hmmm, if you count the stars similar to ours in the whole universe then there must be earth like planets near those stars
meaning, we can't avoid getting contact from the "others"
but I'm pretty sure they won't visit us since: 1.)if they were very advanced, they're smart enough to just send robots/drones/etc. to visit our planet since the conditions are here are surely hazardous to those "aliens"
Yes. I'm 100% sure that Aliens (and UFOs) are existing. (cientists too! - the universe is BIG very very very BIG!^^) But they will not visit us. They wouldn't travel billions of lightyears through the universe just too see the Earth. The will lough about us! ;D
Yes, definitely. There are an infinite amount of worlds and Earths out there that can support life. So who's to say that extraterrestrials haven't visited before, are here now, or will drop by in the future?