Since the 1960s, Drake's equation has been used to estimate how many intelligent and contactable extraterrestrial civilizations exist in the Milky Way galaxy. Following the beaten path, the new formula estimates the frequency with which life occurs on the planet. It can help us find out how likely, in principle, the emergence of life in the universe.
The new equation, developed by Caleb Sharv of the Columbia Astrobiological Center and Leroy Cronin of the School of Chemistry at the University of Glasgow, cannot yet assess the chances of life appearing anywhere, but it holds interesting promise in that direction.
Scientists hope that their new formula, described in the latest edition of the Proceedings of the National Academy of Sciences (PNAS), will inspire scientists to explore the various factors that link life events to the special properties of the planetary environment. More broadly, they expect their equation will ultimately be used to predict the frequency of life on the planet, a process also known as abiogenesis.
Those familiar with the Drake equation will understand the new equation as well. Back in 1961, astronomer Frank Drake derived a probabilistic formula that could help estimate the number of active extraterrestrial civilizations transmitting radio signals in our galaxy. His formula contained several unknowns, including the average rate of star formation, the average number of planets that could potentially support life, the fraction of planets that managed to acquire truly intelligent life, and so on. We do not have a final version of the Drake equation, but we believe that every year it allows us to more accurately estimate the unknown.
The new formula developed by Scharf and Cronin does not aim to replace Drake's equation. Instead, it plunges us deeper into the statistics of abiogenesis.
This is how it looks:
Where:
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Nabiogenesis (t) = probability of a life event (abiogenesis)
Nb = number of potential building blocks
No = average number of building blocks per organism, or biochemically significant system
fc = fractional availability of building blocks over time t
Pa = probability of assembly per unit of time
It looks complicated, but in reality everything is much simpler. The equation, in short, says that the likelihood of life on a planet is closely related to the number of chemical building blocks that support life and are available on the planet.
By building blocks, scientists mean the necessary chemical minimum to start the process of creating simple life forms. These can be basic DNA / RNA or amino acid pairs, or any available molecules or materials on the planet that can participate in the chemical reactions that lead to life. Chemistry remains chemistry throughout the universe, but different planets can create different conditions suitable for the emergence of life.
More specifically, the Scharf and Cronin equation states that the chances of life on a planet depend on the number of building blocks that could theoretically exist, the number of building blocks available, the likelihood that these building blocks will actually become life (during assembly), and the number of building blocks required to produce a particular life form. In addition to identifying the chemical prerequisites for the emergence of life, this equation seeks to determine the frequency with which reproductive molecules arise. On Earth, abiogenesis took place at the moment when RNA appeared. This crucial step was followed by the flowering of simple unicellular life (prokaryotes) and complex unicellular life (eukaryotes).
“Our approach connects the chemistry of the planet with the global rate of origin of life - this is important because we are starting to find many solar systems with a bunch of planets,” said Cronin. "For example, we think that the presence of a small planet nearby - like Mars - may be important because it cooled faster than Earth … some of the chemical processes could begin, and then transfer complex chemistry to the earth to help" push "chemistry on the earth."
One of the important implications of this study is that planets cannot be studied in isolation. As Cronin said, Mars and Earth may have been involved in the exchange of chemicals once in the distant past - and this exchange of substances could serve as the beginning of life on Earth. Perhaps exchanging chemical building blocks between nearby planets could dramatically increase the chances of life emerging on them.
So how many examples of life are there in the Universe?
“This is a difficult question,” says Cronin. "Our work suggests that solar systems with multiple planets can be excellent candidates for closer scrutiny - that we should focus on multi-planet systems and look for life in them." How? It is worth looking for signs of changing atmospheres, complex chemistry, the presence of complex compounds and variations in the climate that may be due to biological life.
We don't have enough empirical data to complete the Scharf and Cronin equation at this point, but that will change in the future. In the coming decade, we will be able to use the James Webb Telescope and the MIT Tess mission to fill in the missing values. In the end, we will find the answer to this question that worries us.
ILYA KHEL