Eh. The amount of oxygen in out atmosphere is pretty much impossible by non-living processes alone iirc. Anyone who can do astro-spectroscopy can probably tell there's life here, from thousands of light years away.
Also remember the periodic waves of “Hillary is bae! Mother of dragons! Yas Queen!” and “I love Mayor Pete” and “KHive ftw!” and even a smattering of Mitt Romney fanboi-ism on /r/politics, as their campaigns rose and fell.
Literally no, I was there and I don't recall that at all.
If Roko's Basilisk is ever created, the resulting Ai would look at humanity and say "wtf you people are all so incredibly stupid" and then yeet itself into the sun
Second would be intergalactic and to a lesser degree interstellar travel. If we assume both 1) intelligent civilizations are extremely rare and 2) faster-than-light transportation is impossible, it could be that everyone is just too spread out to make contact.
Not just too spread out to make contact, too spread out to even detect each other's presence
Well, we've already sent a couple of probes out of the solar system, but they're not really going fast enough to have any meaningful interstellar impact.