Quantifying the complexity of a system

[BWV]

Are there generally accepted methods for quantifying the complexity of a system, enabling comparison and the requirements for quantitatively modeling it? Think everyone would agree that in complexity, for example a double pendulum is less complex than the global climate which is in turn less complex than an animal brain, but is there a useful way to quantify this?

 

[Bystander]

generally accepted methods

https://en.wikipedia.org/wiki/Phase_rule ; https://en.wikipedia.org/wiki/Virial_theorem ; Cramer's rule --- that sort of thing?

 

[BWV]

More along the lines of computational complexity. one measure would be perhaps the length of the algorithm needed to model it?

 

[Andy Resnick]

More along the lines of computational complexity. one measure would be perhaps the length of the algorithm needed to model it?

Like this?

https://en.wikipedia.org/wiki/Kolmogorov_complexity

 

[BWV]

Yes thanks, does this get used at all on biological systems? Wonder how a bacteria would come out