Scientists say it could be 1,500 before humans make with aliens, or for them to communicate with . Astronomers from Cornell University combined two about the of life existing on other planets to form a one. One of these theories is the Fermi Paradox. This states that while of Earth-like planets exist in our galaxy, not has made contact with Earth yet. The other, the mediocrity principle, suggests that because there is on Earth, it will exist on Earth-like planets throughout the .
Researcher Evan Solomonides will present a on his . He said: "We haven't heard from aliens , as space is a big , but that doesn't mean no one is out ." He said extraterrestrials could have received signals from Earth, but they may not have decoded . He said they would need to decode and analyse 3,000 human languages to understand any . Signals from Earth have only reached about 8,500 ; the Milky Way alone contains 200 billion stars. Solomonides said: "If we stop listening or looking, we may miss the signals, so we keep looking."
