How determined are you?

Sure. When we say there is a probablistic element to physics, it is constrained to measurement theory, e.g. asking where the electron is in a hydrogen atom, or where the single photon will fall in a double-slit experiement. But this probablistic nature is not related to evolving some initial conditions at time0 to some final conditions at time1. This is purely deterministic. If you know the stae at T0, you can predict the state at T1. This is what we mean when we say that physics or the universe is deterministic. The probability involved in measurement does not affect this fact. This is one of the sources of great confusion when people try to understand QM.So when I ask, at what level, I am asking if you are referring to evolution of states or just observation.For many years, Hawking was convinced that evolution was not necessarily deterministic, based upon black-hole absorption and radiation. The idea is that a black hole can absorb energy in a definite state, then re-radiate it perfectly thermally, such that all infomation contained has been lost. He held this view despite enormous objection by the rest of the community. It is only in recent years that he has changed his mind. I must say that I always hoped that he would be proved correct, becasue it would make physics that bit more exciting. Then again, theoretical physics really doesn't need any more excitement Sorry, you were talking locally of course. My mistake. Yes, this is totally true and is the basis of causality. However, globally, we could have closed timelike curves (CTCs), a fancy term for time-machines. We can use these CTCs to travel back in time with future information. This obvously has possible profound implications for determinism, free-will, etc.However, the stability of CTCs is much in question. They generally contain what we call a Cauchy Horizon (or surface of infinite blue-shift) (a "normal" event horizon is a surface of infinte red-shift). This horizon is exceptionally unstable to perturbations.In fact, nature seems to conspire to prevent CTCs, despite their theoretical possibility. This led Hawking to suggest the "Chronology Protection Conjecture" or CPC. But surely all the processes within our brains are deterministic, and thus their current state can be predicted from prior states? If the processes are not deterministic, where does the indeterminancy arise? Can we observe it?I'm not disagreeing, BTW, I'm open on all of this...

I would have thought science can say what it can observe. Science can observe matter and energy conforming to the laws of nature in predictable ways (or decide that there are consistant laws of nature from observing the behaviour of matter/energy in controlled experiment. And when something unpredictable happens can it be said that it is due to non-conformance to the laws of nature. If the best answer is that matter and energy do fit the idea of determinism best then determinism would be a scientific theory rather than a philosophy Would these bundles of energy be subject to laws of nature and if not is there any scientific evidence to say matter/energy are not subject to the laws of nature?This message has been edited by iano, 02-Nov-2005 02:49 PM

Doesn't the Uncertainity Principle claim that it is impossible to ever know the initial state? And what about Quantum Tunneling? I was under the impression that Quantum Tunneling demonstrated that the probabilistic nature of sub-atomic particles was not an artefact of measurement. Are you suggesting instead that there is, in effect, a hidden variable that determines this behaviour? If so, then I certainly conceed that is a possible interpretation but I, as a matter of opinion rather than evidential fact, consider it less likely than a genuinely probabilistic world. I'm not arguing for any indeterminacy, I think the process behind our "mind" and actions are just as deterministic as anything else in the universe but I don't think that's relevant to the question of free will. As I see it we have free will if we determine our own actions, and we do.

I believe what nwr is arguing is that the "laws of nature" are emergent from the behaviour of these "bundles of energy" rather than being determining their behaviour.I think he's probably right.

No, not at all. The uncertainty principle is purely related to measurement. It is simply a statement about the non-commutativity of conjugate-pair observables. The initial-state is not a case of specifying a position and momentum of an electron, for example. The position and the momentum are observables of the state, not the state itself. We can prepare an initial-state in a say a position eigenstate. Now it is not that we don't know the momentum, just that momentum is not a well-defined concept for that state. It is not something that exists to know. The state is completely defined without any concept of momentum. Hmmm, sounds like you may be a victim of popular science gobbledegook. There's nothing like New-Scientist to completely confuse a very straight-forward concept There's nothing odd about tunneling. Believe me, unitary (deterministic) evolution of states is at the heart of all QM. To suggest otherwise (as Hawking did) is to really rock the boat, and is a very big issue. Not at all. Hidden variables are not required. All you need is the state vector, unitary evolution via the Schro Eqn, and obsevables as operators and associated eigenvalues of the state vector.

As I understand it the evolution of the wave function is deterministic, however (at least some of the time) it leads to a superposition of states. It is the collapse of the wave function into a single state that is the sticking point.

Curious. Is there any scientific evidence (observational or experimental) to indicate any of this? the last bit has me confused "...rather that being determining their behavior" could you clarify?

Which is why we don't use the term "collapse of the wave-function"! This "collapse" is simply making an observation of the state. If the state is not in an eigenstate of the observable you are measuring, then you will get a probablistic observation. But in a sense that is because you are asking the wrong question.

iano Unfortunately that is not the exact case of things. At less than the planck time of 10 -43 sec the laws of physics no longer apply and there is no "determinent" of the way in which the universe will unfold or even if a universe does unfold. I made mention of this sort of temporal bias to Guidosoft in another thread and at that time.In that thread I used an example of a golf game. If you hit a ball down a fairway try to pick out the precise point at which the ball will come to rest. Of all the possible places that ball could land as a result of the forces that are possibly involved any landing point is possible within the strictures set by those forces.
Yet the forces themselves have no prior agenda set aside that will cause them to act in a certain way at a cetain time. Each of those possibilities are as likely as any other before the event but of course after the event the probability is equal to 1 or determined as you in retrospect are equating it.
Thus your ball is free to move into the sand pit or water or if you are skilled enough at controlling the forces you have command over as well as being able to read the other forces level of involvement as well you may be capable of sinking a hole in one to which I would immediately say PHHHFFFTTT !!! Beginners luck.

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But I realize now that these people were not in science; they didn’t understand it. They didn’t understand technology; they didn’t understand their time.

That doesn't make sense to me. There isn't a state that can be labelled "the state of the system" if the system is in a superposition of states. The wave function may evolve deterministically but it can't predict which of the possible states you will observe if you take a measurement.

Can you firm this up at all? It's a little too easy to sound like some new-ager talking about vibrations and energy and other such stuff...Not trying to be (too ) picky, but what are "bundles" and "energy", and do these exist in space(time) or is space itself made up of these?At what scale are we talking, and in fact, how do they give rise to scale? If it is bulk statistical behaviour, then given the accuracy to which QED appears to operate across the universe, you are almost certainly talking about behaviour far below the Planck scale to generate such a level of conformity.BTW, what is statistics in this context and why does it operate if these "bundles" are not subject to laws per se? For instance, is there any notion of a "number" of these things? Why should this number be conserved? And what is "number" if countability has been relaxed?This message has been edited by cavediver, 11-02-2005 11:07 AM

Yeash, I munged that sentence rather didn't I? Remove the 'being' from that last bit and it should make sense.Essentially rather than having actors (particles; sub-atomic and otherwise) whose behaviour are determined by seperate "laws of nature"; you have individual little things who have behaviour and the combination of the behaviour of many, many of them produce what we call the "laws of nature".Like ants, or flocking birds, the whole may move as though it's being directed by an overarching set of laws but in fact each individual is acting according to a simple set of rules.

Sorry, I'm using state as shorthand for state-vector which I admit can be damn confusing. The wave-function is not supposed to be predicting which state you will observe. If the wave-function is not in an eigenstate of the observable you are measuring, you will get a probablistic outcome. Having a superposition just means you are going to get confused if you try to naively work out the probabilities. BUT, this is still restricting the probability to the measurement process.

To many theologians God's fore knowlege is not just predictive but infalliable. A universe where God can be wrong is impossible therefore moot. By choosing a true propostion and a "corresponding" state of being known by God does not infringe on freewill. God may however decide to keep things interesting by allowing for incorrect choices. Who's to say?
Some might say that the choices we make determine God's past
predictions about the choices and the paradox of retroactive causation is avoided. Or not. It scrambles the brain IMO

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"One is punished most for ones virtues" Fredrick Neitzche

Are you a physcist, Cavediver, or educated as one? I ask because the explaination you're giving me contradicts all the things I've read on the subject - which, admitedly, are not a great deal better than popular science - and I'd like to know whether this is an area of your expertise or not?In particular, the reading I've seen has led me to believe that the Uncertainity Principle is not about measurement it all but is actually a fundemental property of the universe. But how are you getting at these things?