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Post by june on Feb 27, 2010 15:26:09 GMT
I am interested in this idea that you can mess up the future by messing with the past when travelling through time. So, do we know that time is linear? Heloise despises her paternal grandfather. Heloise is homicidal and has been trained in various lethal combat techniques. Despite her relish at the thought of murdering her grandfather, time has conspired against her, for her grandfather has been dead for 30 years. As a crime investigator might say, she has motive and means, but lacks the opportunity; that is, until she fortuitously comes into the possession of a time machine. Now Heloise has the opportunity to fulfill her desire. She makes the necessary settings on the machine and plunges back into time 80 years. She emerges from the machine and begins to stalk her grandfather. He suspects nothing. She waits for the perfect moment and place to strike so that she can enjoy the full satisfaction of her hatred. At this point, we might pause to observe: “If Heloise murders her grandfather, she will have prevented him from fathering any children. That means that Heloise’s own father will not be born. And that means that Heloise will not be born. But if she never comes into existence, then how is she able to return…?” And so we have the infamous grandfather paradox. Before we examine what happens next, let’s consider the possible outcomes of her impending action. First, let’s assume that the many-worlds hypothesis correctly describes the universe. If so, then we avoid the paradox. If Heloise succeeds in killing her grandfather before her father is conceived, then the state of the world includes quantum entanglement of the events involved in Heloise’s mind, body, surrounding objects, etc., such that when she succeeds in killing her grandfather (or willing his death just prior to the physical accomplishment of it), the universe at that moment divides into one universe in which she succeeded and a second universe in which she did not. So the paradox of causal continuity in external time does not arise; causation presumably connects events in the different universes without any inconsistency. But as we shall see in the next section this quantum interpretation trades-off a causation paradox for a personal identity paradox. Next, let’s assume that we do not have the many-worlds quantum interpretation available to us, nor for that matter, any theory of different worlds. Can Heloise murder her grandfather? As David Lewis famously remarked, in one sense she can, and in another sense she can’t. The sense in which she can murder her grandfather refers to her ability, her willingness, and her opportunity to do so. But the sense in which she cannot murder her grandfather trumps the sense in which she can. In fact, she does not murder her grandfather because the moments of external time that have already passed are no longer separable. Assuming that events 80 years ago did not include Heloise murdering her grandfather, she cannot create another moment 80 years ago that does. A set of facts is arranged such that it is perfectly appropriate to say that, in one sense, Heloise can murder her grandfather. However, this set of facts is enclosed by the larger set of facts that include the survival of her grandfather. Were Heloise to actually succeed in carrying out her murderous desire, this larger set of facts would contain a contradiction (that her grandfather both is murdered and is not murdered 80 years ago), which is impossible. History remains consistent. Clear now I was kind of hoping for a 'yes/no' answer ;D
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Post by fretslider on Feb 27, 2010 15:28:33 GMT
Heloise despises her paternal grandfather. Heloise is homicidal and has been trained in various lethal combat techniques. Despite her relish at the thought of murdering her grandfather, time has conspired against her, for her grandfather has been dead for 30 years. As a crime investigator might say, she has motive and means, but lacks the opportunity; that is, until she fortuitously comes into the possession of a time machine. Now Heloise has the opportunity to fulfill her desire. She makes the necessary settings on the machine and plunges back into time 80 years. She emerges from the machine and begins to stalk her grandfather. He suspects nothing. She waits for the perfect moment and place to strike so that she can enjoy the full satisfaction of her hatred. At this point, we might pause to observe: “If Heloise murders her grandfather, she will have prevented him from fathering any children. That means that Heloise’s own father will not be born. And that means that Heloise will not be born. But if she never comes into existence, then how is she able to return…?” And so we have the infamous grandfather paradox. Before we examine what happens next, let’s consider the possible outcomes of her impending action. First, let’s assume that the many-worlds hypothesis correctly describes the universe. If so, then we avoid the paradox. If Heloise succeeds in killing her grandfather before her father is conceived, then the state of the world includes quantum entanglement of the events involved in Heloise’s mind, body, surrounding objects, etc., such that when she succeeds in killing her grandfather (or willing his death just prior to the physical accomplishment of it), the universe at that moment divides into one universe in which she succeeded and a second universe in which she did not. So the paradox of causal continuity in external time does not arise; causation presumably connects events in the different universes without any inconsistency. But as we shall see in the next section this quantum interpretation trades-off a causation paradox for a personal identity paradox. Next, let’s assume that we do not have the many-worlds quantum interpretation available to us, nor for that matter, any theory of different worlds. Can Heloise murder her grandfather? As David Lewis famously remarked, in one sense she can, and in another sense she can’t. The sense in which she can murder her grandfather refers to her ability, her willingness, and her opportunity to do so. But the sense in which she cannot murder her grandfather trumps the sense in which she can. In fact, she does not murder her grandfather because the moments of external time that have already passed are no longer separable. Assuming that events 80 years ago did not include Heloise murdering her grandfather, she cannot create another moment 80 years ago that does. A set of facts is arranged such that it is perfectly appropriate to say that, in one sense, Heloise can murder her grandfather. However, this set of facts is enclosed by the larger set of facts that include the survival of her grandfather. Were Heloise to actually succeed in carrying out her murderous desire, this larger set of facts would contain a contradiction (that her grandfather both is murdered and is not murdered 80 years ago), which is impossible. History remains consistent. Clear now I was kind of hoping for a 'yes/no' answer ;D Er, yes.
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Post by chefmate on Feb 27, 2010 21:16:03 GMT
It's a good thing we can't go back and change things.
I was talking to my oldest son, age 23, and told him I made some terrible choices in my late twenties but without making those choices, he never would have been born so I can't sit and regret because then I would deny life to two children or maybe things would have worked out differently but that is beyond my scope of imagination to figure out
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Post by gabriel on Feb 28, 2010 6:50:01 GMT
So I get in a lifeboat and I go where and I do what? I don't exist, I haven't been born, my parents haven't been born. My life is in the future. What if I meet my grandparents and stop them from marrying and having my parents, or kill them or...Interesting concept.
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Post by beth on Feb 28, 2010 13:25:38 GMT
What if, by some quirk of fate, you go down with the ship or get thrown off a life boat? (edited by Beth to eliminate common Eng. slang)
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Post by mouse on Feb 28, 2010 15:29:01 GMT
the signing of the treaty of rome...where i could make sure it was never signed
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Post by june on Feb 28, 2010 16:24:37 GMT
What if, by some quirk of fate, you go down with the ship or get tossed off a life boat? Must. Not. Make. Tossed. Off. In. Lifeboat. Gag. ;D
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Post by beth on Feb 28, 2010 19:53:26 GMT
the signing of the treaty of rome...where i could make sure it was never signed Which one?
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Post by gabriel on Mar 1, 2010 7:30:20 GMT
Well, having prior knowledge, I'd make damn certain I was on Murdoch's side of the boat. As long as I was on the bridge or the upper decks, I'd have a fair go. 3rd class - h'm - could be a problem there. If I went into the water well I'd die from hypothermia. So, what happens to my descendants and all the people I'm destined to meet and influence (good or bad).
Tinkering with time is a really interesting idea. Would I like to go back and fix up the many, many mistakes I've made in my life? And if I fixed them, how would that affect other people?
I suppose I could always just go suckers and move on...
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Post by mouse on Mar 1, 2010 9:08:49 GMT
the signing of the treaty of rome...where i could make sure it was never signed Which one? no 1....
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Post by gabriel on Mar 1, 2010 10:37:05 GMT
What if, by some quirk of fate, you go down with the ship or get tossed off a life boat? Must. Not. Make. Tossed. Off. In. Lifeboat. Gag. ;D Don't book passage on ships you know are going to sink. That's the dilemma with time travel. Choose where you're gonna show up. I know which side to hang around. Prior knowledge. Hoary concept but what are you gonna do? Die? Not if I can help it.
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Post by beth on Mar 1, 2010 13:48:49 GMT
OK, so if time travel were possible and you went back a hundred years and died there, nothing would be altered until the time of your birth. At that point, you and any and every person, action, etc. to do with you would never happen - exactly as though you had never been born. Is that the general idea?
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Post by gabriel on Mar 3, 2010 11:19:25 GMT
OK, so if time travel were possible and you went back a hundred years and died there, nothing would be altered until the time of your birth. At that point, you and any and every person, action, etc. to do with you would never happen - exactly as though you had never been born. Is that the general idea? No because everything you do, every person you meet, you will influence the past and the future. For good or bad. Intentionally or not. Life will go on but if you die, then all the people in your life will be affected. Some of them may not exist because you die. Certainly not your children and grandchildren. What if you are a doctor or paramedic. If you don't exist then what happens to the people whose lives you have saved? It's like a neverending spiral - you know those ones you hang up outside and get blown in the wind? They twirl around and never seem to stop. Time travel of course doesn't exist but it is a fascinating concept. How could you move forwards or backwards in time without affecting the people you've been in contact with?
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Post by beth on Mar 4, 2010 3:02:05 GMT
I'm pretty sure there won't be time travel because if it had developed in the future, we'd surely have travelers here and now. Too bad. What a concept!
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Post by mouse on Mar 4, 2010 9:26:17 GMT
the powers that be would never allow it....far far to much freedom in time travel..people might actually learn the truth
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Post by DAS (formerly BushAdmirer) on Mar 7, 2010 0:27:13 GMT
I'm pretty sure there won't be time travel because if it had developed in the future, we'd surely have travelers here and now. Beth - What about Warren Buffet who has accumulated billions of $$ in the stock market sinced starting with only a $10,000 nest egg? He's now one of the world's richest men. Surely he's a time traveler. He gets the Wall Street Journal a year ahead of everyone else :-)
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Post by beth on Mar 7, 2010 2:17:57 GMT
You've got a point. If they're out there, it would certainly be to their advantage to lay low, eh?
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Post by beth on Apr 18, 2010 1:12:51 GMT
I've been giving a little more thought to "where would I like to go and when", and think I've had a change of heart. I'll pick the 1950s - not that the time was so special (tho' it was filled with interesting events), but for a few people I'd have liked to meet - or, at least, observed: Several musicians but especially Glenn Gould, as well as the female jazz/blues singers and Leonard Bernstein. A few writers, but especially Gore Vidal and Ayn Rand and Ernest Hemingway.
May change my mind again, but right now, this seems good.
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