[Guest]

This is a spin-off from rookie1ja's Lazy-Bones Paradox (if there is a destiny, why bother going to the doctor's when ill?). A belief in destiny may lead to bad decision making, but that's not to say the belief itself is incorrect.

I'd like to get some thoughts on the Destiny vs Free Will subject, but first let's get a few things out of the way:

The question of destiny doesn't depend on some quasi-religious notion of a "master plan". Destiny may simply exist without anyone knowing what the "plan" is, perhaps just as a consequence of physics. If the current state of the universe and the laws of physics acting upon it dictate all that happens, then this determines the future regardless of whether we can predict it. In my opinion destiny simply requires there to be just one possible future.

Clarification of "possible": "Possible" is often taken to mean "something we do not know to be untrue (or impossible)". If I bought a ticket for last night's lottery but haven't checked the results yet, and you ask me "Did you win the lottery?", I might answer "It's possible, I don't know yet". In reality, the outcome is already determined, so my winning the lottery is only possible if it actually happened. I either won or I didn't, I just don't know which it is, so I used the word "possible" to indicate a lack of knowledge in this case. But that's not what I mean when I say "one possible future". I mean only one future which may happen (regardless of knowledge).

Picture a hypothetical observer standing outside of time. Would they see time as a line, as a single sequence of events from the distant past to the distant future? If so, however unpredictable the future may be, destiny is a reality. In this case, the notion of "free will" may be a useful one, but it is an illusion (caused by our inability to keep track of the underlying mechanics, the cause and effect which dictates our every thought). You might say that those who believe in destiny and make bad decisions because of it were destined to do so, and those who believe in free will and make good decisions because of it were equally destined to do so.

You might argue that Free Will can exist alongside Destiny. Consider this example:

You've been kidnapped and locked in a room with a red door and a green one. You are told "You have the freedom to leave the room by whichever door you choose, and accept the consequences". So you choose (say) the green door, which leads to a reward and an exit. Later you find out that the red door was a fake door with just a wall behind it. The maker of this room (having studied the way you think in infinite detail) knew that you were certain to choose the green door and therefore didn't bother building a second exit. It's true that you had "the freedom to leave the room by whichever door you choose", since you would only ever have chosen the green door, regardless of how "free" you thought your choice was. Freedom doesn't necessarily mean that there is more than one possible outcome.

For the purposes of this debate, however, I would like to define "Free Will" as the ability to make more than one possible choice. Which makes it utterly incompatible with Destiny.

So it's a fight to the death. And I propose that the deciding factor is whether or not we have more than one possible future.

Let battle commence!

[Guest]

Oh how nice to see this old chestnut resurrected, and with a few fresh opinions too.

...if the reductionist philosphy is true (which I'm strongly inclined to believe given that everything in this universe is bound by the laws that govern it), then the Multi-verse explanation for the dual-slit trick has to be false because no other realities are possible...alternatively worded, if someone could prove the multi-verse, it would prove free will in this universe.

I doubt anyone could prove the multi-verse, although I think Occam's Razor points to it. But does it imply free will? In a multi-verse, when confronted by a choice, there may indeed be several possible futures which represent different decisions you could make. However, you cannot choose one of those possible outcomes and not the others. The fact that they are possible means that they will all happen. A version of you in one of those futures might look back and say you chose that one and not the others. But on what basis can it be claimed that one such future is "real" and the others not? IMO, we often use the word "real" like some object-oriented programming languages use the keyword "this" (only with no scope to reference beyond "this"). If we accept that usage, it could give us a sort of free will, but fudged to the point of being an illusion manufactured by words and limited perspective (EDIT: no it doesn't, it just gives you randomness)

@araver:

I'd like to question what it is you mean by free will. I'm inclined to agree with what Unreality is saying, which I'll paraphrase by saying that free will is a supernatural concept. And by "supernatural" I mean "that which we assert as being intrinsically beyond understanding". That's not just stuff which is not currently understood, or even stuff which will never be understood. It's stuff which by nature defies understanding, stuff which can't possibly make sense. This seems to me to be what is being asserted when someone asserts free will. When faced with the dilemma between decisions being dictated by physical forces (determinism) or not (meaningless random events), you assert a third option: that something mysterious is at work (free will).

IMO supernatural is just lazy. It declares a non-acceptance of rationality and rational enquiry, and thus avoids having to think about things. There is every reason to think such a world view is without basis, pointless, overcomplicated, and explains nothing. But if you have abandoned reason, that's no objection.

Is that fair criticism of your point of view? Or are you asserting a form of "free will" which amounts to randomness? Or something else?

[araver]

@araver:

I'd like to question what it is you mean by free will. I'm inclined to agree with what Unreality is saying, which I'll paraphrase by saying that free will is a supernatural concept. And by "supernatural" I mean "that which we assert as being intrinsically beyond understanding". That's not just stuff which is not currently understood, or even stuff which will never be understood. It's stuff which by nature defies understanding, stuff which can't possibly make sense. This seems to me to be what is being asserted when someone asserts free will. When faced with the dilemma between decisions being dictated by physical forces (determinism) or not (meaningless random events), you assert a third option: that something mysterious is at work (whooo). IMO supernatural is just lazy. It declares a non-acceptance of rationality and rational enquiry, and thus avoids having to think about things. There is no reason to think such a world view is necessary, but if you have abandoned reason, that's no objection. Is that fair criticism of your point of view? Or are you asserting a form of "free will" which amounts to randomness? Or something else?

I'm not suggesting the supernatural tag, but yes, there are things that are undecidable. Putting aside our immense species ego - there are things undecidable for Turing machines, why can't there be things undecidable for human beings?

Somehow your definition ("that which we assert as being intrinsically beyond understanding") is not exactly what I had in mind although it's close. Example: The halting problem for Turing machines is undecidable. We as human beings know that. Doubtful of the exact way in which this can be done, but maybe a Turing machine can actually decide that the halting problem for Turing machines is undecidable.

So if a Turing machine can say that something is undecidable, why can't a human being say that something is undecidable? (case in point - non-determinism).

On the other hand "stuff which by nature defies understanding, stuff which can't possibly make sense" is a different concept. I see no contradiction in undecidability. Some thing either is or is not, we can never know for sure (except for a finite number of cases).

I'm not in favour nor do I suggest any 3rd party mysterious supernatural force to explain something like "free will". I did not even go beyond the point that "free will" exists.

My theory in the previous posts (or speculation according to unreality) is that the following 2 systems still look consistent (i.e. contain no contradictions) from everything we know so far (state-of-the-art science):

System S

S1) non-determinism exists.

S2) our reality (human existence however you want to call it) is in a plane (dimension, order of logic, universe, however you want to call it) in which non-determinism cannot be detected.

System P

P1) non-determinism does not exist.

P2) anything that is perceived as non-determinism (local aspect) is in fact a part of a global deterministic picture.

1) I did not state that we live for sure in system S (which allows a macro-form of free-will, albeit not detectable by us) or in system P (which negates any form of detectable free-will).

2) I did say that system S would probably be much richer than system P - since most of the time (at least in computer science) non-determinism allows for more things than determinism does i.e. has a different generation power / can reach farther.

3) I stated that I would like to live in system S (it would be more fun because of point 2 above) or if possible in a similar system where axiom S2 can be broken and the consistency somewhat repaired.

4) I also said that it may very well be undecidable if we live in a system P, or a system S, or any other type. That would not surprise me, since many somewhat simpler (IMHO) things have been proven to be undecidable (albeit for mechanical constructs, not for the human minds).

So going back to your original inquiry - what it is that I call free-will. I guess I call free-will another name for non-deterministic choice. For the purposes of this discussion, free-will's existence would mean a detectable manifestation of non-determinism which cannot be explained by any possible deterministic theory. Don't really care for practical reasons - it may be a particle manifesting it or a human-being or simply a non-constructive proof that such a manifestation can be detected.

Aside from this, maybe my grasp of English is not very good, but I was also not always serious in this discussion mixing logic theories with preferences. Point 3 for example is somewhat of a joke i.e. Early morning, two computer science students return to the university with a serious hang-over after the night before. On their way to the Formal Languages class one of them says: "I don't care what Turing says about that Turing machine. I'd rather it stopped."

EDIT: typos and a clarification.

Edited November 29, 2010 by araver

[Izzy]

I doubt anyone could prove the multi-verse, although I think Occam's Razor points to it.

In what way is an infinite number of universes with infinite more spawning at each infinitely small interval of time simpler than one universe?

There may be more than just this universe, but I find the argument for infintiely many with all possibilities carried out weak. I feel like something that major is something we'd have some sort of evidence for by now. *shrug*

It would imply free will in at least ONE universe. For simplicity's sake, say a universe with only one particle exists. This particle can either move up, down, or forward. In universe x, this particle decides to continue moving forward, which creates universe y. The particle in universe y now has the option to move up or down. It decides down, but in the universe z that spawns after this, it MUST move up, and no longer has free will.

Though, thinking about it further, in universe x, the particle could have not had free will at all and simply HAD to continue moving forward. Meh.

[Izzy]

why can't a human being say that something is undecidable?

We do, all the time. However, we admit that it's mostly due to our current (lack of) knowledge of the universe, not necessarily because an answer in indeterminable. I think some day our understanding of the universe will be complete (am I just overly optimistic? ) and the gaps for "negatives" (God, free will, etc.) will disappear. We might not, at this point, be able to disprove negatives, but we can certainly eliminate places for them to hide. So, I don't actually think anything is undecideable forever, just at present.

[araver]

We do, all the time. However, we admit that it's mostly due to our current (lack of) knowledge of the universe, not necessarily because an answer in indeterminable. I think some day our understanding of the universe will be complete (am I just overly optimistic? ) and the gaps for "negatives" (God, free will, etc.) will disappear. We might not, at this point, be able to disprove negatives, but we can certainly eliminate places for them to hide. So, I don't actually think anything is undecideable forever, just at present.

Seriously, in about 5 years, if you take a science-path (dark side or not) and you still hold that opinion, come back and infect me with it.

I sure wish certain things I've seen / discover / do can be unseen / undiscovered / undone.

[Izzy]

What's the dark side of science, theology? *cough*

Yeah, I fully know that my knowledge of the sciences is very limited (my chem teacher likes to call us her 'cute baby chemists' and my physics teachers likes to write problems in which chem students die ), but.. I don't see why not. Maybe not in our lifetime, and maybe not even in the lifetime of our species, planet, or galaxy, but if it's out there, it's observable, and if it's observable, we ('we' includes futuristic alien species >_>) can learn about it.

[Guest]

I'm not suggesting the supernatural tag, but yes, there are things that are undecidable. Putting aside our immense species ego - there are things undecidable for Turing machines, why can't there be things undecidable for human beings?

I'm sure there are things which are undecidable, but that doesn't mean we are justified in positing the existence of things which we might like to exist but have no reason to think exists. Even (especially!) if they are described as being impossible to prove or disprove by nature. The supernatural tag is one which I am asserting. I was challenging you to say what free will is, without making it supernatural. Maybe it amounts to randomness ("non-determinism" sounds like randomness to me), is that all there is to it? If I make decisions based on some quantum-level random factor, is it "free will"? Isn't that just like flipping a coin to decide?

[Guest]

In what way is an infinite number of universes with infinite more spawning at each infinitely small interval of time simpler than one universe?

Because it's a simpler model. The amount of information the model stores is irrelevant, the point is that the rules are simpler. Namely, we lose the distinction between things which are real, and things which are possible but not real. And with it we lose the need to somehow make that distinction, to decide what happens and what does not. The mechanism which decides the location of a photon in a double slit experiment no longer needs to be some sort of cosmic random position decider. The photon is everywhere it could be, simple as that!

There may be more than just this universe, but I find the argument for infintiely many with all possibilities carried out weak. I feel like something that major is something we'd have some sort of evidence for by now. *shrug*

Let's say we had a bet about where a photon would be detected in a double slit experiment, and in this universe you won. Perhaps you feel that the universe in which you won the bet is real and the one in which you lost is not. However, the universe in which you lost the bet is still a valid universe, mathematically speaking. Still logically consistent with consistent properties, it just isn't this version of events. One of those properties is that in that other universe you would believe that the universe in which you lost the bet was real, and the one in which you won was not. How then, do you know that your belief in the reality of this universe is any better, and not just a mathematical construct, within a hypothetical scenario? The belief would be just as strong in either case.

What I'm getting at is this: If you want to posit the concept of "reality", as a distinction which singles out one universe from all the possible universes, you need some basis for that. Your belief that this is real is not a valid basis. You would think that anyway. In that case "real" just means "this", in other words, the set of things with which you can still interact. That's a useful distinction to make, but it's subjective. It's hard to make a case for the word "real" meaning more than that.

It would imply free will in at least ONE universe. For simplicity's sake, say a universe with only one particle exists. This particle can either move up, down, or forward. In universe x, this particle decides to continue moving forward, which creates universe y. The particle in universe y now has the option to move up or down. It decides down, but in the universe z that spawns after this, it MUST move up, and no longer has free will.

Though, thinking about it further, in universe x, the particle could have not had free will at all and simply HAD to continue moving forward. Meh.

If you think of the particle as a wave, there's no forcing of decisions. It spreads out in all directions it can. It looks like a particle to us because we can only observe it as being in one place, when really it's a slice of a wave.

[araver]

I'm sure there are things which are undecidable, but that doesn't mean we are justified in positing the existence of things which we might like to exist but have no reason to think exists. Even (especially!) if they are described as being impossible to prove or disprove by nature. The supernatural tag is one which I am asserting. I was challenging you to say what free will is, without making it supernatural. Maybe it amounts to randomness ("non-determinism" sounds like randomness to me), is that all there is to it? If I make decisions based on some quantum-level random factor, is it "free will"? Isn't that just like flipping a coin to decide?

Well, as I said, no logical justification that system S exists and we're in it. Just preference. That my right, right?

To refine it more for your challenge, I believe we are exercising a form a free-will which may not be apparent. Semantically it is very close to randomness, but not equivalent.

I'm still pondering how to explain my idea in English, so I will make another try using some high-level definitions from Comp Science.

In a deterministic context, for any situation, you have a set of rules that prescribes at most one action to be performed. A deterministic algorithm is forced to make the action the rules prescribe (including a block/no action/stop/whatever).

In a non-determinist context, for any situation, you have a set of rules that (possibly) prescribes more than one action for a given situation. How that action is decided/taken can be seen in many ways (some of which may lead to different definitions of free-will):

Way 1) "The lucky guesser paradigm" - E.g. for an algorithm if there is a non-blocking finishing path, the algorithm always chooses that path.

Way 2) "The infinite branching/multiverse paradigm" - E.g. at each decision point everything is branched into many copies each following a possible action.

Way 1 can sometimes be viewed as way 2 with survival of the possible branches (makes sense since no-action=block=termination is possible at some decision-points, depending on the rules).

These concepts can be applied (mapped semantically) to different entities - algorithms, humans, universe.

Non-determinism for humans would be a form of simple free-will (I can choose either chocolate ice-cream or fudge) but does not deny the fact that the set of choices is actually restricted by rules (I can't have both at the exact same time, but I can settle for both one after another. If want to eat fudge after chocolate ice-cream that is.

No-rules-free-will is indeed IMHO a very naive opinion. Ruled-free-will is plausible. And possibly not-bustable by any Mythbusters (i.e. undecidable).

On the other size, randomization is just a simulation of non-determinism (agreed, useful for practical reasons) not non-determinism itself. It does not capture the essence of the non-determinism. EDIT: essence=view. I can't express this better in English, sorry.

Overall I have no problem with accepting non-determinism because it does not violate Occam's razor in any way, it is consistent as a logical theory (does not contradict itself) and it sounds much fun than determinism. Even if it allows for a primitive form of free-will and not a full-fledged "I can do what I want" free-will people usually ask for.

It may *seem* counter-intuitive at the moment, agreed. But so did infinite numbers for prehistoric men, and let me ask you, why do we believe in infinity now? It certainly did not manifest to each and everyone of us since then

Also, I'm siding with Tegmark e.g. on quantum suicide and immortality and the multiverse hypothesis classification, but I've only discovered him/his classification now, on my sabbatical, long after I developed most of the above convictions (college/post-grad).

Edited November 30, 2010 by araver

[Izzy]

The multi-verse doesn't account for why the photon landed in a particular spot in this universe. In reductionism, no randomness is involved where the photon lands. Through predictions, we can only guess where the photon will strike according to its wavefunction. Where it actually lands is determined by its position, velocity, and the forces acting on it. Since we can't know both the position and velocity without acting on it, it logically follows that we can't accurately predict where it's going. Our uncertainty of the system doesn't change the trajectory of the photon. If we knew less about the system, the photons wavecloud (umm, word?) would grow, but the photon still went whichever way it went regardless where we think it could have gone. Instead, if we knew everything about a system, probabilistically speaking, there's only one place it can go. Meaning, that the photon (which doesn't need to know where it's going) could have only gone on place anyway. Since it can only go to one place, there aren't alternative places for it to exist, so alternative universes needn't exist.

Sorry if the wording is.. a little confusing. I blame a combination of being exhausted and English not being my native language either.

I would love to see the mathematical model for this. Are we just basing it off of probability? We both know randomness doesn't actually exist. Pseudorandom implies predictable, and where it's predictable probability is meaningless.

I never used the term 'real'. If multiple universes exist, then they are just as 'real' as this one. However, the evidence is still lacking. (Unless I see something mathematically mind-blowing. )

Well.. particle-wave duality. I thought particles are like.. particles that just move as waves that retain particle properties?

[Guest]

The multi-verse doesn't account for why the photon landed in a particular spot in this universe. In reductionism, no randomness is involved where the photon lands. Through predictions, we can only guess where the photon will strike according to its wavefunction. Where it actually lands is determined by its position, velocity, and the forces acting on it. Since we can't know both the position and velocity without acting on it, it logically follows that we can't accurately predict where it's going. Our uncertainty of the system doesn't change the trajectory of the photon.

The reason I mentioned a photon in a double slit experiment is that the experiment demonstrates that the position of the photon is not just unknown, it's undecided. The probability waveform represents a range of places where the photon could be, and until observed it acts just as a waveform, having an interference pattern. Where the waveform creates destructive interference, that represents places where we know the photon will not land. Cover one slit, and there is no interference pattern. Now a photon might land in those places. So there are places that a photon might land after being fired at a single slit, where it will not land when it has a choice of two slits. If we think it's just passing through one slit or the other, and we don't know which, that doesn't make sense. It couldn't generate an interference pattern unless it was actually passing through both slits, and remember this is a single photon we're talking about. That demonstrates that our uncertainty about where it's going is not just a lack of precise knowledge, it's down to the fact that the photon is really going in a broad range of possible directions, spreading out like a wave, and only when observed does it revert to being in one place and "choose" a position. From the observer's point of view, seeing a single outcome, the waveform looks like a probability function, and the position of the particle seems to be randomly chosen based on that.

[Guest]

On the other size, randomization is just a simulation of non-determinism (agreed, useful for practical reasons) not non-determinism itself. It does not capture the essence of the non-determinism. EDIT: essence=view. I can't express this better in English, sorry.

Your English is excellent, I wish my Italian was as good. Just to be clear, by "random" I meant having several possible outcomes, of which only one occurs. In that strict sense there can be no randomness in a deterministic system, like the random number generator of your PC is not really random, just difficult to predict and without an obvious pattern. Similarly in a deterministic universe a coin toss is not strictly random, it's just unpredictable. But looking at a quantum level you can see how conceivably you might look at outcomes as being truly random, and if you look at it that way then you're not in a 100% deterministic universe. Previous states of the universe affect the probability of future events but do not dictate their outcome (that's not exactly my point of view, I'm just trying to ascertain if it's yours).

Looking at it that way, you could make a case for free will, but it's not very satisfactory IMO. Consider the case of you choosing fudge or chocolate ice cream. Maybe if some god-like character were able to evaluate the precise state of the universe, they would know all there is to know about the factors which will influence your decision, even knowing the state of every subatomic particle in your brain. However, if the laws of physics are not completely deterministic, this god might still not know which flavour you will choose. A complete analysis of the situation may reveal that there is an 80% chance of chocolate and 20% chance of fudge. Those are the probabilities but you have to let the situation play out to find out which you actually choose. Now, is that free will? You could call it that, but to me it just looks like a random event that has an 80% chance of going one way and 20% chance of going the other. The phrase "free will", IMO, suggests more than that, that there is a "magic" factor at work, a spark of something mysterious that causes the decision to go one way or another based not just on probability, but on something. The implication, I think, is that a soul or some such thing is at work manipulating the outcomes. The term "free will" is distinct from "indeterminate" in that implication, and it stems from our inbuilt tendency to imagine ourselves as a mind which is somehow more than matter, indeed it pins the non-material nature of the mind on the idea that it can influence indeterminate outcomes. Viewing ourselves as a physical system where outcomes are probabilistic rather than determinate seems to lack the extra element of mind that free will implies. Where do you stand on this? Are your "free will" decisions just a case of rolling the quantum dice, or is there more?

[Izzy]

It couldn't generate an interference pattern unless it was actually passing through both slits, and remember this is a single photon we're talking about.

But..

1. This is speculation. There could very well be something else going on that we don't know about. And oh god no, I'm not talking Copenhagen interpretation here.

2. The multi-verse still doesn't actually explain the interference pattern. The photon is carrying out all it's probable locations in other universes, while only one is being carried out here, right? If there was an overlapping of universes, we should be able to see that more than in a single experiment. With the multi-verse, the dual-slit trick is expected to look as if we're observing the photon.

3. The multiverse also doesn't explain why the interference pattern dissapears when the photon is being 'watched'.

*EDIT* Btw, one particle doesn't by itself produce an interference pattern. It's only when multiple are fired that it becomes obvious *something* is going on.

Edited November 30, 2010 by Izzy

[Guest]

Hmmph. I'm in danger of sounding like someone who thinks he knows things about things about which he knows nothing. Still, I'll take a wild swing at these anyhow.

*EDIT* Btw, one particle doesn't by itself produce an interference pattern. It's only when multiple are fired that it becomes obvious *something* is going on.

But one particle is still subject to that interference pattern probabilistically, you know it won't end up where there is destructive interference. So it is not acting as you would expect from a single particle.

1. Yes it's speculation, but there's no denying that the presence of other possible routes that a particle could have taken (given the uncertainty of its position and velocity) affects the route it does take, so a simplistic particle view doesn't work. If it looks like a probability wave, maybe it is, but I'm not trying to say only one interpretation could work.

2 and 3. My understanding is that when a particle/wave starts interacting with other things beside itself, the more that interaction spreads, the less able it is to interact with other versions of itself in other outcomes. Exactly how that breakdown occurs I don't know, maybe the involvement of other particles increases the complexity of the situation and that rules out meaningful interactions between different outcomes. Anyhow that's why the interference pattern disappears when being 'watched'. If you can pin down the photon as having passed through one slit or another, this necessarily involves that photon affecting other things, so you're already in a universe that cannot interact with one where the photon went through the other slit. Does that make any sense? I dunno. Say if you were to position a photon sensor at a point where there was destructive interference, you'd see no photons. Now change that to a photon sensor which also senses what direction the photon came from, enough to determine which slit it came through. Now it can see photons because the interference pattern disappeared. How does that work? I've no idea, but here's a thought. Maybe in cases where there is destructive interference, there are two outcomes where you see the photon, but they cancel each other out in some way so they don't happen, like a positive and negative version of events. Put a direction sensor in there and the outcomes don't cancel out any more because the effect is different. Just blathering, I haven't a clue really.

[Izzy]

Hmmph. I'm in danger of sounding like someone who thinks he knows things about things about which he knows nothing. Still, I'll take a wild swing at these anyhow.

If I knew anymore, I'd correct or affirm what you're saying, but I'm in the same boat as you. (This is either a or moment.)

But one particle is still subject to that interference pattern probabilistically, you know it won't end up where there is destructive interference. So it is not acting as you would expect from a single particle.

But it's acting exactly as I would expect. As I understand particle-wave duality (and I could be totally wrong?), a particle is a chunk of matter with a definite position, like a pen on your desk, that moves as a wave, like a surfer. If I had a board in the ocean with two slits in it for surfers to pass through, I would expect a similiar interference pattern because of the nature of waves.

1. Yes it's speculation, but there's no denying that the presence of other possible routes that a particle could have taken (given the uncertainty of its position and velocity) affects the route it does take, so a simplistic particle view doesn't work. If it looks like a probability wave, maybe it is, but I'm not trying to say only one interpretation could work.

I don't understand why the presence of other possible routes affects the route taken. If I'm Googlemaping something, then yes, but only because I'm a conscious being able to make decisions (deterministic or not). A photon is not. Think of it like me rolling a ball down a hill. Given the bumps, differences in textures, grassier area, and so forth, there are many possible routes down. The ball takes a route, and in that trial, it is unaffected by other routes. If repeated over and over, yeah, other routes will show up in the trials and ones will become more probable than others, but the probability of this doesn't actually change where the ball is going. It's simply where we expect the ball to travel if repeated over time. This will also create some sort of pattern, perhaps not as elegant as one of a particle because it's "probability wave" isn't as cool.

For points 2 and 3, *shrug* What you say makes.. sense, ish, but whether or not the world actually works like that I don't know.

[Guest]

If I knew anymore, I'd correct or affirm what you're saying, but I'm in the same boat as you. (This is either a or moment.)

"If you think you understand quantum mechanics, you don't understand quantum mechanics" - Feynman

Actually I've been meaning to read that book you suggested by Bohr, bought it but not got into it yet. Too many more fun alternatives. I'm currently reading Metamagical Themas by Douglas Hofstadter which I could recommend to any Braindenner. Wonderful stuff!

I don't understand why the presence of other possible routes affects the route taken.

Where there is destructive interference between the light from a twin slit, no photons hit. Cover up one slit and suddenly the photons from the remaining slit start hitting the spot where the interference was. The presence of the other slit was stopping them before! This particular situation is illustrated better, I think, in this paper. Skip to page 5, left hand column (the baseball diamond). The basic idea is that each photon has two paths it can take to 2nd base, then (regardless of how it arrived), it can go to one of the 2 catchers. The photons are equally likely to go via 1st or 3rd base, and then equally likely to go to the left field or right field catcher. But the 2nd base mirror is cleverly arranged so that the waveforms via 1st and 3rd combine to create destructive interference for the left field catcher, so no light actually goes there and it all goes to the right field catcher. But block either 1st base or 3rd base and now there is no intereference to the light coming through the other way, and the two catchers get half of the light each. When you start thinking about that in terms of individual photons, it's rather odd. Suppose one photon is fired, and it decides to go via 1st base. When it arrives at 2nd base it can either go to the left or right field catcher. But its decision is influenced by other things that could have happened. If 3rd base was blocked, no problem. But if 3rd base was open, that particle could have gone via 3rd base, with equal probability. The fact that it could have done so means that it can only go to the right catcher. Why?

I prefer to think that the photon did not decide to go via 1st base or 3rd base, but that it went both ways (think of it as splitting into two ghost particles representing a 50% probability that a particle is there). If they both make it to 2nd base then the interference between the two causes them to combine into one particle that goes to the right field with 100% certainty. If you block 3rd base, the 50% particle going via 1st base gets to 2nd base and splits again, going 25% to left field, 25% to the right, without interference. So 25% of the time you will get a particle at left field, 25% of the time at the right, and 50% of the time you will get nothing because the particle went via 3rd base and got blocked. That's how I see it anyway.

[Izzy]

By Bohr? The only book I can remember suggesting you is "Quantum Theory" by Bohm. I still haven't finished it, it isn't exactly an easy read, but it's wonderful where math is concerned.

Hmm. I was just skimming through Jim Al-Khalili's "Quantum: A Guide for the Perplexed" which I read maybe three years ago for some terms.

I wrote off the sum-over-histories explanation off when I first read this (not sure why). In it, the photon remains as a particle, but explores all possible paths taken simultaneously, however unlikely those paths are. Summed together, all paths cancel each other out leaving just the physical path taken by the photon. But, the way the paths cancel depends on what options are available; if both slits are open, more paths are available and the cancellation is different.

The dynamical reduction theory is also briefly mentioned. It doesn't actually say what it is, only that it agrees with all current observations, but needs something further to account for the collapse in wavefunction. I'll look into that and report back after I study for the physics test tomorrow. >_>

[Guest]

Wow -

Did the original track of this thread diverge...

Imagine God. (Hard to do, but slightly possible.) You live outside of time. Everything is known from beginning to end, because beginning and end have no meaning - everything's just there.

Envision a running movie projector. The take-up reel is 'History', the feed reel is 'Future', and all of us mortals are trapped under the projection head, which is 'Now'.

As God, you can see what's on the feed reel, because you're outside of time. You're examining the feed reel:

"Hmm - Sam picked door #1 on Let's make a deal." That fact is about to be moved under the projection head.

Does Sam have free choice, or is he pre-destined to take dorr #1 ??

The answer is, he has (had) (will have) FREE CHOICE. Just because God can see what choice Sam picked doesn't mean that Sam was pre-destined to pick it!

He simply did.

[Guest]

By Bohr? The only book I can remember suggesting you is "Quantum Theory" by Bohm. I still haven't finished it, it isn't exactly an easy read, but it's wonderful where math is concerned.

Oh yeah, that one! I was probably thinking of Niels Bohr or something

The dynamical reduction theory is also briefly mentioned. It doesn't actually say what it is, only that it agrees with all current observations

Sounds good! I'll go with that one. I'm a dynamical reductionist, that's me.

[Guest]

Wow -

Did the original track of this thread diverge...

Imagine God. (Hard to do, but slightly possible.) You live outside of time. Everything is known from beginning to end, because beginning and end have no meaning - everything's just there.

Envision a running movie projector. The take-up reel is 'History', the feed reel is 'Future', and all of us mortals are trapped under the projection head, which is 'Now'.

As God, you can see what's on the feed reel, because you're outside of time. You're examining the feed reel:

"Hmm - Sam picked door #1 on Let's make a deal." That fact is about to be moved under the projection head.

Does Sam have free choice, or is he pre-destined to take dorr #1 ??

The answer is, he has (had) (will have) FREE CHOICE. Just because God can see what choice Sam picked doesn't mean that Sam was pre-destined to pick it!

He simply did.

Maybe I'm bring to simplistic about this, but it seems the fact that the"choice" is already on the reel means it is predestined. It shouldn't matter if any being can"see"it or not. It has already been determined but just has yet to occur, ie it has yet to play out for the audience. How about more of a live theater performance where there is a script that should be followed but nothing really is stopping the players from acting out on their free will to alter the way things are played out.

Edited November 30, 2010 by maurice

[araver]

Sorry I did not reply sooner

Your English is excellent, I wish my Italian was as good. Just to be clear, by "random" I meant having several possible outcomes, of which only one occurs. In that strict sense there can be no randomness in a deterministic system, like the random number generator of your PC is not really random, just difficult to predict and without an obvious pattern. Similarly in a deterministic universe a coin toss is not strictly random, it's just unpredictable. But looking at a quantum level you can see how conceivably you might look at outcomes as being truly random, and if you look at it that way then you're not in a 100% deterministic universe. Previous states of the universe affect the probability of future events but do not dictate their outcome (that's not exactly my point of view, I'm just trying to ascertain if it's yours).

Yes, I am agreeing with that definition of randomness. There's just a tiny difference - previous states dictate the range of possibilities (aka the rules) of future events in a larger sense of causality. But if you agree that previous states actually determine the probability of future events, it's one darker shade of grey than what I'm comfortable with. E.g. there's nothing inconsistent in saying that previous states may determine that the result of a coin flip is either head or tails, but not directly determine the probability to be 50-50. There's not anything mathematically wrong with non-deterministic universes in which the notion of probability cannot be developed/ascertained for sure. Yes, it sounds counter-intuitive and yes, it does not sound like our universe, but this is why I keep maintaining these two concepts distinct: non-determinism and random-ordered non-determinism.

Looking at it that way, you could make a case for free will, but it's not very satisfactory IMO. Consider the case of you choosing fudge or chocolate ice cream. Maybe if some god-like character were able to evaluate the precise state of the universe, they would know all there is to know about the factors which will influence your decision, even knowing the state of every subatomic particle in your brain. However, if the laws of physics are not completely deterministic, this god might still not know which flavour you will choose. A complete analysis of the situation may reveal that there is an 80% chance of chocolate and 20% chance of fudge. Those are the probabilities but you have to let the situation play out to find out which you actually choose. Now, is that free will? You could call it that, but to me it just looks like a random event that has an 80% chance of going one way and 20% chance of going the other. The phrase "free will", IMO, suggests more than that, that there is a "magic" factor at work, a spark of something mysterious that causes the decision to go one way or another based not just on probability, but on something. The implication, I think, is that a soul or some such thing is at work manipulating the outcomes. The term "free will" is distinct from "indeterminate" in that implication, and it stems from our inbuilt tendency to imagine ourselves as a mind which is somehow more than matter, indeed it pins the non-material nature of the mind on the idea that it can influence indeterminate outcomes. Viewing ourselves as a physical system where outcomes are probabilistic rather than determinate seems to lack the extra element of mind that free will implies. Where do you stand on this? Are your "free will" decisions just a case of rolling the quantum dice, or is there more?

If some god-like character, outside the universe, were to evaluate the state of a non-deterministic universe, he could just narrow down the possibilities not state one exact deterministic way it would go. It still preserves some sort of free-will while still giving him a sort-of-all-knowing thing. But it would be simpler to not have such a character as an all-knowing observer. That way, locally, my free-will can actually count if no one's looking

Not that much into physics actually, and I did not read all the posts in the thread before posting, so I guess I do have a different view of free-willness that I advocated. The tiny-idea was that choosing is done at the precise moment where you choose one outcome out of many possible outcomes bounded by a set of non-deterministic rules. It is conceivable (to me) that the universe exists because many entities/agents choose outcomes that interact between themselves and determine the next state (It's hard not to think linearly at this or impose a sequencing or order to it). I'd like to think that we're such agents, but at the level we're perceiving it (brain, senses, consciousness), it looks deterministic. I do not know if a soul qualifies as an entity in such a theory.

I'm not sure if I'm making sense right now. If I'm not, I'll try to clarify once I get rid of the flu

[Guest]

It's like Special Relativity - it depends on the location of the observer. For all us mere mortals, we are trapped under the projection head of Time. Our choices are free-will choices because we are temporal beings.

"Destiny" to me implies that the chooser of a path had no choice - only the illusion of choice. This is not the case for us mortals. Only the being who lives outside of time might see choices as 'Destiny'.

No amount of Computational Reductionism can make me believe that my choices are physico-mechanical - that would imply that the concept of "human intelligence" is just an illusion.

[Izzy]

Fssjr, and your evidence for this, aside from "lawl bro, God gave us free will!" is..?

[Guest]

I think that if the exact wherabouts and activities of all things were known, then one would technically be able to calculate how they would all interact with each other, and one would be able to discover what would happen in the future. Does that make sense? Of course you probably wouldn't be able to calculate it as fast as everything was going on. I believe there are causes for all things, even those considered random. The way the dice lands depends on how hard you throw it, surface it lands on, angle you throw it, which side it initially lands on, etc. And so destiny.

Edited December 1, 2010 by NickFleming

[unreality]

I think that if the exact wherabouts and activities of all things were known, then one would technically be able to calculate how they would all interact with each other, and one would be able to discover what would happen in the future. Does that make sense?

Yes that makes sense provided the initial condition you gave is true, but (unfortunately for your argument, fortunately for the universe and us (I think)), it's not. http://en.wikipedia.org/wiki/Heisenberg's_uncertainty_principle

That's what muddies the waters so to speak.

I'm actually still in agreement with you, I think that these things are deterministically calculable IF you could have the info but the limit isn't on the info existing, just on the info being ascertained. I'm no physicist though, maybe someone with a better background could give us Heisenberg's uncertainty principle in layman's terms