

how fast is this time travel?

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Re: Gnegg's Paradox

Postby gmalivuk » Sun Jan 18, 2009 2:39 am UTC

drunken wrote:These mechanisms however imply that when you travel back to your own universe, you could also travel back to a different time in your own universe. This is normal everyday time travel and is subject to all the same paradoxes as a single universe theory, and explains none of them. If the mechanism required that you always arrived back at the same time in your own universe, there is still nothing to stop you travelling back to the previous universe, at a time earlier than your last visit, and setting a deadly trap or leaving a message for yourself. Again the same paradoxes apply. So no possible explanation of a multiple universe theory actually helps with any of the time travel paradoxes

Except for the fact that every single multiple universe theory I've ever seen used for time travel involves universes splitting when you arrive in them. That is, if you travel back into your own past, your arrival itself splits the universe at that instant, because of course the actual past timeline of yours doesn't involve a future version of you back in it. After that point, it's a different universe from the one you started in, so no paradoxes.
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