Since the 1960s, the Drake Equation has been used to predict how many communicative extraterrestrial civilizations exist in the Milky Way galaxy. Along these same lines, a new formula seeks to estimate the frequency at which life emerges on a planet—a calculation that might allow us to figure out the likelihood of life arising elsewhere in the universe.
The new equation, developed by Caleb Scharf from Columbia Astrobiology Center and Leroy Cronin from the School of Chemistry at the University of Glasgow, can’t yet be used to determine the chances of life existing elsewhere, but it’s a promising start in that direction.
Fundamentally, the researchers hope that their new formula, described in the latest edition of the Proceedings of the National Academy of Sciences, will encourage scientists to study the various factors that link origin-of-life events to specific characteristics within planetary environments. More conceptually, they hope their equation will eventually be used to predict the frequency at which planets experience an origin-of-life event, also known as abiogenesis. As the researchers explained to Gizmodo, “This would allow us to figure out the likelihood of life arising elsewhere in the Universe.”
Above: Video explainer on the Drake Equation
Those familiar with the Drake Equation will be familiar with how this works. Back in 1961, astronomer Frank Drake crafted a probabilistic formula to help estimate the number of active, radio-transmitting alien civilizations in the galaxy. His formula was packed with several unknown values, including the average rate of star formation, the average number of planets that can potentially support life, the fraction of planets that actually go on to develop intelligent life, and so on. We don’t have a definitive answer to the Drake Equation, but we’re certainly getting better at filling in the blanks.
The new formula developed by Scharf and Cronin isn’t an attempt to replace the Drake Equation. Instead, it’s meant as a deep dive into the more granular issue of abiogenesis.
Here’s what the formula looks like:
- Nabiogenesis (t) = Liklihood of origin of life events
- Nb = Number of potential building blocks
- No = Mean number of building blocks per organism, or biochemically significant system
- fc = Fractional availability of building blocks during Time t
- Pa = Probability of assembly per unit time
It looks complicated, but it’s fairly straight forward. The equation is basically saying that the probability of life arising on a planet is closely tied to the amount of life-sustaining chemical “building blocks” available on the planet.
By building blocks, the researchers are referring to the minimum chemicals required to start the processing of making a simple life form. This could be DNA/RNA base pairs or amino acids, but it could also mean any available molecules or materials on the planet that can get involved with the chemical reactions that could lead to life. Chemistry is still chemistry across the universe, but other planets may have stumbled upon different approaches for spawning life.