Kenneth Arnold witnessed unusual flying objects near Mount Rainier in 1947, which sparked early interest in UFOs. In the same year, the Roswell incident involved a crashed object on a New Mexico ranch that was purported to be an alien spacecraft by some. While the US military claims it was only a weather balloon, conspiracy theories persist. Recent CIA reports acknowledging the existence of UFOs may convince more people that aliens could exist. The document discusses the definitions of aliens and provides examples of early UFO sightings to argue that while aliens have not been proven, their existence can no longer be ruled out.