Susskind and Hawking on hard determinism

[schmitmg]

Does anyone know the stances of prominent physicists (Susskind, Hawking, others) on hard determinsm?

 

[stevenb]

Does anyone know the stances of prominent physicists (Susskind, Hawking, others) on hard determinsm?

I think they do.

 

[Chalnoth]

Does anyone know the stances of prominent physicists (Susskind, Hawking, others) on hard determinsm?

I'm pretty sure any scientist worth their salt agrees with hard determinism, that free will is just an illusion. However, I don't think many have made their stances public on this matter.

The only way out of hard determinism, after all, is some sort of supernatural entity, and most scientists don't go for that.

 

[schmitmg]

I'm pretty sure any scientist worth their salt agrees with hard determinism, that free will is just an illusion. However, I don't think many have made their stances public on this matter.

The only way out of hard determinism, after all, is some sort of supernatural entity, and most scientists don't go for that.

How is hard determinism justified in light of spontaneous generation? Is there believed to be some unidentified cause for this phenomanon?

 

[Chalnoth]

How is hard determinism justified in light of spontaneous generation? Is there believed to be some unidentified cause for this phenomanon?

Huh? Spontaneous generation is an old, falsified theory regarding the origin of life, specifically that life was produced from non-living matter spontaneously all the time. This does not happen. What are you talking about?

 

[schmitmg]

Huh? Spontaneous generation is an old, falsified theory regarding the origin of life, specifically that life was produced from non-living matter spontaneously all the time. This does not happen. What are you talking about?

My bad. It must be clear by now I am no physicist; I am more informed about philosophy, which I admit is not as interesting. I think I meant to use the term "spontaneous particle creation."

So... my revised question is: How is hard determinism defensible when we consider spontaneous particle creation?

Is the creation of these particles truly spontaneous? Or are there specific conditions necessary for their creation?

Because clearly, if spontaneous particle creation can occur without a cause, hard determinism cannot be valid.

Also, the double slits experiments seem to invalidate hard determinism. Hard determinism demands there must be a singular inevitable effect for every cause. The double slits experiments produce multiple effects for a single cause (and the experimenters insist the conditions are constant). How then are hard determinism and quantum physics combatible?

 

[Chalnoth]

My bad. It must be clear by now I am no physicist; I am more informed about philosophy, which I admit is not as interesting. I think I meant to use the term "spontaneous particle creation."

So... my revised question is: How is hard determinism defensible when we consider spontaneous particle creation?

Let's consider the two different aspects of hard determinism separately:

1. Logical determinism: All propositions are either true or false. This is not contradicted by quantum mechanics in any form.
2. Causal determinism: the statement that all effects have causes. This one gets a little bit complicated, because in physics there is often no clear distinction between "cause" and "effect". However, we can recover the same meaning through invoking what is called "unitarity". If a set of physical laws are unitary, then this is an indication that if we know the entire state of the system at a given time, then we can, given sufficient computer power, calculate the state of the system at any other time. So far, all discovered laws of physics hold to this statement. There was some thought that quantum mechanics was non-unitary, due to its apparent random nature under wavefunction collapse, but this was basically solved by Everett back in the 50's.

In this view, the vacuum itself has a dynamic wavefunction, and if we knew that wavefunction perfectly, we could, in principle, calculate each and every particle that fluctuated out of the vacuum. So yes, it is the underlying behavior of the vacuum itself that would be the "cause" in this sense.

This gets a little bit more complicated in terms of wavefunction collapse. As Everett showed, the appearance of collapse happens without inserting an assumption of collapse into quantum mechanics. So there is no reason to believe that there is any such thing as real wavefunction collapse. But even if we postulate that wavefunction collapse is real, instead of each "effect" being a result of fully-deterministic evolution, some "effects" are random results of the underlying behavior, and we could, if we knew everything, compute the probability distribution of each result. I don't think this changes any of the philosophical implications in any meaningful sense.

The only way I've seen that people have attempted to change this picture in a meaningful sense is to attempt to invoke the effects of observers in determining the underlying behavior. But that's magical thinking that almost nobody within physics takes seriously.

 

[Chronos]

In this universe just about anything possible must eventually happen, given enough time. This is not so much deterministic as it is inevitable under the rules of quantum theory. Does that mean we are unique? Almost certainly. Does it mean there are no other sentient intelligent life forms in the universe? Almost certainly not.

 

[Dmitry67]

I'm pretty sure any scientist worth their salt agrees with hard determinism, that free will is just an illusion.

1. This is definitely not true in multi-history universe
2. Truly infinite worlds (where initial conditions are not prepared artificially in a very specific way) have the same properties as MWI, the only difference that 'alternatives' are far from each other in space while in MWI they coexist in the same one.
3. In both cases I have no idea how to define 'FREE WILL' when ALL alternatives occur:

You can chose between alternatives A and B ==> you have free will
Choice between A and B is predetermined ==> no free will
Both A and B are guaranteed to occur ==> ?

 

[Chalnoth]

1. This is definitely not true in multi-history universe
2. Truly infinite worlds (where initial conditions are not prepared artificially in a very specific way) have the same properties as MWI, the only difference that 'alternatives' are far from each other in space while in MWI they coexist in the same one.
3. In both cases I have no idea how to define 'FREE WILL' when ALL alternatives occur:

You can chose between alternatives A and B ==> you have free will
Choice between A and B is predetermined ==> no free will
Both A and B are guaranteed to occur ==> ?

MWI doesn't imply that all alternatives occur. It only implies that all possible alternatives occur. It is not necessarily the case that anything we could imagine is actually a possible alternative.

In either case, what does occur is everything that does occur is due to purely deterministic evolution of the wavefunction, so there is no choice to be had, so free will is just an illusion.

 

[naturale]

The most active in determinism of the prominent physicists is Gerard 't Hooft. From his website you can see that one of his research interest is: "Fundamental aspects of quantum physics. I have deviating views on the physical interpretation of quantum theory, and its implications for Big Bang theories of the Universe. This topic has been expanded upon in recent publications, cf. "The mathematical basis for deterministic quantum mechanics"; The Free-Will Postulate in Quantum Mechanics; Entangled quantum states in a local deterministic theory, arXiv:0908.3408 (see my publication list)."

The 't Hooft idea is that "there is a close relationship between the quantum harmonic oscillator and a particle moving along a circle". From this idea follows arXiv:0903.3680 (Compact time and determinism: foundation) which I believe is the most promising and powerful approach to determinism in relativistic quantum mechanics. The "particle along a circle" in this case is the "de Broglie internal clock", that is a periodic phenomenon (a periodic field) with periodicity in time T=h/E. The de Broglie internal clock of an electron is faster that 10^-20 s(<h/m_e c^2). As for a "dice rolling to fast" w.r.t the resolution on time it is impossible to predict the outcomes. This is why quantum mechanics appear to be indeterministic. But as for a dice, if you time resolution is sufficiently good (modern experimental techniques are far to reach a time resolution of 10^-20 s) you would be able to describe the underlying deterministic dynamics.

 

[MathematicalPhysicist]

In this universe just about anything possible must eventually happen, given enough time. This is not so much deterministic as it is inevitable under the rules of quantum theory. Does that mean we are unique? Almost certainly. Does it mean there are no other sentient intelligent life forms in the universe? Almost certainly not.

No, these are the rules of probability, that everything which is possible must eventually happen.

Monkeys as we speak are trying to crack Shakspeare's Romeo and Juliet.

 

[Chalnoth]

No, these are the rules of probability, that everything which is possible must eventually happen.

Monkeys as we speak are trying to crack Shakspeare's Romeo and Juliet.

Everything that we can imagine, however, is not necessarily possible. We don't necessarily know what the outer bounds of possibility are. In fact, we actually can't know because we can't have the full information of the underlying wavefunction available to us (even if we did have the computer power to process such a massive beast).

In fact, in a rather deep sense, our universe hides from us so much of its information, that the argument over whether the universe is purely deterministic or deterministic + random is largely academic. As far as every observation we will ever make is concerned, the universe is deterministic + random. But, I claim, this difference is not a departure in any sense from the philosophical implications of hard determinism.

 

[twofish-quant]

I'm pretty sure any scientist worth their salt agrees with hard determinism, that free will is just an illusion.

I don't believe in hard determinism. I don't think that free will is an illusion.

The only way out of hard determinism, after all, is some sort of supernatural entity, and most scientists don't go for that.

There are a number of other ways. One is that collections of objects exhibit behavior that is independent of those objects, and "will" comes from the behavior of those objects.

Personally, when someone says that the *ONLY* way something is possible, I'm not going to accept that statement unless they show me a formal mathematical proof. There is a big difference between saying *I've proved mathematically that the only answer you can get when you add 2 and 2 is 4* and *I think this is only possible because I can't imagine it*.

"Proof by lack of imagination" is something I expect from creationists, and I'm getting worried that people I used to respect like Dawkins are showing the sort of habits I've learned to dislike from creationists.

Of course the problem with trying to prove the non-existence of free will by mathematical methods is that then you have to make the statement in formal mathematical terms, which as far as I can tell hasn't been done.

 

[twofish-quant]

1. Logical determinism: All propositions are either true or false. This is not contradicted by quantum mechanics in any form.

But it is quite strongly contradicted by Goedel's incompleteness theorem which says that any consistent formal system which is stronger than mathematics contains statements that are unprovable.

Also one very interesting field of mathematics is non-standard logic.

2. Causal determinism: the statement that all effects have causes. If a set of physical laws are unitary, then this is an indication that if we know the entire state of the system at a given time, then we can, given sufficient computer power, calculate the state of the system at any other time.

But quantum mechanics kills this because there is behavior that is not obviously specified in the state of the system. I have two uranium atoms with identical state, one decays now, one decays a million years from now.

Also, you run into problems when the computer is part of the system rather than something external. If you have the computer as being external to the system, then you run into thermodynamic and Maxwell daemon type problems. One you put in thermodynamics, you find that it is impossible to build a computer with infinite computer power, at which point things get interesting.

What you end up with are states that are not observed and *cannot be observed*. If we just label those states "free will" then free will exists.

In this view, the vacuum itself has a dynamic wavefunction, and if we knew that wavefunction perfectly, we could, in principle, calculate each and every particle that fluctuated out of the vacuum.

But we can't. In fact I'm pretty sure that you can mathematically show that you can't know the state of a wavefunction perfectly. What happens is that if you *could* know the state of a wavefunction, it turns out that you run into huge causality problems.

This is actually a major problem in quantum computing.

We could, if we knew everything, compute the probability distribution of each result. I don't think this changes any of the philosophical implications in any meaningful sense.

Again, if we could know everything and if we could compute everything, then we'd have huge thermodynamical problems. There are some fundamental limits in how much you can compute and how fast you can compute. The basic issue is that if you had infinite compute power, then you could construct Maxwell's daemon.

The fact that you are limited in what you can observe and what you can compute, and those limitation are *fundamental* has a lot of philosophical implications.

But any case, statements about the universe that assume the existence of infinite compute power are flawed, because you can show that these contradict thermodynamics.

 

[twofish-quant]

In either case, what does occur is everything that does occur is due to purely deterministic evolution of the wavefunction, so there is no choice to be had, so free will is just an illusion.

Define "illusion" (seriously).

 

[twofish-quant]

Everything that we can imagine, however, is not necessarily possible. We don't necessarily know what the outer bounds of possibility are.

Actually we do. You can use formal mathematical methods to show that certain things are not possible.

The problem with using that to prove things about "free will" is that you can't put the term "free will" into formal mathematical language.

This is a problem because if you have a discussion in which the terms are *not* rigorously defined. Then you have problems because people take results from definition A and apply them to definition B.

I believe that it is possible to show that if you assume the Rules of Quantum Mechanics and thermodynamics are correct that any complex system will exhibit behavior at time t+deltat which cannot be calculated from the observable state of the system t. (If anyone disagrees we need to have that discussion.) This is a statement that can be mathematically proved correct or incorrect.

Now if I *define* "free will" as quantum states of a system that cannot be observed or computed. It's a definition, and if you accept that definition, then mathematically free will exists. Now you can challenge that definition, but then it's not clear what the rules are for defining which definition is correct or not. It's also dangerous when people use the same word to mean two different things.

As far as every observation we will ever make is concerned, the universe is deterministic + random.

Or you can argue that there is some external supernatural force that is pulling the strings. That also fits the observations. Now you may not like the idea of some supernatural force, but you can't exclude that explanation from the observations.

But, I claim, this difference is not a departure in any sense from the philosophical implications of hard determinism.

But it is. In law and ethics, "free will" is an rather important concept. If I shoot someone, it matters a lot if I "intentionally" did it or I "accidentally" did it. Now it may in fact be that when a lawyer, ethicist, or philosopher utters the term "free will" he is really talking about something other than quantum states, and it's not my definition of free will.

But if it is the case that we are talking about different things, then it because dangerous for physicists to make statements about "free will not existing."

Also I do think that when physicists make statements, that they need to be really careful that any scientific authority that they have isn't used when they make non-scientific statements.

 

[twofish-quant]

In fact, in a rather deep sense, our universe hides from us so much of its information, that the argument over whether the universe is purely deterministic or deterministic + random is largely academic. As far as every observation we will ever make is concerned, the universe is deterministic + random.

First of all, it's not clear that there isn't an observational way of distinguishing different interpretations of quantum mechanics. As far as I am aware, no one rigorous demonstrated that the different interpretations of QM are observationally equivalent.

Second of all, what we can know and what we can't know about the universe is not an academic exercise. A lot of the research I'm interested in comes from trying to make faster and smaller computers, and we are hitting some fundamental mathematical and physical limits. What can be computed and what *can't* be computed is a very active area of research with a lot of practical applications. For example, whether it is mathematically possible to break encryption or whether the laws of the universe mean that you can't decode the messages the bank and the ATM are sending each other makes a lot of difference.

 

[Dmitry67]

But quantum mechanics kills this because there is behavior that is not obviously specified in the state of the system. I have two uranium atoms with identical state, one decays now, one decays a million years from now.

Also, you run into problems when the computer is part of the system rather than something external. If you have the computer as being external to the system, then you run into thermodynamic and Maxwell daemon type problems. One you put in thermodynamics, you find that it is impossible to build a computer with infinite computer power, at which point things get interesting.

Not only this, but also a probalem can be well-defined and have a solution, but it can be non-calculable

Also, as I suggested before, it is possible that things like 'free will', 'consciousness' have some weird mathematical properties so they can't be, in principle, understood. Check the first post here:

https://www.physicsforums.com/showthread.php?t=337197&highlight=banach

Finally, Goedels theorem is in fact very important. For example, the well-known Game of life on infinite board has very simple, deterministic and calculable physical laws, however, Goedel theorem is applicable to it (because you can build real, infinite Turing Machine in that universe) so some statements about gave of life can't be proven or rejected.

 

[Chalnoth]

There are a number of other ways. One is that collections of objects exhibit behavior that is independent of those objects, and "will" comes from the behavior of those objects.

That's, um, impossible. Because the behavior isn't independent of the components. The behavior may be radically different and not easily computable from the components, but it is still dependent upon them.

Personally, when someone says that the *ONLY* way something is possible, I'm not going to accept that statement unless they show me a formal mathematical proof. There is a big difference between saying *I've proved mathematically that the only answer you can get when you add 2 and 2 is 4* and *I think this is only possible because I can't imagine it*.

I don't see how it's that hard. If the fundamental laws of physics are unitary, then the physical configuration at anyone specific time has a one-to-one correspondence to the physical configuration at any other time. Yes, you might be right that the actual configuration could conceivably be uncomputable, even with infinite computer power. But it doesn't actually matter, because if unitarity is true, then the system before and after some passage of time, due to the one-to-one correspondence, are actually just the same system. You can't "sneak in" free will without breaking that one-to-one correspondence.

Of course, we know that actually calculating the behavior of a brain is a practical impossibility, and you're right that it may even be a fundamental impossibility. However, this just means that the illusion of free will is a really really good illusion. It doesn't mean that free will actually exists, just that the illusion is good enough that we don't need to worry about it. Not knowing or even being unable to know the result doesn't change this, as long as the result is necessarily a consequence of the previous configuration.

The only way around this, as near as I can see, is to redefine free will so that it is consistent with determinism. But classically free will has been considered to be in opposition to determinism.

 

[TrickyDicky]

That's, um, impossible. Because the behavior isn't independent of the components. The behavior may be radically different and not easily computable from the components, but it is still dependent upon them.

And actually those are called "emergent properties or behaviours" and are considered dependent of the components in a very, very far sense from that of "hard" determinism, so you should check again what "hard" determinism is, because otherwise you are admitting twofish-quant is right.

I don't see how it's that hard. If the fundamental laws of physics are unitary, then the physical configuration at anyone specific time has a one-to-one correspondence to the physical configuration at any other time. Yes, you might be right that the actual configuration could conceivably be uncomputable, even with infinite computer power. But it doesn't actually matter, because if unitarity is true, then the system before and after some passage of time, due to the one-to-one correspondence, are actually just the same system. You can't "sneak in" free will without breaking that one-to-one correspondence.

Of course, we know that actually calculating the behavior of a brain is a practical impossibility, and you're right that it may even be a fundamental impossibility. However, this just means that the illusion of free will is a really really good illusion. It doesn't mean that free will actually exists, just that the illusion is good enough that we don't need to worry about it. Not knowing or even being unable to know the result doesn't change this, as long as the result is necessarily a consequence of the previous configuration.

The only way around this, as near as I can see, is to redefine free will so that it is consistent with determinism. But classically free will has been considered to be in opposition to determinism.

You again have softened your determinism quite a bit, which is not bad. As soon as you realize that Hume proved centuries ago that the idea of the one to one correspondence in time of systems(causalty) is what actually turns out to be a darn good illusion (and of real practical utility indeed), you will also have rejected soft determinism.

 

[Chalnoth]

And actually those are called "emergent properties or behaviours" and are considered dependent of the components in a very, very far sense from that of "hard" determinism, so you should check again what "hard" determinism is, because otherwise you are admitting twofish-quant is right.

Huh? Hard determinism, as near as I can tell, makes no assumptions whatsoever about whether or not we do know or even whether or not we can know our future choices. It's merely a statement that those choices, whatever they may turn out to be, are a consequence of physical law and wholly determined by the previous state of the universe.

You again have softened your determinism quite a bit, which is not bad. As soon as you realize that Hume proved centuries ago that the idea of the one to one correspondence in time of systems(causalty) is what actually turns out to be a darn good illusion (and of real practical utility indeed), you will also have rejected soft determinism.

The difference between "hard" determinism and "soft" determinism isn't an actual difference in discussions about the behavior of the physical universe. It appears to be, instead, a difference in the definition of free will, where for soft determinism one weakens the definition of free will so that it is compatible with a completely deterministic universe. I don't see this as a meaningful distinction, especially because one reaches the exact same conclusions on moral behavior whether through hard determinism or soft determinism.

 

[twofish-quant]

That's, um, impossible. Because the behavior isn't independent of the components. The behavior may be radically different and not easily computable from the components, but it is still dependent upon them.

Yes it is. Temperature is an example of an emergent phenomena that is independent of the behavior of the components. Again, we may be using different definitions of what a "dependent component" is.

To give to other examples, computer programs and money are two things whose behavior cannot be derived or described in terms of their components, because both computer programs and money cannot be broken down into physical components.

Here is an example. I have two $20 bills that are physically exactly identical. Since they have the same serial numbers, one is counterfeit and one is not. This is an example of whether something is real or not has nothing to do with physical properties. Also, how money behaves has nothing to do with the physical manifestation of that money. $20 is $20 whether I represent it in paper money or ledger entries. If I take an bank ledger entry marked $20, and then I copy that ledger entry into something made of stone, and I burn the original paper book, it's still $20.

Also, there are things that are uncomputable as a matter of either fundamental physical or mathematical limits.

Yes, you might be right that the actual configuration could conceivably be uncomputable, even with infinite computer power. But it doesn't actually matter, because if unitarity is true, then the system before and after some passage of time, due to the one-to-one correspondence, are actually just the same system. You can't "sneak in" free will without breaking that one-to-one correspondence.

The problem is that if the configuration of system cannot be determined from observable information (and it can't be) then you have system behavior that is independent and non-determinable from external observation. You may have a one-to-one correspondence between behavior and physical state, but there is no one-to-one correspondence between physical state and observables, then you have a state that allows for behavior that cannot be determined from what is observed.

Of course, we know that actually calculating the behavior of a brain is a practical impossibility, and you're right that it may even be a fundamental impossibility. However, this just means that the illusion of free will is a really really good illusion.

Define illusion. I don't have a good sense of what you would consider an illusion what what you would consider real. It's not immediately obvious to me why you'd consider free will to be an illusion, and electrons and atoms to be non-illusionary. What about marriage? Is marriage an illusion? Money? Is money an illusion?

I don't see how you can come up with a definition of reality by which free will is an illusion but money, marriages, and Newtonian forces are "real." I'd be interested in seeing you try.

Not knowing or even being unable to know the result doesn't change this, as long as the result is necessarily a consequence of the previous configuration.

Except that using scientific arguments you can't force me to accept the existence of the hidden states that you need to get determinism to work. If the result is *unknowable* and *unobservable*, I can come up with perfectly good rules of physics in which the configurations you talk about don't exist at all. If you believe that those states exist, that's fine, but you can't through scientific argumentation force me to conclude that those hidden variables exist.

At this point we are in the realm of theology.

The only way around this, as near as I can see, is to redefine free will so that it is consistent with determinism.

Or to come up a non-deterministic model of the universe. If you are a determinist that is fine, and I'll treat this as a quasi-religious belief just as if you are Catholic. However what I object strongly to is your original statement that which is that no scientist worth his salt would reject hard determinism. I think I'm a scientist. I reject hard determinism. Statement False QED.

But classically free will has been considered to be in opposition to determinism.

The fact that people have believed things for thousands of years doesn't make it true.

 

[twofish-quant]

It's merely a statement that those choices, whatever they may turn out to be, are a consequence of physical law and wholly determined by the previous state of the universe.

The moment you show that those states are unobservable and uncomputable, then this is a matter of theology and not science, which you can reject if you don't like it.

I say those states that you talk of don't exist. Since they are not directly unobservable and cannot be computable, then you can't show scientifically that I'm wrong. I can come up with non-deterministic models of the universe in which those hypothetical states that you speak of don't exist, and those models are as good as the ones you come up with.

I don't see this as a meaningful distinction, especially because one reaches the exact same conclusions on moral behavior whether through hard determinism or soft determinism.

Not clear. I don't know if ethicists and physicists are talking about the same thing when we talk about free will. The problem is that formal mathematical logic is not useful in formulating ethical rules. One problem is that most people are not that good at formal logic, and so a system of ethical rules that is based on formal logic turns out to be unusable.

Personally, I don't think that physicists have anything useful to say about moral behavior.

 

[Chalnoth]

The problem is that if the configuration of system cannot be determined from observable information (and it can't be) then you have system behavior that is independent and non-determinable from external observation. You may have a one-to-one correspondence between behavior and physical state, but there is no one-to-one correspondence between physical state and observables, then you have a state that allows for behavior that cannot be determined from what is observed.

So what? That doesn't change anything.

Define illusion. I don't have a good sense of what you would consider an illusion what what you would consider real. It's not immediately obvious to me why you'd consider free will to be an illusion, and electrons and atoms to be non-illusionary.

Free will is defined as the ability to make choices free from constraints: that one can, in principle, make any choice. One may not be able to act on any choice, but one can make any choice. In principle. But the laws of physics guarantee that whatever choice we do make is actually wholly and completely determined by the past physical state of our own brains combined with whatever our brains interact with in the mean time. The idea that we could make any choice at all is an illusion.

One way in which the illusion is maintained is with our own ability to consider hypothetical scenarios. We often consider hypothetical scenarios, and try to consider what their outcomes will be. We then select among the alternatives based upon the perceived desirability of those outcomes. This whole process feels, to us, like we have the option of choosing any of the hypothetical scenarios, when in reality the choice we do make is determined by a combination of our own preferences and the outcome of this hypothetical mind game.

The fact that people have believed things for thousands of years doesn't make it true.

Er, we're talking about language here. As in how words are used. Definitions are only decided through consensus. Believing a definition is a certain way, for thousands of years, certainly does make it so. If you can come up with a new definition, and successfully get others to accept it, then fine. But then we're just arguing semantics and I'm not really interested any longer.

 

[twofish-quant]

In principle. But the laws of physics guarantee that whatever choice we do make is actually wholly and completely determined by the past physical state of our own brains combined with whatever our brains interact with in the mean time.

But they don't.

If you subscribe to the Copenhagen interpretation of QM, the the choices we make are *NOT* determined by past physical state, but contain a random non-deterministic element. Now there are interpretations of QM that are completely deterministic, but they become non-local, which makes that you cannot compute the behavior of any particle without taking into consideration the state of every other particle in the universe.

Assuming there is no observable difference between QM interpretations, you are free to choose whichever interpretation is most pleasing to you. Personally, I like Occam's razor, so I'm not going to assume the existence of unobservable, uncalculable physical states.

The idea that we could make any choice at all is an illusion.

Define illusion.

Er, we're talking about language here. As in how words are used. Definitions are only decided through consensus.

Actually they aren't. One problem with definitions is that even consensus doesn't work, and then you have to ask what is the basis for consensus. In science, we can get consensus because we agree on certain philosophical rules of the game. However, interpretations of QM are an example in which you *can't* get consensus because the rules don't allow for the creation of consensus.

The other thing is that definitions are mental tools, and sometimes you can craft a definition because it is useful. For example, if I am compelled to drink fizzy cola because I've seen adds making me feel good about fizzy cola, that's very different legally and morally from the situation in which I drink fizzy cola because someone has a gun pointed to my head. In one case, I feel good about drinking fizzy cola. In the other case I don't. There are systems of ethics and law that use the concept of "free will" to describe this, and this has nothing that I can see to do with quantum mechanics.

Believing a definition is a certain way, for thousands of years, certainly does make it so.

No it doesn't.

If you can come up with a new definition, and successfully get others to accept it, then fine. But then we're just arguing semantics and I'm not really interested any longer.

I'm not sure why not. I started to be very interested in semantics and the meaning of words once I figured out that they had a great deal to do with how the world works.

Now in physics and mathematics, people try very hard to avoid arguments based on semantics, and to do this, physicists and mathematicians have come up with a very restricted language that removes as many semantic issues as possible. This is great for doing physics. Horrible for ethics, which makes me wonder whether "free will" as you've defined it has anything to do with "free will" the way it is used in most ethical systems, and I don't think it does.

In most legal and moral systems, free will refers to the *feeling* of freedom. The fact that this feeling corresponds to physical states (and in fact you can probably reproduce that feeling with the right combinations of neurotransmitters) is irrelevant. If I hand my money over to someone in expectation of a new car, this is very different than if I hand my money over because someone is pointing a gun at me. the fact that I've been brainwashed into likely new cars is legally and morally irrelevant in a lot of moral systems.

What has this got to do with quantum mechanics? Pretty much nothing, which was my point.

 

[twofish-quant]

In any case, if someone is a hard determinist, that doesn't matter to me. I need to emphasize that I would have skipped this discussion except for the statement...

I'm pretty sure any scientist worth their salt agrees with hard determinism, that free will is just an illusion. However, I don't think many have made their stances public on this matter.

This is just false. I'm a "scientist worth my salt" and I'm not a hard determinist. Whether hard determinist is true or not is something I'm curiously not very interested arguing in, and I try to avoid that argument if possible.

What I do object strongly to is the idea that you can't be a good physicist and reject determinism.

 

[Chalnoth]

But they don't.

If you subscribe to the Copenhagen interpretation of QM, the the choices we make are *NOT* determined by past physical state, but contain a random non-deterministic element. Now there are interpretations of QM that are completely deterministic, but they become non-local, which makes that you cannot compute the behavior of any particle without taking into consideration the state of every other particle in the universe.

Assuming there is no observable difference between QM interpretations, you are free to choose whichever interpretation is most pleasing to you. Personally, I like Occam's razor, so I'm not going to assume the existence of unobservable, uncalculable physical states.

There are two ways to approach this point. One way is to point out that there is no difference between pure determinism and determinism + randomness, as far as free will is concerned. That is, you can't "sneak in" an unconstrained choice just by having the result of a physical process be random, as an unconstrained choice would break the randomness. The other way is to point out that QM requires no postulate of collapse to provide the appearance of collapse, and thus that particular postulate is unlikely to be required.

I'd also like to point out that decoherence does lead to observable effects, and has been observed.

Define illusion.

Better to define free will, and demonstrate that it doesn't exist. We still obviously have the perception that we have free will, and if free will doesn't actually exist, then that perception is an illusion.

Actually they aren't. One problem with definitions is that even consensus doesn't work, and then you have to ask what is the basis for consensus.

Definitions of words are arbitrary. There is no objective meaning of the series of letters (or sounds) that make up any word. Words only take on meaning through use, as a medium of conveying meaning between two people. Consensus on meaning, therefore, is the only basis for the meaning of a word.

One might attempt to convince others to take on a different meaning for some word or other, with the argument that a certain meaning is preferred due to, say, it being less ambiguous, or more applicable to some physical scenario, or whatever. But to attempt to claim that there must be some "basis" for a consensus regarding the definition of a word is ludicrous.

The fact remains that by a "hard" definition of free will, that is free will is the ability to make choices free of constraints, it definitively does not exist. If you weaken the definition of free will so that it is compatible with completely deterministic physics, then that obviously does exist (because with the softer definition you are merely equating the appearance of free will as being free will, which you're free to do).

However, interpretations of QM are an example in which you *can't* get consensus because the rules don't allow for the creation of consensus.

Given that quantum decoherence has been observed, it is unreasonable to consider any QM interpretation which requires any additional postulates beyond the wavefunction dynamics as being remotely likely.

 

[Chalnoth]

What I do object strongly to is the idea that you can't be a good physicist and reject determinism.

I sincerely doubt that you actually reject determinism. The most that is remotely reasonable to reject about determinism is the possibility of randomness in fundamental physical law. Beyond that, I really don't think it's reasonable to reject determinism, and I'd be extremely surprised if more than a small fraction of scientists in general did so.

 

[twofish-quant]

That is, you can't "sneak in" an unconstrained choice just by having the result of a physical process be random, as an unconstrained choice would break the randomness.

That depends on the details of what choice is.

Better to define free will, and demonstrate that it doesn't exist. We still obviously have the perception that we have free will, and if free will doesn't actually exist, then that perception is an illusion.

I'm still confused by your use of the word "illusion" since I don't know what you mean by it. Or for that matter what you mean by "exist". If free will is an emotional state then it obviously exists and is obviously no more "illusionary" than any other emotional state.

There is no objective meaning of the series of letters (or sounds) that make up any word. Words only take on meaning through use, as a medium of conveying meaning between two people. Consensus on meaning, therefore, is the only basis for the meaning of a word.

But that involves an agreement between two people, and they don't have to care what the rest of the world thinks. That's different from consensus. Also, you can have definitions that just don't make sense. I simply do not understand what you mean by illusion, and I strongly suspect that we have different definitions of "exist."

But to attempt to claim that there must be some "basis" for a consensus regarding the definition of a word is ludicrous.

It's not. Part of the problem with definitions is that you can come up with definitions that are self-contradictory. I can define "maxdfd" as the integer denominator of p/q such that p^2/q^2 = 2.

Part of my philosophy involves heavy emphasis on the idea of "use". In this view, definitions are tools to be used for social construction. I can define anything as anything, but some definitions are better because they are more "useful."

The fact remains that by a "hard" definition of free will, that is free will is the ability to make choices free of constraints, it definitively does not exist.

If you define it that way then fine it doesn't. I can't will a brick to move faster than c, and my ability to influence the world around me is limited by physical limits. But I already knew that, and I don't think any disputes that.

If you weaken the definition of free will so that it is compatible with completely deterministic physics, then that obviously does exist (because with the softer definition you are merely equating the appearance of free will as being free will, which you're free to do).

And for any moral and ethical system that I can think of, that's good enough.

There is some connection with the predestination paradox that Christians have to deal with. In some forms of Christian theology, you must make a voluntary decision to be saved to avoid hellfire, but this poses a problem since God knows who is going to be saved in advance. The way that you get around that is that only God knows this, mortals can't, and therefore you need to create ethics that presume that presume voluntary salvation even though God knows ahead of time who is going to make that "voluntary" choice.

 

[twofish-quant]

I sincerely doubt that you actually reject determinism.

Do have have to tattoo it on my face to convince you?

I REJECT DETERMINISM! I REJECT DETERMINISM! I REJECT DETERMINISM!
I REJECT DETERMINISM! I REJECT DETERMINISM! I REJECT DETERMINISM!
I REJECT DETERMINISM! I REJECT DETERMINISM! I REJECT DETERMINISM!

The most that is remotely reasonable to reject about determinism is the possibility of randomness in fundamental physical law.

Reasonable to you perhaps.

Or you can say that it's a divine mystery that no human being can understand. (Personally, I don't take that route, but it's a perfectly reasonable one for someone to take.) Or you can say that the QM randomness really isn't random, but at critical moments God changes the odds so that stuff happens.

Beyond that, I really don't think it's reasonable to reject determinism, and I'd be extremely surprised if more than a small fraction of scientists in general did so.

I'd be less surprised. The thing about scientists is that most scientists that I know don't try to mix their personal philosophical/religious beliefs with their role as a scientist, so you sometimes end up being quite surprised at what people really believe.

 

[Chalnoth]

Wow, seriously? That's...um...surprising. Because there is no possible way around determinism. It is fundamentally impossible to get out of it.

A simple proof of determinism just comes from noting that the universe must be self-consistent. That is, it cannot possibly contradict itself. And if the universe is self-consistent, then it must be describable through a set of entities combined with a set of rules governing the interactions between those entities. If we write down such a set of rules, and it turns out that it appears to change dependent upon the situation, then we can simply write down a new set of rules that takes that change in situation into account. If there is an element of randomness in the universe, then it can always be described via some probability distribution.

This does not guarantee that we know what these rules are, or even that we can know them. But I'm pretty sure it's a rock-solid proof for such rules existing, provided you accept that reality cannot contradict itself.

 

[naturale]

Do have have to tattoo it on my face to convince you?

I REJECT DETERMINISM! I REJECT DETERMINISM! I REJECT DETERMINISM!
I REJECT DETERMINISM! I REJECT DETERMINISM! I REJECT DETERMINISM!
I REJECT DETERMINISM! I REJECT DETERMINISM! I REJECT DETERMINISM!



Reasonable to you perhaps.

Or you can say that it's a divine mystery that no human being can understand. (Personally, I don't take that route, but it's a perfectly reasonable one for someone to take.) Or you can say that the QM randomness really isn't random, but at critical moments God changes the odds so that stuff happens.



I'd be less surprised. The thing about scientists is that most scientists that I know don't try to mix their personal philosophical/religious beliefs with their role as a scientist, so you sometimes end up being quite surprised at what people really believe.

After a century there are eminent physicists that are trying to formulate a deterministic theory of quantum mechanics:

Fro instance [http://physicsworld.com/blog/2010/07/torino_peers_into_the_quantum.html" ]: "One of the speakers was physics Nobel laureate, Gerard ‘t Hooft, who was looking at local determinism. He was comparing the theory of quantum mechanics with the manner in which Maxwell formulated his celebrated equations of electromagnetism. His conclusion being (as far as I understood!) that critics of quantum mechanics cannot make such a clear distinction between the accuracy of ‘deterministic’ approaches like electromagnetism and the “non-deterministic” theory of quantum mechanics.
‘t Hooft described how Maxwell had visualized space as being filled at all points with gears and switches, which all had an effect on each other. The laureate’s argument was that, while this approach worked for electromagnetism, quantum mechanics is a far more encompassing theory. He believes this approach is simply not feasible in the search for equations of the entire physical universe – there is too much going on that we will always have to break things down into estimates and probabilities."


Determinism is a scientific argument and not a philosophical/religious beliefs. This means to try to interpret physics (including quantum mechanics) in terms of deterministic physics, such the classical Hamilton principle, classical trajectories, and so. When you say "I REJECT DETERMINISM!", you are just trying to mix your personal philosophical/religious beliefs with your role as a scientist. At least you can say that ordinary textbooks say that ordinary quantum mechanics is a indeterministic theory. But if you are a scientist you are supposed to go beyond textbooks and you can't exclude that quantum mechanics emerge from an underlying deterministic theory (for instance without hidden-variables). In science everything is true as long as the contrary has not been proved.
Actually, there already exists an extremely interesting deterministic field theory that reproduces exactly quantum mechanics (Feynman path integral, commutation relations, ...). The quantization is achieved by imposing boundary conditions. See tread "https://www.physicsforums.com/showthread.php?t=424579"".

 

[twofish-quant]

Because there is no possible way around determinism. It is fundamentally impossible to get out of it.

There is no experimental result that I know of that requires a belief in determinism.
There is no mathematical result that I know of that requires a belief in determinism.

In the absence of experiment or rigorous mathematics, we are no longer in the realm of physics.

A simple proof of determinism just comes from noting that the universe must be self-consistent.

First of all, there is no reason why the universe must be self-consistent. There are workable systems of mathematical logic that allow for inconsistent statements, and I'm open to the possibility that the universe could be modeled by one of those systems.

And if the universe is self-consistent, then it must be describable through a set of entities combined with a set of rules governing the interactions between those entities.

Goedel has mathematically proved otherwise. If you have a self-consistent series of rules, there are well-posed questions that you cannot prove within the set of those rules.

If we write down such a set of rules, and it turns out that it appears to change dependent upon the situation, then we can simply write down a new set of rules that takes that change in situation into account.

Actually you can't. It turns out that you run into some fundamental mathematical limits on computability.

If there is an element of randomness in the universe, then it can always be described via some probability distribution.

And once you are in probability world, then it's non-deterministic.

But I'm pretty sure it's a rock-solid proof for such rules existing, provided you accept that reality cannot contradict itself.

You really need to read up on Kurt Goedel. because he mathematically *PROVED* that any system of logic that is more complex than arithmetic is either incomplete or inconsistent. Also you do need to read up on non-standard logic

http://www.earlham.edu/~peters/courses/logsys/nonstbib.htm

and in particular paraconsistent logic

http://en.wikipedia.org/wiki/Paraconsistent_logic

Paraconsistent logic is interesting because it shows that you can create workable systems of mathematics that allow for non self-consistent statements. There's also Bayesian logic and Dempster-Shafer theory.

 

[twofish-quant]

After a century there are eminent physicists that are trying to formulate a deterministic theory of quantum mechanics

Yes, and I wish them well. One thing that you do end up getting is that in order to rescue determinism you have to go non-local.

Determinism is a scientific argument and not a philosophical/religious beliefs.

Scientific arguments are based on either mathematical proofs or observations. If you want to believe in determinism, that's fine, but you right now have no scientific reason to compel me to believe in that (nor I you).

When you say "I REJECT DETERMINISM!", you are just trying to mix your personal philosophical/religious beliefs with your role as a scientist.

Guilty as charged. But people that insist that the universe must be deterministic are doing the same thing. As long as we keep to either observational evidence or mathematical proof, there's no problem. If you argue that the universe is deterministic, then I consider this a quasi-religious belief that we can agree to disagree on.

What annoys me again is the statement that no scientist worth his salt would be a non-determinist. I have some fairly sound philosophical reasons for rejecting determinism.

But if you are a scientist you are supposed to go beyond textbooks and you can't exclude that quantum mechanics emerge from an underlying deterministic theory (for instance without hidden-variables).

What I can mathematically do demonstrate that if QM is correct, then you cannot have determinism without rejecting locality, and personally a theory that rejects locality is more aesthetically non-pleasing to me than one that is non-deterministic.

You can create interpretations of quantum mechanics that are deterministic, but there is no experimental reason that I know of for choosing those. Now its quite possible that someone will come up with some ironclad reason in ten years showing that the universe indeed must be deterministic, and it's good that people are working on this. Fine, when someone shows me that reason, I'll change my mind.

In science everything is true as long as the contrary has not been proved.

That's really weird philosophy. I claim that there is a bengal tiger outside your room about to eat you up.

Actually, there already exists an extremely interesting deterministic field theory that reproduces exactly quantum mechanics (Feynman path integral, commutation relations, ...). The quantization is achieved by imposing boundary conditions. See tread "https://www.physicsforums.com/showthread.php?t=424579"".

There are lots of interesting deterministic field theories, but the problem is that then you have the problem of locality. A field theory which is deterministic, but in which every particle is influenced by every other particle in the universe, becomes uncomputable, and that paper you have is non-local.