Cosmos host and astrophysicist Neil DeGrasse Tyson said that it is bold for humans to believe they can define intelligence but he still wonders if there are other intelligent beings in other parts of the universe.
Tyson told Chris Hayes of MSNBC that there are many organic matters in the entire universe and it is possible that some planets have outlived intelligent species. He believes that humans are presumptuous for thinking they are arbiters of intelligence when planets could be much older than Earth and these could even be sending messages to us that while basic for them, are unintelligible based on the current human standards.
"My great fear is that we've in fact been visited by intelligent aliens, but they chose not to make contact, on the conclusion that there's no sign of intelligent life on Earth," Tyson said [video].
Tyson also cited an example, explaining that no one understood radio waves 200 years ago but today, it is just common in present-day Earth.
"We were sending signals out before we were doing it on purpose," Tyson added. "Our early TV shows, like I Love Lucy and The Honeymooners and that sort of thing, Howdy-Doody. These are our cultural emissaries."
He said that the aliens will decode these about Earth's civilization from the radio which is the volume in the solar system. The radio contains human chatter and it is the message we emit.
Some people question Tyson's theory saying the alien race might not assume humans as "dumb" because artificial satellites orbiting Earth are manned and unmanned. They also say that the aliens could make a survey and see roads, cities and intelligent urban design. Some people assume that there aren't many aliens and with the huge amount of stars in the Milky Way, they might not have found the Earth yet.
Tyson also ranked his top five scientific mysteries that he is most excited about. The first scientific ignorance he is interested in is the dark energy that forces the universe to expand. He described it as the mysterious pressure in the space vacuum. He also said that 85 percent of gravity in the universe is sourced from something humans don't know anything about. He called it the dark matter. Tyson also called the time before the Big Bang theory as the negative time and said that humans came from organic molecules to life replicating species. His biggest question of all though is, whether or not humans are alone in the universe.