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Like most philosophers, I like science fiction and stories about time travel. Recently I watched the episode Time of the SyFy seriesStargate Universe. This episode got me thinking about time travel and God, oddly enough.
Imagine, if you will, the following science fiction situation. Sally is working on a time travel project and during one experiment, her own smartphone appears in the lab. Startled, she checks her pocket and finds that her phone is there. Yet it also appears to be on the table. Picking it up, she finds that video has been recorded on it. Much to her horror and dismay, it seems to be a video of her saying that she has killed her husband for having an affair with her friend, only to find out after that she was wrong. In the video, she can she the body of what seems to be her dead husband. The video closes with her future self saying that she is sending back the phone to tell her past self to not kill her husband; future Sally then shoots herself in the head as the phone is being sent into the past.
Being something of a skeptic, Sally checks the phones carefully and finds that (aside from some blood on the future phone that matches her husband’s blood type) the two are identical. This convinces Sally and she does not kill her husband.
Now, let God be brought into the picture, at least hypothetically. If one prefers to leave God out of this game, then an omniscient observer who judges people for their deeds and misdeeds can be used in His place.
In this scenario, what would God actually “see” and how would He judge?
On one hand, the future Sally did kill her husband and send the phone back. After all, without those events, then the phone would not have the video recorded on it and would not have been sent back As such, God would judge that Sally was guilty of suicide and murder, hence worthy of divine punishment. Also, both Sally and her husband would be dead and thus would have gone off to the relevant afterlife (assuming there is such a thing).
On the other hand, the time traveling phone prevented Sally from killing her husband and committing suicide. Thus, Sally would not be judged for these deeds. Also, neither Sally nor her husband would be dead. In effect, that future event never will be, although it must have been (otherwise there would be no phone).
One easy way out of the problem is to follow John Locke’s approach in his discussion of personal identity: since God is good, he would not allow such confusing events (in this case, time travel) to come to pass. Of course, this is not very satisfying as an answer.
Another easy way out is to deny the entire scenario and say that time travel is impossible because of exactly this sort of nonsense. But, where is the fun in that?
Another way out is to use the branching worlds approach: what seems to be time travel is actually travel between possible worlds. So, the phone did not come from Sally’s future. Rather, it is from a possible world in which Sally did kill her husband. So, the Sally of that world is a killer and a suicide; but her actions saved her counterpart Sally from her fate. So, God takes care of the killer Sally and the lucky Sally avoids her fate. Hardly fair, but that is nothing new.
But, let us suppose that the scenario happens as described. From God’s perspective, it would seem that time travel would create all these loops and changes throughout time. Or perhaps not. One classic view of God and time is that God perceives all of time “at once.’ To use an analogy, God’s perspective is like being able to see the entire filmstrip of a movie at once. The past, present and future are just positions on the strip relative to a specific film cell. Hence, He does not see any changes in the past-He merely sees as the events that did occur, shall occur and are occurring all “at once.” So, God would “see” the phone appear from a future that never was to save Sally from committing a murder that never will be.
It is claimed the two phones, save for the bloodstain are identical. However as I read this, the one from the future has the video on it and presumably the one in her pocket does not. If this be the case than they are not identical on two counts. If the phone in her pocket has the video on it then there would be no need for the physical object, the phone, to be returned to the present. A text, voice, or video message from the future to past would suffice. Outside of Quantum theory it is difficult to see how a single object i.e. a phone can exist simultaneously in different places.
Each time we view a film we in a sense perceive past events but we cannot interact with them. There is an interesting short story by John Wyndham Called “Pawley’s Peepholes” which deals with a similar situation.
Whether time travel is cast as travel to possible worlds or travel through time, the basic idea is formulated in the same way.
That formulation is the duplication of identity. But there was never an idea behind it. Nothing that could correspond to a duplication of identity was ever in our conceptual toolbox. The formulation poses a category error, appearing as mere nonsense, a syntactical mishap.
What makes time-travel believable is our ability to reify or substantiate any grammatical combination of terms whatever. THAT’S the mystery of time-travel.
In that case, time travel is as real as the not any What we have is a juxtaposition of terms that we reify as a given our need
Hmm, that is a fun topic :)
The idea of branching worlds is relatively accepted in the world of quantum mechanics, where each relevant event causes such a branching in which different outcomes are realised in different wordls (viz. Schrödingers cat). The reception by Sally of her own phone would be such an event, causing a new lifeline to divert from her original line.
And God, residing in a six dimensional world (with 4 spacetime dimensions, one possible worlds dimension and an extra dimension to be able to see everything at once), would see not a single film but a tree of (4D) films, with branches splitting off all the time.
Don,
True, the phones would not be numerically identical property for property. Of course, the same is true of almost any entity across time. However, it makes sense to say it is the same phone in the same way it makes sense to say that you are the same person as you were an hour ago, even though some of your cells have been replaced.
The problem of multiple location is, I agree, a serious problem. I think it is fatal for theories of metaphysical universals. However, I do try to reconcile time travel (which seems to require multiple location) with the impossibility of multiple location in my book.
As you say, a call or email from the future would have sufficed. I just used the phone because the episode used a physical object (I like to be consistent in my plagiarism).
Time travel seems to make a degree of conceptual sense. After all, we can imagine it and even describe how it would work, complete with lots of math. Of course, you could argue that this is all grammar (as Hume said about personal identity).
Pim,
I’ve always wondered where the branched worlds come from. That is, where does all the extra matter and energy needed to create all these universes come from? I’m sure the cosmology folks have some nifty math that nicely explains it all (away).
So, we’re speculating about what a hypothetical omniscient being would make of a hypothetical set of events in a universe of unspecified properties (as the nature of time and space allowing the phone event are not detailed)? As the HOB would, by definition, know the end at the beginning all the shtik with phones and murders makes no difference to him/her in judging Sally.
Indeed, don’t HOBs characteristically judge internal events as well as external? In the fiction Sally-one-phone kills her husband, the supposed philanderer whereas Sally-two-phones would kill her husband if she supposed him a philanderer. (Sure, we could further hypothesize an epiphany in which she reconsiders her values as a result of the mistake she made/could have made, but let’s stick to the given story.)
Sally is a person who killed/would kill her partner if she believed him to cheat. Personal safety is not the only reason I wouldn’t marry her.
To borrow from the medieval morality play, ‘Everyman’, - if Death came to claim Sally, would the phone incident be written in her FINAL Book of Reckoning? Remembering of course that Good Deeds is the only ‘friend’ who can testify on your behalf when Death comes a’calling.
And in this case, solving the riddle of time travel and sending the phone back in time to her younger self SAVED the life of her husband. And that must indeed count as a good deed. Because she DIDN’T kill her husband. Not any more.
And let us not forget this is an Omniscient God we’re talking about here. Nothing happens or exists without his signing off on the deal memo first. Ergo, God GAVE Sally the ability to ‘discover’ time-travel, just so she could send the phone back and save her husband…from herself.
QED.
Next topic gentlemen? :)
There’s a saying that any universe in which time travel is discovered sooner or later alters its own continuity such that time travel is never discovered, and thus all changes made while it was possible are ultimately “erased” and thus irrelevant.
Speaking as a Catholic, I’d observe that if the only thing that caused Sally to believe her husband was not having an affair was a message from a dead possible future self attesting to it, her faith and trust in her husband must be of pretty poor quality. Even if her choices to murder and suicide were prevented by retroactively altered circumstance, that may well not affect the ultimate fate of her soul, which lies outside Time altogether.
Mike,
It’s very well possible that there isn’t any mass/energy in the universe at all. Cosmologists have tried to add it all up and came very close to zero, considering E = mc^2, and counting the potential energy of gravitation negatively. And besides, who says that mass/energy should be conserved between universes? It is, in our universe, but that is just a single path through the tree, with no physical contact to other branches.
Godel and his best friend Einstein proved there is no such thing a time, per se; there is interval but time as we perceive it does not really exist. In most physics equations, when one takes the math down to the quantum scale and smaller, time disappears. As mortals we could not handle everything happening at once. All things are possible. Everything one can think of exists and much we haven’t imagined exists too. All possibilities move forward concurrently and parallel. We live in a multiverse indeed! Our Universe is only one leaf on a tree and we don’t even know on which branch of the tree the leaf resides. Godel is the gent who discovered it is possible to have a looped universe in which time can actually be circular (the beginning is the end is the beginning). Anything one can imagine exists. Sickening and exciting. Guard where you let your mind wander. Every thought is an act of creation. As the prophets have said; If you thought it you have done it inthe eyes of the Lord. No person is as good as they think.
As an interval sustains all relative temporal relations, then Einstein and Godel can’t be said to have got rid of time. If they want to get rid of time they need to get rid of not only the objects in time, but of time itself. This is possible, but they certainly didn’t do it themselves.
The scenario put me on a tangent as soon as I got to the part where Sally checks the blood types. What if the message was from the future–but is still a fake? As I said, that’s a tangent, but now I really want to see some stories where false messages are sent from the future.
As far as the alternate futures are concerned, it would be rather anthro-centric to think that our actions create the alternate futures, forking only when our actions are dramatic enough to trigger some event altering anomaly (not that anyone here is suggesting this). As a physical phenomena, if it exists, it happens continuously (or perhaps with the same level of atomicity present in our 3-dimensional realm). So, the 4-dimensional space and matter across which these alternate time lines exist is likely already large enough for all possible futures, and always has been.
Re Odins Acolyte 07/07/2010
It is stated that ‘time as we perceive it does not really exist.’ also
‘Everything one can think of exists’
Is there, if not a contradiction, some incompatibility between these two statements?
I am not sure what your definition of existence is. Do you mean something in the world outside of the Human mind, or the Human mind and the outside world, or just what goes on in the human mind, as per solipsism?
For instance you say ‘ Everything one can think of exists’. And ‘Guard where you let your mind wander. Every thought is an act of creation.’ I can think of a frog, part of whose innate anatomy is a tiger’s tail. I am almost certain that such a creature is not to be found in the world outside of my mind. However the neural correlates in my mind supporting such a thought I would agree exists within my brain, but I am not sure that is what you mean. You say ‘All things are possible’. Well slamming a revolving door is not possible, for one thing.
Concerning perception of time I am sitting here trying to perceive time whatever that is. Nothing is happening the best description I can give is something like a continuous present envelops me. Certainly I detect or perceive changes, my hair will become longer for one thing and night will fall. But Time I just cannot perceive, just changes that is all.
You state ‘If you thought it you have done it in the eyes of the Lord.’ Well I have just thought I have walked over Niagara Falls on a tight-rope. Now if the Lord, whatever that is, thinks I have actually done it then, it seems to becoming ridiculous, I am lost for words.
You mean that was YOU on the rope? Man, you’re good dude! ;)
As an interval sustains all relative temporal relations, then we can’t say that time does not exist if we also want to retain intervals.
I did not say they got rid of it.
They proved it ain’t. That is relativity. It getrs more nmind bending too.
Shades of Berkeley, why should the difference between the physical reality of time and what we imagine be any different then the difference between the physical reality of things and what we imagine them?
And, why should intervals of time be any less troublesome then intervals of space? If we consulted Zeno, we might find that we can’t possibly age because we can’t possibly get half way through an interval of time.
But, Zeno went the way of purely academic discussions when we discovered the atom. But no, we had to go and find a way to split the indivisible particle. And, we can’t seem to stop sub-dividing every new particle that we discover. So, atomistic views are far from settled. God help us if we ever discover a particle of time, because we’ll start subdividing that—without end.
Of course time is not what we think. The only reason such a statement is so shocking is that we think we know what matter is. But, until we truly find the indivisible particle that really is the fundamental basis for all time, space, and matter, I say we just go with Berkeley.
It’s all in the mind; what else would create such silly things as name and form?
Think of the dimensions( assuming there are) of reality. I know that the 4th can already be accessed through your though. Say when you imagine something, for a example an apple. Is there really a red fist sized apple popping up in your physical brain each time you do? Most likely not, as one would be insane to think so. So where is this matter or image being conjured up? If one took so far to feel the apple, then take a bite of the apple, & throw it. Where is this occuring? Have u really shrunk your self to be inside your head and throw that apple? Heres were i find dimensions to be real. When we dream, we are not in the awakened mind, but the subconscious mind. The brain is a physical manifestation of consciousness, thus being able to transit between realms unbounded by physical limitation. When in a dream, you have the ability to fly, for many its one of the hardest things to do in a dream. Why? In my dreams im stuck by gravity, walking around as if in a collage of my recent weeks experience. But when I realize its a “dream” and anything is possible, thats when one can fly & do amazing feats possible only in an alternate reality which they call their dreams. I believe when one realizes that in a dream, they are on the next dimension of reality. Forgeting gravity, its a physical trait, you are already on the next level. the concept of Parallel universes wasn’t so far off, saying that we have an parallel body in different universes. Why wouldn’t we? Even our species signature is undisputed. How did we know to call ourselves human, everyone knows it. Hu-man. The word HU from ancient india & egypt translates to god. God-man? The answers to the universe are right there infront of you, just observe without thought & forget that its physical, then will one be able to see time itself like a flowing sun-light trail that mimics every movement.
These posts are getting dafter. Everyone’s having a great time inventing bogus realities from grammatical extravagances and terms kicked out of context.
No? Then perhaps my dimensional spectrum is a disappearing, virtual four dimensional reality cast in the unconsciousness of time going backwards etc, etc, et boring, bloody ridiculous, cetera.
If god were to look at the universes, assuming it created time. It would know that in all the realities there is movement.
Whats “no” time. Stillness.
To see everything it would have to have domain in which nothing exists. How can you exist and try to see all that there is. Your apart of the existence, we are part of the existence & we cannot see the full scheme. But how can a being exist in non-existence? I love when people say god doesn’t exist. It really doesn’t, its non-existent. Its nothing itself. “and from nothing came existence”. A quote i heard on the science channel explaining the bigbang. From a viewpoint of nothing, everything can be seen. Whats nothing? it can’t be blank white or black, those aspects still exist. Nothing is just everything as it is, the infinite possibilities of existence. It like seeing all existence as an ocean, perfectly still, not one ripple or wave. When a ripple occurs that is the creation of a dimension, i’d assume god is walking( who knows there could be many supreme beings) center of this ocean constantly as it is endless. Each ripple is a soul-dimension, a being as me or you all co-existing at the same time.
or should i rephrase that. The ocean itself is the souls, the self-existence that we all are. The ripples are the dimensions we create with each thought.
If god were to look at a tree, there would only be a select number of dimensions, assuming infinite possibilities of dimensions, an endless ocean is a universal concept. Haha or maybe it looks at itself and sees everything.
Back to this question of how God sees Sally’s deeds.
If God has given us rules, then those rules should be consistent both for us and for God, regardless of any differences between what God sees and what we see. Of course, that’s my expectation of God, however silly it is for a human to try and dictate terms to God. I just think it would be silly to be morally bound by rules that are beyond our capacity to comprehend.
Unfortunately, given the size, scope, and lack of consistency in the know religious texts, there would be few clues in those texts about how God would see things. That is, given our tendency to distort any and all of God’s teachings, I should think that God would be putting more effort in explaining things in a way that we could not distort rather than try and give us insight into how God sees things.
And, the possibility that God may be able to see past, present, and future as all the same raises all the usual questions of God’s unlimited capacity. For instance, if God is everywhere, is God everything? Well, I think that might make a nice new religion, but I’m not sure I’m happy with the way that seems to cut into individuality. And, what would be the point of punishing anything if there was no individuality. But, to put that question into the corresponding temporal form, If God perceives past, present, and future as the same, then does that mean that God is past, present, and future? That doesn’t really work for me; I really don’t think God would be completely unbound by laws of any kind. God is subject to laws. We may not know exactly what laws, but there is something about time to which God is bound. So, God’s prescience is not absolute, and we do have free choice that affects the future. Again, if this were not true there would be no meaning to punishment. (Note that these are based on reasonable suppositions given the assumption that God exists, which is part of the discussion.)
So, if there is a God, I’m sure that God’s ability to deal with time is unfathomable to us. And yet, God is going to have to judge our deeds in a manner that is consistent with our capacity to use whatever technology we manage to discover, or God will just have to take that technology away from us. Well, that may simply be Armageddon, and any unresolved issues will be taken up on judgment day.
I think Sally gets points for attempting to right the wrong, and any remaining punishment should only be experienced by the part of Sally or the version of Sally that actually committed the deed. Since, the past Sally is confronted by a different choice given the new information from the future message, the past sally who experiences the act of making that choice should be the only Sally to be judged for that choice and any outcome that comes from it.
While I think God is bound to some rules of time, it would seem that we can allow that God created souls; and as such, God can divide those souls to suit God’s plan. If God needs to divide Sally’s soul into multiple instances according to Sally’s assortment of choices, then that would seem appropriate.
Of course, the physics stuff is all interesting, but I’m not sure that answering the physics questions gives us any more understanding of God’s perceptions than reading any religious texts. That is, if our perception of reality differs from the true nature of reality, then it may well be that God enjoys a unique perspective on reality that has little to do with anything the hard core physicists can come up with.
You argue that God is an object that is bound to rules, just like other objects, even if objecthood isn’t actually physical and temporal.
Your (and many others) idea that God is an object like other objects leads on to absurdities like “is God solid, liquid or gas?”
Well yes, not that I want to get too weird but, I like absurd questions. I want to know if God is solid, liquid, or Gas; and if God is none of those things, which is a reasonable possibility, then by what mechanism is God able to interact with us?
There will always be questions about what if anything limits God. As silly and hackneyed as it is, there is always that question of whether God can create an object so large that God can’t lift it.
I’m just not going to settle for an idea that says that God is so perfect and limitless that there are no rules at all for God. I will however avoid the ire of Kant and not claim that anything real will, in the manner of all real things, have limits.
What I don’t like is defining things purely in terms of what they are not. That is, I would not accept a definition that says that for anything I can think of God is beyond that. I am only going to be happy with definitions that say what a thing is–at least to the point where I can understand how that thing can have anything to do with us.
So, back to the key point. Judgment of deeds hinges on free will, and the idea of a purely deterministic Universe is not all that compatible with the idea that we have choice. So, part of this discussion addresses a concept of alternative futures existing as alternate Universes, and suggests that God would see all those possibilities and be able to pass judgment upon those outcomes.
I see this particular idea of multiple Universes as a funny way for Science to struggle with what are essentially deterministic laws in a World where, psychologically, we think we have choices (and I am biased towards thinking that we have choices). If one accepts that there is absolutely no choice, then it is possible to imagine a Universe that can only turn out in exactly one way, thus making the multiple Universe idea a bit unnecessary. The question I have for the scientists that are descending into this mire is this: if there are multiple Universes for some variety of possible outcomes, then are there Universes where we live out the outcomes of things we would not choose? If we avoid an anthro-centric view, then the possible outcomes are always branching, regardless of what we would choose. Under conditions of that sort, there must then be Universes where the outcomes are unthinkably horrific, simply because they include things we would not choose. Well, I do have to admit that there would not be Universes that included things that would be impossible for use to choose, but I fear that there would be a Universe where all our choices where the most regrettable, yet possible, choices. So, do we really have free will if there are Universes were we unavoidably live outcomes we would not choose?
We seem to have cognitive processes that exist for the purpose of making choices, and these are the same cognitive processes that Scientists are using to conceive of and visualize this idea of multiple Universes. As such, I don’t think they are able to completely separate the two; and to me, that makes the whole discussion of multiple Universes a little suspect (as much fun as it is). I would think there would be alternative approaches to addressing the concept of choice and free will in a Scientific culture that is dominated by concepts of determinism.
Maybe the answer is here:
http://www.youtube.com/watch?v=6aWMYFkH3Gw
You distract from the point. There’s no problem with pseudo-puzzles like “can God create a weight he cannot lift”. That’s clutching at straws. What’s an object that, necessarily, cannot be lifted?
And no, we don’t make choices as we go about things. We construct them ONLY if we need to consider possbilities.
And why create “multiple” universes to cope with determinism? It isn’t needed. If we are the thing itself then we can’t be determined by it.
I don’t know, it looks as though you are citing examples taken from a well worn littany of logically inconsequential puzzles and platitudes .
@John Jones,
I wouldn’t go to the trouble of expressing such thoughts if the usual discussions on this subject hadn’t left me so wanting. And yes, it is “well worn litany” that I’m attempting to address, despite the fact that doing so can look like beating one’s head against the wall.
This is still a subject on which I would like to have a deeper insight. There are questions that I’m trying to address, and I’m not hearing anything that heads in that direction. Some nice reading suggestions (however hefty), if not some more meaningful points on the subject, would be much appreciated.
Here’s the best explanation as to why none of this can happen, courtesy of Joe Bob Briggs and Monstervision:
“”Man was not meant to play with time.” Did he actually say that? So what we’ve got here apparently is TWO different 1993’s. Operating at the same time. Which actually makes sense, because it solves the problem of all time-travel movies. And that is that you can’t go back in time without violating the First Law of Thermodynamics. Okay, I promised I would explain this again, because some of you didn’t get it the first time we showed this movie. If Brad Chapman in this movie is signified as a collection of molecules, “m,” then he can be described at any time “t” by “6n” variables–three variables describing the position of each molecule, because there are three dimensions, and three variables describing the momentum of each molecule. Now, when Brad Chapman travels forward or backward in time, the 6n variables are duplicated at some time t minus a or t plus a. His molecules have disappeared at time t and have reappeared at time t minus a in precisely the same relative configuration. The only problem is, this violates the First Law of Thermodynamics, which states that the mass-energy of the universe (Ue) is constant. Therefore, an observer at rest at time t minus a relative to Brad Chapman would observe an increase in Ue of mc^2 Joules, where m is Brad Chapman’s rest mass in kilograms. And no observer can detect a violation of the First Law. Therefore, the trip back through time would thus violate the First Law of Thermodynamics. Okay, back to the movie.
[fading] What? Ask Stephen Hawking. We’ll go into this in much more detail next week on “Joe Bob’s Summer School.” But this is a preview. Bonus round.”
And later…
“ll right, well, the studio is still buzzing with my demonstration of why the guy in this movie CAN’T go back to 1943. It’s impossible. You know, these time-travel movies always burn my bacon, because it’s impossible. You go back in time, you shoot your grandfather, therefore YOU are never born, so you can’t go back in time and shoot your grandfather, but then you ARE born, you DO go back–it makes no sense. You try to figure out the “Terminator” movies–you can’t! In fact, you know what? It not only violates the First Law of Thermodynamics, it violates the SECOND Law of Thermodynamics. [crew GROANS] All right, fine, I won’t explain it. [crew CHEERS] You try to make the show just a LITTLE bit educational, maybe send the audience away LEARNING something instead of just sittin on the couch drinkin Old Milwaukee and eatin Doritos, and who thanks me? All right. Fine. Back to the movie.
[fading] I think I should explain it. The Second Law of Thermodynamics says that the entropy of the universe is always increasing–going to hell, decaying, fallin apart. You take Brad Chapman and zap him back to 1943, you’ve REVERSED the entropy at that point in time. All right. “That’s all I’m gonna say. Till next week. Guys at Caltech and MIT are gonna write in, saying, “Joe Bob is correct.” . . . Caltech and MIT are UNIVERSITIES. Jeezus.”
No scientist, bard, or seer ever showed or demonstrated the existence of Time.
Why is this? because no-one knows what they mean by Time except me. Time is a jumble of letters that people get misty-eyed about. Saying that one thing comes after another thing NEVER made sense. But we keep on saying it. We keep on turning our fantasies and postures into a pantomime Hawkinian reality.
I haven’t read the whole comment section but I think it’s not appropriate to be stuck on the whole duplicity issue and etc until we can actually achieve time travel. Its just a concept and nothing more. Almost like talking about god’s characteristics.
I think you get the cart before the horse with this scenario. You say:
“Another easy way out is to deny the entire scenario and say that time travel is impossible because of exactly this sort of nonsense. ”
But that’s backwards. If time travel is impossible, it’s not impossible BECAUSE of this sort of nonsense. This sort of nonsense would be impossible BECAUSE time travel is impossible.
This is important because any plausible mechanism for time travel has to accommodate a great many established truths about the nature and behavior of time. Obviously, your scenario includes a causal paradox: Sally never ultimately made the video confession, and so one must wonder about the provenance of the artifact containing the video.
A video file on a phone is a very low entropy configuration of matter. Usually, the heat generated by the operation of the phone and the dispersal of charge from the battery would more than account for this, but in this universe, the video was never taken — the thermodynamic processes that enabled the local decrease in entropy never occurred. So we might have a violation of the second law here if we stick to a one-universe interpretation.
We can also talk about the fact that it’s difficult to see how a macroscopic object like a smart phone can follow a space-like trajectory (i.e., travel through time). To justify this, you’d need to specify a mechanism for time travel that gets around that whole general relativity thing. At that point, we’d have to reevaluate the thought experiment with regard to the particular mechanism for time travel to determine whether this sort of paradox could actually occur under that mechanism.
Basically, when your thought experiment includes two likely violations of natural law, there are good reasons to assume that such an event simply can’t come to pass. So if you want to talk about consequences of such an event, start with explaining why it isn’t out-and-out impossible. Otherwise, you come to the conclusion that the cart pushes the horse — or that the paradoxes are what make time travel impossible (rather than the laws of nature).
..what makes time travel impossible is that no properties have ever been assigned to Time.
The impossibility of time-travel is shown grammatically, not physically.
The great man speaks:
http://www.dailygalaxy.com/my_weblog/2010/07/stephen-hawking-time-travel-to-the-future-is-possible.html
http://www.huffingtonpost.com/robert-lanza/is-there-a-god-or-is-ther_b_639416.html