11 ms·

> if we had powerful enough computers, simulate all sorts of things In reality, we're having a hard time precisely simulating even two atoms interacting, with

> if we had powerful enough computers, simulate all sorts of things In reality, we're having a hard time precisely simulating even two atoms interacting, with all the quantum effects, diffraction, gravity (however minuscule), etc. Our universe is surprisingly detailed. 64-bit floats aren't even close enough to precisely simulate real world. What's the precision of the mass of an electron? What's the precision of its coordinates or motion vectors? Maybe plank length for coordinates, maybe not. What about acceleration? Can it be arbitrarily low? An electron's gravitational field from a billion light years away should theoretically affect us (in time).

xvector 2y ago
The assumption in your comment is that any of this is real to begin with and logic isn't being short-circuited in our brains to make everything "check out" even if it doesn't. If you simulate a universe with cube blocks from Minecraft, it doesn't matter as long as your users think the simulation is real. And since you are simulating their consciousness, you can easily short circuit the train of thought that would cause doubt, or that would attempt logic, etc., so they truly believe their Minecraft cube world is incomprehensibly detailed down to the atoms and galaxies in the sky. They'd happily go on the whiteboard, and prove their theories with math like 2+2=5 and everyone would agree because they literally couldn't disagree - they would feel in their hearts and minds that this is perfectly correct. There's nothing to say that's not happening now. In fact, this is how I see most advanced civilizations performing simulations. The compute savings would be immense if you could just alter user consciousness as opposed to simulating an actual universe.
- genrilz 2y ago
  I always find skepticism like this to be really interesting, since in the end we could always be getting fooled by the Deus Deceptor or something. That being said, let me take a stab at being anti-skeptical for the fun of it. I work around people who do "Computational Chemistry", which is basically running quantum physics calculations. These tend to be done in order to either understand the properties of materials, or to understand the reasons why reactions happen. The results are more advanced materials and better performing reactions. An early and famous example of such technology is the laser. A more typical modern example would be searching for Zeolite catalysts which have particular properties, or trying to create surface coatings which protect implants from being eaten by the immune system, or on which ice cannot freeze. Basically, I believe the advanced calculations to be correct because they lead to things which are (eventually) used in daily life.
  - dekhn 2y ago
    In nearly all situations, these advanced calculations bear only a limited relationship to the underlying physics occurring in material systems. A lot of simulation work involves twiddling parameters until you get the result you want to see, and then just publishing that one simulation. It's sort of a post-hoc retro-causality problem. Many of the things you describe came about because of a combination of immense amounts of lab work (mostly of which were failures), some theoretical concepts, and a person willing enough to twiddle params until they fall up something that works, after which they can optimize the parameters.
    - genrilz 2y ago
      It is true that simulations produce results which may not reflect the underlying system if the simplifications and fudge factors are incorrect. Thus fiddling with parameters is part of the process. In the example I gave of searching for zeolite catalysts, the simulations were just used to identify candidates for labs to study. I don't remember the exact numbers, but I think it brought the list of candidates down from hundreds to less than 10. The majority of these candidates were at least somewhat effective. Unless we believe that pretty much all of those hundred candidates would have been effective, then the advanced calculations were doing some work. The question is, is all that work actually just done because of parameter twiddling? I don't think so. Consider that neural networks are often used lately in order to provide computationally simpler models of various physical phenomena. They can do a somewhat better job if fed with a lot of real data, but they use at least thousands of times more parameters than the simple quantum physics calcs with fudge factors. Thus I think it is safe to say that the structure of the quantum physics calcs does meaningfully model some part of reality. (Unless, as xvector points out, our memories are being continuously overwritten to make reality seem consistent) It's also good to note that the fudge factors (read: parameters) and quantization are done because it would be too computationally difficult to model the parts of the system modeled by fudge factors for systems with a useful amount of atoms in them, and we just don't know how to compute ODEs for complex systems in continuous time and space. In simple systems, (e.g. 2 photons interacting) analytical solutions for ODEs can be found, no fudge factors are needed for computation, and the computed results match the experimental results to within measurement error.
- bufferoverflow 2y ago
  Sure, if we're just fooled, if it's all an illusion, it definitely requires a lot less computation. But if it's a proper simulation, base reality must be even more detailed. Like, a lot more.
  - xvector 2y ago
    > But if it's a proper simulation, base reality must be even more detailed. Like, a lot more. Not necessarily. You could create the feeling or impression of detail on-demand - consider a 2D fractal in software that you can zoom into infinitely. It's not more detailed than our base reality, it's actually quite a simple construct.
dekhn 2y ago
one imagines that post-singularity overloads don't have to worry about IEEE754. Float is likely not the right representation here, but double is enough to represent solar-system-scale differences at centimeter precisions.
- bufferoverflow 2y ago
  > at centimeter precisions So yeah, you're 33 decimal orders of magnitude off from the Planck length. And that's assuming that Plank length is the smallest possible length. So you'd need at least 117 extra bits to get your representations precise. And that's just for our solar system. For the observable universe (~93 billion light years across) you'd need 206 bits of precision.

xvector 2y ago

The assumption in your comment is that any of this is real to begin with and logic isn't being short-circuited in our brains to make everything "check out" even if it doesn't. If you simulate a universe with cube blocks from Minecraft, it doesn't matter as long as your users think the simulation is real. And since you are simulating their consciousness, you can easily short circuit the train of thought that would cause doubt, or that would attempt logic, etc., so they truly believe their Minecraft cube world is incomprehensibly detailed down to the atoms and galaxies in the sky. They'd happily go on the whiteboard, and prove their theories with math like 2+2=5 and everyone would agree because they literally couldn't disagree - they would feel in their hearts and minds that this is perfectly correct. There's nothing to say that's not happening now. In fact, this is how I see most advanced civilizations performing simulations. The compute savings would be immense if you could just alter user consciousness as opposed to simulating an actual universe.

genrilz 2y ago
I always find skepticism like this to be really interesting, since in the end we could always be getting fooled by the Deus Deceptor or something. That being said, let me take a stab at being anti-skeptical for the fun of it. I work around people who do "Computational Chemistry", which is basically running quantum physics calculations. These tend to be done in order to either understand the properties of materials, or to understand the reasons why reactions happen. The results are more advanced materials and better performing reactions. An early and famous example of such technology is the laser. A more typical modern example would be searching for Zeolite catalysts which have particular properties, or trying to create surface coatings which protect implants from being eaten by the immune system, or on which ice cannot freeze. Basically, I believe the advanced calculations to be correct because they lead to things which are (eventually) used in daily life.
- dekhn 2y ago
  In nearly all situations, these advanced calculations bear only a limited relationship to the underlying physics occurring in material systems. A lot of simulation work involves twiddling parameters until you get the result you want to see, and then just publishing that one simulation. It's sort of a post-hoc retro-causality problem. Many of the things you describe came about because of a combination of immense amounts of lab work (mostly of which were failures), some theoretical concepts, and a person willing enough to twiddle params until they fall up something that works, after which they can optimize the parameters.
  - genrilz 2y ago
    It is true that simulations produce results which may not reflect the underlying system if the simplifications and fudge factors are incorrect. Thus fiddling with parameters is part of the process. In the example I gave of searching for zeolite catalysts, the simulations were just used to identify candidates for labs to study. I don't remember the exact numbers, but I think it brought the list of candidates down from hundreds to less than 10. The majority of these candidates were at least somewhat effective. Unless we believe that pretty much all of those hundred candidates would have been effective, then the advanced calculations were doing some work. The question is, is all that work actually just done because of parameter twiddling? I don't think so. Consider that neural networks are often used lately in order to provide computationally simpler models of various physical phenomena. They can do a somewhat better job if fed with a lot of real data, but they use at least thousands of times more parameters than the simple quantum physics calcs with fudge factors. Thus I think it is safe to say that the structure of the quantum physics calcs does meaningfully model some part of reality. (Unless, as xvector points out, our memories are being continuously overwritten to make reality seem consistent) It's also good to note that the fudge factors (read: parameters) and quantization are done because it would be too computationally difficult to model the parts of the system modeled by fudge factors for systems with a useful amount of atoms in them, and we just don't know how to compute ODEs for complex systems in continuous time and space. In simple systems, (e.g. 2 photons interacting) analytical solutions for ODEs can be found, no fudge factors are needed for computation, and the computed results match the experimental results to within measurement error.
bufferoverflow 2y ago
Sure, if we're just fooled, if it's all an illusion, it definitely requires a lot less computation. But if it's a proper simulation, base reality must be even more detailed. Like, a lot more.
- xvector 2y ago
  > But if it's a proper simulation, base reality must be even more detailed. Like, a lot more. Not necessarily. You could create the feeling or impression of detail on-demand - consider a 2D fractal in software that you can zoom into infinitely. It's not more detailed than our base reality, it's actually quite a simple construct.

dekhn 2y ago

one imagines that post-singularity overloads don't have to worry about IEEE754. Float is likely not the right representation here, but double is enough to represent solar-system-scale differences at centimeter precisions.

bufferoverflow 2y ago
> at centimeter precisions So yeah, you're 33 decimal orders of magnitude off from the Planck length. And that's assuming that Plank length is the smallest possible length. So you'd need at least 117 extra bits to get your representations precise. And that's just for our solar system. For the observable universe (~93 billion light years across) you'd need 206 bits of precision.