On 12 Sep 2011, at 21:07, Evgenii Rudnyi wrote:

## Advertising

On 9/12/2011 8:06 AM Jason Resch said the following: ...What about of dumb water molecules, can they not form a wave? Complex things can result from very simple rules, when you have a huge number of those simple things interacting with each other.I will use this example to continue my thoughts about Simulation Hypothesis and Simulation Technology http://blog.rudnyi.ru/2011/09/simulation-hypothesis-and-simulation-technology.htmlI will change the original question as follows. Can we simulate awave starting from water molecules?

`I am not sure it makes sense a priori to talk about the simulation of`

`something physical, if only because those are not well defined.`

`Now if you accept QM, then, the answer is YES. A quantum computer can`

`simulate any physical process, even in polynomial time. Just compute`

`the heisenberg matrix, with some rational approximations. The quantum`

`errors will not grow, thanks to linearity, so you will get your water`

`wave rather well simulated, and then you can simulate that quantum`

`water wave with a classical computer, but you will have an exponential`

`slow down (which is of no concern for the simulated entities which`

`might be there).`

I will consider it not in principle, but rather in the objectivereality given to us in sensation. (This what I have learned in theUSSR: Vladimir Il'ich Lenin: "Matter is the objective reality givento us in sensation")

`The USSR was a religious state. That matter is the objective reality`

`is the gross Aristotelian extrapolation from sensations programmed by`

`billions of years of evolution.`

If we imagine brute-force simulation, then the answer is definite no.

`Due to the real numbers, but with the quantum equation, we can limit`

`ourselves to rational (complex) numbers.`

Even if we consider a level of molecular simulation when the watermolecules are considered classically with a given force field, thenit is definitely out of reach, also for foreseeable future. TheMoore law just does not help.In what sense then do we usually say "Yes, we can do it"? Presumablythis means that we do not have to simulate each molecule to simulatea wave. The laws of continuum mechanics actually suffice. If weconsider this numerically, then there is nice way to come tocontinuum mechanics through coarse-graining. One can think forexample of dissipative particle dynamics (DPD, some equivalent ofmolecular dynamics) where we simulate not water molecules but ratherbigger pseudo-particles. Funny enough DPD is pretty similar tosmooth particle hydrodynamics (SPH), an alternative method todiscretize the Navier-Stokes equations. In this sense a pseudo-particle is some equivalent of a cell in finite elements/finitevolumes. In a way, molecular dynamics is also could be considered asa course-graining scheme. First we use quantum chemistry to evaluatethe force field and then we use it at the next level.In this sense, an interesting question is how simulation hypothesisis supposed to work. As brute-force simulation? Or along the secondway?

`The second way, with rational approximation of the waves (quantum or`

`classical).`

`But all this is not relevant for mechanism, which assumes that the`

`brain is already a simulator. So it has already make the comp`

`truncation, so it might be simulable, even if its material components`

`are not simulable (as it needs to be the case: I recall that if *I* am`

`a machine, then the physical reality (which emerge) cannot be`

`simulable by a computer, but is given as a limiting process pertaining`

`on *all* computations). To sum up: if I am a machine, the physical`

`universe is not a machine, nor is the appearance of the primary matter.`

Bruno http://iridia.ulb.ac.be/~marchal/ -- You received this message because you are subscribed to the Google Groups "Everything List" group. To post to this group, send email to everything-list@googlegroups.com. To unsubscribe from this group, send email to everything-list+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/everything-list?hl=en.