It is complete ignorance to believe we are the only intelligent life in the universe in my opinion. The amount of solar systems, stars, and galaxies out there is mind blowing. The probability of there being habitable planets and moons is therefore HUGE. What I have a hard time believing though, is that "aliens" would try to contact us. If we assume we have been on the planet, say, 2 million years, and they have been around for 4 million years, they are already 2 MILLION years ahead of us in a technological stand point. Making contact with us to them, would be similar to trying to make contact with a school of fish. Unless they are in dire need of water or oxygen or something else, then there would be absolutely NO point for them to contact and try to interact with us. Also, they may not even need water or oxygen in the first place. They might not even be carbon based. Who knows. Some day, I'm confident we will make some sort of contact or something. The universe is HUGE. Just my two cents.