4 ms·
"Critical" has a precise meaning in these kinds of systems; it essentially means when correlation lengths diverge (or, with a finite brain, become the size of t
by evanb 4y ago
"Critical" has a precise meaning in these kinds of systems; it essentially means when correlation lengths diverge (or, with a finite brain, become the size of the whole). In physical systems this happens at 2nd order phase transitions. Unfortunately most familiar phase transitions are first-order (boiling and freezing, for example) but the development of macroscopic magnetism as iron cools is an example.
Away from the critical point the dynamics become either
1) too strong, meaning that information has a hard time getting from one spot to another because it's in too much traffic
2) too weak, meaning that information has trouble being processed, because the traffic is so light that cars don't spend enough time together to come to equilibrium
In these cases the correlations will be short-distance, in contrast to critical.
- paraph1n 4y ago> "Critical" has a precise meaning in these kinds of systems; it essentially means when correlation lengths diverge (or, with a finite brain, become the size of the whole). If someone doesn't know what "critical" means, they also don't know what a "correlation length" is, so I don't think this clarification is very helpful. Who was the intended audience?
- drdeca 4y agoI found it helpful. Presumably the “correlation length” is something kind of like “some length where there is much larger correlation of pairs of things at most this length apart, than there is between pairs of things that are much longer than this length” (but that’s largely just a guess)
- coldtea 4y agoPeople interested to learn more? We don't just learn a new subject through simpler ELI5 explanations. We also learn by immersing ourselves further into the subject (like here, were we were given an alternative, still elaborate explanation), until things "click". In immersive learning (like how kids learn language and most other wordly things naturally outside of explicit teaching) we also get to understand the meaning of an unknown term by compounding other unknown terms, and making correlations, connections, and deductions.
- panda-giddiness 4y agoI think you've assumed that they've just substituted some jargon with some other jargon, but that's not really what happened here. Rather, "critical" is left undefined, even though it's an ambiguous word; evanb merely provided a definition. > Who was the intended audience? From that definition? Obviously physicists, lol
- martopix 4y agoThe meaning of critical in complex systems is accessible only if you studied physics or theoretical neuroscience or something related. I'm pretty sure correlations are familiar to most people in STEM, such as the average reader of HN