Picking up on this idea, Canadian science fiction writer Karl Schroeder has come upon a novel solution to the failure of astronomical observations to solve the Fermi Paradox. He proposes: “any sufficiently advanced technology is indistinguishable from nature.” (This is a takeoff on Arthur C. Clarke’s posit: “any sufficiently advanced technology is indistinguishable from magic.”)
In other words, smart aliens have “gone green” and generate no waste products that we could detect. They therefore blend into the galaxy. Therefore, “artificial and natural systems are indistinguishable,” writes Schroeder.
This implies that no astronomical observations could offer convincing evidence for the handiwork of E.T. The principle of Occam’s Razor will insist that we stick with a natural explanation for space phenomena.