A recently published scientific principle suggests we are not alone in our galaxy. The Astrobiological Copernican Principle assumes that our own existence is neither miraculous nor significant.
36 extra-terrestrial civilizations are estimated to exist within the Milky Way galaxy. While the thought of three dozen different civilizations currently thriving in outer space is pretty wild, this is an extremely conservative estimate. The Strong limit scenario is what was used in the publication. This scenario applies the strictest set of assumptions possible, which yielded a modest number of 36. When the principle is applied on the opposite scale towards its weak limit scenario, the estimated number of extra-terrestrial civilizations dwarfs the current estimate.
The scientific team that helped publish this principle used calculations factoring in simple assumptions for how life develops. Essentially, life can and will form through biological and scientific processes anywhere in our Milky Way galaxy. However, this assumes the conditions in its environment are comparable to our own on Earth.
The sweet spot for life to emerge and flourish is estimated at between 4 and 5.5 billion years, which is when life began here. As we continue the rapid exploration into the final frontier, it seems inevitable that we will soon make contact.