When it comes to the entirety of the Universe, the "stuff" that we're made out of — atoms and their constituent particles — plays an important role. Protons, neutrons, and electrons, in both atomic…
Intelligent aliens, if they exist in the galaxy or the Universe, might be detectable from a variety of signals: electromagnetic, from planet modification, or because they're spacefaring. But we haven't found any evidence for an inhabited alien planet so far. It's also possible that aliens have traveled here and are watching us, and are responsible for some UAP/UFO sightings. If so, however, they can't be made of dark matter or dark energy: a fact we can conclude from already-existing observations. (Credit: Ryan Somma/flickr) Member-only story Ask Ethan: Could there…