- Are we really alone in the universe?
- Has alien life already visited Earth?
- Here are eight claims by those who think there is life out there.
The universe might not be infinite, but it continues to expand (at a rate of around 73 kilometers per second per megaparsec) — if that tells you anything. The observable universe is already 93 billion light-years in diameter, and scientists believe there is much more space outside that area.Â
Knowing this, it is hard to believe we are alone in the universe, and many scientists think we are not. This doesn’t mean they believe in the existence of “little green men,” though. Alien life can take many forms. In fact, NASA Chief Scientist Ellen Stofan expects to find evidence of extraterrestrial microbes in about 20-30 years.