A new study that combines biological and cosmological models has come to the conclusion that life in the universe is most likely much more common than previously thought, however, it may not be necessarily so in our immediate galactic neighborhood.
According to Tomonori Totani, a professor at the University of Tokyo, “if there is one thing in the universe that is certain, it is that life exists. It must have begun sometime, somewhere. ”
Since the only life we know of is based on Earth, studies on the origins of life are limited to the specific conditions we find here. In other words, we tend to understand life as something we see on Earth.
Therefore, most research in this area looks at the most basic components common to all known living things: ribonucleic acid, or RNA.
This is a much simpler and more essential molecule than the more famous deoxyribonucleic acid or DNA, which defines how we are put together.
But RNA is still orders of magnitude more complex than the types of chemicals one tends to find floating in space or stuck to the face of a lifeless planet.
RNA is a polymer, which means it is made of chemical chains known as nucleotides. Researchers in this field have reason to believe that RNA of no less than 40 to 100 nucleotides in length is necessary for the self-replicating behavior required for life to exist.
Given enough time, nucleotides can spontaneously connect to form RNA under the correct chemical conditions. But current estimates suggest that the magic number of 40 to 100 nucleotides should not have been possible in the volume of space that we consider the observable universe.
“However, there is more to the universe than the observable,” said Totani. “In contemporary cosmology, it is agreed the universe underwent a period of rapid inflation producing a vast region of expansion beyond the horizon of what we can directly observe. Factoring this greater volume into models of abiogenesis hugely increases the chances of life occurring.”
Although we can’t possibly know how big the universe is, astronomers theorize that the observable cosmos is home to around 10 sextillion stars.
Statistically, matter in such a volume should only be able to produce RNA of approximately 20 nucleotides. But it is calculated that thanks to rapid inflation, the universe can contain more than 1 googol (the large number 10100) of stars, and if this is the case, then the most complex and life-sustaining RNA structures are more than probable, astronomers say that they are practically inevitable.
“Like many in this field of research, I am driven by curiosity and by big questions,” explained Totani.,
“Combining my recent investigation into RNA chemistry with my long history of cosmology leads me to realize there is a plausible way the universe must have gone from an abiotic (lifeless) state to a biotic one. It’s an exciting thought and I hope research can build on this to uncover the origins of life.”