Re: Let There Be Something
On Nov 6, 2005, at 2:34 AM, Russell Standish wrote:On Sat, Nov 05, 2005 at 09:57:17AM -0500, Bob Hearn wrote:However, one can easily imagine a perceptual 2D world existing for conscious entities. Even if there is no self-consistent 2D physics leading to atoms, planets, etc., one can computationally simulate Flatland (a la Abbott) or a Planiverse (a la Dewdney) in a 3D universe, with no requirement for a consistent micro-physics. (In fact the Planiverse is my simulation domain for my AI work.)Assuming computationalism, I would argue that conscious observersexperiencing 2D environment are possible, but perhaps unlikely. Why?Because 2D networks are highly constrained, and so it is difficult toevolve complex structures in 2D. 3D and higher is not so constrained,so evolution is possible.I wasn't clear... I wasn't suggesting a simulation at the atomic-equivalent level, on the assumption that such might not be consistently possible. Instead I was suggesting designing or evolving intelligent creatures in a computer, in a 3D world, but creatures whose perceptual environment is a 2D world, simulated at some gross physical level. Conceivably even a human brain, suitably modified, could exist in such a perceptual environment, without realizing it was "really" a 3D entity.Bob - Robert A. Hearn [EMAIL PROTECTED] http://www.swiss.ai.mit.edu/~bob/
Re: Let There Be Something
On Nov 5, 2005, at 2:22 AM, Russell Standish wrote:Game of Life is an example 2D system capable of universalcomputation. I'm not sure this implies consciousness is possible in2D, but it needs to be considered.It does imply that if the Game of Life is the laws of physics of your universe, then consciousness is possible, because at the very least a 3D physics could be simulated. Whether that should be interpreted as consciousness in 2D may be a subtle issue, because the perceptual world of the conscious entities would be 3D - perhaps that was your point?However, one can easily imagine a perceptual 2D world existing for conscious entities. Even if there is no self-consistent 2D physics leading to atoms, planets, etc., one can computationally simulate Flatland (a la Abbott) or a Planiverse (a la Dewdney) in a 3D universe, with no requirement for a consistent micro-physics. (In fact the Planiverse is my simulation domain for my AI work.)So, whether it's the base physical reality you care about, or the perceived reality of the conscious entities, I would say 2D consciousness is possible. (Admittedly, in the latter case, one has to consider whether the 2D creatures could at some point develop science sufficient to prove that they must be simulated in some higher-dimensional physics!)I think Turing machines are impossible in 1D, however...No, there are 1D cellular automata that are computation universal. Here's an abstract from a paper showing it; I don't seem to be able to find the paper online. The paper is from 1990. However, there are references to earlier constructions, e.g. here: http://www.stephenwolfram.com/publications/articles/mathematics/85-twenty/18/text.html . Again, I can't find the cited paper online.The relevant Mathworld page is rather confused and misleading: http://mathworld.wolfram.com/UniversalCellularAutomaton.htmlThere it seems that by "universal" they mean that there is a certain class of 1D CA that can simulate any other 1D CA in that class. Hmm, so what? Cute, but hardly surprising. Mathworld is a great site, but it's too bad in some ways it's so tied in with the Wolfram mythos. There's a huge spin put on pages like the one above that you have to try to penetrate.Bob - Robert A. Hearn [EMAIL PROTECTED] http://www.swiss.ai.mit.edu/~bob/
Re: What is the 'Unruh Effect'?
Hello, list. I occasionally posted here, years ago; lately I've lurked. Russell, your book is high on my 'to read' list! On Oct 7, 2005, at 6:04 PM, Stephen Paul King wrote: Hi Russell and Friends, I just ran across the following post and thought that you might find it interesting. Any comments? Onward! Stephen One comment - the Unruh effect has some strange consequences. There was a result last year that two observers sharing an entangled states (e.g. EPR pairs) will disagree on the degree to which they are entangled, if one observer is in an accelerated frame. This is truly bizarre. Paper at http://www.arxiv.org/abs/quant-ph/0410172 . From the abstract: Two observers determine the entanglement between two free bosonic modes by each detecting one of the modes and observing the correlations between their measurements. We show that a state which is maximally entangled in an inertial frame becomes less entangled if the observers are relatively accelerated. This phenomenon, which is a consequence of the Unruh effect, shows that entanglement is an observer-dependent quantity in non-inertial frames. Bob Hearn - Robert A. Hearn [EMAIL PROTECTED] http://www.swiss.ai.mit.edu/~bob/
