Paradoxes

[NEO1970]

Curious..

If Time Travel is really possible, what would the beneifts/dangers be?

[Sephiroth]

I tend to think that if it really was (on the macroscale), causality would be violated and the universe could not exist. I find the idea of some kind of reinforcement loop operating at a quantum level interesting, since it seems that quantum information can (does) travel just as easily backwards or forwards in time, but for me, people going back in time is pretty damn dangerous...it destroys the universe!

[manephelien]

Yeah. The only way we might someday travel in time would be through relativistic effects on ships traveling at a significant percentage of the speed of light. However, such a trip would be strictly one way.

[Sephiroth]

The same thought had crossed my mind.

[Jon George]

I told you my thoughts on this last year, when I met you ...

[Interference]

Originally Posted by Sephiroth

people going back in time is pretty damn dangerous...it destroys the universe!

Nu-uuh. It just destroys people. The Universe can take care of iself. There are no great cosmic ramifications to us manipulating time, because we are cosmically insignificant. All we can do is mess up things on our own planet, and perhaps the home planets of some of the aliens living here. But suns won't go nova and rifts aren't going to open up and nexii aren't going to swallow galaxies whole. We aren't that important, honestly. Nobody's grandfather's life is that important.

[j. d. worthington]

Originally Posted by Interference

Nu-uuh. It just destroys people. The Universe can take care of iself. There are no great cosmic ramifications to us manipulating time, because we are cosmically insignificant. All we can do is mess up things on our own planet, and perhaps the home planets of some of the aliens living here. But suns won't go nova and rifts aren't going to open up and nexii aren't going to swallow galaxies whole. We aren't that important, honestly. Nobody's grandfather's life is that important.

While I'll agree that our relative importance isn't that great, you're making an assumption that -- from my understanding of the concept -- isn't supported by the philosophical/physical underpinnings of the entire idea of time and time travel... namely, that everything in the universe is effected when such happens, because it is the entire universe together that makes time as we know it. Therefore... yes, if an individual went back in time, it would alter the universe, because it would no longer be the same universe it was before such a thing took place (if you follow my meaning). You altered the entire picture by shifting things into places they weren't before, whether it be people, mountains, planets, or ants.

Anything larger than the smallest subatomic particles (which seem to have this capability built into their physical nature) is likely to cause this sort of disruption. How large the ripple would be... that one's a point of debate. But even the sending back of an ant to where it wasn't in the universe before would mean it isn't the same universe as before, and so potentially the results could be enormous... let alone a conscious, thinking being who could either deliberately or in a panic cause all sorts of havoc.... havoc that would reach out far, far beyond our own little mudspeck across the entire spacetime continuum....

[Interference]

I take your point, JD, but I don't think the Universe is a stranger to dealing with cataclysmic events. What do black holes do if they don't locally mess with spacetime?

Of course, I have a conveniently non-scientific view of spacetime. In it, I can envisage all time and space taking a form where if you mess around with one bit of it, the rest doesn't get too upset about it, certainly not to the extent of going into self-destruct mode.

Originally Posted by j. d. worthington

Therefore... yes, if an individual went back in time, it would alter the universe, because it would no longer be the same universe it was before such a thing took place (if you follow my meaning).

Agreed, but the difference would be minor, like an abrasion. Important to humanity and possibly our planet, but of no real import to the rotation of the galaxy or the galaxies around us.

If I create a localised paradox, why should it have any more repurcussions than my amplifier feeding back would have on a West Life gig in Sydney (sadly, can't get them much further away from me than that). Would the Universe - and that means every part of every part of everything from what we see to what we can't possibly imagine - really reel in pain if I went back in time and gave myself a better career or a better lunch? Yes, there'd be knock-on effects, but only locally, only on this biosphere.

Would Hawking have been stupider if Einstein had died in a Nazi concentration camp?

I think even some of the more enlightened humans are really two-faced. We say "Oh, the insignificance of our existence" when we see a picture of our planet from the moon, but then we go right ahead and place ourselves at the top of the importance chart when it comes to a hypothetical list of things that could bring the universe to an end. Is it so hard for us to believe that nothing we can ever do will ever have a lasting impact on a Universe that, let's face it, only endures our existence for a fraction of a fragment of a microsecond in cosmic terms?

Hey, these are the thoughts that keep me sane

EDIT

Oh, yeah, just to point out, I'm not actually a psycho serial killer who's just found a great way to appease my evil conscience - honest. (no evil grin - I'm practicing sincerity this month)

[j. d. worthington]

Originally Posted by Interference

I take your point, JD, but I don't think the Universe is a stranger to dealing with cataclysmic events. What do black holes do if they don't locally mess with spacetime?

There's a rather large difference... black holes are something that are (so far as we know, anyway) are created naturally... they are the end result of certain aspects of the physical universe without any conscious control or development. Time travel would require a conscious manipulation of the basic fabric of spacetime (at least, as said, for anything larger than the tiniest particles), as it does not naturally allow flow both ways, only one for anything of larger size.

Of course, I have a conveniently non-scientific view of spacetime. In it, I can envisage all time and space taking a form where if you mess around with one bit of it, the rest doesn't get too upset about it, certainly not to the extent of going into self-destruct mode.

Here's where I start running into serious problems with the concepts behind the terminology... it may simply be a different idiom, but the universe doesn't "get upset" about anything. It isn't conscious. It is a machine. Period. Living beings within the universe may be a different matter, but the universe itself shows no signs whatsoever of consciousness, and therefore does not have any emotional state of any kind.

Therefore, it doesn't "go into self-destruct mode"... it's more of an analogy to an unravelling of a garment, once a tiny piece of it gets snagged on something; though it may be something completely negligible in itself, the physical effect of the disruption of the fabric, beginning on an almost unnoticeable level, can eventually cause the entire garment to unravel... yet the garment doesn't "self-destruct"... it it "chaoticized" by a random element. So with humans time-traveling. We can't consciously will to affect the universe in such a way and bring it about because we willed it; instead, the very fact of such time travel may (note, may... there is a heated debate on this one ongoing, though the evidence seems once again to be piling up in favor of the older model ruling time-travel out for just this sort of reason) be just such a physical disruption of a sort not naturally part of the fabric of spacetime, to cause such an outcome. Which leads us to --

I think even some of the more enlightened humans are really two-faced. We say "Oh, the insignificance of our existence" when we see a picture of our planet from the moon, but then we go right ahead and place ourselves at the top of the importance chart when it comes to a hypothetical list of things that could bring the universe to an end. Is it so hard for us to believe that nothing we can ever do will ever have a lasting impact on a Universe that, let's face it, only endures our existence for a fraction of a fragment of a microsecond in cosmic terms?

Again, it isn't us as human beings that are important here... the same is true for anything that would create an artificial disruption of this sort in the fabric. It has nothing to do with our ego... it could be a slug, should such exist with such a power. It could be a conscious planet... it could be a conscious galaxy (given any such unlikely phenomena). The point is that is it a disruption of naturally-occurring physical laws, and therefore a disruption of the very nature of entity itself. Which, frankly, is why I still think that time-travel is always going to be an impossibility in actuality... however much of a theoretical possibility it may be.

On a couple of other points:

Agreed, but the difference would be minor, like an abrasion. Important to humanity and possibly our planet, but of no real import to the rotation of the galaxy or the galaxies around us.

Again, you're making the mistake of comparing the universe to a biological organism, and an abrasion (again, something which occurs naturally all the time) to a genuine disruption of the naturally-occurring order of the universe. There's a huge difference there. And, again, anything that affects time (which is predicated on the very movement of the universe itself) will necessarily have an effect upon the whole, as it is all involved in creating that state which we call "time". (Actually, Clark Ashton Smith did a rather neat little bit with this in his "The Chain of Aforgomon", where a sorcerer's demon threatened him that, when he conjured him again, the pentacle wouldn't hold him. Of course, the sorcerer didn't ever call him again... but a friend of his, many incarnations later, cast a spell to recover memories of past lives, and thus relived a spell where he had turned time back on itself... and so everything in the universe repeated at that point, and the demon's prophecy was fulfilled. Note: None of the actions were repeated in any sense we would understand... yet, paradoxically, they were, in effect... and that was quite enough.)

If I create a localised paradox, why should it have any more repurcussions than my amplifier feeding back would have on a West Life gig in Sydney (sadly, can't get them much further away from me than that). Would the Universe - and that means every part of every part of everything from what we see to what we can't possibly imagine - really reel in pain if I went back in time and gave myself a better career or a better lunch? Yes, there'd be knock-on effects, but only locally, only on this biosphere.

Again, the biological analogy. No, the universe would not "reel in pain"... the universe would not be aware. Beings within it might be aware of something happening (or might not, depending on the effect and the rate of speed of its result). And yes, this would be the case even in such a minor thing... because a macrocosmic body violated the normative physical laws under which the universe works. You are seeing the relationship as too limited. What is time? How is it "created"? What makes it? How does it relate to the working of the universe? I think you'll find that you simply can't have a paradox in time without involving everything in the universe. It is impossible for it to be localized. Earth, our solar system, our galaxy, have some peculiarities in the way time flows here, but the basic nature of time is related to the basic nature of the structure of physical entity, and cannot be separated from it, or isolated from the whole in any way.

As for your other query:

Would Hawking have been stupider if Einstein had died in a Nazi concentration camp?

No, not stupider. But he wouldn't have had the information he has found necessary to build his own models. Again, interrelationships such as this are actually specious... they don't apply; but taking the question qua question... Einstein himself would not have developed relativity had it not been for Galileo, Copernicus, Tycho Brahe... or Michelson and Morley. They would each have been as brilliant in essence... but without the foundation to work on, they would not have achieved what they have. (They may have achieved other things equally valuable, but they would not be the same things.)

Incidentally... it may not "destroy" the universe, but it would cause a major disruption, because time cannot be turned back on itself, nor created before it exists, without involving the whole. One might as well expect to drop a 10-ton boulder and expect it to fall up under normal conditions... it's physics, not teleology, involved here.

[chrispenycate]

There are several spacetime models that do allow information, and occasionally matter, to travel against the entropic arrow. The simplest is a totally predestined universe where if you are going to travel back in time then you have already done so, and so nothing is changed - the situation now is the summed result of all the interferences and free will is an illusion caused by our sensory perceptions.
Alternatively time travel requires a transmitter and a receiver, so one can never go back in time further than the invention of the machine (but when it's invented, chaos ensues)
Or only information can travel, not matter or energy (thus maintaining the laws of conservation of this, that and the other) and we haven't yet learn't to detect the information our distant descendents are frantically sending back ("the history books were clear; it was discovered in the twenty-first century. And despite everything we told them, they still went and invaded")
Or the "The universe spawns a new set of potential universesequal to the sum total of all the particles in the univese in the period of time in which a particle can take two different actions, but the majority of these reinforce to make a "consensus" universe before the next split" In chaos like that, the guy with the AK47 at the crucifixion is just considered too improbable by the majority of universes and "poof"

[NEO1970]

Thank you all for the insight about time travel; there are may theories out there, and scifi has sure done its job on getting us thinking...
What is everyones opinion on the existence of black holes? I found an article on NASA's site about it... Now lets look at this: we enter & travel thru a black hole. Now, in theory, could that possibly allow us to travel thru time?

[Sephiroth]

This turned into a great discussion. j.d. has made all of the points I might have...probably better than I would have.

time cannot be turned back on itself, nor created before it exists, without involving the whole

This was, in essence, what I was thinking when I said what I did.

As for black holes, going by current theories, you might be more likely to end up in another, parallel universe than time travelling as we normally think of it (assuming that you survived). Braneworld theories conceptualise our universe as a 3-D 'membrane' to which all of our fundamental forces and particles of matter are 'tied'.......except gravity. The membrane exists in a fourth large spatial dimension called the 'bulk', which contains other membranes...other universes.

All of this has emerged from string theory, and what makes gravity different is that its strings (gravitons) are closed loops, so they can 'float off the membrane'. This has led some cosmologists to suggest that the extreme gravitational conditions inside a black hole might make it possible to contact or even move into (ignoring the fact that it would probably kill you) an adjacent universe. For the time being this is highly speculative.

[Interference]

Hey, JD, good points well made, but oh, so familiar. (Sorry, not being rude, I just like the way it sounds.)

For some reason, and I know it's a flaw in my writing, I can't seem to explain this properly. Now, you and I both know - or at least I do, and I hope you will in a moment - that I'm not really likening the Universe to an emotional organism. Just using short-hand. It's lazy, but it saves me sitting up all night looking up the physics, which I wouldn't understand, anyway. (Although a cup and saucer can be upset. )

To me, it matters nothing whether Einstein comes up with the necessary theories or some spotty kid from Newark, New Jersey. The theories will arise because people will look for them. The identity of the individual is irrelevant and determines only which generations will benefit from them. So, no Einstein doesn't necessarily mean Hawking won't have the building blocks to devise his own views. It might, it might not. It doesn't matter as at some point someone in human history will.

My broader picture is that human history is inconsequential to Universal history. Life arises and falls away throughout the Universe and whether we understand our cosmic environment or not is surely, largely, irrelevant. Life is natural. Perhaps intelligence is, too. Perhaps the intelligence to discover time travel is as natural as - a black hole. (What if every black hole were the result of some intelligent race dabbling with time travel? I just know you're going to hate that idea, but it might be worth a short story some time.)

Okay, so anyway, something happens and your metaphorical garment is snagged and begins to unravel. I have no problem with this at all. I agree with it. Maybe the unravelling of the Universe (metaphorically) will begin with some human act. God knows, we're responsible for plenty of unravelling on Earth. Personally, I'm dubious. It's a big and ancient Universe. As I tried to say, if it can withstand the thousand natural shocks it's been heir to on a regular basis since the day it was ... ummmm ... extant, a couple of manmade - or even slug-made - ones wouldn't necessarily impact on it very much. It's hardly going to change the hour or day of the Big Crunch (or whichever natural end you might subscribe to).

My point about ego is slightly important, but I'll let it pass. Humans will be Humans, after all. But then Daleks are Daleks, too.

If we ever come to understand Time properly, I believe everything will be explained, including the importance or otherwise of not messing with it. I have faith in the Universe. I think it'll know what to do when the time comes, in its non-anthropomorphic, unconscious, non-corporeal way.

I will look up the word teleology and use it some time. Thanks .


And thanks, too, for making me write this out. It's an incompletely formed idea, and someone smarter and more scientifically tuned in will probably do the math on it one day off his or her own bat, probably on a napkin at a dinner party which will be completely forgotten a couple of hours later, but it's one that, if true, throws open the doors of potential (though potential is unlikely actually to be a building) widely enough to let us see how time is, in the end, just another dimension for us to explore while we await our own natural extinction.