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Time Travel Realities
JamesKeenan
Registered User regular
Registered User regular
Time Travel. There's a lot to the potential subject. Whether it's possible at all, how it could be possible at all...
What scientific principles would it possibly violate? Why not, maybe?
How could it work in the first place? Multiple Universe Theory? Extra dimensions for time and potentiality? Wormholes?
Hopefully a worthwhile, speculative conversation can come out of this.
What scientific principles would it possibly violate? Why not, maybe?
How could it work in the first place? Multiple Universe Theory? Extra dimensions for time and potentiality? Wormholes?
Hopefully a worthwhile, speculative conversation can come out of this.
JamesKeenan on
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But we can talk about theoretics, at the very least.
But moreover, that is the point of the discussion. To debate what could be possible compared to what we know, or think we know.
It's not as if we're without food for thought.
I didn't mean exactly that the method of time travel be ignored, so much that no one method dictate the entirety of the discussion.
But really, I'm not sure it does matter. If one wants to talk simply about the reality of what might occur if you take a bathysphere with two Tesla coils duct-taped to it, or if you shoot radiated Nitrogen into a container of Tachyons, or you simply wish for it out of a Genie.
The means are as theoretically up for discussion as the ends.
The manner in which the time travel functions will determine if we can, for example, go back and kill Hitler in any meaningful fashion. Do we come back and all our friends congratulate us? Is it impossible for us to go back "home" since we destroyed the line of causality for sending us back in the first place? Do we go back and find nobody knows what we went back to do or in fact thought we were sent back for an entirely different reason?
Really the worst thing about time travel Sci-Fi is that it is all almost nearly the same basic premise of time travel when we have very little clue how it'd actually work out. It's wide open country and everybody just hangs around the rest stops and ignores all this virgin landscape that could be explored.
However, it's not so much literal time travel as it is exploiting time dilation. And there's absolutely no way to go into the past.
But were it possible by any means to travel back in time, I want to imagine there's some thought experiment to show how detrimental this could be. Some kind of event on the atomic scale or entropic process. Something to the effect of, "Time travel couldn't work, because then you could divide by 0."
It's not exactly possible to show a lack of possible detriments.
Trailer:
As far as I know thusfar it mostly turns out that what looks like it might send you back in time tends to fall apart when you actually try to put it together.
The way I'm thinking about it would be much more practical to go forward, grab a sports stat book and go back than it would be to go back, make your mom fall in love with you and get her together with your dad at the Under the Sea dance, and get back to the right present.
http://www.physorg.com/news63371210.html
I've always thought the biggest problem with time travel was that most authors treat our universe as a two dimensional line that you can jump back forth on. They don't ever seem to account for the fact that not only are you moving through time, but you have to move through space as well, meaning our planet is not stationary and never occupies (as far as we know) the same point in space.
For example, if I want to travel back to ancient Egypt, say 4,000 years ago, I have to travel to the point of space Earth occupies 4,000 years ago. Which who the fuck could ever calculate where that was? I would image our planet, solar system, galaxy, cluster of galaxies, etc has moved a lot in just 1 year.
Well, your location would have to change too, but it's potentially helpful the gravity bends timespace. If you are just flipping the direction of your time scalier and actually traveling back through time, it may not make too much of a difference. If you are teleporting or taking a wormhole back in time, it would be helpful if the destination was where the earth was when you are going to get there.
That would depend if the three-dimensional "location" was actually a Cartesian coordinate system. Where is the relative origin? Space? Earth? Some unknown constant? I think "where the hell am I?" is just as important as "when the hell am I?" (Sorry Doc.)
Let 'em eat fucking pineapples!
And I've just gone cross-eyed. o_O
Let 'em eat fucking pineapples!
This question has got me really stumped. You're right, normally people assume that your position won't change when you travel through time, put they don't specify how you measure your position. If you say that your position on the planet stays the same, then, there you go, but it's equally as valid to say that your position relative to the sun would stay the same. There's no "universal coordinate system" that we could use to decide. Maybe this is one of the paradoxes of time travel- there's no way to know where you'd end up in space.
edit: now that I've thought about it some more, it's only a paradox for INSTANTANEOUS time travel- going time A to time B without experiencing anything in between. If you have continuous time travel (for instance if you could travel faster than light, you'd gradually travel backwards in time) then your time would change along with your position, so it wouldn't be a problem.
Depends on how you're moving through time. If you're using some complicated bit of wormhole tomfoolery then you come out wherever the wormhole mouth is. If you're just falling through time somehow then, given the lack of a universal coordinate system of independent reference frame, it seems at least basically logical that you would assume a state requiring a minimum energy change, so you'd follow some sort of space-like geodesic warped by the local gravitational fields and end up in basically the same place relatively to the nearest massive bodies. If you're on Earth and jump a relatively small amount of time you'd probably stay on Earth. Long enough paths would be increasingly perturbed by the effects of other massive bodies (other planets, comets, etc.) so you might end up inside the planet or drifting in space somewhere... But this is entirely un-founded speculation based on the usual minimum-energy rule of thumb.
It's easy enough to say "time travel doesn't work because of causality violation" but there's no actual physical law preserving causality. "Time travel doesn't work because it breaks the second law of thermodynamics" will usually work, though, unless you finagle your definition of 'time travel' to get around it somehow. Moving backward in time would revert the universe to a state of lower entropy with no external thermal reservoir to power the effect. Can't do that. So then you have to call in alternate universes and whatnot to make it work, at which point it stops being speculative physics and starts being made up physics.
No clue if there's any theory behind it, but I just think it would be hilariously anticlimactic.
I was assuming something with at least a shred of physical reality. If you have the ability to just bop around the timeline then you apparently have both the capability to randomly reposition yourself along the temporal coordinate axis and a means of specifying a temporal 'distance' to move. Time doesn't have a universal coordinate system or reference frame any more than position does. Go back in time 5 million seconds. 5 million seconds relative to what? The relative velocity of the sun from the Earth? The center of the Milky Way? Tau Ceti?
And if you can randomly reposition yourself in time according to some reference frame then you can probably just directly manipulate your spatial coordinates in that reference frame the same way.
Assuming you were just sliding along a line of temporal distance away from your initial location I'd assume that your spatial position would remain basically fixed in your local frame of reference, but that may not really make sense. I mean, how do you move along a temporal distance? What's your velocity? Seconds per second? What's measuring that latter 'second'?
This is why physicists rely on weird pieces of spacetime geometry or FTL travel to do their time traveling. Give me a nice, relativistically-accelerated wormhole any day. All this jumping around in time stuff is just riddled with logical inconsistencies.
This does bring up an interesting idea (in my opinion). If time travel is based on there existing countless alternate realities (the grandfather problem I think would only exist if there is only one timeline) and time traveling is basically jumping into a different stream without affecting the reality you originally came from... wouldn't you be able to strip mine the different pasts and futures for resources?
I've read about this a couple of years ago and was almost tempted to make a 'crazy science ideas - how far did they get?' thread. About 6 years ago there was a documentary on with him (might have been a Horizon), as he was planning on building one with high powered lasers. Would have thought there's enough crazy rich people to fund something like this, so what happened to it?
The alternate theories one is good, at least in my opinion, because I can actually wrap my head around it. Of course, the problem with mining resources, for example, would be transporting them. But feasibly, you could--after all, who is to say that transporting a mountain through time is any harder than a single person. It's pretty inefficient (and requires a lot of people) though.
Let's say you have two Universes, Universe A and Universe B (or, if you prefer, the Fighting Mongooses). A time traveler goes from 2009 to 1914 to shoot Gavrilo Princip in the face, stopping him from assassinated Archduke Ferdinand, with the admirable (though admittedly uncertain) hope of stopping the first and second World Wars (as he is aware of them). He is successful, and travels back to 2009. The two World Wars never happened--at least, not the wars he knows of, the Russian Revolution happens in 1929 (or some other year of your choice, or not at all), Japan and Germany are still imperial powers, et cetera (the details are not important).
He's in Universe B. He cannot return to Universe A, ever. In fact, in Universe A, as far as everyone is concerned, the time traveler simply vanished without any trace, as though he'd been annihilated from existence in a furnace or buried in a cement block dropped to the bottom of the ocean. There is no change. Franz Ferdinand still dies. Trying to intercept himself is hopeless--if he could, somehow, he'd simply end up in Universe C. Just as likely, he can't, because he's going to end up in Universe C, and the original him never went there.
Universe B is all kinds of different (good or bad, no one could really say). In fact, if the time traveller's grandfather only met his grandmother because her first husband died in the firebombing of Dresden (or, for example, they were both in the Red Army in the Revolution and met through that), he doesn't exist. In fact, even if his entire family history is the same, that just means there's another one of him, walking around, maybe thinking about time travel (though this cycle--Universe B's traveller could travel and disappear--could be repeated infinitely). The two can meet with no repercussions, because they are not connected to one another. One can die, and it makes no difference. Basically, the time traveler, upon returning, has effectively come into existence from nothing, no biologic origins in that universe, no history, nothing. Just like he vanished in his own.
Most sadly, I suppose, is that he can never go back. His family and loved ones in Universe A will acknowledge that he died (or, at least, vanished from existence). He will not actually know anyone in B, including his own parents (or, at least, they will not know him).
The original actor for Marty McFly in Back to the Future, before Michael J. Fox, brought this up, I think. He mentioned that it must have been a tragedy to return to a universe, albiet a better one, where you did not know what happened for all those years. It's kind of like that, you could say (though I think those films subscribe to the one universe notion).
EDIT: Damn, top'ted.d Sorry about rambling, it's hard to describe concisely.
Shit, you'd damned well better do it. Otherwise all those weasel degenerate other yous are going to do it to you first. You have to be preemptive about it, and I doubt they are going to go down without a fight. Shit, they are probably working on a first strike capabilities right now. Some of them are even more advanced than us, and we sit here twiddling our thumbs while they plot the destruction of everything we know and love.
There's an interdimensional missile gap.
I'm pretty sure that's the plot of a Jet Li film.
You have successfully built a time tunnel. This time tunnel once activated allows you to send information back to the beginning of when the time tunnel was activition. So for instance the beginning of the time tunnel activation is Y. X is created every single instant in the future that the time tunnel has remained open, and X can send information to Y. Y however cannot send information to X.
Upon opening of the tunnel X sends a message to Y. X message is from an indeterminable time period. The message says "Do not ignore. Shut down and destroy the time tunnel."
Now, what do you do? This message has been sent, suggesting that you have ignored this message and continued to run the time tunnel. The message is specific, but in an X period of time you do not write "DEFINITELY do not ignore" because the message would show that. Similarly however if you choose to listen to the message and destroy the time tunnel, the message ceases to exist and as such the period after receiving the message ceases to exist as well. A causality error in time occurs.
Paradox problems.
Of course, the implication is that the effect is somewhat localized--it didn't rearrange the synapses in everyone's brains (or at least in Tim Allens--maybe it is intended to ignore his?), otherwise everyone wouldn't even realize that.
Then again, I'm only speculating as to how the brain works.
Honestly, I think causality is a big enough boy to take care of itself. I don't think paradoxes matter at all to reality. Shit just happens. The absolute worst that might happen is you may make some weird matter if you send it back in time and then make it so you didn't send it back in time.
It will probably still be there. Depending on some possible structural things about the universe, it's possible that it won't be there as well. Matter can more or less exist like that. I want a mirror from partially existing future, cause I think it might be fun to shine lights at. Other than that, I'm not too worried.
This actually is a very easy paradox to over come though. You are already in the future the second you turn the thing on. You just send the message yourself, and turn the machine off. It's not like anyone is going to be around to blame you if something horrible happens anyway.
Time tunnel questions: would the person on the reciving end of the tunnel get every message ever sent from the future simultaneously? Every message sent is being sent back to the exact same time.
Briefly put: the more someone attempts to alter the past (murdering major world leaders and such), the less impact they can have on the present. Eventually, they become an insubstantial ghost, having altered their past to the point that they no longer interact with our present.
I would think that if all the matter and energy you ever put into the tunnel came out at t=0, you would create a new Big Bang in your lab the instant you turned it on. Of course this also creates a paradox since if the machine is destroyed when it is activated, it can't exist in the future to send things back.
http://bit.ly/2I5BPV
I really like this idea, regardless of the merit of the individual "correctness" behind it.
It is always talked about how time is the "fourth" dimension. We can move in space in the other three (x,y,z) but movement in the fourth is limited to one direction (arbitrarily called "forward" for the sake of what I am saying). If one was able to move in a different "direction" in the fourth dimension, everything else is still moving in the constant "forward" dimension.
Imagine a car as the fourth dimension (time). Everyone (that we know about) is in this car, moving in one direction at the same relative rate. (Or, if you want to be more correct, there are a bunch of different cars, all moving in the same direction, but at different speeds) Now, say someone could remove themselves from their car and move in a different direction, or stop the movement of their car relative to the other cars.
Are there more cars behind you? Meaning that if someone moves themselves in the fourth dimension relative to all the other matter in their previous location, the matter (atoms etc) would still be moving relatively uniformly in the same "direction" in the fourth dimension. Therefore it would really be impossible to interact with past versions of the matter you "left" as it has already moved on relative to you.
This raises the question, however, of what exactly one would encounter if one were moving in different "direction" in the fourth dimension relative to the rest of the universe.
All motion is relative. Just recite the words "this is the point of reference" while the machine is on.
There is also the hall of mirrors paradox. Namely, you build a time tunnel with one end in the future and one in the past, that stay open continuously (IE for every second that passes externally, a second passes for the past end and future end). Eventually both ends would have to exist concurrently (so you have a worm hole, which you can pop into one end and emerge from the other say 1 minute in the future, and visa versa.)
Now lets say you bring those ends together so that they face one another. Now you place some media between them, that takes an electron exactly 1 minute to pass through. Then you fire an electron into the future end so that it comes out the past end.
The electron goes through, comes out the past end, goes into the future end 1 minute later. It goes back to the past end and makes the trip again, but while it is doing that, at the same time the original electron is making the trip. So now you have an infinite amount of electrons occupying the same space for approximately 1 minute. So not only have you thus created an infinite amount of mass and energy, but you've also created a singularity.
This is a bigger problem than it looks like initially. Say instead of having a wormhole with one end facing the other, instead you have one with one end at the beginning of the universe, and one say 10 billion years later. If even one photon can make it from the past end of the wormhole to the future then you essentially will have the entire universe filled up with duplicates of that one photon as it makes the trip over and over and over again. Even if both of those ends only exist for a very small amount of time, if it's possible for a single particle to make the trip from one end to the other and back then essentially the entirety of the universe along the path of that particle becomes filled with infinite energy.
So yeah.
Would that work with my wang?