For 60 years, astronomers have used the Drake equation to investigate the likelihood of intelligent life evolving elsewhere in the Universe.
Now, researchers have devised a novel method to examine the question by looking at one of the fundamental properties of our Universe: the fraction of dark energy it contains.
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Revisiting the Drake equation
Created by Dr Frank Drake in the 1960s, the Drake equation attempts to calculate the number of intelligent, technologically advanced species in the observable Universe.
It uses various factors to work out the number of habitable planets in the Universe and the likelihood of those planets creating advanced civilisations.
But as many of these quantities are currently unmeasurable, it’s more a discussion point than a workable scientific tool.
Is dark energy the answer?
The study instead looked at how likely it was for stars and planets – considered vital precursors for life – to form in a universe with a certain amount of dark energy, examining how star formation changed if the fraction of dark energy changed.
Dark energy is the mysterious substance that is theorised to be accelerating the Universe’s expansion, and is thought to make up about 70% of our Universe.
"Understanding dark energy and the impact on our Universe is one of the biggest challenges in cosmology and fundamental physics," says Daniele Sorini from Durham University, who led the study.
"The parameters that govern our Universe, including the density of dark energy, could explain our own existence."
Too much or too little dark energy would change the Universe’s ability to form structure, and so alter the number of stars being produced.
The study found that in the best-case scenario, dark energy allowed 27% of gas to form stars.
Our Universe converts around 23%, meaning we don’t live in a universe that has the highest odds of forming intelligent life, suggesting there could be some other special ingredients that allowed life to flourish at least once.
A recipe for a Universe
Words: Chris Lintott
We’d like to be able to explain why our Universe has the recipe it does, why it has this combination of matter and dark energy stirred just right to create the cosmos we live in.
It’s tempting to reach for anthropic arguments – the idea that the Universe is the way it is because otherwise we wouldn’t be here to see it.
This explains why we don’t see a value of dark energy that is, for example, a million times larger than we do.
Such a Universe would expand far too rapidly for stars or planets to form.
But what this work shows is that we could happily exist in a universe with a wide range of values for dark energy – and so we still need a proper explanation for what we observe.
