This is a pretty interesting article on the likelihood of contactable, intelligent life. The article, a summary from the full report in the Astrophysical Journal, suggests that there are 36 intelligent civilizations in our galaxy capable of communicating with others, today. And the likely furthest distance to the nearest one is 17,000 light years away. By comparison, the Orion Nebula is 1,300 light years away, Alpha Centauri is the nearest star to our Sun at 4 light years, the Andromeda galaxy is 2.5 million light years away, and our entire galaxy is 100,000 light years from end-to-end. Note that this estimate of 36 is just for our galaxy and there are an estimated 100 – 200 billion galaxies in the universe.
One of the keys is the word “today”. Civilizations come and go, and there’s plenty of time for more of them to have existed previously. The report also asserts that, while it is a speculative theory, alien life would have similarities in appearance to life on Earth and that we wouldn’t be super shocked by seeing them.