Is Earth the only planet in the universe that bears a form of intelligent life? Based on scientific observations so far, it sure seems that way.
But there are a number of reasons that could explain why scientists have not yet been able to detect aliens anywhere else in the Milky Way.
About half a century ago, these variables were compiled into what’s known as the Drake Equation. Back in the 1960s, an American astrophysicist and astrobiologist named Frank Drake proposed an equation that could estimate how many intelligent civilizations exist in our universe.
The equation looked at variables like how many stars there were and their interactions with any planetary bodies.
It was not supposed to yield a solid number. It was meant to act as a guide to future researchers, helping them in their search for extraterrestrial life.
However, one variable has been missing from the Drake Equation—the effect of dark energy on star formation rates in the universe.
“Understanding dark energy and the impact on our universe is one of the biggest challenges in cosmology and fundamental physics,” said Daniele Sorini, the lead author of the study and a physicist at Durham University in the United Kingdom.
“The parameters that govern our universe, including the density of dark energy, could explain our own existence.”
Dark energy is a mysterious force driving the accelerated expansion of the universe. Scientists don’t know what it is made of, but they can tell how much of it there is. Dark energy makes up approximately 71.4 percent of the matter-energy content of the universe.
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Dark matter makes up another 24 percent, and the remaining 4.6 percent is normal baryonic matter. All stars, planets, black holes, dust, humans, and basically everything else we can see and touch are made of baryonic matter.
The Drake Equation assumes that one of the conditions for life to form is a star. It may not be true, but the chances of life emerging somewhere far away from an energy source are extremely remote.
If it is assumed that a star is required for life, knowing the rate of star formation in our universe could tell experts the odds of finding life.
Stars form from clouds of gas and dust that collapse into dense clumps. They build up so much mass that the heat and density in their cores trigger nuclear fusion. Dark energy’s outward pull can impact the rate at which this occurs.
The researchers analyzed different dark energy densities in a model universe to calculate the matter conversion rate so they could determine the most efficient rate for star formation.
They discovered that the most efficient rate was when 27 percent of the matter in the universe was being converted into stars.
Our universe has a 23 percent conversion rate. Since humanity likely did not develop during the most optimal conditions for life, it’s possible that intelligent life could have emerged somewhere else in the universe.
“Surprisingly, we found that even a significantly higher dark energy density would still be compatible with life, suggesting we may not live in the most likely of universes,” said Sorini.
The research was published in The Monthly Notices of the Royal Astronomical Society.