By Casey Frye, CCNN Writer
According to a new theory about the cosmos, aliens populated space long before humans did. And… they weren’t restricted to a single planet either! The organisms may have been spread across numerous ancient planets.
Immediately after the Big Bang – a large explosion that gave birth to the universe itself – there was lots of leftover heat floating around in space. This heat, called cosmic microwave background (CMB) radiation, kept planets warm and cozy enough to sustain liquid water, one of the main ingredients for life. Apparently, these conditions may have given rise to microbial life (tiny living organisms) all over space!
As the effects of the Big Bang settled down, however, the CMB temperature cooled along with it. In fact, it went all the way down to an ultra-freezing -454 degrees Fahrenheit! That’s way too cold for water to remain in liquid form. As the universe took on these icy temperatures, the only planets that could sustain life were those found in the habitable zone – a region of space that’s just close enough to a star for life-giving warmth, but just far away enough to not be dangerously hot.