Registered: Oct 2005
Posts: 403

"Now, of course, the single greatest modeling challenge for NKS is fundamental physics." (from David Brown
at http://forum.wolframscience.com/sho...=&threadid=1684)

Mr. Brown, I'm going to pick on you a little bit. But it's not personal. The sentiment you express in that sentence of yours I quoted is a thematic sentiment in a great enough segment of NKS discussion that I've heard, for me to want to say a bit of what I think about it.

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With respect, I understand that the statement you made above represents a view held by many who come to NKS from physics, and while I certainly recognize that an NKS theory of our "physical" world would be a historic breakthrough of the first order, I don't think that the above statement will be true for many people for more than about 15 years (from now)...if it's even true now.

It would be an amazing and profound thing if we, organisms within our "physical" world, modeled the physics of our world with NKS, or modeled them completely with any methodology. It would be the ultimate look in the mirror, perhaps.

But thinking isn't going to stop if that happens, science isn't going to stop if that happens. Even though our world, from our point of view, has a shit-ton of atoms, modeling the particular world we're in, while profound (from our point of view) is hardly the greatest challenge---or even the greatest modeling challenge---for NKS, or any other discipline.

Given the limit of running a simulation of a particular system from within that system...the limitation of running out of building blocks to use for the simulation of the thing as your simulation, in accuracy, in completeness, in size, approaches those of the universe you're simulating...having a GUT, while amazing and useful and profound, won't be the end of modeling...

Modeling the behavior of a corporation who is modeling your behavior, for competitive purposes, for example, will be more of an engineering and a theoretical challenge, I think. Modeling the behavior of the simplest organism or culture of organisms will be a greater challenge than modeling the physical universe...and before you say it, I think that is true even though the world of the corporation, simple organism, and culture I am talking about modeling are of course in actuality built on top of the substrate of our physical universe.

While true, that doesn't matter, practically, for the majority of simulations people do now, or are going to do.

Simulating the universe based on an accurate model of physics is of course highly useful...for understanding and observing in high detail small little parts of what goes on in our world...like the first parts of XYZ-type-of-explosion, etc. And of course whoever creates such a model will be the next Newton, in terms of human history books. And that matters to people's egos, in addition to the accomplishment having real value.

But to say it's the greatest modeling challenge for NKS is just wrong. It might be the greatest in some philosophical sense, it might be the greatest in some sort of metaphysical sense, but in an engineering sense, in a theoretical sense, it is not the greatest challenge for NKS.

If we were living inside an Amiga (if we were complex emergent beings running on an Amiga), then us coming up with a model that matched the output of whatever processor is in an Amiga, would be profound. It would mean a lot to us. (As an aside, it wouldn't even mean that we understood the workings of the Amiga's processor, and it wouldn't give us a clue as to what it might mean from some other organism's point of view that "we were running on an Amiga". But that's not the point I want to assert here. What I want to assert here is that:) Once we modeled the output of the Amiga's processor such that we completely understood the instructions that figured into the running of the universe that we were running on, there would still be lots for us to do...and I think: greater things for us to do, in terms of engineering and theory.

That's because it doesn't matter, in many ways, that we're running on an Amiga. There are probably already many systems in our world (running on top of the physics of our world...systems) that I suspect will be harder to model than the physics of our world...greater challenges of modeling (in an engineering sense, in a theoretical sense) than the modeling of our particular universe. (Assuming you don't have access to the rules of the system...which in *most* cases you won't.) And frankly (and I know that some physicists aren't going to like this) but: coming up with a physics GUT doesn't mean you understand everything that is built with physics. It doesn't even mean you can practically simulate any particular thing that happens as a result of physics. Even theoretically, there are theoretical limits on physical simulation of the universe, from within the universe---correct me if I'm wrong, please, physicists...but even if you could control a huge portion of the atoms in the universe while simulating the universe with those atoms, is it not a snake eating its tail?...is there not a simple, practical limit there on the completeness of a simulation of a thing that is running within the [limited] resources of the thing itself (such that you approach a situation where your simulation *is* the thing, and it becomes completely accurate yet fails to maintain the characteristic of a simulation wherein you can figure out some useful information about a future event *before* it happens...I've been told on this site before that I (misunderstand? misapply? http://forum.wolframscience.com/sho...=&threadid=1371) this idea of Hawking's...but I believe he very clearly says exactly this)? The physics GUT gets a lot of air-time, it's profound, it's elusive, it will add someone's name to the books of human history, but...it's not, in many ways, the end-all be-all that it is sometimes touted as. Whether it's with NKS, or whatever theory, when someone comes up with the first widely-accepted GUT, this is what is going to happen: it'll be on the front page of all the papers, no one will understand it, someone will get their name next to Newton's, and then everyone (regardless of their education) will be like: so now what? And then we'll use the GUT in select simulation projects where it will be exceedingly useful, and the majority of simulation will continue, unaffected and largely uninformed by the particular GUT. Then, some years later, someone is going to come up with another GUT, based on different theory, and they'll work equally well and we'll work on translating the theory of the one into the theory of the other...

Our universe is special to us because it's ours. But systems running essentially in emulation mode on our particular hardware can be more profound to us, as engineers and theoreticians, than the physical universe. (And the fact that one is running on the other does not even mean that the substrative system has a meaningful relationship with the system it supports...knowing everything about physics does not necessarily translate into knowing anything meaningful about a particular system physics supports. This should be clear if you think about it via the Amiga analogy: Linus Torvalds' knowledge of the Linux kernel gets him 0% of the way down the road of understanding many of the programs people run on Linux...maybe I'm running an old Apple OS 9 emulator and programming emergent, sentient beings in C on top of that. There's no meaningful relationship, there, between the thoughts of the emergent beings and the Linux kernel. A theory of the Linux kernel will not essentially be useful or even needed in order to do the more profound (greater?) simulation and modeling of the thoughts of the emergent beings that some of us would want to do if we were other beings within that particular universe...)

I understand, I think, the weight that is put on modeling our particular universe. I agree that is profound from a philosophical point of view and from what I can really best call a metaphysical point of view---or a religious point of view...but beyond the specific religion, essentially, of our particular universe, there are all kinds of other universes to model...and because there are necessarily more than one of those emulated universes, whereas since our universe is one...the one...our *uni*verse...that verse is absolutely not the greatest one we will encounter, even though it certainly has a special place in our understanding.

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crosspost on my site :: http://matthewvantemple.wordpress.c...ysics-and-guts/

Last edited by inhaesio zha on 03-19-2010 at 05:19 AM

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