Why do people talk about the decline of American power? Where is the evidence?

[starcraft]

I read a paper recently (written from an Australian strategic policy perspective) talking about where and how our economic and military efforts should be distributed in the coming decades (primarily between China and the USA). The paper was well researched, and generally held that against a standard base, the US was not declining economically, and certainly not militarily.

Against the shifting base that is the global geo-political relality, the paper acknowledged that the influence of the US was become relatively weaker, but that general comments on the matter GREATLY exaggerate the speed and intensity of this decline.