4 ms·

Wouldn't that physical analogy be caused by factors unknown to this algorithm though? Air flux, non-homogeneous air, air impurity etc. Would flames not be symm

by xster 9y ago

Wouldn't that physical analogy be caused by factors unknown to this algorithm though? Air flux, non-homogeneous air, air impurity etc. Would flames not be symmetrical if all of the above plus everything imaginable like quantum physics, solar activity, dark matter, wtv, are all controlled for?

godelski 9y ago
If we're going to the level of QM, then no. Because QM is inherently a random process. Like radioactive decay is a great way to make true random number generators. The real world has truly random events, and while it bothers many people, physicists don't generally argue about this point (anymore). Maybe if you had a perfectly homogeneous air density (which you'd never see, even in a really good vacuum and near absolute zero temperature. You can thank QM for that), that constantly stayed homogeneous. Problem in real world conditions is that nothing is perfectly homogeneous (entropy exists), so things will heat up unevenly, certain parts will gain more velocity than others, and just a small offset can create a large change in outcome. Short answer is that these systems are chaotic in nature, so they are not stable. But that doesn't have anything to do with simulations (except what you are trying to emulate). As far as simulations, numerical accuracy will play a role, but really what you look for is if it is realistic, because the real world has random events. That's more what I was trying to get at. You want something that represents reality, not an overly simplified example that you can't use in a meaningful way. Even with these inaccuracies you can get representative models (they will reflect what happens in a physical experiment). And I say representative, because you aren't going to account for all those factors in a simulation, but you are accurate enough to make extremely effective conclusions. I'll even note that some people will add random noise into their simulations (I don't know if this author did, but numerics can play that role).
- spynxic 9y ago
  > The real world has truly random events, and while it bothers many people.. Replace the word random with unpredictable and it shows why some people are bothered. To say something is fundamentally unpredictable means that it is immeasurable and not merely complex.
  - dragonwriter 9y ago
    > To say something is fundamentally unpredictable means that it is immeasurable. No, it just means that the measure cannot be predicted in advance. OTOH, the observer effect can make measurement problematic.
    - godelski 9y ago
      This is true (Heisenberg uncertainty more says you can only get so much resolution in your measurement), but I was staying more general because there are other events that are random. Radioactive decay is completely random and isn't affected by an observer.
      - cjslep 9y ago
        That is because you don't actually observe the radioactive decay event; you observe it's byproducts. And the presence of an observer of those byproducts certainly changes their behavior (attenuation/scattering, energy, absorption depending on detection method) as opposed to if there were no observer looking at that byproduct.
        godelski 9y ago
        I was more referencing the actual event of decay. Sure, the byproducts exhibit the standard quantum effects. the byproducts are particles after all. And just to be clear, you do not think an observer has to be a conscious being, right? I only ask because pop culture science gives this impression. A photon can be an observer.
  - godelski 9y ago
    Random is the word we use in physics. It isn't wrong. You're kind of just giving the definition of random. True random. Not pseudo random, which computers give you (and is usually called pseudo random explicitly). And you can measure the events, you just can't PREDICT it with certainty. Though you can predict it stochastically.

by xster 9y ago

godelski 9y ago

If we're going to the level of QM, then no. Because QM is inherently a random process. Like radioactive decay is a great way to make true random number generators. The real world has truly random events, and while it bothers many people, physicists don't generally argue about this point (anymore). Maybe if you had a perfectly homogeneous air density (which you'd never see, even in a really good vacuum and near absolute zero temperature. You can thank QM for that), that constantly stayed homogeneous. Problem in real world conditions is that nothing is perfectly homogeneous (entropy exists), so things will heat up unevenly, certain parts will gain more velocity than others, and just a small offset can create a large change in outcome. Short answer is that these systems are chaotic in nature, so they are not stable. But that doesn't have anything to do with simulations (except what you are trying to emulate). As far as simulations, numerical accuracy will play a role, but really what you look for is if it is realistic, because the real world has random events. That's more what I was trying to get at. You want something that represents reality, not an overly simplified example that you can't use in a meaningful way. Even with these inaccuracies you can get representative models (they will reflect what happens in a physical experiment). And I say representative, because you aren't going to account for all those factors in a simulation, but you are accurate enough to make extremely effective conclusions. I'll even note that some people will add random noise into their simulations (I don't know if this author did, but numerics can play that role).

spynxic 9y ago
> The real world has truly random events, and while it bothers many people.. Replace the word random with unpredictable and it shows why some people are bothered. To say something is fundamentally unpredictable means that it is immeasurable and not merely complex.
- dragonwriter 9y ago
  > To say something is fundamentally unpredictable means that it is immeasurable. No, it just means that the measure cannot be predicted in advance. OTOH, the observer effect can make measurement problematic.
  - godelski 9y ago
    This is true (Heisenberg uncertainty more says you can only get so much resolution in your measurement), but I was staying more general because there are other events that are random. Radioactive decay is completely random and isn't affected by an observer.
    - cjslep 9y ago
      That is because you don't actually observe the radioactive decay event; you observe it's byproducts. And the presence of an observer of those byproducts certainly changes their behavior (attenuation/scattering, energy, absorption depending on detection method) as opposed to if there were no observer looking at that byproduct.
      - godelski 9y ago
        I was more referencing the actual event of decay. Sure, the byproducts exhibit the standard quantum effects. the byproducts are particles after all. And just to be clear, you do not think an observer has to be a conscious being, right? I only ask because pop culture science gives this impression. A photon can be an observer.
- godelski 9y ago
  Random is the word we use in physics. It isn't wrong. You're kind of just giving the definition of random. True random. Not pseudo random, which computers give you (and is usually called pseudo random explicitly). And you can measure the events, you just can't PREDICT it with certainty. Though you can predict it stochastically.