It seems to be a little 'arrogant' to Beieve that Alien Civilizations may Exist, & even be far more advanced than we are, BUT, the thought that they could have spaceships capable of reaching us on Earth is unthinkable to so many. "Why?" Surely our own adavanced technology may be as primitive to other civilizations, just as stone age man is to us? .... Our 'Typical Human' attitude to anything seems to be, "If we don't understand it,cannot control it, then Deny it Exists or Destroy it or Both." ... What an arrogant & ignorant species we are. ... If You were an Alien, would You want to make contact with a species like Us.?