Jackhammer 
Some people refuse to believe in aliens even if they landed in their backyard to take a dump but don't deny evidence that shit exists.
https://www.nbcnews.com/now/video/di...0-241946693913
That being stated, when we send self-replicating evolving machine Von Neumann probes into space they'll arrive as highly advanced craft that aliens call UFOs. And the craft can create robots that genetically engineer biology and seed planets with life to prepare planets for the probe senders with a habitable ecosystem biosphere for them to colonize. It explains much about many UFOs, technology and biogenesis of life.
If/when we release Von Neumanns they eventually evolve to be technologically advanced enough to time travel and visit us in the past before they were released, they'd be UFOs to us. We'd think it's alien tech when we created the initial probes.
Originally Posted by Till
