I'd say it's hard to believe aliens developed tech that allows them to travel long enough distances to come to our planet to mess around. But, there's other ways aliens could exist. For example, humans could have developed tech a long time ago and colonized outer space somehow, and they could have done that long enough to have evolved into a separate species. I like the theory that alien life forms like tetra grades were on meteors and asteroids that were brought to our planet when the planet was still being developed and evolved in the primordial soup along with local species that were evolving naturally on the planet. I know the government likes to talk about aliens when they are trying to distract the populations from other things going on at that time, but that doesn't prove aliens don't exist. Anyways, I'd like to hear your theories on why aliens couldnt possibly exist. Although, even if there are no aliens on this planet, it is still possible in my opinion for life to develop on planets too far away to interfere with our evolution.