[amarte]

Nature/the world is what is being described. QM, thermo, fluid dynamics, signal processing, information theory, probability, etc.. are descriptions which have been devised to depict and communicate nature/the world. We never say that da Vinci's painting of Mona Lisa is so good that the historic woman who was Mona Lisa was paint.

[citrablue]

They're more than descriptions because (most of them) make testable predictions about the world. Doesn't mean they're correct, of course, but making predictions is really important.