Thoughts on the Fermi Paradox. part One

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Thoughts on the Fermi Paradox. part One

Сообщение DARPA » 24 мар 2015, 21:20

Known paradox that for more than half a century, is located in the center of scientific research associated with attempts to make contact with extraterrestrial civilizations, is named after the American physicist of Italian origin, the Nobel laureate Enrico Fermi.
According to the recollections of that same year the conversation in the laboratory at Los Alamos, Enrico Fermi formulated it as follows: "Well, and where are they then?" Meaning, of course, the scientific question, "Are we the only reasonable and technologically advanced civilizations in the universe? "

More deployed, mathematical language other than emotional exclamations Fermi paradox problem was expressed in the form of so-called Drake equation, which has made a professor of astronomy and astrophysics Frank Donald Drake year after a summer day at Los Alamos, where he was made the very sacramental "Where they hell are you? "Fermi converted both to his colleagues and to thus unobservable aliens.


Here is a visual record of this equation in the form "for children":



Drake equation output should give us the number of civilizations, which must already exist in the observable part of the universe, and which could potentially enter into contact with us. This number N.

Then we follow the measurable parameters which, in general, yield calculation and observation and, based on the type of formula (multiplication factors) - each affect the total value of civilizations N.

The first option - it is the number of R, which is equal to the number of stars formed per year, for example, in our Galaxy. You can, in general, expect that some signals from other civilizations can cross and vast expanses of intergalactic empty space, but to demonstrate the approach Drake and sufficient amount of our own, very rather big Milky Way Galaxy.
According to initial astonomicheskim and astofizicheskim data existed in the 1950s, in our galaxy formed about 10 stars for each year of its existence. Recent estimates suggest 7 stars a year in the galaxy, which is correlated with the initial estimate of the time of Drake. It seems to be a little bit, but in the future we can see that it is not important. It is important that the stars in our galaxy are formed - and the pace of their education in the past was, most likely, not lower, and even higher than it is now.

The second parameter, which today is also clear, thanks to recent studies of outer space and the stars close to us - is the parameter fp, who talks about how much of the stars formed subsequently acquires planets.
Intuitively, before it was clear that most star systems should have planets and our solar system in this regard, it is not unique, but clear evidence of this fact have been obtained only recently.

This is due to the work of several machines, which were launched into Earth orbit to detect so-called exoplanets, namely near-Earth Telescope NASA "Kepler" and European telescope COROT.
To date, these two spacecraft (and, first of all, "Kepler") can boast the largest contribution to the existing to date list of exoplanets in 1901 (as of 03/15/2015).
Found 1901 exoplanet is in 1199 star systems, with 428 of them, as in our solar system, there is more than one found exoplanets.
In addition to clearly established exoplanets, which are recorded repeatedly passing in front of its own disk stars (orbital telescopes capture the smallest regular oscillations observed luminosity of stars), only the "Kepler" there is at least 4,175 potential candidates for exoplanets.
Here is an illustration of what "seen enough" for mankind "Kepler" in less than six years of observations in space:



Our own Sun and Earth are shown outshining her to scale in the second row illustration.

When considering exoplanets, of course, it is worth considering the fact that the current methods of registration of exoplanets is still imperfect: a method of registering a partial eclipse of the parent star exoplanet allows you to quickly detect only those planets, the plane of rotation which practically coincides with the beam directed from the star to the solar system .
Only in this case the planet is easily recorded on each pass it between the parent star and the solar system.
In addition, of course, the smaller the planet and the longer its period of revolution around the central star, the longer it takes Space Telescope in order to confidently detect at least a dozen passes in front of exoplanets disk parent star.
For example, Jupiter with its period of revolution around the Sun in 12 years, yet would still does not find himself an observer of other solar systems, even if he already came to the attention of extraterrestrial telescopes, such "Kepler" for his term in orbit.

In general, the field of view of the telescope "Kepler", which is fixed between the constellations Cygnus and Lyra, and on one side of the famous "Summer Triangle" includes about 2.5 million distinct in its optics stars, which will very soon get a very rich observed facts model of planetary evolution in our galaxy:



In any case, even with such a fragmented and incomplete information about the observed exoplanets, the initial assumption about Drake parameter fp, is part of the formula and accepted Drake equal to 0.5, does not look so much divorced from reality.

Today it is almost won the hypothesis that the formation of stars in our galaxy everywhere comes from the initial gas-dust cloud that after the formation of the central star inevitably generates at least a few planets. According to recent studies, at least 30% (0.3) of solar-type stars have planets, and, for the above reasons of incompleteness and the difficulty of obtaining data on Earthlike planets, this assessment in the future will only grow. In addition, infrared studies of dust disks around young stars formed now show that 20 to 60% (from 0.2 to 0.6 in the category parameter fp) solar-type stars can form planets like Earth.



It is the observation of gas and dust clouds around stars are formed, by the way, is connected and the first in the history of mankind direct observation of an exoplanet orbiting a bright star in the southern sky, Fomalhaut and dubbed Fomalhaut b.

In general, summing up the latest facts about the parameter fp Drake in the formula, we can say that he can not be lower than 0.1, but it can reach up to values ​​close to unity (almost any star system has a planet).

The next parameter formula Drake, ne says the number of planets that are suitable for life in all its forms in the calculation of one star system.
Ultimately, the weight quickly open "Kepler" planets such as "hot Jupiters", which have a period of revolution around its sun in a few days and sometimes have a temperature of a few hundred or even a thousand degrees Kelvin, are unsuitable for the existence of life slip or remotely resembling earth.

Of course, in works of fiction, along with excellent Venusians and Martians are always severe and huge octopus floating in the atmospheres of gas giants, and even some "solar prominences reasonable", but it's better to start from the fact that we can understand and stable for a long period of time life can exist only on the terrestrial planets.

Of course, here we are embarking on a very slippery slope of our internal beliefs and assumptions, falling into the trap of the so-called "carbon chauvinism", but I must say, this approach is not without a certain sense.
Other things being equal, in our universe is that hydrogen, oxygen and carbon are not only the most common but also the most convenient chemical elements for the construction of living beings.



The initial conditions of the "Big Bang", the mechanics of the subsequent burning stars in our universe and the resulting stable isotopic composition of chemical elements such that the most common chemical elements we are hydrogen, helium, carbon, oxygen and nitrogen.
Subsequent chemical elements are already in a much more modest amounts, since the majority of stars burning ends with the formation of carbon, nitrogen and oxygen (in the reactions of combustion of hydrogen, helium and CNO-cycle), and the rest of the "zoo" of terrestrial and extraterrestrial chemistry already obtained as a result of an explosion of new and supernovae, or as a result of the slow decay of uranium and thorium.
This is what caused, by the way, the local peaks of iron (sometimes referred to as the more "fusion coals") and lead (radioactive decay product of most heavy isotopes) in the graph Abundance of the chemical elements.

In addition, purely for reasons of classical chemistry, namely the carbon in our universe is the most interesting "building block" for the complex chemical compounds, without which it becomes difficult to imagine an ordered structure characteristic of all life.
In particular, at the moment known to science inorganic compounds, there are about 100,000, while the organic - more than 8 million, and each year more open about 300,000.

That, however, is not to say that alien life is required in everything and in all aspects of life on earth to copy - for example, have long been known xeno-nucleotides, which, in general, no worse can cope with the functions of coding information is very characteristic and is likely vital for what we call a capacious word "life."
Koroma, recent studies show that alternative life can do without nucleic acids themselves, even altered the chemical composition, encoding information through alternative, much more resistant to temperature and pressure peptidonukleinovye acid.

In general, it is, of course, expands the boundaries of permissible for the origin of life, but a universal concept of "Goldilocks Zone" is vital for parameter estimation in the formula ne Drake.


Comparison of the "Goldilocks Zone" for the sun and colder, but also has a planet in the habitable zone of the star Gliese 581.

It is clear that there is nothing surprising in the fact that in a single star system just two planets can be a potential habitable zone. So, for our solar system in the habitable zone and are just two of the planet - our earth and much more distant and cold Mars, and in the star Gliese 581 in the habitable zone, too, get two planets, with reference letters c and d.
But Venus is in the habitable zone of the solar system, unfortunately, is not included. That is why all the processes terraforming Venus somehow tied to the anti-greenhouse effect - otherwise excessive solar radiation still ruin even artificially induced life in the Venusian orbit.

In general, as of January 2015, we already know for a minimum of 30 exoplanets that surely fall in the "Goldilocks zone", in order to have conditions similar to ours, and allows you to have a life based on carbon compounds and water:



Of course, even in comparison with 2.5 million stars caught in the lens "Kepler", it seems downright meager quantity, but I hope that you understand that not all the planets are in the "Goldilocks Zone" managed to find for such a short period of the existence of effective orbital projects on the search for exoplanets and restrictions on the availability of fixing the planets in the studied stars.

Evaluation of the grapnel parameter ne was quite optimistic and was 2 (based on the presence in our solar system of two potentially entering the zone of habitability of planets and very interesting law Titius-Bode). To date, based on studies on the search for extrasolar planets already known, that the mass of the satellites of other stars are very exotic, strongly elliptic orbits of the planets ("hot Jupiters") simply is immersed in the outer corona of their stars, and the number of planets in the habitable zone yet much less than the original estimate of Drake. As I said, today we know about 1200 planetary systems, which are reliably detected a total of 30 potentially habitable planets. If based on these observations confirmed, we obtain a lower bound for ne, equal to 0.025.
However, on the other hand, in the case of observations of our solar system at distances comparable to those on which the telescope "Kepler" has made most of his discoveries, our own system, most likely, would be appreciated, as consisting of the Sun, Jupiter and Saturn as all the other planets would be technically very difficult or time-consuming to register.
Based on the foregoing, it can be assumed that in the future, against the background of the project "Kepler" and his followers, the parameter estimate ne will gradually grow. Currently, most researchers still ne aside for a very wide range of values ​​from 0.05 to 2.

Further three-parameter formula Drake fl, fi, and fc - which respectively characterize the likelihood of life, the emergence of reason or need for the implementation of the contact occurred civilization are already quite speculative values.

Even the first, the most simple to the evaluation value, the probability of life fl, is already quite complex in the assessment. The thing is that today we have only one object that is reliably and in sufficient detail tells us about the origin and development of complex organic life - is our own planet Earth.

All other concepts of the origin or development ksenozhizni anyway based on the weight of the implicit assumptions that take - or else deny certain factors as essential for the emergence and existence of complex life for a sufficiently long period of time.

And here, by the way, in the framework of objective rather than speculative research, we really would have helped our own candidates who are in the "Goldilocks Zone" - a seemingly empty and cold today Mars.

To date, on the basis of studies already carried out repeatedly in several automatic missions to Mars, it is clear that no complex organic life on Mars today, no.
This fact alone is quite limited fl parameter value of 0.5, although the Drake believed that life is always there in suitable conditions for it and believed in such a way that fl = 1.
On the other hand, the presence on Mars even weak traces originated, and then suddenly the lost life, will allow us to more fully understand the uniqueness of our own universe destiny expressed in an interesting hypothesis, "the uniqueness of Gaia" and, oddly enough, will allow us to significantly raise the lower boundary of the parameter fl.

If on Mars, for example, will find the remains of stromatolites that prevailed on Earth as much as 2 billion years old and still alive and still - it will say exactly what is the uniqueness of the Earth.

The position of the Earth and the solar system in something unique, based on the facts that have been accumulated by mankind. Spiral galaxies contain a lot of turns of massive stars, which end their way of life as a supernova. Close supernova explosion and its gamma radiation is believed to make the higher forms of life impossible and greatly complicates the recovery of the victims of the lower forms of life. Our solar system is on a special orbit within the Milky Way: it is almost a perfect circle the average radius at which the star system moves with the same speed as the gravitational shock waves that form helical windings of our Galaxy.
Sun and Earth is between the spiral turns of the Galaxy over the past few hundred million years, or more than thirty full galactic rotations, that is, almost all the time while on Earth, there are higher forms of life.


We - in the center of the blue ball between the galactic spiral arms Sagittarius and Perseus. And, by the way, inside this ball gets 90% of individual stars visible to us.

Another possible and necessary element of our unique environment - is our moon. Popular early giant impact hypothesis states that our natural satellite, so unlike the moons of Mars, was formed due to a rare collision still young Earth from another planet had undergone a similar orbit. Hypothetical planet the size of Mars, conventionally called Theia, roughly about 4.45 billion years ago, "caught up" the Earth, coming out of a comfortable and secure behind the Earth Lagrange point on her own orbit. It is important that the collision of two protoplanets with the formation of the new moon occurred in a very unlikely situation - it was supposed to happen only at a certain angle, right angle would destroy the earth, while a more gentle angle of collision would lead to the fact that Theia would simply ricocheted from Earth, while not creating a mass of debris collision debris that formed the young and the moon in low Earth orbit.

According to all astronomical calculations, it is the next high tides caused by the near-earth young moon, the earth's axis stabilized: without the influence of fluctuations in the Earth's axis of the Moon, as well as others, "moonless" (Mercury, Venus) or "malolunnyh" planets (Mars) would be much more and would lead to huge changes in climate that could destroy regularly evolving life or downgrade it back to simple forms.
In addition, the lunar tides, probably made the initial heating of the Earth's core, which allowed the world due to a huge dynamo, earned within the earth, to get a strong magnetic field, which is not Mercury, Venus or Mars. They greatly reduce the influence of the solar wind, which would clearly have a negative impact on the development of life on Earth.


"Kepler" before launching into orbit.

But here, in matters of the uniqueness of the Earth, we are also able to help the aforementioned Space Telescope "Kepler": according to the latest estimates, it will be able to help other computer programs and data processing to detect exoplanets open even satellites, provided that their weight is not less than 0.2 the mass of our Earth.
Of course, this is not yet the moon, which is smaller than the Earth 81 times, but just neveroyano, especially when you consider the fact that "Kepler" will be able to do it at a distance of 500 light years.

In 2002, American scientists Charles Laynviver and Tamara Davis was rated as the parameter fl> 0.13 for planets with more than a billion years of existence in the case of contact with them in the "Goldilocks zone", mainly, of course, based on the basis of the history of life on Earth itself . Laynviver in his later work in 2004 also found that only about 10% of stars in our galaxy are suitable for life in terms of the presence of heavy elements, the distance from the spiral arms and their characteristic supernova and sufficiently stable in structure. Such stars are not too massive to quickly "burn out" in the new, but not too light and cold, as in this case, the "Goldilocks zone" is very close to the central star, very narrow and produces, in addition, due to the strong tidal forces of the parent stars very specific conditions on the planet, which in principle can be life.
Basically, if you put restrictions two works, it turns out that fl must even in the worst case will still be> 0.013 - 1.3% of all possible options and combinations of "star + planet" on the unknown planet in the habitable zone anyway there is life.


The width of the habitable zone stars depending on the temperature within the main sequence. The colder and less star (and this condition is satisfied on the main sequence strictly) - the narrower the habitable zone.

However, all these calculations and research, as I mentioned, suffer a fair amount of speculation - such as Jupiter's moon Europa is thought to have under the outer crust of ice water deep enough and very hot due to the tidal forces of Jupiter under-ice ocean, the depths of which are very similar depths of Earth's oceans. The existence of extremophiles on Earth, such as tardigrades, does the existence of life on Europa is quite possible, despite the fact that Europe is in all respects is the estimated habitable zone of the solar system.

It is interesting that of the stars in our galaxy, which satisfy the conditions Laynvivera, about 75% are older than our Sun, which is very interesting in the framework of our future story.

In general, today the parameter fl usually take in the range of 0.013 to 1, indicating that life, in general, is quite common phenomenon: once arisen, in most cases it does not want to die - even history itself land filled with droughts and floods, volcanic eruptions and asteroid impacts, glaciation and other environmental catastrophes, nevertheless confident, time after time, restores itself after the most horrible, it would seem - fatal accidents for the entire biosphere.


All previous mass extinctions on Earth, apparently, had a purely biogenic nature: one life at the expense of their best just to kill another organization, the older life. No exception to this rule is the current extinction caused by human already.

The next parameter of the formula Drake - is the probability of intelligent life on the planet, fi.
On the one hand, starting on the parameter fi rassuzhat we embark on a very very thin ice, because today, even taking into account the "semi-intelligent" dolphins and chimpanzees, as well as the untimely deceased Neanderthal Remember, we can only talk about one known to us reasonable form - Homo Sapiens Sapiens, more known under the name of "man."
That, in general, it immediately puts us in a sense shackles "anthropic principle": willy-nilly, we ascribe intelligence and intelligent beings acts, in fact evolved in very different conditions, it is possible - in strikingly dissimilar to the terms of current or historical land.
For example, as an option, the mind may well arise as a distributed mechanism similar to a beehive or anthill premind characteristic of social insects.
What has been, in general, the rocks and the corresponding formation of purely scientific cartoons to the question posed in the Fermi Paradox:


"Hell, we searched all these fucking tiles in search of pheromones! If there was intelligent life, we would have just found it! "
The first intelligent ant colony trying to find us.

In any case, based on the fundamental features of life and of our own evolutionary experience is likely to be expected that any intelligent life for quite a long period of time will escalate your energy use to the point to become noticeable in the galactic scale and, at the same will follow the path of continuous development of its civilizational features and spatial expansion.

Scientists involved in the problem of the search for extraterrestrial intelligence (SETI) and classify civilization - in their ability to generate and use energy.
Civilization type I (even though it will be reasonable and ants from Tau Ceti) generate energy in amounts roughly equal amounts of energy received their planet from its star, and Type II civilization already operate orders of energy comparable to the energy emitted by the central star of their own.
Under this classification refers to humanity "type 0.7" - in the world today is produced on a logarithmic scale only 0.7 on the amount of energy it takes to be called a civilization of type I.
Today, based on astronomical and astrophysical observations can already say with certainty that there is no Type I civilizations within 10 000 light-years from Earth, and civilizations type II - no, not only within our own galaxy, but also in our neighboring galaxies that make up the with her single galaxy cluster.
Presumably, in improving the technology of observation, these limits will be expanded further.

Another interesting attribute of intelligent life, as I mentioned, is ineradicable desire for the development of new prostanstvo. Thus, in general, does not matter, Does intelligent life that sends to the stars of the colonists, frozen yaychekletki - or colony drone-replicators. We are talking about the process exponentially:


For how long intelligent civilization could colonize the galaxy? The answer is: enough only 5 million years.

Even today, humanity already has all the necessary technology and capacity to build a huge "Generation ship" that can quietly at a speed of only 0,01c (3000 km / second) for 500 years to reach the nearest star to us.
Even without taking into account future progress, this colonization can be repeated step by step, and already in 7500-th iteration of the process to enter the limits of our vast Milky Way.
Period of time in 5 million years, huge for us today - a brief moment in the life of the Galaxy. Civilization that would hypothetically could make such a jerk in the spatial expansion, sometimes also called the "civilization of type III», meaning that it is able to single-handedly take advantage of the resources of our entire galaxy.
Also, remember, 75% suitable for the origin of life is much older stars of our sun, which is observed by us delet picture even more mysterious: many intelligent species on the planet could be capable of the origin of life for billions of years before the dinosaurs became extinct on Earth :


Comparison of Earth and Planet X hypothetical early: handicap 3.46 billion years amid 5 million years of expansion on the entire galaxy.

And it is here that we have and there is the same Fermi cry: "Where they hell ?!"

After all, if we substitute in the formula Drake modest parameters fi (rationality) and FC (desire to carry civilization contact), today hypothetically taken at a very modest level of 0.01, the total value of the number of civilizations in the formula N Drake will still be very large: affects a huge age of our galaxy, even in conditions very different from the current (for the majority of stars suitable for sustaining life on criteria Laynvivera, this age is about 8 billion years old).

So, we have:
N = R * fp * ne * fl * fi * fc * L
L, as I said, on the basis of purely physical restrictions on the mustache of the Galaxy, the chemical composition of stars, etc. we have about 8 billion years old, or 8 * 109 years. We substitute all other parameters in the formula by taking the last two, the most obscure now parameters (probability of occurrence of the mind and the likelihood of its ability to pin) initial assessment of the Drake adopted them as 1% in each case (fi = 0,01, fc = 0 01)

N = 7 * 0.5 * 0.013 * 0.01 * 0.01 * 8 * 109 = 36400

Thus, based on the maximum available to us today an array of raw data about our galaxy, we can, based on the formula Drake say that today we would have been neighbors for at least 36,000 unique civilizations of the Milky Way, many of whom would have been ahead of us in the development by as much as three and a half billion years.

And it is here that we come to an interesting problem, which in cosmology and the problem SETI called Great Filter.



Apparently - somewhere on the way to the future we are waiting for the same Armageddon which for so long and tedious, we were told all the prophets.
Although, as an option, the Great Filter has occurred somewhere in our biological past - and we're just the last (and first) of the survivors.
DARPA
 
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