You would be retarded not to. There are so many galaxies and planets we dont even know of you would be retarded to think werre the only ones. Also thats why i dont have religion.
Ya they cross our borders daily.
Unless your talking about living things outsider planet earth, then yes. If we found water on a planet right next to us who knows whats on other planets in other galaxies.
Think about the billions of stars in a single galaxy. Multiply that by several planets for each star. Multiply that by the billions of galaxies in the universe.
Yes, I believe that life exists outside of the planet earth. Do I believe they've made contact with us or ever will, no. If we ever find out that life exists elsewhere the info will come from SETI, and it will be via radio communication. It will take most likely thousands or even millions of years for a radio signal to travel from earth to a planet where there is life.