pbla4024 0 #26 February 9, 2006 You are a bit mistaken here. 1) Sensitivity to initial conditions is not enough to get chaotic behaviour 2) Sensitivity to initial conditions comes from dense periodic orbits and transitive flow. This is theorem from late nineties, really nice one :-) Fido Share this post Link to post Share on other sites
TomAiello 26 #27 February 9, 2006 If there was a physics forum, you know I'd be moving this discussion... -- Tom Aiello Tom@SnakeRiverBASE.com SnakeRiverBASE.com Share this post Link to post Share on other sites
base736 0 #28 February 9, 2006 QuoteI don't believe chaotic dyanamics play what I would call a major role in the openings, but that's just an opinion. I'm inclined to agree, and I'll cite the fact that I have found I can predict off-headings in certain scenarios (say, crosswinds on a static line) with great repeatability as evidence. I suspect that shoulder-dropping on an otherwise clean jump is one such scenario. I also think Tom's on the right track. We could sit here and BS about it for weeks, or somebody could bomb out to a forgiving 'S' and do five in a row with each shoulder low. I know what's on my agenda for my next trip south. Heck, I might give it a shot on my next trip west, though that'll be largely S/L and less forgiving objects. Share this post Link to post Share on other sites
base428 1 #29 February 9, 2006 Just watch any Bridge Day video and you can see the effect of dipping a shoulder. In most cases, dipping your right shoulder will cause your canopy to open to the right. But let's not forget about how important wind direction is, which may provide some influence in 460's openings to the opposite side.(c)2010 Vertical Visions. No unauthorized duplication permitted. <==For the media only Share this post Link to post Share on other sites
base736 0 #30 February 9, 2006 QuoteQuote[...] on an otherwise clean jump [...] Just watch any Bridge Day video [...] I think we might be talking about different things entirely. Share this post Link to post Share on other sites nicknitro71 0 #31 February 9, 2006 QuoteYou are a bit mistaken here. 1) Sensitivity to initial conditions is not enough to get chaotic behaviour 2) Sensitivity to initial conditions comes from dense periodic orbits and transitive flow. This is theorem from late nineties, really nice one :-) You first must define the initial condition. If the initial condition is the pack, then I can make it in a way that the behavior of the opening will be chaotic For our case, let's assume the initial condition is the body position (1) and the chaotic motion the canopy deployment (2). Is 2 sensitive to 1? You decide. How do we know, or don't, that a body in FF does not follow periodic orbits and transitive flow? How do we know, or don't, that the opening of a canopy gives rise to strange attractors? Honestly if I had to bet my few pennies, just out of gut, I'd say that it does. I think the first point to be analyzed is the determinism or not of a BASE deployment, that nobody has addressed quite yet. Is a BASE deployment a deterministic or non-deterministic system? Here is my ignorant 0.02. From the jumper's view at the exit point, the deployment is clearly a non-deterministic system. He only knows enough variables to be unable to determine the next state. However as 460 pointed out, sometimes going by "feel" could lead to some sort of determinism. This leads to my other point. Knowing enough variables, a BASE deployment could be a deterministic system. Now, the problem is, how many variables do we really have to know in order to have this system of deterministic nature? Do we need to know every single wrinkle in the fabric of the canopy, the relative humidity of the air at every single point of the deployment, a front coming in that is 300 miles away, the location of dark energy? Bottom line is this before I get too damn metaphysical: I think that a BASE deployment is very much dependent of the initial condition along its variables, whatever the initial condition might be. The system as far as we are concerned at the exit point is non-deterministic however knowing enough relevant variables, it might be possible to model a BASE deployment with an isomorphic deterministic system. Maybe.Memento Audere Semper 903 Share this post Link to post Share on other sites pbla4024 0 #32 February 9, 2006 You should use unpredictable instead of non-deterministic here. Hamilton systems with positive Ljapunovs' koeficients are non-predictable but deterministic. To get nondeterministic systems you have to go outside continuum mechanic (e.g. QM, cause we now there are not hidden parameters due to non-validity of Bells' inequalities). Ps.: I guess we will be banned quite soon for usage of inappropriate vocabulary :-) Fido Share this post Link to post Share on other sites Tenshi 0 #33 February 9, 2006 Hay guys, I'm just a wannabe and all...but consider this. In "a year in the life off" Jeb Corliss hits the falls. In the latest movie (the one with the duane footage) he talks about letting his left shoulder drop. Dropped left shoulder, went left. Take care!!!! Share this post Link to post Share on other sites bob.dino 1 #34 February 9, 2006 Could you point me in the direction of some background reading on this? /is an engineer, not a physicist Share this post Link to post Share on other sites nicknitro71 0 #35 February 10, 2006 I guess my definition of non-determinism is different than yours and that would not surprise me because I encountered in at least three different types of indeterminism. At any rate, I am seeing this with a Systems Science (SS) view because we are dealing, at least I thought so, with a system here. In SS a non-deterministic system is one in which a state has multiple points of continuations where the p for the continuations is not known from previous states. Predictability or non-predictability is a feature of a system state but not the system label. In the deployment system the next state, at least from the jumper's prospective, cannot be determined and can have multiple continuations hence the indeterministic nature (one continuation is just as random as another). Now, if the most relevant variables were known, then the next state's uncertainty could be known (the deterministic system). I do not understand your point about Bells inequalities and how it applies to this situation. Simply put if hidden variables were present and those were responsible for the outcome then yes, the distributions generated will have to obey to Bells inequalities. Quantum mechanics does not suggest that this does not hold water, only that under certain conditions Bells inequalities could be violated but honestly our example does not offer any proof of this kind, unless I am missing something fundamental, case that very well may be. One more thing, many quantum physicists are still split about the deterministic or non-deterministic nature of the universe...I got my view but it's just an insight, if that. Memento Audere Semper 903 Share this post Link to post Share on other sites Zennie 0 #36 February 10, 2006 I've found that if I eat a burrito my offheadings tend to be more to the left. Hot Pockets tend to cause more rights.... - Z "Always be yourself... unless you suck." - Joss Whedon Share this post Link to post Share on other sites pbla4024 0 #37 February 10, 2006 Exits delta>0 with following properties: For every epsilon>0 exists t>0 such, that: 1) Distance of points in time 0 is less than epsilon 2) Distance of points in time t is greater than delta I think this is generic definition of sensibility to initial conditions. But what I want to say is that such sensitivity is not enough for chaotic behaviour. Check wikipedia http://en.wikipedia.org/wiki/Chaos_theory, they state three conditions, sensitivity, mixing and dense periodic orbits. And sensitivity is result of mixing and dense periodic orbits. Fido Share this post Link to post Share on other sites pbla4024 0 #38 February 10, 2006 Try James Gleick, "Chaos". Nice introduction, a bit of history. Ps.: We drifted far away from topic, don't we? Fido Share this post Link to post Share on other sites Prev 1 2 Next Page 2 of 2 0
nicknitro71 0 #31 February 9, 2006 QuoteYou are a bit mistaken here. 1) Sensitivity to initial conditions is not enough to get chaotic behaviour 2) Sensitivity to initial conditions comes from dense periodic orbits and transitive flow. This is theorem from late nineties, really nice one :-) You first must define the initial condition. If the initial condition is the pack, then I can make it in a way that the behavior of the opening will be chaotic For our case, let's assume the initial condition is the body position (1) and the chaotic motion the canopy deployment (2). Is 2 sensitive to 1? You decide. How do we know, or don't, that a body in FF does not follow periodic orbits and transitive flow? How do we know, or don't, that the opening of a canopy gives rise to strange attractors? Honestly if I had to bet my few pennies, just out of gut, I'd say that it does. I think the first point to be analyzed is the determinism or not of a BASE deployment, that nobody has addressed quite yet. Is a BASE deployment a deterministic or non-deterministic system? Here is my ignorant 0.02. From the jumper's view at the exit point, the deployment is clearly a non-deterministic system. He only knows enough variables to be unable to determine the next state. However as 460 pointed out, sometimes going by "feel" could lead to some sort of determinism. This leads to my other point. Knowing enough variables, a BASE deployment could be a deterministic system. Now, the problem is, how many variables do we really have to know in order to have this system of deterministic nature? Do we need to know every single wrinkle in the fabric of the canopy, the relative humidity of the air at every single point of the deployment, a front coming in that is 300 miles away, the location of dark energy? Bottom line is this before I get too damn metaphysical: I think that a BASE deployment is very much dependent of the initial condition along its variables, whatever the initial condition might be. The system as far as we are concerned at the exit point is non-deterministic however knowing enough relevant variables, it might be possible to model a BASE deployment with an isomorphic deterministic system. Maybe.Memento Audere Semper 903 Share this post Link to post Share on other sites
pbla4024 0 #32 February 9, 2006 You should use unpredictable instead of non-deterministic here. Hamilton systems with positive Ljapunovs' koeficients are non-predictable but deterministic. To get nondeterministic systems you have to go outside continuum mechanic (e.g. QM, cause we now there are not hidden parameters due to non-validity of Bells' inequalities). Ps.: I guess we will be banned quite soon for usage of inappropriate vocabulary :-) Fido Share this post Link to post Share on other sites
Tenshi 0 #33 February 9, 2006 Hay guys, I'm just a wannabe and all...but consider this. In "a year in the life off" Jeb Corliss hits the falls. In the latest movie (the one with the duane footage) he talks about letting his left shoulder drop. Dropped left shoulder, went left. Take care!!!! Share this post Link to post Share on other sites
bob.dino 1 #34 February 9, 2006 Could you point me in the direction of some background reading on this? /is an engineer, not a physicist Share this post Link to post Share on other sites
nicknitro71 0 #35 February 10, 2006 I guess my definition of non-determinism is different than yours and that would not surprise me because I encountered in at least three different types of indeterminism. At any rate, I am seeing this with a Systems Science (SS) view because we are dealing, at least I thought so, with a system here. In SS a non-deterministic system is one in which a state has multiple points of continuations where the p for the continuations is not known from previous states. Predictability or non-predictability is a feature of a system state but not the system label. In the deployment system the next state, at least from the jumper's prospective, cannot be determined and can have multiple continuations hence the indeterministic nature (one continuation is just as random as another). Now, if the most relevant variables were known, then the next state's uncertainty could be known (the deterministic system). I do not understand your point about Bells inequalities and how it applies to this situation. Simply put if hidden variables were present and those were responsible for the outcome then yes, the distributions generated will have to obey to Bells inequalities. Quantum mechanics does not suggest that this does not hold water, only that under certain conditions Bells inequalities could be violated but honestly our example does not offer any proof of this kind, unless I am missing something fundamental, case that very well may be. One more thing, many quantum physicists are still split about the deterministic or non-deterministic nature of the universe...I got my view but it's just an insight, if that. Memento Audere Semper 903 Share this post Link to post Share on other sites
Zennie 0 #36 February 10, 2006 I've found that if I eat a burrito my offheadings tend to be more to the left. Hot Pockets tend to cause more rights.... - Z "Always be yourself... unless you suck." - Joss Whedon Share this post Link to post Share on other sites
pbla4024 0 #37 February 10, 2006 Exits delta>0 with following properties: For every epsilon>0 exists t>0 such, that: 1) Distance of points in time 0 is less than epsilon 2) Distance of points in time t is greater than delta I think this is generic definition of sensibility to initial conditions. But what I want to say is that such sensitivity is not enough for chaotic behaviour. Check wikipedia http://en.wikipedia.org/wiki/Chaos_theory, they state three conditions, sensitivity, mixing and dense periodic orbits. And sensitivity is result of mixing and dense periodic orbits. Fido Share this post Link to post Share on other sites
pbla4024 0 #38 February 10, 2006 Try James Gleick, "Chaos". Nice introduction, a bit of history. Ps.: We drifted far away from topic, don't we? Fido Share this post Link to post Share on other sites
