On Sunday, July 14, 2024 at 5:42:23 AM UTC+2 Jason Resch wrote:



On Sat, Jul 13, 2024, 9:54 PM PGC <multipl...@gmail.com> wrote:



On Sunday, July 14, 2024 at 3:51:27 AM UTC+2 John Clark wrote:

Yes it's possible to have a universal Turing machine in the sense that you 
can run any program by just changing the tape, however ONLY if that tape 
has instructions for changing the set of states  that the machine can be 
in. 



It still boggles my mind that matter is Turing-complete.


Turing completeness, as incredible as it is, is (remarkably) easy to come 
by. You can achieve it with addition and multiplication, with billiard 
balls, with finite automata (rule 110, or game of life), with artificial 
neurons, etc. That something as sophisticated as matter could achieve it is 
to me less surprising than the fact that these far simpler things can.


In hindsight, every result is easy to come by. You assume sophistication to 
beat simplicity. That's just weird, given how little we actually know. 
Without that simplicity for example, we wouldn't have discovered computers.
 



And this despite parts of physics being not Turing emulable. 

Finite physical system's can be simulated to any desired degree of 
accuracy, and moreover all known laws of physics are computable. Which 
parts of physics do you refer to when you say there are parts that aren't 
Turing emulable?


? You write so much about these topics, I cannot understand how you make 
that statement. Many of the known laws are but there is so much more to 
physics than known laws and their solutions. And to any desired degree of 
accuracy? I'll write fast and clumsily as I am by no means an expert and 
gotta go: 

Some finite-state physical phenomena present significant challenges to 
computational simulation due to their inherent complexity and the 
limitations of current computational models. One example is quantum 
entanglement and superposition. In quantum mechanics, particles can exist 
in multiple states simultaneously, which you know, and influence each other 
instantaneously at a distance, a phenomenon known as entanglement. 
Simulating these quantum behaviors on classical Turing machines is 
inherently difficult because it requires representing exponentially growing 
state spaces. 

Turbulence in fluid dynamics is another challenging phenomenon. Turbulent 
flow in fluids features chaotic and unpredictable patterns, including 
vortices and eddies. Although Navier-Stokes equations describe fluid flow, 
solving these equations accurately (really accurately, beyond engineering 
application) for turbulent systems is computationally intensive and doesn't 
look feasible for all conditions, particularly at high Reynolds numbers 
where the flow becomes highly chaotic. This makes precise simulation of 
turbulent behavior quite the biscuit. Tao had the paper about when we can 
expect blow out and the results are sobering at this time. 

Weather systems also exemplify the difficulties in simulating complex 
physical phenomena. Despite significant advancements in weather modeling, 
predicting weather with high precision over long periods remains a 
challenge due to the chaotic elements and the large number of interacting 
factors involved. The inherent unpredictability of weather systems 
underscores the limitations of current computational approaches.

Magnetohydrodynamics (MHD) adds another layer of complexity, particularly 
when modeling fusion processes and fluid behavior in stars, which also 
boggles my mind. MHD describes the dynamics of electrically conducting 
fluids like plasmas, liquid metals, and saltwater, combining principles 
from both magnetism and fluid dynamics. The equations governing MHD are 
highly nonlinear and coupled, making them difficult to solve to understate 
things. Simulating fusion reactions, such as those occurring in stars, 
involves not only MHD but also nuclear physics, thermodynamics, radiation 
transport, and things I can't probably name. These interactions take place 
under extreme conditions of temperature and pressure, further complicating 
the modeling efforts. This is some fancy shit, but do show me any 
simulation you know of with high or infinite accuracy.

In the context of astrophysics, modeling the behavior of fluids in stars, 
such as the convective and radiative zones, requires simulating the 
intricate interplay between gravity, fluid dynamics, magnetic fields, and 
nuclear fusion. The immense scales involved, both in terms of size and 
time, along with the chaotic nature of the processes, make it a challenging 
task to say the least. Accurate simulations of these phenomena are crucial 
for understanding stellar evolution, but they remain computationally 
intensive and challenging due to the complex, multi-physics nature of the 
problem.

Biological systems, such as protein folding, further illustrate the 
challenges of finite-state simulations. Protein folding involves a protein 
chain finding its energetically favorable three-dimensional structure, 
which is critical for its biological function. The number of possible 
configurations for a protein is astronomical, making it a computationally 
hard problem. Although molecular dynamics simulations and AI have advanced 
our understanding here and there, achieving precise predictions for protein 
folding remains difficult due to the immense complexity of the process.

These examples are just what springs to mind immediately but there are so 
many other things like gravity, solving the field equations in GR etc. etc. 
etc. which highlight the significant challenges posed by complex physical 
systems to computational simulation. While ongoing advancements in 
computational methods and technologies continue to improve our ability to 
simulate these phenomena, certain aspects of their behavior remain unclear 
to say the least, emphasizing the need for further research and development 
in both computational theory and physical sciences. 

Again, I would have thought that you reading this list for years, just like 
most regular members/poster, are aware of these difficulties. What can I 
say Jason? There's unknown stuff too. And LLMs by themselves are zombies. 
;-)

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