Time Travel Ramblings

[Daruko]

I posted this originally in the wrong context, and so this is a repost.

The subject matter is just basically my irritation with the so-called grandfather "paradox" and the overwhelmingly abundant crappy interpretations of how time travel would work. 

time does not flow in a linear fashion... so the grandfather paradox and the "where are the travelers from the future if it can be done?" dilemna don't really apply.   This has been illustrated not only in physical models of time, but I think there are a lot of ways it can be illustrated on more philosophical terms.  There are probably tons of zen koans about time which illustrate the illusory nature of "common sense causality".

Time does not flow, or that is to say, it SEEMS to flow, but operates much differently than it appears on the surface.  There is no moving line forward that becomes a different series of events, causing the universe to implode or something, because you moved through space-time and made alterations.   Because THIS time, right now, while you're making the alterations... that moment is it's own special case.  It is now.  Nature need not make excuses for our tendency to confuse what is now with what is "to be" or "has been".  "To be" and "has been" misrepresent time, except when not taken literally and used only out of convenience.  If I go "back" in time to 10 years ago, and meet myself, I see no reason for any paradoxes, and I certainly wouldn't expect (like these stupid time-loop synchronistic movie interpretations) to suddenly REMEMBER meeting myself 10 years ago.  10 years "ago" is really 10 years "over there", from a physics standpoint.  Another coordinate, if you will.  Once it is now, it is neither here nor there, no matter what other space-time memory slices you're associating it with.  If you are here, now, it doesn't matter whether it's 1950 or 1970 or 2070.  If you kill yourself in 1980 and then jump back to present day, would you really expect to find that you ceased to exist?   

I certainly don't completely understand time, but it's weird to me that people get so hung up on the grandfather paradox, that they use it as justification for imposing new restraints on the physically possible.  I blame it on this:

Stephen Hawking once suggested that the absence of tourists from the future constitutes an argument against the existence of time travel—a variant of the Fermi paradox. Of course this would not prove that time travel is physically impossible, since it might be that time travel is physically possible but that it is never in fact developed (or was cautiously never used); and even if it is developed, Hawking notes elsewhere that time travel might only be possible in a region of spacetime that is warped in the right way, and that if we cannot create such a region until the future, then time travelers would not be able to travel back before that date, so "This picture would explain why we haven't been over run by tourists from the future."[10] Carl Sagan also once suggested the possibility that time travelers could be here, but are disguising their existence or are not recognized as time travelers.[11]

Talk about whacked out theories?  It's not that I subscribe to one opposing viewpoint.  I'm certainly not with the Presentists or the Eternalists (although I do agree the universe is "happening").  But why do we constantly suppose that nature can't possibly contradict our maps, when we already know goddamn well the maps are off.  We know enough about time travel to screw with our own notions of causality, and break and bend the rules the same way we have done with lightspeed impedence.  But it's as if we are following a map in the woods, and suddenly come upon a lake that isn't marked on the map.  We know damn well that lakes exist, but there's no explanation for how THIS lake is right HERE in THIS forest.  It's not on the map, so you know what?  It's not there.  I didn't see a lake, did you?  Mere hallucination if you did, because it's not on the map.  Besides, how many times have I walked through this same forest.  If there were lakes not on the map, then why am I not bumping into them all the time?    Why just THIS lake, in THIS forest?   My point is, until the limits have been clearly defined (and they never will be), why make skeptical conclusions FIRST?  If the contradiction on the map needs worked out, then why still assume that the implications of the contradiction can be explained by the map?

Theoretically time travel is possible.  We haven't seen any time travelers (that we recognized anyway), and we don't know what would happen for an observer to "alter" perceived causal trajectories and then return to his original location in space-time.  I'm gonna take a stab in the dark and give my best guess.  I'd say that if he returns to his original location in space-time, he's not going to notice a thing.  It will appear as if he made no alterations.  I'd guess that if his time machine has a better map than we do now, it will know how to follow that new causal trajectory and return him to a DIFFERENT and causally-associated space-time which appears very (maybe) similar to his original starting point (before any of this time-traveling nonsense).  This would be the world in which he had never been born, say, due to the alteration he made in a causally connected time slice (killed his grandfather).    He may very well find his laboratory is now a gas station.

I don't know, and this is a very MWI sort of guess, but it makes much more sense to me then to suppose that 1)time travel isn't possible despite it's theoretical possibility, BECAUSE we haven't seen people "from the future" and 2)if i went back in time and killed my grandfather, i would go poof!  OR the universe would go poof!  and then based on that 2nd absurd notion: 3)I can't go back and kill my grandfather after all.  The universe isn't "large" enough for processes that appear contradictory?

Well, anyway... We'll see if anyone is in the mood for this nonsense.

[Thurnez Isa]

don't you need a device upon where you jumping too
a machine at point A and a machine at point B??
like you can't just jump into nothing


BTW: Please quick simple, practical answer please
i may use the idea in the future....
but please no theoretical hippie crap

[Cramulus]

I have trouble swallowing any discussion about time travel because there is literally no way to talk about it without heavy amounts of conjecture, logical paradox, and talking out of your ass.

time does not flow in a linear fashion... so the grandfather paradox and the "where are the travelers from the future if it can be done?" dilemna don't really apply.   This has been illustrated not only in physical models of time, but I think there are a lot of ways it can be illustrated on more philosophical terms.  There are probably tons of zen koans about time which illustrate the illusory nature of "common sense causality".

There's a "physical model of time" which illustrates time not flowing in a linear fashion?
and why do you buy that model instead of the alternatives?

[Quotes from Sagan and Hawking]

Talk about whacked out theories?

show me a non-whacked out discussion about time travel, and odds are I'll show you someone who is overly confident in their assumptions. OR people who admit they know nothing.

I don't know, and this is a very MWI sort of guess, but it makes much more sense to me then to suppose that 1)time travel isn't possible despite it's theoretical possibility, BECAUSE we haven't seen people "from the future" and 2)if i went back in time and killed my grandfather, i would go poof!  OR the universe would go poof!  and then based on that 2nd absurd notion: 3)I can't go back and kill my grandfather after all.  The universe isn't "large" enough for processes that appear contradictory?

If/when someone figures out how to travel through time, I'm guessing that the science which facilitates it is our of our comprehension right now.

Just like how you can't explain to an alchemist why, say, Voice over IP is cool. And a caveman couldn't have invented a typewriter. It's not just that we don't know how time travel would work, the science which facilitates time travel doesn't even exist yet.

'cause right now, Time Travel is a bunch of squiggles on paper,
or a thought experiment

so it seems silly (to me) to talk about how it would or wouldn't work.

Not that it's not a fun topic to think about. Just that talking about it concretely is very difficult.

[The Good Reverend Roger]

If I can't go back 2,000,000 years and wipe out every semi-erect primate in central Africa, I'm not interested.

[Triple Zero]

If I can't go back 2,000,000 years and wipe out every semi-erect primate in central Africa, I'm not interested.

so then we'd get .. lizard people? wolf people? you'd rather have otherkin and furries??

[That One Guy]

If I can't go back 2,000,000 years and wipe out every semi-erect primate in central Africa, I'm not interested.

so then we'd get .. lizard people? wolf people? you'd rather have otherkin and furries??

But ... if THEY were the "people", wouldn't that make their equivalent those freaks that dress up like hairless apes for sex?

[AFK]

If I can't go back 2,000,000 years and wipe out every semi-erect primate in central Africa, I'm not interested.

so then we'd get .. lizard people? wolf people? you'd rather have otherkin and furries??

We wouldn't get anything because we wouldn't be we, oui?

[The Good Reverend Roger]

If I can't go back 2,000,000 years and wipe out every semi-erect primate in central Africa, I'm not interested.

so then we'd get .. lizard people? wolf people? you'd rather have otherkin and furries??

But ... if THEY were the "people", wouldn't that make their equivalent those freaks that dress up like hairless apes for sex?

Probably.  There is no end to perversion.

[Daruko]

don't you need a device upon where you jumping too
a machine at point A and a machine at point B??
like you can't just jump into nothing


BTW: Please quick simple, practical answer please
i may use the idea in the future....
but please no theoretical hippie crap

From an Einsteinian view, kind of yes maybe, but no.   It really depends on the type of time machine we're talking, and even pre-quantum mechanics models of time allow for time travel without a machine at point B.   There are a lot of different methods which have been explored.

This is sort of along the lines of what Hawking was talking about when he refuted the possibility of time travel due to the inability for a built machine to satisfy the "weak energy condition".   

I'm going to refute this in detail later, or at least summarize Amos Ori's recent refutation.

There are still possibilities to build time machines with positive energy densities, and I'm sure there are at least a handful of models based on this line of thinking, but I'm more interested in Quantum Mechanical models here, and Everett will certainly come to play.

That's part of my frustration.  I'd love to see even one movie or book depict time travel as described by Everett, Feynman, and currently Deutsch and Lockwood, among others.  We can do away with those nasty paradoxes, as well as the convenient one way set ups.

This is a short reply for you Thurn.  I'm long-winded anyway, and time is a complicated subject.  I need to do some work for work at home tonight, but afterwords I hope to elaborate more concisely, and answer cram.  I've got some of that post put together already.

Also, science is always theories.   No hippie crap.

[Faust]

ugh....

In the morning I'll post some form of response to this

[Jasper]

If I can't go back 2,000,000 years and wipe out every semi-erect primate in central Africa, I'm not interested.

so then we'd get .. lizard people? wolf people? you'd rather have otherkin and furries??

But ... if THEY were the "people", wouldn't that make their equivalent those freaks that dress up like hairless apes for sex?

This line of inquiry assumes that intelligent life forms are inevitable in our little slice of spacetime.

[Daruko]

There's a "physical model of time" which illustrates time not flowing in a linear fashion?
and why do you buy that model instead of the alternatives?

i don't necessarily.  but it seems more sensible to me at this time than the alternatives i know well.

show me a non-whacked out discussion about time travel, and odds are I'll show you someone who is overly confident in their assumptions. OR people who admit they know nothing.

You can count me as one of the latter.

If/when someone figures out how to travel through time, I'm guessing that the science which facilitates it is out of our comprehension right now.

Fixxd.  Also, I might just be inclined to disagree.  But you could be right.  Depends on what you mean by right now.

the science which facilitates time travel doesn't even exist yet.

the science already suggests it's possible.  facilitation may not be far.

I'm not sure the science isn't getting there.  The engineering is not there.

But is it possible?

'cause right now, Time Travel is a bunch of squiggles on paper,
or a thought experiment

so it seems silly (to me) to talk about how it would or wouldn't work.

I think some intend to do it.

Not that it's not a fun topic to think about. Just that talking about it concretely is very difficult.

I agree completely.

Everett started down a road that offers a much more coherent explanation of time travel as a PHYSICAL possibility.  It must be said that there are other interpretations which leave possibilities for time travel... I'm not even going to TOUCH Einstein-Rosen bridges yet.    The "many worlds" interpretation of quantum mechanics allows a time traveler to go back in time and "create realities", in the sense that there is an alternative history for every possible outcome of every decision made.  Common sense may deem this too absurd, but just examine the model, I say.  It dissolves every classical paradox for time travel; an aspect that is merely in an implication of the theory.  Every quantum event is depicted as a split in an infinitely larger and more complex structure than our directly observible space-time physics.¹ 

I am not endorsing this model at THE correct interpretation of quantum mechanics, but I am suggesting it resolves paradoxes, provides coherent explanations for processes which previously had none, and provides us a more powerful tool for computing probabilities than any piece of technology previously devised.

Anyway, most time travel stories in popular culture are illogical.  You can't "change" the past to be different from what it was, because the "past", "present", and "future" only occur once.  Therefore, in science fiction and similar scenarios in which time travel is depicted, all the author must do is concoct a coherent scenario in which everything happens once and in a consistent way (the TV show "Heroes" comes to mind as a recent example).

This is partially the cause of my annoyance.  If you're going to write science fiction, or talk about time travel, can't SOMEONE devise a plot that utilizes an alternate model to mere logical coherence?  Many things are logically possible.  While it might make devising a time travel related plot easier, it's relevance towards actually understanding time travel is zero, and for one who take an interest in these ideas, it's quite frankly boring (perhaps like this post).  Hence, it becomes a tired old plot device for me, because I'd like to see some enactments of less paradoxical and/or convenient/cliche theories, which imply it is PHYSICALLY possible to travel through time.  Though no logical or conceptual analysis may reveal a concept as being metaphysically impossible, there are still innumerable concepts, logically consistent, which are in fact physically impossible*.

Now that I've written this much, I'm rethinking "Back to the Future".  I'm realizing that movie may not have been incompatible with this model insofar as it complied with the known laws of physics.  Complied generally, because "engineering" the time machine is a whole other facet of time travel speculation.  This is a foggier area for me to make guesses because it relates to human ingenuity.  It seems that curiosity and creativity lead to either better models or better engineering eventually... when the models don't permit something we imagine, we seem to either develop workable models that do, or engineer something that works in that model better than we though possible.  Newtonian physics suggested new possibilities, and new impossibilities.  We engineered things that made us rethink the possible, and then we developed new models.  This introduced new possibilities, etc., Enter Einstein, etc... Kurzweil would call this a "paradigm shift" and I might say any faith I have in the continued manifestation of current physical impossibilities becoming current physical possibilities is a product of my part-time optimism.  However, physical possibilities which might seem infeasible from an engineering standpoint are limitations of ingenuity, not of physics.  In the meantime, the models only seem to be opening up new possibilities on their own.

<sup>1. "apparently", but I am going to go into this in another post.  I want to cite where we ARE observing it.

Citation for Citation Needed = Many Worlds</sup>
Here's a link more entertaining and straightfoward than this babble:  http://www.telegraph.co.uk/earth/main.jhtml?xml=/earth/2007/09/21/sciuni121.xml

This has been illustrated not only in physical models of time, but I think there are a lot of ways it can be illustrated on more philosophical terms.  There are probably tons of zen koans about time which illustrate the illusory nature of "common sense causality".

I'm gonna get to this.

[The Good Reverend Roger]

If I can't go back 2,000,000 years and wipe out every semi-erect primate in central Africa, I'm not interested.

so then we'd get .. lizard people? wolf people? you'd rather have otherkin and furries??

But ... if THEY were the "people", wouldn't that make their equivalent those freaks that dress up like hairless apes for sex?

This line of inquiry assumes that intelligent life forms are inevitable in our little slice of spacetime.

Let me know when they show up.

[Jasper]

Wouldn't know one if I saw it.

[The Good Reverend Roger]

Wouldn't know one if I saw it.

I wish BMW hadn't gone nuts.  He would have liked this fread.