As @Mariah says, given the scale of the universe and the fact that in the Milky Way alone there are about 20 billion stars similar to our sun, it seems extremely likely that there are millions of other planets out there similar to our earth. Many had opportunities to spawn intelligent life before us. It follows that many should have civilizations far more advanced than ours, with the capacity for interstellar travel and communication.
This begs the question, why have we failed to discover any real evidence of intelligent life beyond the earth? This is called the fermi paradox.
There are several possible explanations. I could try to write about them hear, but honestly you need to just go watch this video now – it is fantastic.