lifeinthecosmos

Hey all, I'm taking a speech class this quarter and for the persuasive speech, I submitted my topic as 'Why Life Most Likely Exists Elsewhere in the Cosmos'. Whether it be microbial life or actual sentient life with comparable or greater intelligence, I'm not sure, but with the sheer size of our galaxy (400 billion stars) along with the size of the universe itself, filled with outrageous amounts of galaxies, the probability for at least some kind of independent development of basic microbial life seems great. So, one of the main reasons for me is the fact that we evolved. We're the products of (roughly) 13.7 billion years of cosmic evolution. Therefore, seeing that we're already discovering significant amounts of extra solar planets, it seems that the development of planets is common (at least in our galaxy), which increases the chance for small, rocky worlds to be located in the goldilocks zone for various stars, increasing the chance for liquid water and, subsequently, microbial life to develop. Furthermore, we've even recently discovered (rather roughly) some small planets that, seemingly, have water on their surface (wasn't there that news article a bit ago about the recent planet that they detected water on as well as the megaearth article?). I know the majority of the extrasolar planets are Jupiter-sized, but it's really just the fact that our current methods for planet searching are not technologically advanced enough to zoom in on comparatively small planets at incredible distances from our lonely point in the cosmos. So, really, it's about the size of the cosmos, the fact that humanity has consistently tried to make it seem like we're the only ones on this grand cosmic stage, the fact that evolution simply begs us to consider that life evolved elsewhere in this enormous thing we call the universe...and... I guess that's about it. It just seems odd to think that we're the only ones. However, I know there are some theories out there. Was it called the 'anthropic principle'? Something like this. The idea that the development of earth required too many variables to be perfect -- that the cosmic lottery requires so many 'numbers' to be right, it demands us to say the earth is the only planet hosting life in the cosmos. Not sure if I have the principle completely correct, but basically, it's saying that things like the alignment of the barrier planets (correct terminology?) is perfect to stop too many things from hitting earth, thus allowing it to develop life, etc etc. How are those in the anthropic camp doing? How have things evolved? Finally, this speech has to be between 5 to 7 minutes, so I'm just going to touch on the most fundamental reasons for why life (be it microbial or more developed) most likely exists in the cosmos. Crunch time is coming and I just haven't had the time to do all the independent research I wanted, so I was wondering if I could get some input here from people who've thought about it more. What would you consider the fundamental reasons, and perhaps, play devil's advocate, considering what might be strong arguments against the hypothesis. Thanks all.