1. ## Simulation

Simulations is a computerized reproduction or image of a situation or set of conditions used to model a real-life situation. So what are some events that cannot be simulated anyways?

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2. ## Re: Simulation

Do you mean in theory or reality?

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Convenience is the first step to enslave yourself. Freedom is inconvenient.

3. ## Re: Simulation

I would like to hear both, but I first ment in reality.

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4. ## Re: Simulation

This question may still be too open-ended depending upon what you are looking for. Deciding what "cannot be simulated" and what is "exceedingly difficult to simulate" often blurs at various boundaries and it is not just as simple as a distinction between theory and reality. As an example, simulating multi-body gravitational systems is difficult. But note that we can simulate these systems. However, due to perturbative effects, that simulation will not necessarily correspond to reality and then one has to ask if we are really and truly simulating it. For many problems in physics, it is impossible to calculate what actually happens. Yes, we know the laws governing the situation, but if there are more than two or three objects obeying these laws, the equations become so complicated that they are virtually impossible to solve exactly. The idea of simulation also speaks, of course, to the complexity of the system, to what degree it is conformational, and the degree to which we have insight into the variables of the system. Understand also that there are whole classes of problems that cannot be simulated digitally (almost any non-linear math application will highlight this).

In general, the uncertainty principle of quantum mechanics has a lot to say on what we can simulate. For example, the theory known as Quantum Chromodynamics (QCD) when formulated with a finite quark density has what is known as a "complex fermion determinant". This cannot be simulated by any simulation methods we know of but many feel that something will be possible. The notion of something called "quantum entanglement" is also something that cannot be simulated right now. Also it is the case that quasiclassical molecular dynamics interactions can be simulated but there is a huge question still open about just how accurate these are for things known as "nonadiabatic transitions". If they are not accurate at all then, in reality, we are not able to do these kinds of simulations. Speaking of that last point, cellular dynamics and genetic modelling is a big area of research right now in terms of how certain elements can be simulated. In theory this is all very much possible; in reality, we have a long way to go. Also consider quantum computers. Certain elements of these types of systems cannot be simulated simply because the simulations would be larger than the thing being simulated in the first place.

Just a few other things:

<UL TYPE=SQUARE><LI>It is the case, with NASA, that microgravity vacuum environments cannot be simulated on Earth at a sufficient scale which is why some experiments simply have to be done in space.
<LI>Systems with emergent properties (like consciousness) can be very difficult to simulate, bringing up the notion of just how far the concept of "artificial intelligence" will get.
<LI>Mental processes within human beings can often not be simulated, particularly when one gets to the level of what is known as "content fixation". There are some who believe that, in theory, this will become possible.
<LI>An interesting paper by Takayuki Kitamura (and a few others) called "Atomic Mechanics Simulation on Nucleation Process of Grain Boundary Groove in Aluminum Conductor of Microelectronic Packages" showed how even relatively simple things cannot always be simulated.[/list]

However consider that some things can be simulated with a great degree of exactness. As just one example, current simulations of the human heart (which is composed of millions of simulated nerve and muscle cells, which in turn are composed a dozens of simulated ion channels in a simulated cell membrane) are extremely accurate, so much so that these are routinely used to study heart disease and the effects of drugs. Structural simulation is now a very good science, used in various engineering and construction projects around the world. Queuing theory is an excellent example of a simulation-type modeling that shows practical benefits in wide areas of application.

Basically the things that often cannot be simulated (at least so far as we are able to do so) are those things that are described as having complex interrelations between variables or if they have emergent and/or epiphenomenal properties. Remember also that much of simulation can be a study of approximations depending upon the nature of the simulations.

[This message has been edited by Cryptonomic (edited 12-17-2002).]

5. ## Re: Simulation

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[This message has been edited by jonno (edited 12-17-2002).]

6. ## Re: Simulation

I was going to say the same thing, but Crypto beat me to it

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Steve_Jones@SoftHome.net

7. ## Re: Simulation

<BLOCKQUOTE><font size="1" face="Verdana, Arial, Helvetica">quote:</font><HR>Originally posted by mugerem:
Simulations is a computerized reproduction or image of a situation or set of conditions used to model a real-life situation. So what are some events that cannot be simulated anyways?

<HR></BLOCKQUOTE>

How about the unexpected event?

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-- Jean

Something that you say or do today will make a difference to someone else.
Make it a GOOD thing!

8. ## Re: Simulation

<BLOCKQUOTE><font size="1" face="Verdana, Arial, Helvetica">quote:</font><HR>Originally posted by Jeanj:
How about the unexpected event?
<HR></BLOCKQUOTE>

Many simulations are designed such that unexpected events can be ferreted out, at least to some degree. This is the case with open-ended simulations, for example, that model systems with free variables. That also speaks to what I mentioned regarding systems that have emergent properties or elements of systems that could be considered epiphenomenal. (In fact, many risk-based simulation systems are designed for exactly this kind of thing: to simulate situations in a relatively open-ended fashion, subject to certain boundary conditions or contraints, and then see what can potentially emerge in the simulation. If the simulation is an accurate representation of the real world, you can do some predictive modeling of unexpected events. That is part of being proactive. Performance simulations in software testing are a perfect example of this.)

It is a good point you raise, though. Do we actually simulate the unexpected event? By definition of intent we do not because that is why we say it was unexpected. But, in reality, if the unexpected event happens as part of the simulation then, of course, it has been simulated. So unexpected events can be simulated (and often are), even if they were not foreseen in all of their particulars.

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9. ## Re: Simulation

I thank to you all for giving me the different extent about simulation. Aspecially to Cryptonomic. I was thinking about mind infact. I thought that the mind is not been fully understood at all, so how could it be simulated...Which the info that I got explains it well...
And yes I am glad I asked
Thank you..

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10. ## Re: Simulation

<BLOCKQUOTE><font size="1" face="Verdana, Arial, Helvetica">quote:</font><HR>Originally posted by mugerem:
I was thinking about mind infact. I thought that the mind is not been fully understood at all, so how could it be simulated...<HR></BLOCKQUOTE>

"Mind" is actually a wide topic but, with that, you are correct that large parts of this are not understood. What is understood (to varying degrees) are the underlying biological bases of what makes up the mind - i.e., the brain. In other words, if we understand the basis of what allows the concept of a "mind" to exist, it is interesting to consider to what extent we may be able to simulate that concept of "mind" rather than just its underlying basis.

In fact, one of the growing theories about those who study the mind and the brain is that the notion of "intelligence" arises from an ability to mentally simulate the world around us or to simulate situations within the context of that world. Simulation, by this logic, is a very powerful method for improving your survival ability because if you can simulate, you can plan and anticipate. The theory goes on to say that once you simulate the world, it follows almost automatically that you get an ability for abstract thought. One of the "symbols" you acquire is that of your "self". And beyond that lies the notion of consciousness. If you are interested in that kind of thing, I highly recommend Antonio Damasio's book The Feeling of What Happens: Body and Emotion in the Making of Consciousness.

This also speaks to the notion of artificial intelligence. Many would argue that the brute-force simulation of a thinking brain no more produces a thinking brain than the simulation of anthing else. (Or, more accurately, no more produces an actual mind.) These people would argue that the notion of consciousness is a biological consequence of the phsyical nature of brains. Without biological brains, or objects that reproduce the objective sensation of consciousness, no consciousness is possible. For more on that kind of thing (both for and against the idea) you might read Roger Penrose. Two books are The Emperor's New Mind and Shadows of the Mind.

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