There is a chance we can see another intelligent life in the universe

"Human beings are the only intelligent life in the universe". I completely disagree with this hypothesis. I like to watch stars and also like to go to planetarium. Every time I watch stars, I feel how enormous the universe is. Human beings don't know much about the universe. Though our scientific technique is developing, the universe is filled with riddles and mysteries. The universe is infinite space and have limitless stars. We can only see few of these.  Why we can say "Human beings are the only intelligent life in the universe"? There are no reasons for this hypothesis. There must be another intelligent life in the universe.