There are an equal number of reasons why 'they' would cover anything up as not but anyone with a modicum of selflessness and open-mindedness would accept that we can't be the only life in the universe. Quantum Physics develops the advance of speed and destruction - the faster we go the more we can destroy. Advanced technology would suggest that as we can now fly at 1000mph we can also produce a bomb with an energy wave from its epicentre that can wipe out a small Country - I'm thinking of Hiroshima in 1959, 50 years ago, so what we can/could do now is worrying! So if 'life' out there ever made its way to our door in a very advanced space-ship with uber-amazing technology, imagine what one of its photon torpedoes might end up doing to our little world. Spread that fact and yes, panic would ensue and a cover-p might be in order. Gene Rodenberry, the creator of Star Trek, was a member of "The Cirle Of Nine". Research it and ask yourself if the content of Star Treck's technology was based on scientific theory, is it not perhaps how things could evolve. Trekies out there who know the evolution of the story and its culture in detail will perhaps more readily understand what I am saying. And please, do not think I believe that Star Trek is real but it is a very sound model of how things could, and probably will evolve. Unfortunately we won't live long enough for you all to know I'm right.