According to a new study that recasts the Drake equation using probabilistic logic, the universe must either be teeming with life or contain no life at all.
A general principle in Search for extraterrestrial intelligence (SETI) means that if we find technologically advanced aliens, there will probably be many, many more cases. Alien life Two cases (we and New Discovery) are out of existence.
In a new paper, astronomers David Kipping of Columbia University in New York and Geraint Lewis of the University of Sydney describe how this logic works based on the probability distribution introduced by biologist and mathematician JBS Haldane in 1932. Earth-like exoplanetsAll with similar characteristics. Considering their slight differences, we expect life to arise in all or none of them; There is no obvious reason why half of these are the same Planets For example, life supports and half does not support.
Various effects can be shown on a U-shaped graph with probability on the y-axis and area of planets on the x-axis. The two ends of the U-shape correspond to no or very few planets with life and many planets with life. A U-shaped trough corresponds to the lowest probability, representing half of the planets with life.
Related: The Drake Equation: Estimating the odds of finding ET
Now Kipping and Lewis popularized Haldane’s logic The Drake equation. Created by Astronomer Frank Drake Before the first SETI conference, at Green Bank Observatory In 1961, the Drake equation took on a life of its own as a means of providing the workshop with an agenda that was used to estimate the number of technological life forms. Milky Way.
The Drake equation is written as N = R* x fp x ne x fl x fi x fc x L, where N is the number of civilizations, R* is the star formation rate, fp is the fraction of stars with planets, ne is the number of potentially habitable planets, and fl Fraction of habitable planets capable of producing life, fi is the fraction producing „intelligent” life, fc is the fraction containing communicative life, and L is the average lifetime of civilizations.
Astronomers know the star formation rate (less than 10 Solar masses per year in our galaxy) and the fraction of stars with planets (almost every star has planets) is good. The number of habitable planets is less known, but astronomers are learning more about them every day as they study. Extraterrestrial atmospheres with The James Webb Space Telescope and categorize those worlds. The values of the other four terms remain a complete mystery, rendering any attempt to use the Drake equation less than satisfactory.
However, the first six terms of the Kipping and Lewis Drake equation describe the „birth” of what they call extraterrestrial technological phenomena, or ETI. This is how they refer to technological alien life, neatly ignoring terms like „civilizations,” „species,” and „intelligence,” which have proven problematic (for example, how do we define intelligence?) but never properly describe alien life. Meanwhile, the final word, L, relates to the „death” or otherwise disappearance of the ETI.
Splitting the terms of the Drake equation this way allowed Kipping and Lewis to simplify the formula, to read: The time-averaged number of ETIs in a galaxy is the birth rate of ETIs multiplied by their death rate.
„The beauty of our approach is that it’s completely generic,” Kipping said Space.com. This means we don’t need to worry about terms in the Drake equation that we don’t know.
„We’re not assuming any particular mechanism or mechanism of birth,” Kipping said. „Births may occur by spontaneous emergence, or Panspermia Seeding, or empire-building, or whatever else you want—there’s a birth rate.”
Kipping and Lewis hypothesized that a steady state is the Drake equation, where an equilibrium birth and death rate is approximately equal, which will inevitably be reached after enough time has passed. Both astronomers related this to Haldane’s prior („prior” is the name for a type of probability distribution, like a U-shaped curve) through a property called the occupation fraction, f. Exoplanets are mentioned in the example. In this article, a high value of F – close to 1 – corresponds to every planet with life, and a low value – close to or equal to 0 – corresponds to no life-free planets.
The problem SETI scientists face is that, based on observations so far, F is probably not close to 1; Otherwise, we would have noticed by now that we are not alone in assuming that intelligent aliens have spread throughout the galaxy and are adept at building mega-structures. Tyson swarms and emits radio signals. This means that if we are not truly alone in the universe, the occupation fraction should be close to 0.5, placing it in the unlikely valley of a U-shaped curve. Based on that U-shape, we’re likely to be relatively alone—technical life is rare elsewhere in the universe.
„These are phenomena of life, first through the signals they generate, and then through their colonization through megastructures,” Lewis told Space.com. „If such an ETI arose during the life of the Milky Way, they could have colonized the entire galaxy in 10 million to 100 million years, and even after they fell, their debris would be around for a long time. True. If we don’t see anything there, if they were, they would have disappeared long ago, their signatures. are extinct, and we are back to our original premise—ETIs appear to be rare in time and space.”
Related: The search for aliens
Yet Kipping and Lewis are not suggesting giving up on SETI. If we ignore the lack of evidence for a moment, the standard Drake equation predicts a crowd universe We are equally likely to be single. For a crowded universe, the occupation fraction should be close to 1, which is still possible under certain circumstances. Perhaps the ETI stayed in their own region, and ours solar system It is happening in an area where no one has ever spread. It means aliens are far away, and our strategy of looking for them around the stars is wrong. These inhabited regions can be more clearly detected in other galaxies. „I would certainly argue for extragalactic SETI,” Kipping said.
Or maybe Interstellar travel And megastructure-building is too difficult, or they might not even be favored by the more frugal, less colonized, existence-dwelling ETI. Given the lack of radio or optical signal detection, SETI does not yet have the evidence to be particularly comprehensive in its search, and we can Easily missed a signal.
Complex life is possible, but the development of technological life is rare.
The birth and death rates of ETI have not reached a steady state after all, which means there will still be time for new ETI to appear on the scene and increase the occupied area. Given the age of the universe and the limited lifetime of ETI, this seems unlikely.
Research is currently available Front axleand submitted to the International Journal of Astrobiology for peer-reviewed publication.
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