4 ms·

I felt like I followed the proof. The claim is actually very narrow: that to be a perfect regulator of a system you need an exact model. Obviously, lots of devi

by tlb 7y ago

I felt like I followed the proof. The claim is actually very narrow: that to be a perfect regulator of a system you need an exact model. Obviously, lots of devices in our world can regulate things reasonably well with simple models. For instance, a standard thermostat keeps your house at 20 +/- 2 degrees C. In order to keep it at 20.00000000 exactly, it might need to model every air molecule bouncing around.

marcosdumay 7y ago
That's a problem, because we don't actually use "perfect" regulators for any system. I'm very willing to believe those things don't even exist. So, it may be a correct proof, but it's a useless one.
- staticautomatic 7y ago
  The implication being what, exactly?
  - marcosdumay 7y ago
    Well, except for the fact that the article is trivially wrong, and that there is no reason to trust its conclusions, I don't think there are any. But you didn't need my comment for that, the fact that there is an entire engineering discipline thriving on doing exactly what the article claims to be impossible should suffice.
pfedak 7y ago
The issue I'm having with the claims is that their use of the word "model" seems to connote exactly of the opposite of what someone reading the paper without seeing their definition would suggest, and indeed what other commenters here are taking it to mean. The colloquial restatement of the theorem suggests a regulator "is a model of [a] system" if the regulator's action is a function of the system, and nothing else. As in, a constant regulator that has only one state still meets the criteria for being a "model". The possibility that is excluded is that the regulator has additional details that don't correspond to states of the system. In your thermostat example, the theorem doesn't even begin to say that, even though that's what the title suggests, and what everyone wants to believe. In fact, the theorem merely says a thermostat that only depends on the temperature of the room is simpler than one that also cares if the walls are blue.

by tlb 7y ago

marcosdumay 7y ago

That's a problem, because we don't actually use "perfect" regulators for any system. I'm very willing to believe those things don't even exist. So, it may be a correct proof, but it's a useless one.

staticautomatic 7y ago
The implication being what, exactly?
- marcosdumay 7y ago
  Well, except for the fact that the article is trivially wrong, and that there is no reason to trust its conclusions, I don't think there are any. But you didn't need my comment for that, the fact that there is an entire engineering discipline thriving on doing exactly what the article claims to be impossible should suffice.

pfedak 7y ago

The issue I'm having with the claims is that their use of the word "model" seems to connote exactly of the opposite of what someone reading the paper without seeing their definition would suggest, and indeed what other commenters here are taking it to mean. The colloquial restatement of the theorem suggests a regulator "is a model of [a] system" if the regulator's action is a function of the system, and nothing else. As in, a constant regulator that has only one state still meets the criteria for being a "model". The possibility that is excluded is that the regulator has additional details that don't correspond to states of the system. In your thermostat example, the theorem doesn't even begin to say that, even though that's what the title suggests, and what everyone wants to believe. In fact, the theorem merely says a thermostat that only depends on the temperature of the room is simpler than one that also cares if the walls are blue.