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Drake's equation does not work - and here's how to fix it


The theory that the first detection of extraterrestrial intelligence will occur using radio waves, was expressed long ago. But it is possible that there is such a thing in space that we still could not even dream of searching

In 1961, scientist Frank Drake wrote a simple-looking equation to estimate the number of active, technologically advanced, and messaging civilizations in the Milky Way. There was no convenient way to simply estimate this number, but Drake had a brilliant idea to write down a lot of parameters that could be estimated, and then multiplied. If the numbers are correct, then you will get the exact number of technologically advanced civilizations with which humankind could communicate, located within our Galaxy, at any moment. The concept is brilliant, but the more we learned about our Universe, the less it became useful. Today, the Drake equation does not work, but we know enough about the Universe to create an improved method for counting.


The possibility of the existence of another inhabited world in the Milky Way is incredible and attractive, but if we want to know how real it is, we definitely need to deal with science.

The Drake equation, to be exact, says that the number of N civilizations existing at some point in our Galaxy is equal to the product of seven different unknown quantities related to astronomy, geology, biology and anthropology, each of which is repelled from the previous one. It:

  1. R * , the average star formation rate.
  2. f p , the proportion of stars with planets.
  3. n e , the average number of stars that have planets, among which there is a planet capable of supporting life [ in fact, the average number of star planets capable of supporting life / approx. trans. ]
  4. f l share of these planets on which life originated.
  5. f i share planets with life, where intelligent life appeared.
  6. f c share of these planets with intelligent life, capable of sending messages through interstellar space.
  7. L, the length of time that such a civilization transmits or listens to messages.

Multiply the parameters between each other, and, in theory, you will receive the number of technologically advanced civilizations in the Milky Way, transmitting messages,


Fantasy artist on the subject of potentially habitable exoplanets in orbit around a sun-like star. But we may not need to look for another planet resembling Earth in order to find life. In our solar system may already be all the necessary ingredients. We just do not know how life is common.

Here are just a lot of big problems with this layout. Writing an equation in this form contains several unspoken assumptions that do not reflect reality. The problems with his current utility are as follows:


The latter assumption motivated the creation of SETI - a project to search for extraterrestrial intelligence using radio antennas - which did not find anything.


Atakam millimeter-range large antenna array, ALMA is one of the most powerful radio telescopes on Earth. And this is only a small part of the array that forms Event Horizon Telescopen, capable of shooting the Magellan Clouds (shown here) and all the stars of the southern sky, unlike most observers in the northern hemisphere.

This, however, does not mean that there are no more worlds with intelligent life! Despite the uncertainty about the existence of other sentient beings and their desires and opportunities to try to find us and contact us, the possibility of existence of intelligent aliens able to communicate or travel in space is of great interest not only among scientists, but also of all mankind. Many parts of the Drake equation can be problematic, and the main one is that they contain enormous uncertainties: they are so large that any assumptions about the value of N, the number of civilizations in our Galaxy, do not make sense. But now is the year 2018, and we already know a lot about the Galaxy and the Universe, which we did not know in 1961. And here is a better approach.


Stargardens in the Large Magellanic Cloud, a satellite galaxy of the Milky Way. By observing star clusters inside and outside our galaxy, as well as measuring the size of the Milky Way, we can quite easily determine the number and types of existing stars

1) N s : the number of stars in the galaxy. Why assess the speed of star formation when you can just look at the number of stars today? We know how large our galaxy is, how thick it is, how big the central bulge is , and how mass is distributed in it. Based on our observations with the help of especially powerful telescopes that study both the entire sky and its individual parts with great care, we can simply declare that in our Galaxy there are from 200 to 400 billion stars. The 2-fold uncertainty is a good indicator, and this gives us a very optimistic start: every star has chances for success. Let's pick a larger number.


Picture of a Kepler telescope searching for planets. He found thousands of planets orbiting the stars of the Milky Way, and told us about the masses, the radii and the distribution of worlds outside the solar system.

2) f p : share of stars with planets. We can leave this parameter of the original equation, but after the operation of the Kepler telescope it means little. Why? Because it is close to 100%! The proportion of stars that have their planets, if we take into account our observations and the knowledge gained, is no less than 80%. The fact that the proportion of stars with planets is close to 1 means an easy victory for the optimists.


Moon and clouds over the Pacific Ocean, photographed during the Gemini-7 mission. On Earth, revolving around the sun, conditions are suitable for life. What about other stars?

3) f H : proportion of stars with conditions suitable for life. Here the story becomes more interesting. How many stars from the main class have worlds capable of supporting life? A star like our Sun is capable of this - with such a mass, radius and lifetime - this proves our existence. But what about a more massive star? At some point, the star will be too massive and too quickly burn all its fuel, so intelligent life does not have time to develop next to it.

On the other hand, low-mass stars may be unstable, they can produce flares that can blow off the planet’s atmosphere, or produce so little ultraviolet light that life does not appear. You can worry about enough heavy elements, or that in certain parts of the galaxy the conditions are too chaotic to sustain life. These values ​​are unknown, but we can probably say with a high degree of confidence that at least 25% of the stars in our galaxy are capable of having inhabited planets.


Molecules of sugars in the gas surrounding a young star resembling the sun. The basic ingredients of life can exist everywhere, but life will not appear on every planet containing them.

4) n p : the number of planets around inhabited stars with conditions suitable for life. We received a huge amount of information from this area, studying exoplanets, but many questions remained. What makes the world inhabited? In the early solar system, Venus, Earth and Mars had similar conditions. On the outer part of the solar system on worlds such as Enceladus and Europe, there is a subsurface ocean, and possibly underwater life. In systems with gas giants located where conditions are close to those of the earth, life can appear on large moons. And although in this case the uncertainty is very high, I think it can be fairly accurately said that on average, stars, next to which a potentially inhabited world can appear, will have approximately one world with the best chances for life. We are interested in this particular world, and we say that n p = 1.

By this time, we can already multiply the four first numbers and get an approximate number of worlds in the Galaxy with good chances for the emergence of life: 100 billion. A promising start.


Structures found on ALH84001 meteorite originating from Mars. Some believe that these structures may be ancient Martian life.

5) f l : the percentage of such worlds on which life appears. There will have to agree with Drake, because this is one of the greatest questions of the search for life outside the Earth. On how many of all the potentially inhabited worlds does this incredible first step take place, during which the living emerges from the inanimate? Or, if primitive life originates from interstellar space, how many worlds does life fix on land, in the oceans, or in the atmosphere? We do not know the answer to this question even within the Solar system, where, possibly, there are as many as 8 worlds on which life appeared at some point. Life can be widespread, and with an optimistic estimate, the chances of its occurrence can be 10%. Or it may be an extremely rare occurrence, one case per million.


Signs of the presence of organic molecules that produce life are found throughout the cosmos, including the largest of the nearest star formation regions: the Orion Nebula. Someday we may be able to look for signs of biological processes in the atmospheres of Earth-sized planets located in other stellar systems.

In this case, the uncertainties are huge, and any chosen value will not be better than any other. Sometime in the future we will have the opportunity to conduct our first checks. When our technology allows telescopes to determine the contents of the atmospheres of the worlds, we can look for signs of biological processes, such as methane, molecular oxygen and carbon dioxide. This will be indirect evidence, but, nevertheless, a huge step in the direction of assessing the likelihood of life on the planet. If we assume that there is life on one of every 10,000 potentially inhabited worlds, which will not be a worse conjecture than everyone else, then it will turn out that there are life on 10 million worlds of the Milky Way.


Ligand-dependent ion channels are the most important channels where there are many working in biology, and they are especially important for the work of the human body. Unicellular organisms can reproduce very quickly, but multicellular organisms are required to produce complex functions and structures.

6) f x : share from planets with life, where complex and differentiated organisms have evolved. The definition of "rationality" of life is a vague task at best, since even our best scientists still argue over whether species such as dolphins, apes, octopuses, etc., can be considered reasonable. However, no one will argue with that , whether the organism is classified as complex and differentiated: such an organism should have different parts of the body with different functions and structures that have macroscopic dimensions and a multicellular structure. Before the appearance of the first multicellular organisms on Earth, life developed for billions of years, and then it took hundreds of millions of years before the appearance of sex as a tool of reproduction.


Bonobo catching termites is an example of a complex and differentiated organism using primitive tools. It cannot be considered scientifically and technologically advanced, but it is definitely considered multicellular, differentiated and very interesting from the point of view of astrobiology.

Earth is once again our only laboratory, but let's be optimistic about the lack of evidence and assume that there is one chance in a thousand that the world, starting with a primitive, self-replicating molecular information coding information, can create something like a Cambrian explosion . This gives us 10,000 worlds in the Milky Way, overflowing with diverse, multicellular, highly differentiated life forms. Considering the distance between the stars, we can assume that another similar planet on which it happened is just a few hundred light years from us.


Figure 1991 of the space station " Freedom ", which is in orbit. Any civilization that has created something similar will definitely be considered scientifically and technically advanced.

7) f t : the proportion of such worlds on which there is currently a technologically and scientifically advanced civilization. This question pushes the questions asked by the Drake equation into the background. What is the difference, the first is the case of the emergence of a technologically advanced civilization or the tenth? Who cares if they use radio waves? What does it matter if they blow themselves up, or die out, or do they have a desire to travel in space, or not? The main question is whether there are aliens that are rational in a way similar to us, that is, scientifically and technologically advanced.


Composite picture "that's it yes" ['holy cow'] from the Martian mission Phoenix, on which water ice is clearly visible under the supports of the descent vehicle. To find out the maximum amount of information about the presence or absence of life on the planet, you definitely have to land there and look for its guaranteed signs.

Naturally, there is no evidence of this anywhere except on Earth, which means a huge range of possibilities. This may be 1% of all planets, or the emergence of humanity may be a wild accident, and the probability of this will be one case per billion. On Earth, 500,000,000 have passed since the Cambrian explosion, and a technologically advanced view of the planet has existed for no more than 1000 years. If we assume that humanity will last for several thousand more years in such a state, then it turns out that the Earth spent one hundred thousandth part of its time together with complex, differentiated organisms that are in a technologically advanced state.

With such estimates, even if there are 10,000 such worlds in the Milky Way, the probability that another technologically advanced civilization exists at the same time with us will be approximately 10%.


Perhaps the desire to conquer the cosmos appears immediately, when in one place the intellect, the use of tools and curiosity converge.

Considering all the above, the last three quantities - f l , f x and f t - are distinguished by enormous uncertainty, which at the moment makes it impossible to make accurate estimates.

Knowing how many worlds with life exist in the Milky Way, and finding at least one of them, we would have an incredible impact on our own existence and on our understanding of our place in the Universe. The next step, obtaining information about the presence of complex, differentiated, large organisms on another planet would revolutionize our capabilities. And the chance of messaging, meeting and sharing knowledge with a scientifically or technologically advanced alien civilization would forever change the course of human development. All this is possible, but we still need to know so much if we want to find out the answers to these questions. These steps need to be taken; rewards for them are too high if there is a chance to find answers.

Source: https://habr.com/ru/post/415667/

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