Quantum myth 3: nature is fundamentally random

[Ken G]

So we can see through this that "Nature" is inherently unpredictable in principle because we simply cannot know all there is to know about every "thing": every time we learn about one "thing", more "things" become unknown simply through the act of learning about the first "thing". Like smacking worms at a carnival game.

I think you may mean "whack-a-mole" (a critter with a more viscerally satisfying quality, somehow), but I completely agree with what you are saying. It starts from a set of familiarities, and what we are not familiar with we can really say nothing about, outside of the connections we can find with things we are familiar with. That is also how I (and I believe Bohr) would answer the "measurement problem" in quantum mechanics.

But this only proves a fundamental limitation on our ability to obtain knowledge, and not, necessarily, a fundamental randomness.

Yes, the difficulty in separating those would seem to be as "fundamental" as anything in science.

Thus, I'd say that QM proves that nature is inherently unpredictable and that, indeed, Demystifier's third "myth" is indeed a myth.

I was with you until here-- but in my view, human theories never prove anything inherent about nature other than that humans can gain insight and power over nature by creating theories about it. We want to be careful not to reverse the appropriate logic that nature informs theories and theories inform our understanding of nature. I think you were mostly saying "quantum mechanics does not prove that nature is inherently random, but does show that a concept of unpredictability is useful in understanding nature", which I completely agree with. But I agree with that even on the more general grounds that "theory _____ does not prove that nature is inherently _____".

 

[reilly]

Agreed.

Another way one might look at it, a pseudo-proof if you will:

Let us assume in a perfect universe that observing some "thing" 'A' requires, at a minimum, it to interact with some other "thing" 'B'. Let us also assume that predicting a future interaction between 'A' and 'B' requires an earlier observation of both 'A' (interacting with "thing" 'C') and 'B' (interacting with "thing" 'D').

Therefore, in order to make any prediction about 'A', we need no fewer than three additional "things" 'B', 'C', and 'D'. One quickly sees that knowledge about any "thing" always requires additional "things" to come into the equation, about which we will always initially lack knowledge, and about which we cannot obtain more knowledge without introducing more "things". So we can see through this that "Nature" is inherently unpredictable in principle because we simply cannot know all there is to know about every "thing": every time we learn about one "thing", more "things" become unknown simply through the act of learning about the first "thing". Like smacking worms at a carnival game.

But this only proves a fundamental limitation on our ability to obtain knowledge, and not, necessarily, a fundamental randomness. To me, the latter is more of a leap of faith than the former, as the former flows logically from what I think are self-evident assumptions. Thus, I'd say that QM proves that nature is inherently unpredictable and that, indeed, Demystifier's third "myth" is indeed a myth.

peter0302 -- You have pretty much paraphrased Hume's argument that causality is ultimately an empty concept. However, as you effectively suggest, Hume did not know anything about Kierkegaard and his leaps of faith.
Regards,
Reilly

 

[DrChinese]

Remember, David Hume destroyed the idea of causality quite a long time ago, ...

He argued FOR causality. I think he believed it was obvious. (But his argument was circular...)

 

[StatusX]

That's what randomness in principle means. Determinism, on the other hand, means that in principle if all starting conditions were identical the result would always be A. I don't see why that distinction is meaningless. Can we replicate all starting conditions? No, obviously not, not for the whole universe. So, for now, it would appear we cannot test the distinction. It is, therefore, not a scientific statement. But I disagree with those that say it's meaningless.

By unpredictable in principle, I mean "assuming we could get the starting conditions exactly the same (this is where 'in principle' comes in), there could still be different outcomes for the experiment." I still maintain this is the same as randomness, and I don't know if you or Ken disagree. If so, can one of you provide an example that would satisfy one definition but not the other?

As for whether we can test whether the universe is truly random (in the above sense) or if it is merely the case that outcomes of experiments can depend in chaotic ways on arbitrarily small differences in initial conditions (which is what you seem to be presenting as the alternative), I'll agree we can never be sure. But the point is that QM, the theory, takes the former view. It could be the wrong theory, but that is not what we're debating.

 

[Ken G]

By unpredictable in principle, I mean "assuming we could get the starting conditions exactly the same (this is where 'in principle' comes in), there could still be different outcomes for the experiment." I still maintain this is the same as randomness, and I don't know if you or Ken disagree. If so, can one of you provide an example that would satisfy one definition but not the other?

I already did-- "God did it". But we did agree that science has no use for the distinction-- all science can achieve is a prediction over some uncertainty interval, and all we mean by "predictable in principle" is that the uncertainty interval could always be made smaller than any specified measurement error. So I see it entirely as a difference in precision-- in science, "unpredictable" means "prediction is less precise than the measurement, in a non-systematic way", and "deterministic" means "prediction is more accurate than the measurement can test". Randomness is the scientific model for handling unpredictability, and I don't know of any other that science can use.

As for whether we can test whether the universe is truly random (in the above sense) or if it is merely the case that outcomes of experiments can depend in chaotic ways on arbitrarily small differences in initial conditions (which is what you seem to be presenting as the alternative), I'll agree we can never be sure. But the point is that QM, the theory, takes the former view.

Not necessarily. I would say that QM takes no position on that issue at all, at least not in the sensible Copenhagen interpretation. There is no requirement to do quantum mechanics that says the universe must make its decisions that way, it is just the best we can do given what information we are choosing to track and what questions we are using it to answer. In other words, quantum mechanics takes no stance on what will happen if the universe is returned to an exact configuration, because the whole idea of doing that is outside the logic of quantum mechanics.

 

[Ken G]

He argued FOR causality. I think he believed it was obvious.

I certainly don't think he believed it was obvious, as this was one of the defining aspects of his philosophy. To say he argued "for" it, while reilly has said he showed the limitations of the idea, is a bit of an oversimplification. I think a more complete understanding of what he was saying would bridge this seemingly opposite divide between you and reilly on this matter.

I'm no expert on Hume, and even the experts appear to argue this point vehemently, but what I can gather from that debate is that Hume clearly rejected the old idea that causes were linked to effects by some kind of divine providence. If you remove that link, what remains? To Hume, what remains is simply that we notice one thing, and its similarities, appears from experience to precede another thing and its similarities. When this happens often enough, we form a concept of necessary connection between them. Other philosophers looked to explain this necessary connection as something outside the human mind, but I think Hume was content to leave it in the human mind. That is consistent with reilly's point that Hume exploded the importance of causality as an aspect of reality, versus as a model of reality. Hume didn't reject causality as an important thing our minds look for, but as an important element of reality outside our minds. That may also explain why you say he was "for" causality, because he did see it as a natural thing for a thinking mind to look for.

 

[ThomasT]

The only meaningful use of the word "fundamental" in physics is to mean "does not stem from any other theory"-- in other words, it describes a relation between theories, not a relation between theory and nature.

I was looking for something a bit different as a response to my question about the meaning of the word fundamental in the context of fundamental quantum. However, since I generally like the way you express things, I'll leave it at the above.

The simple truth is that it is not any theory's job to tell us what nature fundamentally is, the whole point of a theory is to replace that impossible task with something possible.

This is a good way to put it I think. One doesn't need to get too terribly technical with regard to recognizing the acceptability of certain statements (at least when they're expressed in more or less ordinary language) about the quantum theory or about nature.

 

[peter0302]

By unpredictable in principle, I mean "assuming we could get the starting conditions exactly the same (this is where 'in principle' comes in), there could still be different outcomes for the experiment." I still maintain this is the same as randomness, and I don't know if you or Ken disagree. If so, can one of you provide an example that would satisfy one definition but not the other?

Hehe, sorry for the wordsmithing. :) Unpredictable, in principle, means that if you _could_ recreate starting conditions, you would have the same outcome, but since you cannot, in principle, recreate starting conditions, it is unpredictable in principle. Random means that if you _could_ recreate starting conditions, you would NOT have the same outcome.

As for whether we can test whether the universe is truly random (in the above sense) or if it is merely the case that outcomes of experiments can depend in chaotic ways on arbitrarily small differences in initial conditions (which is what you seem to be presenting as the alternative), I'll agree we can never be sure. But the point is that QM, the theory, takes the former view. It could be the wrong theory, but that is not what we're debating.

Yeah, we can't ever know. Perhaps the discussion really is pointless. :(

 

[reilly]

These two quotes help support my claim about Hume and causality.

…that all our reasoning concerning causes and effects are derived form nothing but custom; and that belief is more properly an act of the sensitive, than of the cogitative part of our natures.(Hume by Barry Stroud p76, Routledge, 1977
There is no phenomena in nature, but what is compounded and modified by so many circumstances, that in order to arrive at the decisive, we must carefully separate whatever is superfluous, and inquire by new experiments, if every particular circumstance of the first experiment was essential to it. These new experiments are liable to a discussion of the same kind; so that the utmost sagacity to choose the right way among so many that present themselves..(A Treatise of Human Nature p225,Penguin Classics edition.)

peter0302 and Ken G provide admirable arguments in favor of Hume's skepticism about causality.
Regards,
Reilly

 

[tomasko789]

Maybe it is a little bit offtopic, cause it is far from the philosophical dispute on what is randomness and determinism.
However, my view of this problem is quite simple. As we look at the quantum theory, it is deterministic in all its points. Given an initial state of a closed system, we can predict the time development in any time.
The problem arises as soon as we want to check our predictions and we need to pursue a measurement. We need to transfer the information which is hidden in the quantum system to our minds. And here is my point. As far as I know, all the quantum measurements are based on the interaction of the quantum system with a measurement device. This device is always a system in thermodynamical equilibrium. This interaction destroys the state of the system and gives us the result of the measurement. The way this happens is in fact deterministic, but we don't know the state of the measurement device.
The outcome is, everything is deterministic, but in order to transfer the quantum information to our mind deterministically, we would need to know the exact quantum state of ourselves, because otherwise the quantum system neccessarily comes in touch with our "thermal" brain, and this destroys the determinism of the measurement.

 

[orubi]

Is the Schroedinger time-dependent equation deterministic? why?

 

[peter0302]

Is the Schroedinger time-dependent equation deterministic? why?

Most certainly yes. We can calculate the probability amplitudes of a particle's location at time 't' with great precision, and there is no randomness to the calculations. The randomness only comes into play when we attempt to find physical meaning in the wavefunction, i.e., to predict _where_ a particle will emerge, as opposed to calculating the probability density of where it will emerge.

 

[orubi]

Can it be consider deterministic because of its linearity?. That is, because it is not susceptible to slightest differences in initial conditions, so that in the evolution of one superposition of states each component evolves independently from the other? Are there any changes we can perform on the Hamiltonian's equation that introduce ramdomness intrinsically in the evolution of the Schroedinger's equation (by the way, Fermi introduced a term in the Hamiltonian describing the energy dissipation by radiation reaction force)? Does determinism in the evolution of the time-dependent equation depend on which hamiltonian we choose?

 

[Ken G]

The outcome is, everything is deterministic, but in order to transfer the quantum information to our mind deterministically, we would need to know the exact quantum state of ourselves, because otherwise the quantum system neccessarily comes in touch with our "thermal" brain, and this destroys the determinism of the measurement.

I completely agree with your description of the "measurement problem", and why too much is made of it. Indeed it is very similar to how I think of it, with one important exception-- the way you are framing it is essentially "the universe is really deterministic but we are limited by the scientific method to actually establish that". The way I would frame it is "everything we can say about determinism in the universe stems from application of the scientific method, therefore any inherent limitation in that method must also carry over into an inherent limitation in what we can say about determinism in the universe." In other words, it's not that determinism is real but our models of it fall short by virtue of the way we do science, but rather, determinism is itself a model that stems from a system that can never establish it perfectly. Hence, at some level determinism is ontologically self-inconsistent when applied directly to reality, but can be effective in the right circumstances as a model of reality. What would it mean, anyway, to say that "the universe is really deterministic"-- as determined by whom and by what means?

 

[tomasko789]

I'm not sure if i get your point right, but I'd have one remark.
It is for sure an interesting phylosophical question what in fact determinism is. However, talking about quantum mechanics we should rather consider the inherent determinism or randomness of the theory itself and not going so far beyond the physics.
Consider, for example classical mechanics. Imagine, you have a ideal gas, consisting of tiny balls in the box, which behave according to Newton's laws. If you want to do any measurement of the state of the gas inside, you also have to interact with it somehow, introducing some contact with outer world, which is in thermal state, thus affecting the gas in random manner. Thus,the situation is IMHO pretty much the same. However, in this case, I personally would consider such a system deterministic. The quantum mechanics is for me just different, more sophisticated way to establish the equations of motion.

 

[Ken G]

Consider, for example classical mechanics. Imagine, you have a ideal gas, consisting of tiny balls in the box, which behave according to Newton's laws. If you want to do any measurement of the state of the gas inside, you also have to interact with it somehow, introducing some contact with outer world, which is in thermal state, thus affecting the gas in random manner. Thus,the situation is IMHO pretty much the same.

Again we are thinking similarly, I've made that point myself, and again it says that too much is made of the "measurement problem" in an expressly quantum mechanical situation (as a similar problem exists classically).

However, in this case, I personally would consider such a system deterministic. The quantum mechanics is for me just different, more sophisticated way to establish the equations of motion.

I agree that we are led to the same conclusion both ways, but where we disagree may be our conclusion about reality. We both have used the word "deterministic" to describe a theory, not necessarily a reality, because determinism is itself an aspect of a model. As with any model, the task of comparing it to reality falls to us, and we determine how we will make that connection. The concept of "determinism" never survives that connection, it is lost in how we do science.

So neither theory "tells us" that reality is deterministic, though both theories are themselves deterministic until they make a testable prediction. The testable prediction, by virtue of the testability, requires that contact is made with elements that are outside the theory, and those elements will introduce the concept of randomness. We agree there. Where we may disagree is that you seem to view that as a kind of side effect of testing theories (as when you said "everything is deterministic", it's not clear what you meant there), but since the whole point of a theory is to be tested, I do not distinguish the expectation that the theory must be testable from the theory itself. In that sense, no theory is truly deterministic once its encounter with reality is included in the grand picture-- it is only the theory as idealization (i.e., as a mathematically structured object) that is deterministic.

Hence, everything is not deterministic, but key elements of the models are. We recognize that the wave function will evolve deterministically, but when we go to test it, we will encounter an incomplete ability to predict the testable outcome, and that incompleteness will obey an uncertainty relation (as alluded to by peter0302 as well). Some would count that as a lack of determinism, not so much in the theory itself, but in its point of contact with the rest of the scientific exercise. Others see that apparent breakdown in determinism as so severe that they feel the need to outfit an exostructure of "many worlds" just to avoid it, but you and I can question as to whether or not that is really necessary.

 

[Ken G]

Can it be consider deterministic because of its linearity?. That is, because it is not susceptible to slightest differences in initial conditions, so that in the evolution of one superposition of states each component evolves independently from the other?

The linearity of the Schrodinger equation doesn't mean it can't have sensitivity to initial conditions, i.e., a linear operator can treat nonlinear potentials. Chaotic systems like a 3D anharmonic oscillator can have a Hamiltonian, and nonlinearities in hamiltonian mechanics are important in the thermodynamic concept of "ergodicity".

 

[peter0302]

Right, as I keep saying, chaos does not equal random.

As I sit here I realize that the only things that are truly deterministic both in theory and in practice are things that don't exist physically, i.e., mathematical concepts. 2+2 always equals four _in theory_, but in nature you never get two things that are identical in every way (let alone 4), so one must always impart human understanding such as classificaiton to make _any_ mathematical statement whatsoever. Otherwise, there are always unpredictable (random?) differences between two physical things, which ultimately prohibit you from making absolute statements about nature, even statements so simple as 2+2=4.

Since the wavefunction is, we all agree, deterministic and governed by the Schrodinger equation, is this not an argument for the non-physicality of it?

 

[Ken G]

As I sit here I realize that the only things that are truly deterministic both in theory and in practice are things that don't exist physically, i.e., mathematical concepts.

I agree completely, we can imagine that determinism is a word that may apply to reality, but in fact it only ever applies to our models. It is important to recognize our successes, but also not to take them too seriously.

2+2 always equals four _in theory_, but in nature you never get two things that are identical in every way (let alone 4), so one must always impart human understanding such as classificaiton to make _any_ mathematical statement whatsoever.

I think that's a particularly clear way to say it. I had an argument on another forum about something very similar, I should have used that example.

Since the wavefunction is, we all agree, deterministic and governed by the Schrodinger equation, is this not an argument for the non-physicality of it?

I would agree, except to say that one does not need an "argument" for non-physicality, it should be the default stance. That's the fundamental puzzle of intelligence-- how do we make progress understanding a physical world by piecing together a bunch of non-physical mental constructs? How does a physical world build an intelligence that can understand how the intelligence got built? We may never lick that puzzle, I don't know.

 

[Hurkyl]

The way I would frame it is "everything we can say about determinism in the universe stems from application of the scientific method, therefore any inherent limitation in that method must also carry over into an inherent limitation in what we can say about determinism in the universe."

Again, I disagree. Yes, it's obvious that if you make an a priori assumption of determinism when applying the scientific method, then yes, the results of all of your analyses must agree with determinism, but that's an inherent limitation of making such an a priori assumption -- I see no logical argument that suggests that the scientific method itself implies determinism.

 

[Ken G]

The way I would frame it is "everything we can say about determinism in the universe stems from application of the scientific method, therefore any inherent limitation in that method must also carry over into an inherent limitation in what we can say about determinism in the universe."

Again, I disagree. Yes, it's obvious that if you make an a priori assumption of determinism when applying the scientific method, then yes, the results of all of your analyses must agree with determinism, but that's an inherent limitation of making such an a priori assumption -- I see no logical argument that suggests that the scientific method itself implies determinism.

Neither do I, so that is not what I said. I said two things, first that everything we know about deterministic behavior is a product of the application of the scientific method. Do you agree? Then I said that given that, if the scientific method encounters limitations in being able to label a physical process as deterministic (such as problems introduced by measurement), then that same labeling problem must extent to our very understanding of how the concept of determinism can apply to reality in that situation. Do you agree? That's all I said, so to disagree, you must disagree with either the first or the second aspect. I was talking about difficulties science has in addressing determinism, so of course I was not assuming that science must deal only with determinism.

 

[peter0302]

That's the fundamental puzzle of intelligence-- how do we make progress understanding a physical world by piecing together a bunch of non-physical mental constructs? How does a physical world build an intelligence that can understand how the intelligence got built? We may never lick that puzzle, I don't know.

It is like asking whether a computer can be self-aware? Or, if we consider a computer simulation - like the Sims - can a player, within the boundaries of the simulation, understand how the simulation works? To some extent yes, but eventually he encounter, at the smallest level, the limitations of the simulation, and reach a point where he can look no further. And moreover, since the system is not designed to let you look too deep, you might start to see some very odd and non-intuitive things the deeper you look. "Glitches" in the system resulting from its inherent limitations. So you reach a point where observation within the rules of the system is no longer possible, and you have to resort to guess-work - postulate + logic - to figure out the rest, and hope that all your observations of the "glitches" fit your hypothesis.

 

[reilly]

I don't grant this much significance yet, reilly. I can't say whether these observations made in brain science are incompatible with free will or not because I don't know what free will is. I can only think of the vaguest of definitions.

I can grant that dislike of cooked turnips may not be a free choice. No taste is, whether it is a taste for Beethoven or a taste for torturing young boys. But what about the choice to act or refrain from acting on that taste? Christians, Muslims, etc. would say therein is the free choice.

But what is a free choice? I can't isolate it to say for certain whether anything is a "free choice" or not.

I find it interesting that such a fundamental questions of physics could be at all related to a fundamental question of morality and/or religion.

I couldn't find the article I wanted to suggest, The Butler Made Me Do It; Science News...10 or more years ago. You can find lots on the free will topic: GOOGLE,[ "free will", unconscious ].

Regards,
Reilly Atkinson

 

[Ken G]

It is like asking whether a computer can be self-aware?

With one potentially important difference-- we know the computer is following an algorithm. Do we know that about reality?

So you reach a point where observation within the rules of the system is no longer possible, and you have to resort to guess-work - postulate + logic - to figure out the rest, and hope that all your observations of the "glitches" fit your hypothesis.

Yes, and face the possibility that there may be no way to "figure out the rest", not just because it's hard to do, but because there is no more that can be "figured out".

 

[reilly]

With one potentially important difference-- we know the computer is following an algorithm. Do we know that about reality?

Yes, and face the possibility that there may be no way to "figure out the rest", not just because it's hard to do, but because there is no more that can be "figured out".

Self aware? Maybe, maybe not.But I think it could be: the basic idea is, a pyramid of "watchers"(this is the core of Minsky's "Society of Mind" models.) For example; an image(s) can be stored in computer memory. At the crudest level, and somewhat oversimplified, a sequence of neural networks is trained to recognize the image, it size, color. location, duration,...Then translation networks map language descriptions into or onto the image, which can respond to queries about the image. That is, one constructs a system able to pass a Turing-like test, so that self-awareness can be demonstrated. Not easy, but certainly possible, in my opinion -- Steven Grossberg at Boston U, had completed some of this approach a some years ago, with a special type of neural network, so called Adaptive Resonance Networks. And yes, this would initially require brute force and probably more computing power than is currently available.
Regards,
Reilly Atkinson

 

[Ken G]

But I think it could be: the basic idea is, a pyramid of "watchers"(this is the core of Minsky's "Society of Mind" models.) For example; an image(s) can be stored in computer memory. At the crudest level, and somewhat oversimplified, a sequence of neural networks is trained to recognize the image, it size, color. location, duration,...Then translation networks map language descriptions into or onto the image, which can respond to queries about the image. That is, one constructs a system able to pass a Turing-like test, so that self-awareness can be demonstrated.

Yes, I would not go on record to say it can't be done, I'm just agnostic about whether or not a self-aware brain can figure out what self-awareness is. That agnosticism is related to the issue of whether or not a Turing test can really cut it-- it seems to me, a Turing test is the prescription whereby a brain can fool itself into thinking it is in contact with another awareness, but the best it can do might not be good enough. (No harm in trying of course.)

Right now, the logic seems to be, "I'm self aware, so I will posit that anything that responds to stimulus in a way that is indistinguishable from how I would must also be self aware". The best we can do, perhaps, but is it ever enough? How do we bridge the gap between an operational definition of how awareness acts, and what it is actually like to be self aware?

It reminds me of your point about Hume and causality-- if we see a close connection between two things, such as our own awareness and how we act in various situations, can we reliably reason backward from those actions by other agents and infer they have a similar self awareness? The problem, as with cause and effect, is that one cause may always be followed by a certain effect, but that effect may not always be preceded by that cause. Even if it always seems to be, we never really get to know the complete connection, the "divine providence" if you will, until we've "seen under every rock" and noted every possibility in the whole universe. How else can we rule out the possibility that something that we know is not self aware in the way we experience it could still support an architecture that could "fool" a Turing test?

It reminds me of when Kasparov was beaten in chess by Deep Blue. Kasparov knew that Deep Blue was programmed essentially expressly to beat him (it has never played a public game with anyone else, presumably because it might present "bugs" against a different style player), so it must have given him a weird feeling of looking in the mirror. Was he seeing a reflection of his own awareness in the actions of the machine? Perhaps Kasparov has a more visceral sense of artificial intelligence than anyone else, as a result, but even so, are we forever relegated to seeing only that part of ourselves when we look outside?

 

[Hurkyl]

I posit that a generic discussion of artificial intelligence or sentience belongs in either the computer or philosophy forum (depending on the content) -- if we think such notions are relevant to the thread, we ought to write down an operational definition, and work solely with that.

 

[Ken G]

The hope for sentience to be on topic in a thread on randomness is the hope that we can use the concept to understand the apparent randomness of human behavior in terms of internal degrees of freedom, internal sentience. But that just leads to the usual paradox that neither internal randomness nor internal determinism seems to explain where sentience comes into play. If we remove from the equation "sentience is what I have" on the grounds that such a subjective requirement is unscientific, I'm not sure there's anything left science can talk about, on a "randomness" thread or any other for that matter. We can look at the biological process of a brain making a decision, and look at what is inherently random and what isn't, that's the "operational definition" approach that we probably can do no better than. Like randomness, sentience then becomes a model of something else.

 

[peter0302]

I wasn't intending to talk about AI, but it is an example of why we, _inside_ the universe, cannot know everything there is to know about the universe from the inside. And I think I "proved" that theorem in an earlier post, because the "stuff" needed to observe "A" is always greater than "A".

The computer simulation is a great example because you will reach the limits of self-awareness within the confines of the system, outside of which you cannot step. You can experiment within the system to learn its rules, but you cannot discover the mechanisms enforcing those rules. That is why the computer cannot be 100% self-aware - it cannot use its own programming to learn everything about its own programming.

 

[reilly]

Determinism is plausible when and if the Law of Large Numbers/Central Limit Theorm converges for a set of experiments -- measure the initial conditions and the outcomes -- mass sliding down an inclined plane; a months movement of the earth; starting a car and getting it moving, ...Our intuition suggests these are deterministic situations; and many measurements will confirm determinism within experimental error.(This is pretty much the main idea behind Shannon's work, made rigorous by Feinstein. -- see Khinchin's Mathematical Foundations of Information Theory, Dover-- a superb book.

RE self awareness -- indeed it's not usually considered an appropriate topic for physics threads. I beg to differ, given Sir Francis Crook's take on the matter -- neural hypothesis and all that; he really talks about the physics of the brain as paramount for the study of mental phenomena. With all due respect, it would appear that few if any here have spent much time with the research literature of brain science; there are no theorems, no grand philosophical pronouncements Rather one sees articles like, Attentional Mechanisms in Visual Cortex(Maunsell and Ferrera), Neurophysiological Networks Integrating human Emotions (Halgren and Marinkovic), two of 92 papers, mostly experimental, in The Cognitive Neurosciences --edited by M.S.Gazzaniga . I have the first edition of this bible (1997); there's a revised one out. A must read if you want to get a real sense of what's going on, and how far the field has come from the days of intense AI and philosophical arguments, which are more and more becoming historical curiosities. There are tons of data on everything to the specifics of neuro-transmitters to consciousness. And that's where the action is.

Back to physics.
Regards,
Reilly

Re Turing? What's better?