NationStates Jolt Archive

Proof traveling back in time is impossible:

After the point of the invention of time travel, there is an infinite time(for the reasons of this argument) Now once the technology has been created, assuming it is not destroyed, there will be an infinite jumps back in time after that point. Now even if the travelers were perfect in their attempts to hide their presence, law dictates that the information would leak out into that time. Therefor, with infinite travelers going back in time, to our own, and all previous times, we would certainly know about the technology.

As for time travel into the future, if you believe Einstein's relativity, then you know that it is possible, because traveling at very high speeds will in affect, put you ahead in time.

Proof traveling back in time is impossible:

After the point of the invention of time travel, there is an infinite time(for the reasons of this argument) Now once the technology has been created, assuming it is not destroyed, there will be an infinite jumps back in time after that point. Now even if the travelers were perfect in their attempts to hide their presence, law dictates that the information would leak out into that time. Therefor, with infinite travelers going back in time, to our own, and all previous times, we would certainly know about the technology.

As for time travel into the future, if you believe Einstein's relativity, then you know that it is possible, because traveling at very high speeds will in affect, put you ahead in time.

The second point has been physically proven.......

As for the first. So? Any kind of grasp of basic physics tells you it's impossible. Your argument is redundant.

Remember this?
"The news item is a little old, but its interesting nonetheless:

To sum it up: A guy made 350 million bucks from a starting capital of 800. Each and every one of his 126 high risk trades unexpectedly gave him a profitable turnout. FBI suspects he was dealing with insider knowledge, so he is being retained until he reveals his sources.

Up to there, it sounds like normal white-collar fraud, but heres wehre it gets interesting: He claims to be a Time-Traveller from the year 2256 and said that he can prove this by giving us historical facts that have not taken place yet, such as Bin LAden's hideout or the cure for Aids.

All he wants to do now is travel back home in his "time craft" though he is unwilling to reveal its location out of fear of it falling into the "wrong hands". Officials are quite sure his time traveller story is totally bogus, BUT... sources at the Security and Exchange Commission have confirmed that there is no record at all of this man in any registries whatsoever prior to December 2002".

Isn't time travel simply a matter of finding something with gravitational force large enough to bend space-time (oh, say a black hole), and then travelling in the right direction?

Isn't time travel simply a matter of finding something with gravitational force large enough to bend space-time (oh, say a black hole), and then travelling in the right direction?
That may be technicaly correct, but my paradox(I say my, though I'm certain others have come up with it independantly and previously to my own) But even if we could do it, we Haven't, and won't. Otherwise we would currently have the ability due to the infinite travelers that would have visited us.

Further, spaghetification throws your black hole theory right out, as it is impossible for a physical form to travel anywhere near a black hole without being destroyed. But that is a slightly different argument.

Remember this?
"The news item is a little old, but its interesting nonetheless:

To sum it up: A guy made 350 million bucks from a starting capital of 800. Each and every one of his 126 high risk trades unexpectedly gave him a profitable turnout. FBI suspects he was dealing with insider knowledge, so he is being retained until he reveals his sources.

Up to there, it sounds like normal white-collar fraud, but heres wehre it gets interesting: He claims to be a Time-Traveller from the year 2256 and said that he can prove this by giving us historical facts that have not taken place yet, such as Bin LAden's hideout or the cure for Aids.

All he wants to do now is travel back home in his "time craft" though he is unwilling to reveal its location out of fear of it falling into the "wrong hands". Officials are quite sure his time traveller story is totally bogus, BUT... sources at the Security and Exchange Commission have confirmed that there is no record at all of this man in any registries whatsoever prior to December 2002".

Time paradox: Having been from that year, his appearance would have been recorded in our history(you read it, therefore it was publicized) and he would certainly have noticed that he had been captured in this time, and then avoided going at all. Unless of coruse it was such a small issue that he never bothered checking, or ever encountered that news bit. Further still, that is only one of the theoretical infinite travelers... They can't all be locked up and deemed insane, thats alot of people!

time travel IS possible, not at the moment maybe not for aeons but is it physically, it has been proven but you may only travel forwards in time. using the same technology you can hyperspace, that is basically how time travel works, by travelling to a parralel galaxy or universe and seeing what happens there.

Further, spaghetification throws your black hole theory right out, as it is impossible for a physical form to travel anywhere near a black hole without being destroyed. But that is a slightly different argument.

Although Hawking radiation opposes your point. as anything passing the event horizon could theoretically be carried out (Not physically, an imprint, data, whatever you wantr to call it.).

Proof traveling back in time is impossible:
<snip>


However, physics does allow the theoretical possibility of effect preceding cause ;) And your reasoning can be circumvented if you accept "parallel worlds" - though that is admittedly a concept I prefer to see in tv-series like Sliders and read about in novels than actually do serious physics on.

time travel IS possible, not at the moment maybe not for aeons but is it physically, it has been proven but you may only travel forwards in time. using the same technology you can hyperspace, that is basically how time travel works, by travelling to a parralel galaxy or universe and seeing what happens there.

You do realize that your post makes no sense whatsoever right.....

Although Hawking radiation opposes your point. as anything passing the event horizon could theoretically be carried out (Not physically, an imprint, data, whatever you wantr to call it.).
Not that I am going to tackle this theory, but: By what?

However, physics does allow the theoretical possibility of effect preceding cause ;) And your reasoning can be circumvented if you accept "parallel worlds" - though that is admittedly a concept I prefer to see in tv-series like Sliders and read about in novels than actually do serious physics on.

Yeah. But whilst parallels are theoretically sound. They are impossible to reach.

Well, assuming we don't find a way through black holes or methods to travere 9 dimensional space. Or whatever the current theory is on it. I don't keep up.

Remember this?
"The news item is a little old, but its interesting nonetheless:
snip
Uh, no I've never heard about that. But it sounds very interesting. Do you have a link?

However, physics does allow the theoretical possibility of effect preceding cause ;) And your reasoning can be circumvented if you accept "parallel worlds" - though that is admittedly a concept I prefer to see in tv-series like Sliders and read about in novels than actually do serious physics on.

Well, perhaps traveling to a different point in a parellel world is possible, but that is hardly anywhere near traveling back to a point in time in the same world as you originated in, so is not really a time travel argument at all.

Uh, no I've never heard about that. But it sounds very interesting. Do you have a link?
Most likely a net/urban legend...

Well, perhaps traveling to a different point in a parellel world is possible, but that is hardly anywhere near traveling back to a point in time in the same world as you originated in, so is not really a time travel argument at all.

No, but it could be used to explain why we are not knee-deep in timetravellers.

Not that I am going to tackle this theory, but: By what?

Pure chance, basicly.

Not that I am going to tackle this theory, but: By what?

The theory states that whilst matter cannot escape after passing the event horizon, Hawking radiation can.

As far as Hawking was concerned this just confirmed the fact that matter couldn't. But now they think this could cause an imprint of the data to leave.

So whilst no matter leaves. knowledge could heoretically be gained of what happened to that matter upto that point and also what it was.

Time paradox: Having been from that year, his appearance would have been recorded in our history(you read it, therefore it was publicized) and he would certainly have noticed that he had been captured in this time, and then avoided going at all. Unless of coruse it was such a small issue that he never bothered checking, or ever encountered that news bit. Further still, that is only one of the theoretical infinite travelers... They can't all be locked up and deemed insane, thats alot of people!
Given that presently, we do not have any concept of how to control time travel (if possible), there are a huge amount of possibilities to deal with this. The paradox effect may be dealt with by creating an "alternative future" whilst having no effect on his own personal present/future time, so when he returns to the "future", it would not be the same "present" that he had left from, but one that had been influenced by his actions in the past. Consequently, he would have "returned" to a different "present"

Uh, no I've never heard about that. But it sounds very interesting. Do you have a link?
I managed to find something.......
http://tv.yahoo.com/news/wwn/20030319/104808600007.html

Most likely a net/urban legend...
Nope, it really occurred (not neccessarily the time travel) but he certainly did manage to accrue all that cash. It was even news here in Britain

You do realize that your post makes no sense whatsoever right.....

yes

Most likely a net/urban legend...
Has all the hallmarks of one - an amazing story from the not-too-distant past, with definite numbers (126 deals, 350million dollars) to give it legitimacy, and of course he's been arrested by the FBI and held at an unspecified location, so we have no way of finding out if it's true. But it relies on our distrust of Govt organisations and love of conspiracy and fantasy to make us think it might be possible.
As you said, there's lots of holes once you start looking into it. Instead of doing business deals, why didn't he just go in and pick the winning numbers of the state lottery when it was $300 mill? Far easier and no-one would suspect him of anything.

Okay, suppose time travel to the past is possible.

Every trip made to the past will cause some changes. Every change in the past will influence the course of history after it. Sooner or later these changes will lead to a world in which the time machine was never invented.

I managed to find something.......
http://tv.yahoo.com/news/wwn/20030319/104808600007.html
It said the page had expired.
Is that part of the conspiracy?

I think time travel is very possible, just not for humans because at the moments its impossible for us to transcend our coporeal existence. The past and the future exist at this very moment as well as the present. We are like a snail travelling across a marked ruler passing each checkpoint as it travels up it. Those marks the snails pass , dont just exist as the snail passes them. They exist before and after the snail passes them, its just that the snail can only percieve the mark once its passing it. We are the snail. But then, a here people cry "where does free will come into this". Its quite simple people always have the choice of free will, yet they so rarely use it. They rarely exceed or divert from their defined traits.

As you said, there's lots of holes once you start looking into it. Instead of doing business deals, why didn't he just go in and pick the winning numbers of the state lottery when it was $300 mill? Far easier and no-one would suspect him of anything.

Well.. the exact lottery numbers may no longer have been known in his time, while the stockmarket kept better records ;) Yes, I can poke a lot of holes in this argument too. But it's fun ;)

Back on topic: we can readily *observe* the past though, since the speed of light is finite. So looking at distant galaxies is also looking into the past.

I managed to find something.......
http://tv.yahoo.com/news/wwn/20030319/104808600007.html
Quite impressive... maybe he is from the future and confessed truthfully, knowign that he would not be believed. But wait, remember my earlier statement about him finding out about being caught? Well if he had researched to find all those stock payoffs, he certainly would have noticed his own influence of them. Once cannot trade that succesfully without leaving a substantial mark on the progress of such stock. He would have inevitably seen his own work, and then, when seeing it end, must have at least suspected its abrupt end was due to his capture, or death, or something else of that nature. Still beign a risk taker at heart, he may have gone ahead with it hoping that perhaps he simply "came home." But he would have to be pretty stupid to assume. This is obviously not a stupid man, seeing as how he posses advanced technology, most likel advanced learning techniques, and lastly, a good head for buisness...

Okay, suppose time travel to the past is possible.

Every trip made to the past will cause some changes. Every change in the past will influence the course of history after it. Sooner or later these changes will lead to a world in which the time machine was never invented.
Paradox in itself, therefore not a viable point. I agree, but its more redundant than I was accused of being.

It said the page had expired.
Is that part of the conspiracy?
Well, I've accessed it, so has demented hamsters. maybe the FBi want to block this thread...OOOOOHHH!

Well.. the exact lottery numbers may no longer have been known in his time, while the stockmarket kept better records ;) Yes, I can poke a lot of holes in this argument too. But it's fun ;)

Back on topic: we can readily *observe* the past though, since the speed of light is finite. So looking at distant galaxies is also looking into the past.
Looking at the past in that matter is akin to looking at a television in Virgina while you are sitting in California so you can find out who won Survivor before anyone else around you (even assuming they are watching a satelite TV system and receiving the same transmission the Virginian's are.) Its pretty ridiculous.

You just can't prove it either way. How do you know that our scientists were wrong and that time travel IS possible. Just because our current perceptions do not allow for it, that does not necessarily mean it does not exist.
For all we know, the universe may just have it's own way of straightening out paradoxes. It is quite possible that time travellers have been influencing today's events. It is possible that they have been doing this for thousands of years. It is simply improbable. That is the only argument you can make on our current knowledge: is it probable or improbable?

I dug this one up. The story about the time travelling investor is complete bogus.

Origins: All one need know about this article is that it originated with the Weekly World News, an entertainment tabloid devoted to inventing fantastically fictitious stories while keeping its tongue firmly embedded in its cheek to a depth not measurable by any instrument known to man. Unfortunately, Yahoo!, a primary news source for many people on the Internet, reprints some Weekly World News articles in their TV News section under a heading of "Entertainment News & Gossip," a title that doesn't convey a strong "bogus" warning to readers who don't notice the original source is the Weekly World News (or don't know what the Weekly World News is).

Despite this item's tabloid origins (and the fact that it was covered nowhere but in the Weekly World News), it has showed up in a variety of magazines and newspapers, reprinted verbatim as a "real" news item -- to the amusement and consternation of FBI and U.S. Security and Exchange Commission officials, who have been flooded with a rash of inquiries from journalists seeking confirmation for a bit of fiction:

The spokesman at the US Security and Exchange Commission in Washington gives a weary s

igh and then a slightly strained chuckle when he hears the words "time trave

ller" and "inside trader".

"This story is pure fantasy. There is no truth in it at all," he says. "This is the kind of story that belongs in the same file as 'Elvis Shrine Found on Mars.'

"You know something? We have had an enormous number of calls from the media on this one. It has been absolutely amazing. Of course, we had to look into it, but as far as we know, it’s just not true."

As if this tale weren't already implausible enough on its face, the Edinburgh Evening News wryly noted:

"Even a non-time traveller could have told him that profiting from 126 consecutive high-risk trades over two weeks was sure to get him noticed," commented the Guardian.

A handful of others pointed out that any time traveller with half a brain would not bother popping back to 2003, just when the stock market is in free fall and anyone who actually makes any money at all would stick out like a 25-ft. tall green alien with two heads.

In a follow-up article in their 29 April 2003 issue, the Weekly World News reported that mysterious time-traveling Andrew Carlssin had been bailed out by an "unidentified benefactor" who ponied up $1 million, then jumped bail before an April 3 court hearing and disappeared without a trace.

http://www.snopes.com/humor/iftrue/insider.htm

Now, back to the original post...

After the point of the invention of time travel, there is an infinite time(for the reasons of this argument) Now once the technology has been created, assuming it is not destroyed, there will be an infinite jumps back in time after that point. Now even if the travelers were perfect in their attempts to hide their presence, law dictates that the information would leak out into that time. Therefor, with infinite travelers going back in time, to our own, and all previous times, we would certainly know about the technology.

As for time travel into the future, if you believe Einstein's relativity, then you know that it is possible, because traveling at very high speeds will in affect, put you ahead in time.

You're mistaken about Einstein's theories. Travelling at high speeds (close to the speedo of light) won't put you ahead in time. Its just that the time you spend will seem (relative to the time of an observer) shorter. If you left earth at near the speed of c, then came back, you would be young but the world would be old. However, you didn't actually travel through time. You just experienced less time relative to observers on earth.

You just can't prove it either way. How do you know that our scientists were wrong and that time travel IS possible. Just because our current perceptions do not allow for it, that does not necessarily mean it does not exist.
For all we know, the universe may just have it's own way of straightening out paradoxes. It is quite possible that time travellers have been influencing today's events. It is possible that they have been doing this for thousands of years. It is simply improbable. That is the only argument you can make on our current knowledge: is it probable or improbable?
While all of that does make sense, you are still forgetting about infinite future history. And so even if time travelors have been shaping our history inperceptibly, one of them(an infite ammount of them actually) would eventually mess up and leak the information. And this also brings up another point: With an infinite history of time travelers comign and going back and forth, they would of course populate our existence with an infinte copies of themselves utterly destroying the universe. In fact, if even one person went back in time, it would destroy the law of perservation of matter. This would of coursem, destroy all of existence.

You're mistaken about Einstein's theories. Travelling at high speeds (close to the speedo of light) won't put you ahead in time. Its just that the time you spend will seem (relative to the time of an observer) shorter. If you left earth at near the speed of c, then came back, you would be young but the world would be old. However, you didn't actually travel through time. You just experienced less time relative to observers on earth.
Thank you for backing up my point by explaing relativity. Yes, you would in affect be travellign forward in time by preserving yoruself as time passed around you. When you ride in a car, everything passes by you(relatively) So it would be much teh same as going to the corner grocery, or in affect, letting the corner grocery come to you. Either way, you get there... right?

Thank you for backing up my point by explaing relativity. Yes, you would in affect be travellign forward in time by preserving yoruself as time passed around you. When you ride in a car, everything passes by you(relatively) So it would be much teh same as going to the corner grocery, or in affect, letting the corner grocery come to you. Either way, you get there... right?
And therein lies the issues with relativity. It would seem like travelling forward in time to the "space pilot" but not in the same sense as "time travel". There would be no blinding flash, and then a sudden reappearence sometime in the future. Regardless, I think we are argueing the same point. (puts it aside)

You have a pretty cool point. However, this assumes a lot of different variables, which admitedly have to do when making theories. But it doesn't prove anything conclusively.

Looking at the past in that matter is akin to looking at a television in Virgina while you are sitting in California so you can find out who won Survivor before anyone else around you (even assuming they are watching a satelite TV system and receiving the same transmission the Virginian's are.) Its pretty ridiculous.

No, it's not. If I am in some way instantly transported 5 lightyears from earth and then look at my home I would see myself 5 years ago. Get about 2000 lightyears away and I may see baby Jesus.

Of course, the 'instantly transported' part is a bit tricky. But I can still look at the history of *other* solar systems. Provided I somehow manage to get a telescope capable of such big resolution ;) Or be content with looking at the birth of stars or galaxies, that already died a few thousand years ago.

In fact, if even one person went back in time, it would destroy the law of perservation of matter. This would of coursem, destroy all of existence.

This isn't necessarily true, if you say that energy and matter must be conserved in the space-time, not just the space. Perhaps it is possible to shift matter from one point in time to another and not break the Law of Conservation of Matter because energy in the space-time would remain constant.

just because people arent claiming there from the future dosent mean there not here maybe they want to protect the past or mess it up anything is possible

I just find it amusing that so many people believe time travelers would come to us. Why should they? Wouldn't it make more sense to go to the distant past, before accurate records were kept? I doubt that we would really know if a "future man" was burned for being a heretic during the Inquisition.

Most likely a net/urban legend...

Or possibly a very good defense to an insider trading charge.

Maybe people from the future helped build the pyramids. Heh, nah.

But, say the... well, not exactly universe... but, I don't know, existance or such, were infinite/circular and the Universe constantly 'dies' and is 'reborn', and say that it does so the exact same way every time, couldn't a person technically travel forward into the past? Then again, in that case you'd have to somehow survive the collapse and rebirth of the universe... huh. Whatever! That's my random, bogus, spur-of-the-moment idea for the day.

It works, I tell you! You just haven't been using enough Jiggawatts!

The only way we think we can time travel now, which is by using the twins paradox on two wormhole mouths, doesn't allow you to travel back before the machine was made. So that is why we are not knee deep in time tourists.

How wormhole time machines work. (http://science.howstuffworks.com/time-travel4.htm)

Your proof is entirely meaningless if you accept the possibility of multiple realities. Someone going back in time invetibly alters that timeline by their very presence. From the point they emerge in the past they are in a separate reality. To observers in their original reality they would simply have gone missing one day, never to return.

Quantum-mechanics says that there is a statistical probability for a particle to be in any particular location in the universe at any instant. Shroedinger's Cat holds that because the system is indeterminate, the particle is in fact at all locations at once. Take that in combination with the fact that there are infinite subdivisions of time, much like there are an infinite number of numbers between 0 and 1, and you have yourself an infinite number of realities. Unless you hold that time itself is quantized, in which case there would be a massively large number of realities but not infinite. I must say though that I disagree with your assumption that there are an infinite number of time travellers unless you agree that there are an infinite number of realities.

So, each of your travellers goes into the past and enters a separate reality that fits the changes they have wrought. Your infinite travelers are spread across infinite realities and their presence can indeed go entirely unnoticed in any one reality.

In a way, you're right. It's not exactly time travel but instead jumping realities. By the by, it's 6 am where I'm at and I've been awake for a very long time now so I'm not positive that I wrote this right or that it makes sense to anyone beside myself. I'll check it again later to make sure I argued it the way I wanted to. My friends and I talk about this sort of thing all the time.

I recently finished reading a fairly unsatisfying paperback novel by Fred and Geoff Hoyle which spent a great deal of time describing several FTL and sub-FTL trips made through interstellar space.

They were trying to explain what the view from inside the ship was like. Looking through a camera mounted on the 'front end', they claimed the light from the stars ahead would be bent inside a visual cone emanating from the camera's point-of-view, so that on a viewscreen, the stars would begin 'clumping' towards the centre of the screen, becoming brighter (and less individually distinct) until they formed a single point of infinitely bright light, that point being composed of all approaching starlight (and having too much signal, the cameras switched off).

Meanwhile, behind the ship, there was a complete absence of light of any sort. Heh?

It's not like it's something I could test myself, and I know one or the other of the authors was actually knighted for his real-life work in astrophysics, but it all seemed sort of contrived and unconvincing.

So I thought I'd throw this question out there for some of your expert opinions:

What would space outside a travelling ship look like as it approaches, and then supercedes the speed of light? And a couple of related questions - would it look different at the front vs. the back (or fore vs. aft I guess - not a nautical type, here)? Would it seem different to a camera eye vs. a human eye?

I'm sure it doesn't look like Star Trek, but - what would it look like?

What would space outside a travelling ship look like as it approaches, and then supercedes the speed of light? And a couple of related questions - would it look different at the front vs. the back (or fore vs. aft I guess - not a nautical type, here)? Would it seem different to a camera eye vs. a human eye?

I'm sure it doesn't look like Star Trek, but - what would it look like?

http://math.ucr.edu/home/baez/physics/Relativity/SR/Spaceship/spaceship.html answers that for speeds approaching that of light.
Superceding c is not possible.

http://math.ucr.edu/home/baez/physics/Relativity/SR/Spaceship/spaceship.html answers that for speeds approaching that of light.
Superceding c is not possible.

Answered it quite well, too - pity the Hoyles didn't think to insert a couple of diagrams, rather than just relying on written descriptions.

And yes, I know it's impossible to supercede c - but it was fictional, and the FTL bits were all alien intervention, and besides, the book had a really unsatisfying conclusion...I think they wrote themselves into a corner on that one. The book was called, 'Into Deepest Space'.

I think it was partly due to the book being somewhere between 30 and 40 years old that I found myself wondering whether what they were describing outside the ship was an accurate description, or if was just theoretical conjecture. From what the link says, I guess they were dead-on. Cool.

Thanks Alma Mater, for clearing it up.

It is physically impossible to go back in time unless you travel to a Red State. In which, you would be going back a 150 years or so.

After the point of the invention of time travel, there is an infinite time(for the reasons of this argument)

You cannot just change the known rules of the universe "for the reasons of this argument" and then claim that you have "proof" that time travel is impossible. I seem to recall that current theory suggests that the life of the universe is likely to be finite... and even if it is infinite, eventually it will cool to the point that it cannot support life. So humanity will definitely be around for a limited time.

Of course, your post includes so many unnecessary assumptions that this one is hardly worth mentioning:

Now once the technology has been created, assuming it is not destroyed, there will be an infinite jumps back in time after that point.

Why? This assumes A LOT.

First: It assumes that there would be no (or very few, or very ineffective) controls on the technology. Just because a technology exists does not mean it is going to be used very frequently. We used nuclear weapons once, and since then we have managed to keep it from happening again. Something similar could happen with time travel if it were felt to be dangerous.

From the way you talk about "infinite" jumps back in time, it also sounds like you may assume the technology could be relatively cheap or easy to use... but if in fact it involves running circles around black holes, managing the instabilities of wormholes, or even just going really really fast... then it is not likely to be the sort of thing "anyone" can do. It will require the organization and resources on the scale of a national government.

You also assume that time-travellers would necessarily show up in a period in which their presence would be obvious. However, there have been long stretches in history where a random person could pop up or live off the grid without much trouble. A prudent time-traveller might avoid eras in which he or she is likely to be found out. (And within periods such as our own, we can expect the prudent time-traveller to go out of his way to remain undiscovered, for the obvious reason: he wants to avoid capture by forces who would be all too interested in his knowledge of the future.)

Now even if the travelers were perfect in their attempts to hide their presence, law dictates that the information would leak out into that time.

What "law"? If time travel were a controlled technology, and relatively few people were sent into the past, why assume that their presence must "leak out"?

Therefor, with infinite travelers going back in time, to our own, and all previous times, we would certainly know about the technology.

Sure. You just have not convinced me that there is any reason to assume "infinite" time travellers. (Or even any very high number.)

You cannot just change the known rules of the universe "for the reasons of this argument" and then claim that you have "proof" that time travel is impossible. I seem to recall that current theory suggests that the life of the universe is likely to be finite... and even if it is infinite, eventually it will cool to the point that it cannot support life. So humanity will definitely be around for a limited time.

OK. We are going to mount an ad absurdium argument against time travel. So we assume that time travel is possible. Now with this assumption time does necessarily become infinite as you can close loops in time. It is still bounded, so the physical univers can finish, but within those bounds there is infinite time available. Humanity would live for an infinite amount of repeated time.


Why? This assumes A LOT.

First: It assumes that there would be no (or very few, or very ineffective) controls on the technology. Just because a technology exists does not mean it is going to be used very frequently. We used nuclear weapons once, and since then we have managed to keep it from happening again. Something similar could happen with time travel if it were felt to be dangerous.

Having shown that time is infinite, on the pressuption of time travel then the strange effects of infinity come into play. All that can happen will happen, a logical consequence. Not only will it happen it will happen an infinite number of times. So time travel will be used infinitely if it exists.

From the way you talk about "infinite" jumps back in time, it also sounds like you may assume the technology could be relatively cheap or easy to use... but if in fact it involves running circles around black holes, managing the instabilities of wormholes, or even just going really really fast... then it is not likely to be the sort of thing "anyone" can do. It will require the organization and resources on the scale of a national government.

It matters not how unlikely or expensive it is. It will happen an infinite number of times.

You also assume that time-travellers would necessarily show up in a period in which their presence would be obvious. However, there have been long stretches in history where a random person could pop up or live off the grid without much trouble. A prudent time-traveller might avoid eras in which he or she is likely to be found out. (And within periods such as our own, we can expect the prudent time-traveller to go out of his way to remain undiscovered, for the obvious reason: he wants to avoid capture by forces who would be all too interested in his knowledge of the future.)

Still on the same line. There would be an infinite number of time travelers. This being the case there will be an infinite number here and now. As a result of this they would be obvious to us.

Sure. You just have not convinced me that there is any reason to assume "infinite" time travellers. (Or even any very high number.) But I believe I have.

Proof traveling back in time is impossible
So was flight. Faster then the speed of sound. Etc....

So was flight. Faster then the speed of sound. Etc....

No. It was just claimed that these were impossible. He is suggesting that there is a logical proof that Time travel to the past is impossible.

I'm not going forward in time anymore. I've broken all of the clocks in my house. The sun doesn't set because my home has no windows. I don't age because I broke all of my mirrors. I don't get tired because I'm never awake. Truly time travels in so such way.

What if a time traveler is incapable of interacting with matter when they appear? This wouldn't explain why they don't just fall through the earth, but you never know.

No. It was just claimed that these were impossible. He is suggesting that there is a logical proof that Time travel to the past is impossible.
Well excuse me, but there just is not.

Proof traveling back in time is impossible:

After the point of the invention of time travel, there is an infinite time(for the reasons of this argument) Now once the technology has been created, assuming it is not destroyed, there will be an infinite jumps back in time after that point. Now even if the travelers were perfect in their attempts to hide their presence, law dictates that the information would leak out into that time. Therefor, with infinite travelers going back in time, to our own, and all previous times, we would certainly know about the technology.

As for time travel into the future, if you believe Einstein's relativity, then you know that it is possible, because traveling at very high speeds will in affect, put you ahead in time.

"information" in physics means interaction between particles.

OK. We are going to mount an ad absurdium argument against time travel. So we assume that time travel is possible. Now with this assumption time does necessarily become infinite as you can close loops in time. It is still bounded, so the physical univers can finish, but within those bounds there is infinite time available. Humanity would live for an infinite amount of repeated time.

No, humanity could live for an infinite amount of repeated time, if they chose to keep jumping backwards. Nothing about the fact that they could "proves" that they would. And even if it did, nothing about the fact that they chose to keep repeating loops of time would require that they would choose to come back to this time (or, for that matter, any time preceding this one).

Having shown that time is infinite, on the pressuption of time travel then the strange effects of infinity come into play. All that can happen will happen, a logical consequence.

No, that is not a logical consequence of the infinite. Suppose I had infinite time on my hands. I could just as well choose to sit around doing nothing as attempting anything else. Once again, your argument lacks an appreciation for choice.

Not only will it happen it will happen an infinite number of times. So time travel will be used infinitely if it exists.

Why? And will everything else be used infinitely, once infinite time is introduced? Does that include the nuclear weapons I mentioned before? If so, you have a lot more worries on your hands than the inherent paradoxes of time travel.

It matters not how unlikely or expensive it is. It will happen an infinite number of times.

I would like you to justify that claim.

Still on the same line. There would be an infinite number of time travelers.

Why? I can easily provide a counter-factual: A guy invents time travel. He goes back in time. He dies in the past. No one else ever discovers time travel. The end.

This being the case there will be an infinite number here and now.

Does not follow.

But I believe I have [convinced you].

Nope.

After the point of the invention of time travel, there is an infinite time(for the reasons of this argument)

Minor fault: while time may exist for an infinite (or nearly infinite) time, humans will not. Additionally, time travel may be subject to range limitations to which we are not aware, or to engineering limits. It may be possible to travel back in time, but not without great expenditure of power, thus limiting the number of trips in a finite human civilization.

Now once the technology has been created, assuming it is not destroyed, there will be an infinite jumps back in time after that point.

No, for the reasons above.

Now even if the travelers were perfect in their attempts to hide their presence, law dictates that the information would leak out into that time. Therefor, with infinite travelers going back in time, to our own, and all previous times, we would certainly know about the technology.

The problem with a multiverse is that there are an infinite number of universes. When you travel back in time, you are traveling to one (not all) of those universes in the past. Even with infinite numbers going back in time, they may not all be from our future.

As for time travel into the future, if you believe Einstein's relativity, then you know that it is possible, because traveling at very high speeds will in affect, put you ahead in time.
Yes, you can go to the end of time rather quickly.

Well excuse me, but there just is not.
See my post #50 (http://forums.jolt.co.uk/showpost.php?p=8314716&postcount=50) just above. Oh yes there is. Or if show me where my argument is wrong, then I will concede your point. Until then it is logically impssible.

Remember this?
"The news item is a little old, but its interesting nonetheless:

To sum it up: A guy made 350 million bucks from a starting capital of 800. Each and every one of his 126 high risk trades unexpectedly gave him a profitable turnout. FBI suspects he was dealing with insider knowledge, so he is being retained until he reveals his sources.

Up to there, it sounds like normal white-collar fraud, but heres wehre it gets interesting: He claims to be a Time-Traveller from the year 2256 and said that he can prove this by giving us historical facts that have not taken place yet, such as Bin LAden's hideout or the cure for Aids.

All he wants to do now is travel back home in his "time craft" though he is unwilling to reveal its location out of fear of it falling into the "wrong hands". Officials are quite sure his time traveller story is totally bogus, BUT... sources at the Security and Exchange Commission have confirmed that there is no record at all of this man in any registries whatsoever prior to December 2002".

Sounds intersting, where did you find this story.

As for time travel into the future, if you believe Einstein's relativity, then you know that it is possible, because traveling at very high speeds will in affect, put you ahead in time.

Then again, Einstein proved that it is physically impossible to go faster than the speed of light...

Sounds intersting, where did you find this story.

It is from the tabloid The Weekly World News.

Then again, Einstein proved that it is physically impossible to go faster than the speed of light...

Doesn't matter - if compared with someone at rest time will run slower for you if your speed is higher than 0. In daily life this effect is too small to be of any significance - but when your speed is approaching c it can easily result in huge differences.

Then again, Einstein proved that it is physically impossible to go faster than the speed of light...

Actually, he proved that it is physically impossible to accelerate past the speed of light, which is much more interesting. It means that anything going slower than light can never pass light... but it also implies that if anything is currently going faster than light, it can never "accelerate" -- slow down -- past the light-speed threshold.

I have not kept up with this research in years... The last I heard, faster-than-light particles were still purely theoretical.

No, humanity could live for an infinite amount of repeated time, if they chose to keep jumping backwards. Nothing about the fact that they could "proves" that they would. And even if it did, nothing about the fact that they chose to keep repeating loops of time would require that they would choose to come back to this time (or, for that matter, any time preceding this one).

The whole crux of the argument is here. The rest follows, either with you or with me except the side argument about the implications of infinity.
OK, you assume that when time is looped it will be repeated. This denies any freedom of will. This also regards events as being fixed. There is absolutely no reason why a loop in time would repeat in content. The time itself can repeat (McTaggert series A time) without the events repeating (Mctaggert series B time). Time is not necessarily defined by the events occurring in it. This being the case there is an eternity for a time traveling humanity to exist in. Not just an eternal repetition of the same sequence of events. (For Mctaggert see LePoidevan and Murray, Philosophy of Time, OUP. It is the first article). Now the consequences of infinity, eternity.
We have assumed that time travel exists. The ad absurdium requires this. Now given infinite time, not just a very long time, but infinite. All that is possible to occur will occur. This is a properety of eternity. It is not my view of it, it is logically necessary. If you disagree it falls to you tio show why some logical possibility is excluded. Choice does not do this, as over infinite time all choices will be made.
Yes this does imply that nuclear weapons will be used, it does imply that we will wipe ourselves out one way or another. It also implies that we will re-evolve, re devlop the time machine, cycle back before the destruction and follow another path etc. All of these actually count as reasons why infinite time is not god, but none count as a reason for the time machine being logically impossible.

Why? I can easily provide a counter-factual: A guy invents time travel. He goes back in time. He dies in the past. No one else ever discovers time travel. The end.
He invents this with no records, no outside awareness of it, then this could be the case. I concede this one, remote possibility. However I do not consider one person discovering how to do something as that something being invented. It would be a case similar, but different because of the nature of the invention, to that of the steam engine of Hero in Alexandria.

Time travel into the past logically can not become an available technology. That may be a better description of my argument. The isolated one off use does not cause the logical problems that its availability as a technology to society causes.

Your other objections follow from the initial disagreement as I understand you. It depends upon your understanding of time and your understanding of infinity.
If you hold those to be different then my argument is powerless. However you would have to justify these differences to cause me to abandon this reasoning.

see told u it could be done ^_^

its not impossibe watch ill post something back in time

Up to there, it sounds like normal white-collar fraud, but heres wehre it gets interesting: He claims to be a Time-Traveller from the year 2256 and said that he can prove this by giving us historical facts that have not taken place yet, such as Bin LAden's hideout or the cure for Aids.

Pfft... If you're a time traveller there's nothing like currency speculation, buying some of MS's IPO and let it grow for 30 years, or take advantage of the internet bubble. You can also bet in sports.

But by far, by far, the best method to get rich being a time traveller is by going back to, say, the 16th century and buy a painting from Rembrandt. Take it back to the 20th century and sell it.

i'm from the future where peoples' knees are backwards and they walk on their hands!

Time is not necessarily defined by the events occurring in it. This being the case there is an eternity for a time traveling humanity to exist in. Not just an eternal repetition of the same sequence of events. (For Mctaggert see LePoidevan and Murray, Philosophy of Time, OUP. It is the first article).

I am familiar with McTaggert, and I know exactly what you are saying. You just assume too much. The fact that there is an eternity's worth of events does not lead to the conclusion that there are an infinite number of time travellers.

Let us say time travel is invented. Furthermore, let us accept the likelihood that it is in any case a very costly procedure. So, humanity (let's just say we're all united on this one) spends a few hundred years making the preparations for a jump back in time. They can only send one person, or a small crew of people, back in time.

Let us say they send the crew back 500 years. Since, as you say, anything can happen in this loop -- which does not have to repeat -- humanity "gains" 500 years in the process. 500 years that they can "use over."

Now, nothing about this argument requires that the experiment be repeated. Perhaps whatever humanity wanted to accomplish with time-travel, they were able to do with that one jump. Perhaps the conditions for such an attempt -- e.g. the existence of a stable wormhole -- are extremely rare. Perhaps something these people do in the past even changes things so that time travel will not be discovered (something of a paradox in itself, but whatever).

Also, the possibility exists that the "gained" 500 years will go by, naturally with some changes due to the time-travelers... and back at the starting point they will once again be able to conduct the time travel experiment. Perhaps, to give your absurdum flavor, they even know about the "first" time this happened... and they decide to do something else with their time-travellers. So, they send them back 1000 years this time. And maybe next time around, they send another crew back 1000 years (say, to our time).

Your argument is that, since time travel has been invented, its loop necessarily occurs "forever" or repeats infinitely. At that time-travelling point in time, or at some later point, people just keep getting sent back... so there are infinite time travels.

However, there is no logical necessity in this at all. If the "first" (as you know, it doesn't really make sense to talk about "firsts" in an infinite loop, but you know what I mean) group of time travellers does not significantly change the past, then we should assume that the people making the time-travel experiment will behave in essentially the same way they did the "first" time. In other words, they send the exact same people back to the exact same point in time, and these people have exactly the same insignificant impact. If anything, they bring back only knowledge of the past.

There may be "infinite" time-travellers, but as long as they are the same people doing the same thing, from the perspective of the rest of us going in a straight line through time... well, there is only one set of time-travellers.

And once you get back to the point of invention, the loop is closed and you are back in your A-series. But then you are dealing with people who have knowledge of time-travel and the results of their experiment with it. There is no logical conclusion about what they do with that knowledge. Perhaps they never use it again. Perhaps they use it very sparingly, and only in cases in which they can be certain not to create the sort of loop you worry about. Again, as long as time-travellers don't change the past, the future will remain the same... meaning that the same people will go back in time.

Infinite loops do not necessarily lead to infinite possibilities.

Now the consequences of infinity, eternity.
We have assumed that time travel exists. The ad absurdium requires this. Now given infinite time, not just a very long time, but infinite. All that is possible to occur will occur. This is a properety of eternity. It is not my view of it, it is logically necessary. If you disagree it falls to you tio show why some logical possibility is excluded.

No, the burden of proof falls on you to show why no possibility is excluded. Nothing about infinite time requires that everything that is possible must happen. If you want to convince me otherwise, you will have to provide an argument that explains it... because it is anything but obvious.

Choice does not do this, as over infinite time all choices will be made.

Why? If at some point I decide, "I will never do X," and I happen to be immortal, why does the fact of my immortality require that at some point I will do X?

Yes this does imply that nuclear weapons will be used, it does imply that we will wipe ourselves out one way or another. It also implies that we will re-evolve, re devlop the time machine, cycle back before the destruction and follow another path etc.

Ah, but here is the problem with your argument. You are trying to equate the "god's eye view" with what happens from our perspective. In the example you give, if we can "follow another path," then anyone who happens to be on that particular path knows nothing of the others. From her perspective, time moves along naturally... and while all those time-travellers may be producing alternate universes, she knows nothing about those, and does not meet the time-travellers -- or if she does, she is automatically on a different path which may or may not contain more time-travellers.

I am perfectly content with the notion of "infinite" time-travellers across the set of all possible universes, but nothing in this proposition requires that there should be infinite time-travellers in any given universe, which is the basis of the absurdum in question.

He invents this with no records, no outside awareness of it, then this could be the case. I concede this one, remote possibility. However I do not consider one person discovering how to do something as that something being invented.

Yes, but your opinion on the matter is not what concerns us. The question is, "Is it logically possible?" And of course it is. But you may protest, "None of us will ever know about it!" Yet the person who invents it will... unless we convince him before-hand that his attempt is logically impossible, and he quits.

Time travel into the past logically can not become an available technology. That may be a better description of my argument. The isolated one off use does not cause the logical problems that its availability as a technology to society causes.

But the isolated use is just another version of the one-time use. Society may realize that time-travel is possible, yet also find that it can only be done a limited number of times, either due to cost or the availability of favorable conditions. This would mean that we would have to think very carefully about what to do with those few chances... but it does not make the project impossible.

Indeed, even if we figure out how to do it, you cannot discount the possibility that we will choose not to use our knowledge at all. We may be a pretty stupid race, but this does not logically preclude the possibility that we might consider it too dangerous to use.

So was flight. Faster then the speed of sound. Etc....
People could see birds flying. No one thought that was impossible.

When faster-than-sound planes were being designed, physics said it was possible, and it was. Try again.

Remember this?
"The news item is a little old, but its interesting nonetheless:

To sum it up: A guy made 350 million bucks from a starting capital of 800. Each and every one of his 126 high risk trades unexpectedly gave him a profitable turnout. FBI suspects he was dealing with insider knowledge, so he is being retained until he reveals his sources.

Up to there, it sounds like normal white-collar fraud, but heres wehre it gets interesting: He claims to be a Time-Traveller from the year 2256 and said that he can prove this by giving us historical facts that have not taken place yet, such as Bin LAden's hideout or the cure for Aids.

All he wants to do now is travel back home in his "time craft" though he is unwilling to reveal its location out of fear of it falling into the "wrong hands". Officials are quite sure his time traveller story is totally bogus, BUT... sources at the Security and Exchange Commission have confirmed that there is no record at all of this man in any registries whatsoever prior to December 2002".
Sounds bogus, but do you have a source anyway?

the amount of energy required to create a portal in time is astronomical and will never be reached. even if it is reached, it would be an impossibility to travel through the wormhole/blackhole you had made.

Sounds bogus, but do you have a source anyway?
It is bogus. Check back earlier in the thread.

the amount of energy required to create a portal in time is astronomical and will never be reached. even if it is reached, it would be an impossibility to travel through the wormhole/blackhole you had made.
You don't have enough jigawatts! I can make up physics too!

I am familiar with McTaggert, and I know exactly what you are saying. You just assume too much. The fact that there is an eternity's worth of events does not lead to the conclusion that there are an infinite number of time travellers.
Yes it does, if time travel is possible. The eternity ensures, as I keep saying, and you do not deny, that all possible events occur. And that these events occur an infinite number of times. That is part of the nature of eternity. To deny it, is deny the eternity of the time available.

Now yes, you can argue that we would not choose to create this eternity. That some generation will just let it all end, rather than creating another concurrent loop. In this sense I concede that I may have overstated the case by making it logically impossible for these reasons. It is still, in my mind though, a real impossibility due to them. (I reserve the right to rethink, hence the word may in my concession.)

Now there are logical problems with returning to a time and this time remaining the same as it was in your experience the first time through. There is the problem of censorship. If I am instructed by a time travelling version of myself from the future as to how to create a time machine. I then do this and use such machine to travel back and tell myself how to make it. There is a paradox about where the knowledge comes from. As far as I am aware the only solution to this paradox would be for it to be impossible to carry information from the future into the past. This would mean that time travel may be happening all the time, simply we do not remember the future due to this censorship. It is questionable in what sense such censored time travel can be said to be real.

John Titor

The eternity ensures, as I keep saying, and you do not deny, that all possible events occur.

Whose posts have you been reading? I certainly do deny it!

And that these events occur an infinite number of times. That is part of the nature of eternity. To deny it, is deny the eternity of the time available.

You can say that as many times as you like, and I still will not be convinced. What I need is an explanation. You have yet to offer one. What is the "nature of eternity" such that all possible events occur? This is not obvious. If you want me to believe you, you will have to explain it to me.

Now there are logical problems with returning to a time and this time remaining the same as it was in your experience the first time through. There is the problem of censorship. If I am instructed by a time travelling version of myself from the future as to how to create a time machine. I then do this and use such machine to travel back and tell myself how to make it. There is a paradox about where the knowledge comes from.

This paradox only occurs when you start the sequence part-way through. Since the only thing that can produce a time-loop is time travel, one has to assume that every loop "starts" with an uncorrupted time-stream. Thus, if you meet your future self and get into this little loop there must be a "first" alternative world in which you start it all up. You must have actually invented time travel, then gone back to tell yourself about it. Now there is the loop... but there is also a "world" in which the loop starts. No paradox. Just a weird experience for those infinite you's who exist in looped worlds.

Of course, the problem is slightly more problematic if you deny the existence of alternate realities -- but that is a theoretical problem, not a logical one. Let us assume a single-stream theory of time: if I go back and change things, they are simply changed. Past, present, and future are inseparably linked.

Here we still have to assume that the loop has a beginning... the problem is that now the beginning gets "erased." So you go along and invent time travel... then you travel back in time and tell yourself how to do it. Suddenly, because of what you have done, all of that hard work you did to invent and understand time travel is undone. It never happened. Instead, your personal history is revised so that a future you came back to tell you about time travel. Of course, that you could not exist, because he has erased the very history that created him in the first place. You try to get around this by assuming that the informed--as opposed to the inventing--you will be smart enough to realize that in order to preserve his own history he has to go back in time to tell himself about time travel. But there is no logical reason for this. For all you know, the future you could have inadvertently changed the past so that the trip back in time never takes place.

So the paradox is actually much more complex than you paint it. (Indeed, your "paradox" is only a paradox as long as you think causality matters... But once you start mucking about with time travel, normal causality is out the window anyway. If the effect can preced the cause, then there is no logical reason that the effect cannot be its own cause.) The problem is not just "where does this information come from," but also "why does it keep coming back?" Theoretically, the loop could cycle between the invention and non-invention of time-travel for eternity... If this sort of thing happens, it is hard to imagine how time keeps going at all! (The simpler version of this is of course the man who goes back in time and kills his own father before the time-traveller is conceived.)

But again, this is a logical problem that only occurs under the theoretical condition that time-travel cannot create/operate within multiple "universes." If you can disprove that theoretical claim and show that there is one and only one stream of time, then maybe you can follow through deductively to prove that time-travel is impossible (or at least never achieved, or perhaps "censored"). But lacking that evidence, there can be no such proof.


*snip*It is questionable in what sense such censored time travel can be said to be real.

If it can bring back information from the past to the future, I would call it very real. For instance, I might like to see first-hand how the pyramids were built. If I can go back and see it, then regardless of whether or not I can affect it I would call my travel very real.

To summarize more briefly my previous post:

There is no logical contradiction in something being its own cause. The logical paradox occurs when something happens that causes itself not to happen.