Time travel =P

[minakichan]

I'm trying to compile various theories and explanations, both scientific and fantastic (although scientific is preferred) on how time travel might be possible, and what factors must be overcome to make it possible (even if it is not probable to overcome said factors). This compilation is partly research for a plunny, part curiosity, since this is such an interesting topic.

What do YOU know about time travel? Do you think it's possible or impossible, and why?

Here's my list:
1) I believe Einstein somehow explained that time travel was possible but very difficult, and only backward travel is possible because the future doesn't exist yet. And I believe it all has something to do with black holes?
2) My physics prof (who was on Conan O'Brien last week o_O) mentioned offhand that "time travel is possible, but then the universe explodes." Whoops.
3) Even if you ignore things like the grandfather paradox or dual existences, some of the inherent contradictions involved in time travel are that a) even if you don't change any events, one's presence in the past introduces and leaves foreign molecules and microbes from another time that normally shouldn't exist, and 2) removing oneself from one timeframe and inserting oneself in another defies the conservation of mass and energy.

[Fish and Chips]

"Time travel is theoretically impossible, but I wouldn't want to give it up as a plot gimmick." - Isaac Asimov

[Cognitive Gear]

In the forward of C.S. Lewis' The Great Divorce, he wrote the following, which has intrigued me ever since:

"I must acknowledge my debt to a writer whose name I have forgotten and whom I read several years ago on a highly coloured American magazine of what they call "Scientifiction." The unbendable and unbreakable quality of my heavenly matter was suggested to me by him, though he used the fancy for a different and most ingenious purpose. His hero travelled into the past: and there, very properly, found raindrops that would pierce him like bullets and sandwiches that no strength could bite--because, of course, nothing in the past can be altered. I, with less originality but (I hope) equal propriety, have transferred this to the eternal."

[Azier the Swordsman]

1) I believe Einstein somehow explained that time travel was possible but very difficult, and only backward travel is possible because the future doesn't exist yet. And I believe it all has something to do with black holes?

The theory I read from Einstein about time travel was actually the opposite.

See, time travel to the future is very possible, because light exists outside of the realm of time. Light has a fixed speed that never changes due to any circumstances. For example, if you were on a train going at 70 mph and you threw a ball at 20 miles per hour, it would actually be traveling at 90 mph.

But if you are on the same train and turn on a flashlight, the light would travel at the same fixed rate it always does. Therefore, if one travels at the speed of light, one actually travels outside the realm of time. If you are on a rocket orbiting the Earth at the speed of light for two years, when you return to the Earth, 20 years would have passed.

It's not uncommon to see this convention used in science fiction stories, but the truth is that it isn't actually science fiction. Of course, the big problem is that once you get to the future with this method, you can't get back. So, too bad for you.

[Nate]

Hey Strong Bad, I built a time machine by putting a Gameboy in a blender. I used your blender and also your Gameboy. I will go into the future and buy you new ones.

[Raiden no Kishi]

Whew, this is tricky.

WARNING! You are about to hear Rai's two zenny, your exchange rate may vary.

As I understand it, God knows the future, so it does exist. We just haven't gotten to it yet. However, I don't think it's possible, whether by some physics law or God's prevention. It'd be too easy to create a paradox. For example, say you want to go back in time and, being INCREDIBLY original, BOOM HEADSHOT Hitler (and I will BOOM HEADSHOT anyone who mentions Godwin or his bloody law). You do so. However, in good old 2008, there is no Hitler, so you have no motivation to BOOM HEADSHOT Hitler. You've never even heard of him! But then, if you don't have the motivation, you don't go back in time to kill him, so he DOES exist. Paradox. And then Campbell yells at you over the radio. Not cool. Besides, there's the tired-but-sensible argument that hey, shouldn't we have heard from the future by now? Some interesting stuff's gone down in our lifetimes. Anyhoo, I totally agree with Asimov on this one.

.rai//

[minakichan]

The theory I read from Einstein about time travel was actually the opposite.

Ohh, is that right? It sounds so interesting! Yeah, I heard that Einstein bit from my high school physics teacher, but I swear he was on crack. Your explanation definitely sounds more... sensible. (As sensible as time travel can be XD!)

WARNING! You are about to hear Rai's two zenny, your exchange rate may vary.

XDDD!!! Hmmm, but what all of your intervention in the past actually causes rather than changes the past events? I'm thinking sort of Harry Potter 3-- going back into the past to cause the present to occur. For example, you go back to try to BOOM HEADSHOT young Hitler before he does anything, but your gun malfunctions and your BOOM HEADSHOT causes him brain damage that turns him into the deranges genocidal maniac tyrant that history remembers him as?

But the "then why haven't they visited us" argument... hrm, I can't think of a rebuttal for that. Unless they're ALREADY AMONG US!!! XD

My two ruples. Clearly I think about this stuff WAY too much!

[Dante]

Good grief, wow there are a lot of users viewing this thread! O_o. Alright time to get to bussiness.

As it turns out the best possible way I've heard of for traveling backwards in time is by making use of the Casimir Effect. As it turns out, this quantum effect has a unique ability, it can create a negative pressure... now that's not entirely interesting in and of itself until you realize that the reason why black holes collapse is not a result of their initial gravity from mass, but from an increased gravitational curvature that comes from added pressure... in other words, positive pressure curves space and "produces" gravity of its own. Because of this, if I remember correctly, the gravitational field of a black hole increases as its pressure increases... but as the gravity increases, this causes the pressure to increase which causes the gravity to increase which... yeah... you get the point.

What does this have to do with Time Travel? Well nothing really, I just like talking about black holes . Ok, no, in reality this does have something to do with time travel, for if positive pressure can create a gravitational field that slows time down to an outside observer (Did I forget to mention that a gravitation field can make time slow down to an outside observer?) allowing an inside observer to travel into the future at an accelerated rate, a negative field should have the opposite effect, and should allow for "backwards" time travel, or even the production of wormholes by turning some of that negative energy into strange matter! Sounds fun right! Well.... :

: There is a problem, it would take a lot of energy. Not like all the power in the world type of energy or even-super-saiyan sorta energy... we're talking I BEAT THE LAWS OF THERMODYNAMICS type of energy! Yeah... And the technology to produce it would be REALLY difficult (While working at ASU I tried to design an apparatus for studying the Casimir Torque... in the process I was neither successful in figuring out a way to get two large scale (cm size) plates close enough together to MEASURE the effect... nor (much to my displeasure) did I properly remember how to spell the word Casimir properly in the Casimir-Lifshitz Force... The name Lifshitz is left off of the scientific theory because other scientists found his name too distracting and couldn't proceed to write papers on the subject. :

: So there you have it, if you want to study this subject further I recommend reading the Misner Thorne and Wheeler phonebook... err I mean wonderful text Gravitation! Its actually rather well written and only requires that the reader hold a nice grasp on Tensor Calculus! Once your finished with this you can then proceed to read through Weinberg's Quantum Theory of Fields Volumes I, II and III! If you do intend on trying this however, I do want to watch... its some sick inner twisted desire to see someone completely consumed by a book with equations far too unwieldy for anyones pleasure reading . :

: Finally however, you can just make use of my theory... Time travel into the future isn't useless as many texts claim, it is really just a matter of perspective and in fact time travel into the future (via normal gravitational curvature) IS time travel into the past... Allow me to explain. Remember our poor soul that we like to drop into a black hole every Tuesday? Well... we're giving him a break this Thursday and we've decided to still him inside of a giant steel ball... Gausses law states that the gravitational forces in all directions will cancel out within this steel ball but the increased gravitational curvature will allow him to view the universe outside moving forward at an accellerated rate! That means that if we just build a giant metal ball (not supercomplicated but hard to find the material for) we can travel to the year 2,500 without aging! YAY!!!! But... There's a problem. We don't have nearly enough junk to do this, but meh... its far more feesible in my opinion than backwards time travel at least the theory makes sense. :

: Now, why do I argue that this IS backwards time travel? Well, if you think about it, while the observer in the ball isn't travelling backwards in time, the other frame of reference (outside the ball) could be considered to be travelling backwards in time to see this observer, much like we look back in time to see the stars... So, because of this effect, our great grandchildren could come and meet a younger version of ourselves from a portion of space connected to the futre via this gravitational gadget... unfortunately we can't get back to the past through this same mechanism... nor can the OBSERVER go backwards in the unvierses time frame. So this seem lame... :

: BUT BEHOLD!!! I provide the solution (you may want to start taking notes in case you ever wanted to build this). Instead, my plan calls for building a giant massive shell around the rest of the universe, leaving yourself inside of a closed bubble awa from it... this way the rest of the universe will progress at a slower rate and you will age at a normal pace... Then when you want to travel "back" to the good old days when you first built your time machine... you just blow up the giant mega shell of doom and walk back like it's 1999! Ok... so you can't go back further than when you built your mega shell... and there not enough material in the universe to build it... and the expanding universe itself gets in the way of your giant physics problem... and you'd likely collapse the shell into a black hole and and... well... its just pointless. :

: Besides which, all you'd be doing with the above worthless contraption is making a device that makes you older and the universe younger... no real gain there, no way to bring back knowledge from a future that hasn't happened either... and thus no time paradoxes... everything is kept in its seperate box... and all paradoxes dissapear if there can be no copy particles present within the history line. (In other words you can't age to 40 and then reverse your aging to 20 again in this system). Meh, I just wrote the above rant because I'm bored... and too lazy to crack out any real theories... but overall, I sadly don't believe I'll get to experience it in my liftime and if I were I'd only get to throw a particle back in time and not my whole body . :

-Pascal

[Fish and Chips]

For example, say you want to go back in time and, being INCREDIBLY original, BOOM HEADSHOT Hitler (and I will BOOM HEADSHOT anyone who mentions Godwin or his bloody law). You do so. However, in good old 2008, there is no Hitler, so you have no motivation to BOOM HEADSHOT Hitler. You've never even heard of him! But then, if you don't have the motivation, you don't go back in time to kill him, so he DOES exist. Paradox.

It's kinda a moot issue, since Hitler is invincible.

[Dante]

and I will BOOM HEADSHOT anyone who mentions Godwin or his bloody law

-After Raiden no Kishi BOOM HEADSHOT's Hitler, the following can now be found on Wikipedia and everyone on CAA looks on his post confused.-

"Godwin's law - As an online discussion grows longer, the probability of a comparison involving Soviets or Premier Alexander Romanov approaches 1." -Wikipedia


-Pascal

: Boom... Headshot sound. :

X_X

[minakichan]

LAWL Pascal, you're amazing. There is a reason that Intro to E&M is going to be the last Physics class I ever take in my life. Science fiction is so much more interesting than real science! XD So I suppose the whole insert-yourself-into-the-19th-century-and-interview-Lincoln stuff doesn't work out... *sadness* Still pretty cool~ I'd love to meet the loser who'd be willing to live in his hyper-time-accelerated universe-observation bubble XD

And Godwin's Law CLEARLY doesn't apply to CAA's Goof Off section XD

[SnoringFrog]

I remember when I brought this up a while back...since then most of my theories have dissolved from my mind. But here's the old topic if you're interested in what was said there. http://christiananime.net/showthread.php?t=28138

Personally, I'm up for saying it's possible, in a way, just not exactly sure how. The easiest method of time travel is quite obvious, at least to me, and that would be the normal traveling we do every single day into the 'future' which is constantly becoming the present ever so briefly before plunging into the past as we reach it.

To travel forwards in time, I've always imagined that if we could somehow find a way to confine a person within something that could then be accelerated to the speed of light ((assuming that they would survive the acceleration process and that we had the energy to sustain it's movements for an extended period of time)), due the the slowing of time by their fast travel, they should, when at the speed of light, be experiencing no aging at all, and thus when they are decelerated and removed from this, to them they will have traveled into the future. However, in this instance, there's no going back for them. Now, how you could go forward in time and still be able to return back to your normal time, I have no clue, and assuming the multi-verse theory to be false ((which, well...I'll not get into that at the moment)), I have even less of a clue.

As to going back into time, I'm lost to that as well now. I used to have a few theories in my mind somewhere, but I kind of lost interest and thus forgot them, I'll try to dig out my notebook that they're all written in though to see what I can recall. At least some, if not all, of them should be in that topic I linked to though.

[AsianBlossom]

God is in perpetual present...so is Heaven. We won't need time-travel in the future because there won't be any reason for it.

Problem solved. ^_^

I think...^_^U

Well, that's what I think. Frankly, if you were going to travel in time, you'd need God's help because it's impossible by human standards. I've heard stories about it happening (take as you will but DON'T criticize or start a debate) with short amounts of time, but those were miracles. To me, building a time machine and having it work seems to belong in fiction...we wouldn't know what we'd be messing with otherwise.

Well, that's all I have to say for now...back to your regularly scheduled thread.

[Nate]

[rocklobster]

See why I put my time travel thread in goof off?

[Nate]

See why I put my time travel thread in goof off?

[AsianBlossom]

Says the guy who wrote the article...XD

Seriously, if he told people it was a joke, he wouldn't get any bites on his offer and he would've wasted money by putting that article in the paper. Right?

[Tundrawolf]

Here's something I thought about really hard when I was a kid.

OK, say you build a time machine.

It can go backwards into time.

ONE PROBLEM.

3 seconds after you punch to button to go BACK, as you are going back, you are also letting up pressure on the button.

Know what I mean? I mean, 1 second ago I hadn't of typed this message, I hadn't of pressed the keys, I hadn't of made an electrical connection inside this computer that put out a character on the screen.

FURTHER,

Let's say it took you 6 years to complete the time machine.

The final step was putting the battery in-from your Honda Civic (It was convenient). You did this 6 minutes ago.

If you go back 7 minutes, suddenly your time machine has no battery.

You would have to literally create another instance of yourself that is immune to all of the laws of space and time, and sort of parallel yourself throughout the universe.

Without direct intervention from God, it is really something that is possible only in our imaginations. Although, prophesy is a gift from God!

[Nate]

By the way, before I get to my actual serious post in this thread, I must show the postscript to my earlier post. A few months after that image was circulated around the internet, a YTMND user posted a picture he claims to have found in his attic, from the Civil War...



Even has the mullet. The world may never know the truth. :O

Anyway. So at work tonight I was thinking about this, and I came up with an interesting dilemma. Let me pose this to you.

Okay, let's say I build a working time machine. I decide to go check out the good old dinosaur era, so I fire up the time machine and blast back to 65 million years BC. I'm admiring the prehistoric scenery when suddenly, boom, I am eaten by a T-Rex. I am now dead.

Okay. So we all know that once we die our soul departs our bodies, and we're in front of the Lord. So ignoring the fact that Heaven might be kind of empty with me being the only human soul that exists in that time period, here is my question.

Now that I'm dead, and my soul has departed to be with the Lord, the fact still remains that 65,001,980 years later I will be born. But wait. My soul is already in Heaven. So are there two of my souls now? Or is the "second" me soulless? The problem of there being two of my souls will be solved of course once I build the time machine and vanish from existence at that point, but until then, I would be both in Heaven and on Earth at the same time...I guess...

[AsianBlossom]

Hm...well, I think if you were eaten by a dinosaur and made it to heaven, heaven would be the way that it is now because there's no past or future in heaven--it's all perpetual presence.

But you do raise an interesting point about the "you being born millions of years later" thing. Quite puzzling.

[minakichan]

Tundrawolf brings up a very, very good point. Hrmmm... trippy =D unless you time travel without a machine, like a black hole or whatever science-y theories there are.

Ditto on the heaven thing. Heh, you could probably meet your great-grandkids in heaven or something, not that you would care by then.

[termyt]

It seems to me that we are three dimensional beings. This means we can freely manipulate the first three dimensions – length, width and depth – but, while we can readily perceive the fourth dimension – time – we are bound by it and can not manipulate it.

One term we use to describe the realm of creatures that have more than three dimensions is Eternity. Eternity is a place not bound by time. Eternal beings would have the ability to manipulate time as we can manipulate length, width, and depth. That is, the physical laws they are bound by allow for them to change time like we can change the three physical dimensions of a piece of wood.

Therefore, although we perceive time as an immutable constant, it may in fact be variable if a four-dimensional force acts on it. It is conceivable that we have witnessed such events leading to theories involving black holes and other phenomena that we are only beginning to gain an understanding of that seem to manipulate time as well as other spatial dimensions.

If all of this is true, then it would be possible for a human being to travel time if they are acted upon by a four-dimensional force. Depending on the physical laws binding such a force, the human could be thrown forward or backward in time would not be able to control when or how they travel.

[Nate]

Hm...well, I think if you were eaten by a dinosaur and made it to heaven, heaven would be the way that it is now because there's no past or future in heaven--it's all perpetual presence.

I disagree; remember the parable of Lazarus and the rich man. If Heaven/Hell were a "perpetual presence" then the rich man wouldn't have begged Abraham to warn his children...they'd already be there.

[Dante]

It seems to me that we are three dimensional beings. This means we can freely manipulate the first three dimensions – length, width and depth – but, while we can readily perceive the fourth dimension – time – we are bound by it and can not manipulate it.

No this is obviously false... I move my fingers as I type this message... I am manipulating the forth dimension with respect from my eyes to my fingers in a relatavistic manner... the effect is pathetically small, but only because I have only an ever so slight power to control time. In fact, right now my fingers are oscillating between red-shifting and blue-shifting in the color spectrum and all the atomic processes within appear to be slowing down before my very eyes... sadly though there is not a single instrument in the entire world accurate enough to measure this pathetic manipulation of time at least not to my knowledge .

However, if I were to a fly on an air-plane (a human created device) this would not be such a small effect. In fact, it does make a measurable difference on an atomic clock.

___________________________________________________________

Concerning the problem of the user pressing the time travel button, this is a simple logical error of bad engineering... Just build your time machine so that it comes along for the ride in the frame of reference, influencing everything save the universe outside and inside. This alone how requires that at a minimum the amount of energy necessary for the machine to work is that necessary to produce and organize all the particles within the machine, but more concerning is not the possibility that there is a duplicate soul in the room... but rather what concerns me is that you and that duplicate soul, time machine what not occupy the same location in space and time... that would be BAAAAAD! Oh, and the planet's spinning around the sun at horrible speed so I hope you can make sure that you don't end up in the vacuum of space... perhaps less painful an end but also rather bad as an end is concerned .

[uc pseudonym]

TV Tropes has already been linked, but it still may be helpful to you to look at their time travel article, which includes many major theories. My own tendency is to say time travel is impossible on a theoretical level.

However, I am fond of one theory of time travel, which stipulates that there are actually two levels of time. Each instant of greater time contains all of normal time. If someone travels in normal time and kills Hitler, in the next instant of greater time there is an entirely changed timeline (possibly including no memory of the change). This allows for changes without the most basic paradoxes.

Of course, time travel in greater time would be impossible, so you could argue that's just a regression. I still find it interesting.

No this is obviously false... I move my fingers as I type this message... I am manipulating the forth dimension with respect from my eyes to my fingers in a relatavistic manner... the effect is pathetically small, but only because I have only an ever so slight power to control time.

This is true, but is the ability to change the rate of movement forward relevant when the discussion is going backward in time? At least I assume that is the topic, because going forward in time is a rather easy form of time travel.

[Nate]

And y'know, another thought crosses my mind.

Same situation as earlier, I go back 65 million years, get eaten by a T-Rex. I have died before Christ died on the cross for our sins. So...where does that leave my soul? XD

[mechana2015]

Same situation as earlier, I go back 65 million years, get eaten by a T-Rex. I have died before Christ died on the cross for our sins. So...where does that leave my soul? XD

In a T-Rex. Then a chevron station.



Bringing religion into time travel creates even larger problems... eschatological paradoxes...yuck.

[AsianBlossom]

Yeah, I say we just leave this messy subject in fiction; where it belongs.

Bringing stuff like this out into the real world only creates fights...and headaches for those trying to figure everything out.

So disagree all you want; we're just not going to talk about it anymore in the context of reality...or at least, I'm not.

[SnoringFrog]

Here's something I thought about really hard when I was a kid.

OK, say you build a time machine.

It can go backwards into time.

ONE PROBLEM.

3 seconds after you punch to button to go BACK, as you are going back, you are also letting up pressure on the button.

Know what I mean? I mean, 1 second ago I hadn't of typed this message, I hadn't of pressed the keys, I hadn't of made an electrical connection inside this computer that put out a character on the screen.

FURTHER,

Let's say it took you 6 years to complete the time machine.

The final step was putting the battery in-from your Honda Civic (It was convenient). You did this 6 minutes ago.

If you go back 7 minutes, suddenly your time machine has no battery.

You would have to literally create another instance of yourself that is immune to all of the laws of space and time, and sort of parallel yourself throughout the universe.

Without direct intervention from God, it is really something that is possible only in our imaginations. Although, prophesy is a gift from God!

This is why I'd like to bring up the theory that you can only travel as far back as long as the time machine had already been invented by the time that you were traveling back to.

[termyt]

No this is obviously false... I move my fingers as I type this message...

Again with the absolutest statements. I guess since it is obviously false, I am either obviously attempting to confuse and mislead people or I am obviously an idiot for presenting it. I'm sure there's more than a few who agree with you on the latter.

I think it's far from obvious or we wouldn't be having this discussion.

Are you really manipulating time, though? To manipulate implies an ability to bring about an outcome that you desire by changing the world around you. In the case of twiddling fingers and flying aircraft, we are not so much manipulating time as traveling through it at a different rate based on factors we do not control.

Even if we move through time at a significantly different rate for a significant period, we have not so much manipulated time as we have been manipulated by it. If anything, it only proves that time is not the constant it appears to be.