Matt, I have several objections. First, as I understand it, your statement about the universe having a finite description length only applies to the *observable* universe, not the universe as a whole. The hubble radius expands at the speed of light as more light reaches us, meaning that the observable universe has a longer description length every day. So it does not seem very relevant to say that the description length is finite.
The universe as a whole (observable and not-observable) *could* be finite, but we don't know one way or the other so far as I am aware. Second, I do not agree with your reason for saying that physics is necessarily probabilistic. It seems possible to have a completely deterministic physics, which merely suffers from a lack of information and computation ability. Imagine if the universe happened to follow Newtonian physics, with atoms being little billiard balls. The situation is deterministic, if only we knew the starting state of the universe and had large enough computers to approximate the differential equations to arbitrary accuracy. Third, this is nitpicking, but I also am not sure about the argument that we cannot predict our thoughts. It seems formally possible that a system could predict itself. The system would need to be compressible, so that a model of itself could fit inside the whole. I could be wrong here, feel free to show me that I am. Anyway, the same objection also applies back to the necessity of probabilistic physics: is it really impossible for beings within a universe to have an accurate compressed model of the entire universe? (Similarly, if we have such a model, could we use it to run a simulation of the entire universe? This seems much less possible.) --Abram On Wed, Sep 3, 2008 at 6:45 PM, Matt Mahoney <[EMAIL PROTECTED]> wrote: > I think that computation is not so much a metaphor for understanding the > universe as it is an explanation. If you enumerate all possible Turing > machines, thus enumerating all possible laws of physics, then some of those > universes will have the right conditions for the evolution of intelligent > life. If neutrons were slightly heavier than they actually are (relative to > protons), then stars could not sustain fusion. If they were slightly lighter, > then they would be stable and we would have no elements. > > Because of gravity, the speed of light, Planck's constant, the quantization > of electric charge, and the finite age of the universe, the universe has a > finite length description, and is therefore computable. The Bekenstein bound > of the Hubble radius is 2.91 x 10^122 bits. Any computer within a finite > universe must have less memory than it, and therefore cannot simulate it > except by using an approximate (probabilistic) model. One such model is > quantum mechanics. > > For the same reason, an intelligent agent (which must be Turing computable if > the universe is) cannot model itself, except probabilistically as an > approximation. Thus, we cannot predict what we will think without actually > thinking it. This property makes our own intelligence seem mysterious. > > An explanation is only useful if it makes predictions, and it does. If the > universe were not Turing computable, then Solomonoff induction and AIXI as > ideal models of prediction and intelligence would not be applicable to the > real world. Yet we have Occam's Razor and find in practice that all > successful machine learning algorithms use algorithmically simple hypothesis > sets. > > > -- Matt Mahoney, [EMAIL PROTECTED] > > --- On Wed, 9/3/08, Terren Suydam <[EMAIL PROTECTED]> wrote: > From: Terren Suydam <[EMAIL PROTECTED]> > Subject: Re: [agi] Recursive self-change: some definitions > To: [email protected] > Date: Wednesday, September 3, 2008, 4:17 PM > > > Hi Ben, > > My own feeling is that computation is just the latest in a series of > technical metaphors that we apply in service of understanding how the > universe works. Like the others before it, it captures some valuable aspects > and leaves out others. It leaves me wondering: what future metaphors will we > apply to the universe, ourselves, etc., that will make > computation-as-metaphor seem as quaint as the old clockworks analogies? > > I believe that computation is important in that it can help us simulate > intelligence, but intelligence itself is not simply computation (or if it is, > it's in a way that requires us to transcend our current notions of > computation). Note that I'm not suggesting anything mystical or dualistic at > all, just offering the possibility that we can find still greater metaphors > for how intelligence works. > > Either way though, > I'm very interested in the results of your work - at worst, it will shed > some needed light on the subject. At best... well, you know that part. :-] > > Terren > > --- On Tue, 9/2/08, Ben Goertzel <[EMAIL PROTECTED]> wrote: > From: Ben Goertzel <[EMAIL PROTECTED]> > Subject: Re: [agi] Recursive self-change: some definitions > To: [email protected] > Date: Tuesday, September 2, 2008, 4:50 PM > > > > On Tue, Sep 2, 2008 at 4:43 PM, Eric Burton <[EMAIL PROTECTED]> wrote: > > I really see a number of algorithmic breakthroughs as necessary for > > the development of strong general AI > > I hear that a lot, yet I never hear any convincing arguments in that > regard... > > So, hypothetically (and I hope not insultingly), > I tend to view this as a kind of unconscious overestimation of the > awesomeness of our own > > species ... we feel intuitively like we're doing SOMETHING so cool in our > brains, it couldn't > possibly be emulated or superseded by mere algorithms like the ones computer > scientists > have developed so far ;-) > > > ben > > > > > ------------------------------------------- > agi > Archives: https://www.listbox.com/member/archive/303/=now > RSS Feed: https://www.listbox.com/member/archive/rss/303/ > Modify Your Subscription: https://www.listbox.com/member/?&; > Powered by Listbox: http://www.listbox.com > ------------------------------------------- agi Archives: https://www.listbox.com/member/archive/303/=now RSS Feed: https://www.listbox.com/member/archive/rss/303/ Modify Your Subscription: https://www.listbox.com/member/?member_id=8660244&id_secret=111637683-c8fa51 Powered by Listbox: http://www.listbox.com
