state-of-the-art

Think of it as in "the state of the dock is very poor" Meaning that the dock is run down. But in the since that you are talking it means top of the line. I don't know if that explains anything.

The earliest usage of the term "state of the art" documented by the Oxford English Dictionary dates back to 1910 from an engineering manual by H.H. Suplee titled Gas Turbine. It reads, "In the present state of the art this is all that can be done."

This passage refers to engineering as "the art". The art of engineering.

In its (engineering's) present condition ( state) this is all that can be done.

Seed's reply is completely wrong. Disregard it.

To expand on Dadpad's answer, the adjectival phrase "state-of-the-art" [often hyphenated] usually means "the most modern possible" or "using the latest techniques". A state-of-the-art computer system is one which incorporates many or all the latest technological advances.

i think Adverb was asking more about the origins of the phrase.

why does "state of the art" mean modern

Are you asking, or paraphrasing Adverb's question?

It means modern in the sense of up to date, the most advanced such and such known to mankind