Your argument for the no-contact is : -Alien are way beyond us (ants). But hey, we study ants at least. That's called the 'Zoo scenario' (we're the pet). Some other arguments are: -They stay in their Dyson sphere, happy with their lives without any need to conquer the galaxy. -They communicate by means beyond our understanding (Snowden used that argument by saying that aliens use encryption) - We're part of the alien: Earth was randomly seeded with life because aliens found it the fastest way to populate the galaxy. The best one: - Everyone stay silent, because there are some killer robots or something out there. (Ancient Aliens need a ton of episodes about that) Other arguments are mostly about death: -Life is ultra rare -Life is fragile ( this article argument's) -Sentience is doomed (to kill itself before take off) All this is so fun