Week 4 - Aliens? Don't think so!

I don't believe there is life on other planets because there hasn't been any evidence of it in scientific research. When you look at pictures of planets you don't see any sign of cities or anything. And it just seems way out there to think that aliens exist. I really wonder who first thought that aliens exist and how they came up with that idea. And if there was life on other planets, wouldn't they be smart enough to be trying to get to earth like we are trying to get to other planets. It seems like we would have seen them when we were in space and all that.