Scientists have recently extrapolated how many Earth-like planets, existing within their suns' habitable zones, there might realistically be in the Milky Way galaxy, and have come up with the figure 8.8 billion.
This number is based on an actual calculation, not an estimation, using data gathered by the Kepler space telescope.
I don't know about you, but I feel it's a given that there's life on other planets. When you think of how many stars there are, and how many planets might be circling those stars, and then that the stars we can see, are just part of a single galaxy among billions...well, thinking we're the only place to harbor life, just seems ludicrous.
So, you may ask, why haven't we heard from anyone else? Well, there's cosmic distances, and the probability that not everyone's gotten to the technological point of broadcasting their voices to the universe. I mean, on Earth, we're the only species to have developed the technology for space exploration. And since the light we're seeing from the stars, is what those stars looked like hundreds of years ago--well, a little over a hundred years ago, WE weren't doing much broadcasting to the universe, either!
So I am confident that we're certainly not alone in the universe. And now we've got 8.8 billion new potential neighbors to say "howdy" to.