Planck length, Planck time, and computation

[westprog]

In recent threads it has been claimed that a computer simulation which operated, accurately, at the planck level, would be effectively equivalent to reality. The (unstated) implication seems to be that at this level, the universe operates like a huge grid, with pieces moving back and forth like a game of chess.

Firstly, let us look at the pragmatic issues involved. The ratio between the planck length and the width of a proton is comparable in magnitude to the ratio between the width of a proton and the length of the Suez canal. It's therefore entirely impossible that a planck scale simulation of even a single atomic particle could be performed with any conceivable computing machinery. The same applies to the planck time, where the ratio between planck time and a single second is vastly greater than between a second and the age of the universe.

Therefore, to create a planck scale simulation of a human brain, most of the universe would have to be converted into a computer. It might be of interest to consider whether such a simulation would be conscious. I think we can agree that it isn't going to happen any time soon.

However, this is not the main problem with this approach. The assumption is that the universe will be, at this scale, effectively computational in nature. There is no reason at all to assume this. It might possess digital qualities, in the sense that as far as we know, any intervals smaller than the planck length or planck time are not meaningful. However, this does not mean that the envisaged neat grid in fact exists. It means that at this scale, it's not possible to say what position a particle has, or when something actually happens. Far from being computational - i.e. having a predictable, certain outcome - reality as we know it simply does not apply.

N.b. I put this as a separate thread as I didn't want to derail the main discussion on consciousness. However, I didn't want to place it in the physics forum as it directly relates to and arises from issues discussed here.

 

[!Kaggen]

In recent threads it has been claimed that a computer simulation which operated, accurately, at the planck level, would be effectively equivalent to reality. The (unstated) implication seems to be that at this level, the universe operates like a huge grid, with pieces moving back and forth like a game of chess.

Firstly, let us look at the pragmatic issues involved. The ratio between the planck length and the width of a proton is comparable in magnitude to the ratio between the width of a proton and the length of the Suez canal. It's therefore entirely impossible that a planck scale simulation of even a single atomic particle could be performed with any conceivable computing machinery. The same applies to the planck time, where the ratio between planck time and a single second is vastly greater than between a second and the age of the universe.

Therefore, to create a planck scale simulation of a human brain, most of the universe would have to be converted into a computer. It might be of interest to consider whether such a simulation would be conscious. I think we can agree that it isn't going to happen any time soon.

However, this is not the main problem with this approach. The assumption is that the universe will be, at this scale, effectively computational in nature. There is no reason at all to assume this. It might possess digital qualities, in the sense that as far as we know, any intervals smaller than the planck length or planck time are not meaningful. However, this does not mean that the envisaged neat grid in fact exists. It means that at this scale, it's not possible to say what position a particle has, or when something actually happens. Far from being computational - i.e. having a predictable, certain outcome - reality as we know it simply does not apply.

N.b. I put this as a separate thread as I didn't want to derail the main discussion on consciousness. However, I didn't want to place it in the physics forum as it directly relates to and arises from issues discussed here.

This should definitely be in the religion section as I cannot imagine how anyone would take Planck scale simulation seriously except as a belief system.

Kind of reminds me a lot of Tippler's book "The Physics of Immortality".
A joke from the beginning tell the end with the crowning joke being the mathematical proofs in the appendices.

 

[Beerina]

Therefore, to create a planck scale simulation of a human brain, most of the universe would have to be converted into a computer. It might be of interest to consider whether such a simulation would be conscious. I think we can agree that it isn't going to happen any time soon.

This assumes the human brain, as a computational device, relies on anything at the subatomic level.

Whatever the physical process is that supports the real, existing phenomenon of consciousness, I see no need to rely on the more funky and tiny aspects of quantum mechanics and so on.

 

[westprog]

This assumes the human brain, as a computational device, relies on anything at the subatomic level.

Whatever the physical process is that supports the real, existing phenomenon of consciousness, I see no need to rely on the more funky and tiny aspects of quantum mechanics and so on.

In general, I agree, and that's one reason why I put this thread separately from the rest. I don't think the nature of reality at the Planck scale has anything to do with any current theory of consciousness, unless it's Penrose's tentative ideas on quantum gravity.

 

[rocketdodger]

The (unstated) implication seems to be that at this level, the universe operates like a huge grid, with pieces moving back and forth like a game of chess.

Not really. The implication is just that any physical system can be *fully* described I.E. modeled to 100% observable accuracy using a finite amount of resources.

Firstly, let us look at the pragmatic issues involved. The ratio between the planck length and the width of a proton is comparable in magnitude to the ratio between the width of a proton and the length of the Suez canal. It's therefore entirely impossible that a planck scale simulation of even a single atomic particle could be performed with any conceivable computing machinery. The same applies to the planck time, where the ratio between planck time and a single second is vastly greater than between a second and the age of the universe.

Therefore, to create a planck scale simulation of a human brain, most of the universe would have to be converted into a computer. It might be of interest to consider whether such a simulation would be conscious. I think we can agree that it isn't going to happen any time soon.

But you are neglecting the implication of planck time -- that a 100% observably accurate model/simulation of any physical system can be single stepped and remain 100% observably accurate.

Thus we could build such a simulated brain with far less resources than you suggest if we use a single CPU for all the calculation, etc. In that case the vast majority of the resources will go to nothing but memory for each elementary particle, which would be what, position and velocity and a bunch of other parameters that go into the quantum calculations?

You don't even need to keep track of the interactions between particles since that is all derivable given their basic attributes.

So the memory required would be just some order of magnitude more than the number of fundamental particles in a human brain. Given that there are already 8 billion such brains on Earth alone, it is obvious that we have enough material to build a simulation with at least 8 billion fundamental particles of storage for each simulated fundamental particle without even leaving our planet.

ETA: Although I admit that in this case it would just take an amazingly long time to simulate even a single neuron firing, never mind the whole brain doing something for any significant amount of time.

However, this is not the main problem with this approach. The assumption is that the universe will be, at this scale, effectively computational in nature. There is no reason at all to assume this. It might possess digital qualities, in the sense that as far as we know, any intervals smaller than the planck length or planck time are not meaningful. However, this does not mean that the envisaged neat grid in fact exists. It means that at this scale, it's not possible to say what position a particle has, or when something actually happens. Far from being computational - i.e. having a predictable, certain outcome - reality as we know it simply does not apply.

You get the wrong assumption.

That was never the assumption.

The assumption is that if those intervals are not meaningful, it means any difference between two systems that are less than those intervals will not result in any observable difference in the behavior of the two systems.

In other words, a fundamental particle 1.5 planck lengths from another one will have the same behavioral influence as one that is 1.4 or 1.6 planck lengths from the other one.

The implication of this is that regardless of whether or not the actual stuff going on is computable, the observable behavior of the universe is computable, and that is all that is needed.

Because what else can you care about besides observable behavior? If it is not observable, what does it matter?

 

[PixyMisa]

In recent threads it has been claimed that a computer simulation which operated, accurately, at the planck level, would be effectively equivalent to reality. The (unstated) implication seems to be that at this level, the universe operates like a huge grid, with pieces moving back and forth like a game of chess.

As rocketdodger noted, that is not necessarily true. What is true is that we can't tell the difference, not in practice, not even in principle.

Therefore, to create a planck scale simulation of a human brain, most of the universe would have to be converted into a computer. It might be of interest to consider whether such a simulation would be conscious. I think we can agree that it isn't going to happen any time soon.

Well, obviously it's not going to happen.

Equally obviously, it would be conscious. Anything else is impossible.

However, this is not the main problem with this approach. The assumption is that the universe will be, at this scale, effectively computational in nature.

No. There is no such assumption.

 

[PixyMisa]

In general, I agree, and that's one reason why I put this thread separately from the rest. I don't think the nature of reality at the Planck scale has anything to do with any current theory of consciousness, unless it's Penrose's tentative ideas on quantum gravity.

Then you have entirely missed the point.

The Planck scale simulation is - as I have said more than once - a reductio ad absurdum counter to the anti-computational argument.

If you don't accept that such a simulation would be conscious, then you believe in magic, or in something even more irrational.

If you do accept that such a simulation would be conscious, but have objections to other points in the discussion, then there may be a basis for worthwhile discussion.

But this is the sticking point. This is the fundamental nature of reality. If you can't accept this, then there is no possibility of rational debate.

 

[Beth]

Because what else can you care about besides observable behavior? If it is not observable, what does it matter?

Consciousness is not an observable behavior and that seems to be something that matters.

 

[Beth]

Then you have entirely missed the point.

The Planck scale simulation is - as I have said more than once - a reductio ad absurdum counter to the anti-computational argument.

If you don't accept that such a simulation would be conscious, then you believe in magic, or in something even more irrational.

If you do accept that such a simulation would be conscious, but have objections to other points in the discussion, then there may be a basis for worthwhile discussion.

But this is the sticking point. This is the fundamental nature of reality. If you can't accept this, then there is no possibility of rational debate.

I'm willing to accept that such a simulation might be conscious, but I don't feel certain that it would be conscious. That doesn't mean I believe in magic, it only means I believe that we don't understand consciousness very well at this point. Which should not a controversial position.

When you require your fellow conversationalists to either declare allegiance to that absolutist position or be dismissed as incapable of rational debate, well, that's why I don't bother to respond to many of your posts. It seems pointless to me.

 

[AlBell]

SRIP!!! Church-Turing !!! Read GEB and oh yeah Strange Loop !!!! Planck !!!

wipe off keyboard, repeat

 

[PixyMisa]

I'm willing to accept that such a simulation might be conscious, but I don't feel certain that it would be conscious. That doesn't mean I believe in magic, it only means I believe that we don't understand consciousness very well at this point. Which should not a controversial position.

Sorry, but no. There's no escape hatch.

The simulation is identical in every respect to our world. Either you accept that the simulation would produce consciousness, or you believe in magic.

When you require your fellow conversationalists to either declare allegiance to that absolutist position or be dismissed as incapable of rational debate, well, that's why I don't bother to respond to many of your posts. It seems pointless to me.

Reality is what it is, not what it seems to you.

 

[rocketdodger]

Consciousness is not an observable behavior and that seems to be something that matters.

wtf?

If you can't observe your consciousness, Beth, then why on Earth do you think you are conscious?

 

[rocketdodger]

I'm willing to accept that such a simulation might be conscious, but I don't feel certain that it would be conscious. That doesn't mean I believe in magic, it only means I believe that we don't understand consciousness very well at this point. Which should not a controversial position.

When you require your fellow conversationalists to either declare allegiance to that absolutist position or be dismissed as incapable of rational debate, well, that's why I don't bother to respond to many of your posts. It seems pointless to me.

But this position reduces to agreement or disagreement that 1 = 1. It is just that simple.

If you agree with monism, then you agree that a 100% accurate simulation of said monism will behave identically to said monism.

If you agree with monism, but think that a 100% accurate simulation would still be "missing" something, then .... you don't really agree with monism.

The identical behavior is implicit in the simulation. That is how it is defined -- a 100% accurate simulation! So your position seems to be that a 100% accurate simulation won't actually be 100% accurate. In other words, that 1 != 1. That is dualism, and it is nonsense.

 

[Beth]

But this position reduces to agreement or disagreement that 1 = 1. It is just that simple.

If you agree with monism, then you agree that a 100% accurate simulation of said monism will behave identically to said monism.

If you agree with monism, but think that a 100% accurate simulation would still be "missing" something, then .... you don't really agree with monism.

The identical behavior is implicit in the simulation. That is how it is defined -- a 100% accurate simulation! So your position seems to be that a 100% accurate simulation won't actually be 100% accurate. In other words, that 1 != 1. That is dualism, and it is nonsense.

No.

 

[gentlehorse]

Consciousness is not an observable behavior and that seems to be something that matters.

wtf?

If you can't observe your consciousness, Beth, then why on Earth do you think you are conscious?

I don't have a dog in this fight, but I don't think she's arguing that the consciousness is unobservable in the first person. She seems to be arguing that it might be possible for an entity to exhibit all the characteristics of human-like consciousness without actually experiencing consciousness, and that there is no way for an observer of the entity's behavior to determine whether it stems from the actual experience of consciousness. P-zombies leap to mind.

I'm sure she'll correct me if I'm reading her wrong.


I should know better than to post in R&P...

 

[Beth]

wtf?

If you can't observe your consciousness, Beth, then why on Earth do you think you are conscious?

I meant, but did not phrase well, that I can be conscious without betraying any sign of it. So how do we define it in such as way as to be able to objectively tell when a machine is conscious?

 

[westprog]

I'm willing to accept that such a simulation might be conscious, but I don't feel certain that it would be conscious. That doesn't mean I believe in magic, it only means I believe that we don't understand consciousness very well at this point. Which should not a controversial position.

When you require your fellow conversationalists to either declare allegiance to that absolutist position or be dismissed as incapable of rational debate, well, that's why I don't bother to respond to many of your posts. It seems pointless to me.

There is no physical theory that claims that even a totally accurate simulation is equivalent to the thing simulated. Funnily enough, in spite of the insistence that not to believe this is to believe in magic, there is no scientific evidence whatsoever to say that a simulation is equivalent in any way to the thing simulated. The justification for this bizarre belief system is usually along the lines of "well, why wouldn't it be?". It's like believing that a voodoo dolly is equivalent to a person. There's just no justification for it.

Secondly, while it may be (and this is again not known, in spite of the misinterpretation of the concept of planck length) that the universe has a finite (though very large) number of states, that does not of itself imply that the universe is computable. In order for the universe to be computable, it's necessary that one state is inevitably followed by exactly one other state. Modern physics says that this is not the case. Of course, real physics is always shunted aside, as we've seen from the digressions on relativity, entropy, Church-Turing and everything else. No references to actual physics, lots of hand-waving and "surely this must mean...".

 

[Malerin]

I don't have a dog in this fight, but I don't think she's arguing that the consciousness is unobservable in the first person. She seems to be arguing that it might be possible for an entity to exhibit all the characteristics of human-like consciousness without actually experiencing consciousness, and that there is no way for an observer of the entity's behavior to determine whether it stems from the actual experience of consciousness. P-zombies leap to mind.

I'm sure she'll correct me if I'm reading her wrong.


I should know better than to post in R&P...

You can observe your own consciousness through introspection, but consciousness isn't a behavior. More to your point, a person deep in thought and a life-like mannequin would both exhibit the same conscious behavior.

 

[Malerin]

There is no physical theory that claims that even a totally accurate simulation is equivalent to the thing simulated. Funnily enough, in spite of the insistence that not to believe this is to believe in magic, there is no scientific evidence whatsoever to say that a simulation is equivalent in any way to the thing simulated. The justification for this bizarre belief system is usually along the lines of "well, why wouldn't it be?". It's like believing that a voodoo dolly is equivalent to a person. There's just no justification for it.

Secondly, while it may be (and this is again not known, in spite of the misinterpretation of the concept of planck length) that the universe has a finite (though very large) number of states, that does not of itself imply that the universe is computable. In order for the universe to be computable, it's necessary that one state is inevitably followed by exactly one other state. Modern physics says that this is not the case. Of course, real physics is always shunted aside, as we've seen from the digressions on relativity, entropy, Church-Turing and everything else. No references to actual physics, lots of hand-waving and "surely this must mean...".

This is really at the heart of it, and seems a very elementary point: a broken power plant and a simulation of a working power plant are the same in that they both don't produce electricity.

 

[Beth]

I don't have a dog in this fight, but I don't think she's arguing that the consciousness is unobservable in the first person. She seems to be arguing that it might be possible for an entity to exhibit all the characteristics of human-like consciousness without actually experiencing consciousness, and that there is no way for an observer of the entity's behavior to determine whether it stems from the actual experience of consciousness. P-zombies leap to mind.

I'm sure she'll correct me if I'm reading her wrong.

I don't think p-zombies can exist. Likewise, I don't think a 100% accurate simulation can exist either. They are interesting thought experiments is all.

You can observe your own consciousness through introspection, but consciousness isn't a behavior. More to your point, a person deep in thought and a life-like mannequin would both exhibit the same conscious behavior.

I think consciousness may well be consider a behavior. At some point in some previous thread, a poster referred to it as 'private behavior'. That prhase seems fairly apropos to me.