もはや

もはや means "no longer", "by now": things have gone past a point, and the earlier state cannot come back. It is an adverb that stands before the predicate, most often a negative or an expression of impossibility. It belongs to writing, the news and formal speech.

With an affirmative predicate, もはや says something has by now become so – often with a note of how far things have gone.

もはや, もう and すでに

In conversation, もう does the job of もはや: もうもどれない戻れない. もはや sounds weightier and more final.

もはや is not the "already" of a finished task. For that, use もう, or すでに in writing.

• × もはや宿題をした → もう宿題をした