Our universe is about 14 billion years old and our galaxy is 4.5 billion years old. Shouldn't there be other intelligent beings out there who have made contact with us by now? The Fermi Paradox suggests two simple options: either there are aliens out there or there's not. If a life-sustaining planet like Earth is extremely rare, perhaps we are alone in the universe. But if aliens do exist why haven't they contacted us? One theory is that they have tried to contact us but we can't communicate with them because we simply don't have a compatible technology.
Learn more about the possibility of alien life in the universe:
The Fermi Paradox (SETI)
"Is there obvious proof that we could be alone in the Galaxy? Enrico Fermi thought so -- and he was a pretty smart guy. Might he have been right? It's been a hundred years since Fermi, an icon of physics, was born (and nearly a half-century since he died). He's best remembered for building a working atomic reactor in a squash court. But in 1950, Fermi made a seemingly innocuous lunchtime remark that has caught and held the attention of every SETI researcher since."