djsalomon@watdaisy.UUCP (Daniel J. Salomon) (11/20/84)
> I sure would like to learn from someone who understands all about rela- > tivity, time and free will. I'm not really being all that facetious... > Norm Andrews, vax135!ariel!norm Free will versus determinism is an ancient unresolved theological problem. "If God knows the future how can we change it with our free will." There is a scientific equivalent of this paradox. "If the current positions of particles and the elementary forces determine the paths and future positions of particles then how can an intelligent being make a decision that changes those paths and affects the real world." When this question is answered, we will know "the meaning of life, the universe and everything."
herbie@watdcsu.UUCP (Herb Chong, Computing Services) (11/20/84)
I hope the answer isn't 42 :-). Herb...
gwyn@brl-tgr.ARPA (Doug Gwyn <gwyn>) (11/25/84)
> I hope the answer isn't 42 :-).
From "A Natural Formulation of Unified Field Theory" (my Master's
thesis), p. 80:
... The multiplier of 1/k on the right-hand side of (D4)
times n^r was called "z1" by Einstein; it is a measure of
the degree to which the field equations leave the
fundamental fields undetermined (one can subject the
remaining degrees of freedom to various boundary
constraints, etc. to obtain a _u_n_i_q_u_e specification). For
the ESK theory in its final form Einstein decided that
z1 (ESK) = 42
...
Not to worry; the pure affine theory gives z1 = 300, so we don't have
the question to the ultimate answer yet.ltn@lems.UUCP (Les Niles) (11/30/84)
In article <watdaisy.6746> djsalomon@watdaisy.UUCP (Daniel J. Salomon) writes: > >Free will versus determinism is an ancient unresolved theological >problem. "If God knows the future how can we change it with our free >will." There is a scientific equivalent of this paradox. "If the >current positions of particles and the elementary forces determine the >paths and future positions of particles then how can an intelligent >being make a decision that changes those paths and affects the real >world." When this question is answered, we will know "the meaning of >life, the universe and everything." But quantum mechanics did away with this possibility. The central idea of QM (if you believe it) is that the universe is *fundamentally* random; it doesn't just appear random because we haven't looked in great enough detail. So maybe this fundamental uncertainty is the origin of "free will." -les niles
gjk@talcott.UUCP (Greg J Kuperberg) (12/02/84)
> QM (if you believe it) is that the universe is *fundamentally* random; it > doesn't just appear random because we haven't looked in great enough detail. > > So maybe this fundamental uncertainty is the origin of "free will." > > -les niles 1) QM, if I believe it? That's like saying, "The heliocentric theory, if you believe it." 2) QM is not necessary for your conclusion. All you need is a *non-linear system*. In a non-linear system, the tiniest local deviation can have serious global consequences. It was demonstrated that simply by exciting one neuron in the human brain, one can cause strange sensations and hallucinations. Another example of a highly non-linear system is the weather. Thus some people are saying that accurate long-term forecasts are impossible, because we cannot keep track of every butterfly who flaps his wings, every particle of air that is influenced by brownian motion, etc. This non-linearity is the true cause of free will (if one is not a dualist), rather than QM fluctuations. Even QM fluctuations are boring and statistically predictable in a linear system. --- Greg Kuperberg harvard!talcott!gjk "Eureka!" -Archimedes
guy@rlgvax.UUCP (Guy Harris) (12/04/84)
> > QM (if you believe it) is that the universe is *fundamentally* random; it > > doesn't just appear random because we haven't looked in great enough detail. > > > > So maybe this fundamental uncertainty is the origin of "free will." > > 2) QM is not necessary for your conclusion. All you need is a *non-linear > system*. In a non-linear system, the tiniest local deviation can have > serious global consequences. But that just says that the universe just appears random because we haven't looked in great enough detail. If you assume 1) a deterministic and complete theory of how the universe works, 2) 100% no exclusions complete knowledge of the initial state of the universe, and 3) enough computing ability to crank the model forward from that initial state, you can predict all future states of the universe. Of course, given that I know of no measurable scientific handle on what "free will" means, I suspect the whole question is somewhat moot... Guy Harris {seismo,ihnp4,allegra}!rlgvax!guy
gino@voder.UUCP (Gino Bloch) (12/06/84)
[this line has a probability of 31% of not being here] > But that just says that the universe just appears random because we haven't > looked in great enough detail. If you assume ... > 2) 100% no exclusions complete > knowledge of the initial state of the universe... > you can predict > all future states of the universe. But QM says explicitly that IN PRINCIPLE you cannot have 100% knowledge of the state of any system. One might hope that this will be disproved someday, but there is currently no evidence (that I know of) pointing in that direction. -- Gene E. Bloch (...!nsc!voder!gino) Mr Humility
gjk@talcott.UUCP (Greg J Kuperberg) (12/07/84)
> But that just says that the universe just appears random because we haven't > looked in great enough detail. If you assume 1) a deterministic and > complete theory of how the universe works, 2) 100% no exclusions complete > knowledge of the initial state of the universe, and 3) enough computing > ability to crank the model forward from that initial state, you can predict > all future states of the universe. ... > Guy Harris A big milestone in weather forecasting was when they computed twenty-four hours of weather in twenty-four hours. The thing about a non-linear system is that it may take more time than you have to predict its future. Some people conjecture that even if we had a computer as big as the Earth, it would take us more than ten years to compute ten years of weather on Earth. Thus what the weather will be ten years from now is *unknowable*, and therefore random. In any case, we would have to know the position of every molecule in the atmosphere, also an impossible task (even in classical mechanics). --- Greg Kuperberg harvard!talcott!gjk "Madam, there is only one important question facing us, and that is the question whether the white race will survive." -Leonid Breshnev, speaking to Margaret Thatcher.
guy@rlgvax.UUCP (Guy Harris) (12/07/84)
> > But that just says that the universe just appears random because we haven't > > looked in great enough detail. If you assume 1) a deterministic and > > complete theory of how the universe works, 2) 100% no exclusions complete > > knowledge of the initial state of the universe, and 3) enough computing > > ability to crank the model forward from that initial state, you can predict > > all future states of the universe. > > A big milestone in weather forecasting was when they computed twenty-four > hours of weather in twenty-four hours. The thing about a non-linear system > is that it may take more time than you have to predict its future... > In any case, we would have to know the position of every molecule in the > atmosphere, also an impossible task (even in classical mechanics). A-*HEM*. We're not talking about whether it's *practical* to predict the future perfectly; we're talking about whether it's possible in principle. The original discussion was about "free will", and the original poster asked whether quantum mechanical uncertainty was responsible for it. Somebody else responded saying that considering the brain as a classical non-linear system could also explain "free will" as well. Well, just because I don't have every line of code in all the software running on this machine memorized doesn't mean I think it does things out of "free will"; I could, if I felt like it (and could summon up the patience), do a detailed simulation of "rlgvax" running the software now on it and predict what it does. (For you CS types out there, think of the difference between wanting to compute the value of an uncomputable function at some arbitrary point in its domain (you *can't* - no algorithm exists) and trying to solve an NP-complete problem (you can, given enough cycles, but there seems to be no polynomial-time algorithm). It may not be an important *practical* distinction in all cases, but it *is* an important philosophical distinction.) Frankly, I think appeals to QM, non-linear systems, or any other physical principle to "explain" "free will" are just handwaving. All statistical theories say is that you can't predict exactly what a system will do, either in principle (QM) or in practice. They don't say that the system can "choose" what to do - anybody who can put the proposition "This system is choosing how it will react to a stimulus with its own free will" in terms amenable to scientific investigation deserves a prize (and if they can experimentally demonstrate the truth or falsity of that proposition, they will probably get several). Guy Harris {seismo,ihnp4,allegra}!rlgvax!guy
ellis@spar.UUCP (01/03/85)
Sorting thru back net.physics articles, I encountered this item from Guy Harris: >> 2) QM is not necessary for your conclusion. All you need is a *non-linear >> system*. In a non-linear system, the tiniest local deviation can have >> serious global consequences. > >But that just says that the universe just appears random because we haven't >looked in great enough detail. If you assume 1) a deterministic and >complete theory of how the universe works, 2) 100% no exclusions complete >knowledge of the initial state of the universe, and 3) enough computing >ability to crank the model forward from that initial state, you can predict >all future states of the universe. I'm willing to grant that perfect knowledge of Guy's (1) and (2) are at least logically possible. That remaining item, number (3) seems to require closer scrutiny. Correct me if I'm mistaken, but I thought that even the simplest Newtonian models of the universe result in intrinsically INSOLUBLE differential equations (like the three-body problem). Doesn't this mean that prediction is impossible, even in a vanilla Newtonian universe with more than two objects? -michael
gwyn@brl-tgr.ARPA (Doug Gwyn <gwyn>) (01/05/85)
> ... I thought that even the simplest Newtonian models > of the universe result in intrinsically INSOLUBLE differential equations > (like the three-body problem). > > Doesn't this mean that prediction is impossible, even in a vanilla > Newtonian universe with more than two objects? The "three-body problem" is NOT insoluble; it just has no simple closed-form solution. Given enough computing resources, one can compute the motion of three gravitating bodies to any desired degree of accuracy. In practice, of course, one does NOT try to calculate even the classical motion of individual gas molecules; the amount of computation is just too burdensome. Instead, one sacrifices some degree of absolute detailed accuracy in exchange for statistical knowledge. That doesn't make things IN PRINCIPLE nondeterministic. The question becomes, how detailed do you want your predictions? Quantum considerations are of an ENTIRELY DIFFERENT type. According to conventional quantum theory, the evolution of a physical system proceeds according to INHERENTLY PROBABILISTIC laws; there are no underlying deterministic mechanisms at work. This notion is quite unsettling to one brought up in the Renaissance tradition.
1314jb@houxf.UUCP (J.BOKOR) (01/05/85)
michael ellis writes: >Correct me if I'm mistaken, but I thought that even the simplest >Newtonian models of the universe result in intrinsically >INSOLUBLE differential equations (like the three-body problem). >Doesn't this mean that prediction is impossible, even in a >vanilla Newtonian universe with more than two objects? A so-called intrinsically INSOLUBLE differential equation has absolutely no relation to quantum mechanical uncertainty. The three-body problem in classical Newtonian theory has no known *analytical* exact solution, but this doesn't mean that 1) such a solution will never be found, or 2) that prediction is impossible. The solution may be obtained numerically to any arbitrary degree of accuracy given sufficient computing time, as implied by Guy Harris' article. The difference is that in quantum mechanics, you can't write down an equation for the coordinates of particles, you can only calculate a probability distribution function for each coordinate. The probabilistic nature of the theory is built into the assumptions used to construct the equations. Jeff Bokor
guy@rlgvax.UUCP (Guy Harris) (01/06/85)
> Sorting thru back net.physics articles, I encountered this item from > Guy Harris: > > >If you assume ... and 3) enough computing ability to crank the model > >forward from that initial state, you can predict all future states > >of the universe. > > That remaining item, number (3) seems to require closer scrutiny. Correct > me if I'm mistaken, but I thought that even the simplest Newtonian models > of the universe result in intrinsically INSOLUBLE differential equations > (like the three-body problem). Note the magic word "computing ability". The fact that there is no closed-form solution to those differential equations is irrelevant. A closed-form solution is no better than numerical integration forward in time, assuming sufficient computing ability (precision, in this case) that there are no numerical problems in the integration; you can't compute the value of the closed-form expression "sin(2*pi*t/T)" to arbitrary precision. (Barring solutions which don't have nice analytical properties, so that *no* precision is "good enough"; a step function could, in principle, cause problems, but are there any real live step functions in nature?) Guy Harris {seismo,ihnp4,allegra}!rlgvax!guy