Excerpt from the book the astronomer about why the aliens not only we have not arrived, but did not attempt to contact.
Where are they?
This is such a short question was asked by physicist Enrico Fermi in the early 1950s, at a dinner with several scientists. They discussed the recent surge in the number of sightings of flying saucers and the possibility of interstellar travel humanity or other creatures. When the conversation turned to aliens, Fermi asked, “Where are they?” The exact words are lost in centuries; perhaps, he said, “Where is everybody?”, what is equally brief.
Despite its simplicity, this question has a rich history.
The basic idea is that, to date, either we should discover intelligent life in the Galaxy, or she was supposed to visit us.
As did not happen neither one nor the other, I do not take into account cases of UFO sightings. Despite the huge amount of blurry photos, obvious fakes and shaky video, there was no single unambiguous evidence that we were visited by aliens, never. Deal with it. ask about where the aliens, is reasonable.
Suppose that aliens came knocking at our door, their circumstances must be similar to our star, like the Sun, a planet like the Earth, billions of years of development and evolution of life, the progress of technology, then the ability to travel from star to star. How likely is that?
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For this we can turn to the Drake equation, named for astronomer Frank Drake. It includes all the necessary conditions developed life, and the assigned degree of probability. If the right to impose all the conditions, the result will be the number of advanced civilizations in the Galaxy (where “developed” means “able to send signals into space” so we would know about their existence).
For example, in the milky Way about 200 billion stars. Approximately 10% of them like the Sun: similar weight, size and so on. This gives us 20 billion stars to calculate. We only now know as the planets formed around other stars — the first planet orbiting a star similar to the Sun, was discovered in 1995, but we believe it is very likely that stars like our Sun, have planets.
Even if we accept the insanely low probability that around other stars have planets (say 1%), still it will be hundreds of millions of stars with planets.
If we accept the insanely low probability that these planets are similar to Earth (again, say, 1%), still it will be millions of Earth-like planets. You can continue this game by estimating how many planets might have conditions for life, how many there is a life, how many there are living entities capable of developing technology…
Every step in this chain are slightly less likely than the previous one, but even the most pessimistic view, this series demonstrates that we should not be alone in the Galaxy. Estimate the number of extraterrestrial civilizations are very different, literally from zero to millions.
Are we alone?
Of course, that’s not very good. The lower estimate is sobering. Maybe, just maybe, we really are alone. In the whole Galaxy, in all the vast trillions of cubic light years of emptiness, our planet’s very first became a haven for creatures able to ponder their own existence Can be lonely and different, and in a minute we’ll know for sure. . This bring us to the place and in a certain way frightening possibility. And this is probably true.
Another possibility is that life may be unique, but “advanced” life forms are rare.
On this subject was written many books, and this is an interesting topic for discussion. Probably, at some point, life becomes prone to introspection and not developing technology or even cares about them (in the psychology of alien creatures are difficult to penetrate). And I hope that by the time you got to this point in the book, I clearly explained that events that destroys civilization, often unpleasant occur in geological time frames. Maybe sooner or later every civilization sweeps away some natural event before she was able to develop a rather perfect method of space travel, to prevent this.
Actually, this answer I do not like. In a few years we will be able to prevent the collision of Earth with asteroids, leading to devastating consequences. We are confident that you can reliably protect yourself from the Sun. Our astronomical knowledge helps to determine which nearby star can explode, so if we see that some of them are close to it, we can make every effort to get away from her. All of these are quite recent developments that have occurred in an instant compared to how long there is life on Earth.
I can’t imagine a civilization that is smart enough to explore the heavens, but not developed sufficiently to ensure their own survival.
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I’m also leery of the upper limit on the Drake equation, if in the Galaxy there are millions of alien civilizations as developed as we are, or even more advanced. If that were true, I think we would have had clear evidence of their existence.
Remember, the Galaxy is not only extensive, it is still many years. The milky Way is not less than 12 billion years and the Sun is only 4.6 billion If we imagine a star, like our Sun, formed only a million years earlier — a drop in the bucket compared to the age of the Galaxy, then it is easy to imagine an alien civilization that appeared over many millions of years before mankind.
We know that life on Earth arose quite easily; it originated as soon as the period of bombardment and the surface of the Earth calmed down enough that life was able to evolve. So, almost certainly, life is taking root at the slightest opportunities, which in turn means that our Galaxy should be teeming with life. Despite a number of epic and devastating disasters, life on Earth still continues. We — intelligent, technologically advanced beings, and we went into space. Where we’ll be in 100 million years?
Taking into account the period of time and space, the alien species must already knocking on our door.
They had at least “call”. To communicate in the vast expanse of outer space is easier than to arrive. We send signals into space since the 1930s, They are relatively weak, and the alien creature it would be difficult to hear them from a distance of more than a few light years, but over time our signals have become more powerful. If we wanted to target in the certain place to focus easily detectable radio signal at any star in the Galaxy is easy.
The reverse is also true: any alien race, having a strong desire to talk with us, could do it effortlessly. That is what puts the project “Search for extraterrestrial civilizations” (Search for Extraterrestrial Intelligence, SETI). This group of engineers and astronomers scouring the sky in search of radio frequency signals. They literally will listen, speak aliens. Technology is advancing so successfully that the astronomer Seth Shostak believes that over the next two or three decades we will be able to explore one or two interesting star systems in the distance light years from Earth. This will allow us to approach the solution of the question of whether we are alone or not.
The only problem with SETI is that the conversations will be quite prolonged. If we detect a signal from the star, which is very close by galactic standards, say 1,000 light years away, the dialogue, in fact, be a monologue. We got a call, answered, then waited for their answer for years (this is the time that our signal reaches them, and then they signal to us). While SETI is a wonderful and worthwhile enterprise (and if they detect the signal, it will be one of the most important events in the history of science), we continue habitually to imagine that aliens arrive to us. Meeting face to face, so to speak, assuming they have a face.
But 1000 light years is very far (9 461 000 000 000 000 km). Quite a long ride, and yet, compared to the size of the milky Way is practically right under our noses.
Maybe that’s why to us nobody came? Apparently, the distance is just too great!
Actually, not really. If you do not lose the sense of scale, journey to the stars did not take much time.
Suppose that we, the people, suddenly decided to Finance a space program. And Finance big: we want to send spacecraft to other stars. This is no easy task! The nearest star system, alpha Centauri (which is a star similar to the Sun, and which is worth looking at), is 41 trillion km away from us. The fastest ever created space probes would have traveled there for thousands of years, so we in the near future should not expect results in the form of beautiful photos.
However, it is the fastest space probe today. Currently we are working on ideas that would build a much faster unmanned space probes, even those who can move with a speed approaching light. Some of these ideas include fusion energy, ion engines (which run slowly but continuously accelerated and over the years to develop great speed), and even the ship exploding behind a nuclear bomb, telling him a major boost, increasing the speed, This is serious: the project is called “Orion” and the development was carried out in the 1960s, the Acceleration is not smooth — kick in a soft place from a nuclear bomb usually this does not happen, but tremendous speed. Unfortunately, the Treaty banning nuclear testing (Chapter 4) prevents the testing of such spacecraft. . These methods can shorten the duration of the trip with thousands of years to just decades.
Perhaps this is to do. Of course, it is expensive. But this idea has no technological barriers, only social (funding, politics, etc.). Speak clearly: when commitment could we build such spaceships now.
In less than 100 years, we could run dozens of interstellar emissaries to other stars by studying our own neighborhood in the Galaxy.
Of course, due to the length of flights and the construction of the fleet we will not be able to see a lot of “real estate”. In a Galaxy billions and billions of stars, and build as many space ships impossible. Send one probe to one star uneconomical. Even if our probe just go right through a star system, circling the planet, and go to the next star on the study of the Galaxy forever. The large space.
But there is a solution: self-replicating probes.
Imagine this: an unmanned spacecraft arriving from Earth to the star Tau Ceti, after the road years. He finds a group of small planets and begins scientific observations. This includes something like a census measurement of all celestial bodies in the system, including planets, comets, satellites and asteroids. A few months research probe will travel to the next star in your registry, but before you leave, he sends the most suitable iron-Nickel asteroid container. This container is, in fact, self-running factory.
Immediately after landing, he starts to drill the asteroid, melting the metal to provide the necessary materials, and then automatically build new probes. Suppose he builds only one probe, and after several years of construction and testing that is sent to another star system. Now we have two of the probe. A few decades later, they arrive to their goals, find the right place and then multiply. We now have four probes, and the process repeats.
The number of robots for the messengers is increasing rapidly, as is exponential growth. If one probe is required exactly 100 years, then to the end of the Millennium we have 2 in the tenth degree = 1 024 probe. Two millennia probes a million. Through 3 000 years there will be over a billion. So, it’s not easy, of course.
Even pessimistic approach shows that we will need around 50 million years, maybe a little less to explore every single star in the Galaxy.
Well, it’s too long! And we are still very far from being able to do it. This is a complex technology.
But wait — remember that civilization about which we spoke and which is 100 million years ahead of us? Having so much time in search of life they could easily examine without exception, all the stars in the milky Way galaxy. If they saw our warm, blue world, presumably, they would have made the mark. It is possible that they came here 50 million years ago and met with us, the people (to drill the moon to the monolith in the spirit of “2001: a Space Odyssey”, maybe not so silly as it seems), or maybe they still couldn’t have made it.
But given the time scale that seems unlikely. To map the entire Galaxy and visit planets suitable, do not need so much time. That’s why I think the answer is “millions of civilizations” in the Drake equation are wrong. We would have seen or at least heard.
According to this logic, the galaxy in the spirit of “Star trek”, where live a variety of alien beings on the same level of scientific and technological development, is extremely unlikely.
If the milky Way is teeming with life, much more likely that civilization would be separated by gaps of millions of years. Some alien creatures will be more similar to q and organian (extremely advanced creatures in the universe of “Star trek”), a couple will be like us, and the rest — no more than extremely primitive microbes and fungi. Another aspect of “Star trek” in this assumption is the First Directive: quarantine developing alien civilizations until, until they develop the technology for interstellar travel. It’s an interesting idea, but I don’t believe in it: this means that all existing alien species, without exception, will abide by it. Enough one dissenter, and the secret will disappear.
American astronomer and science popularizer Philip plate has written a fascinating book about the dangers that can “fall” to Earth from space: about a collision with comets and asteroids, black holes, interplanetary viruses and bacteria, aggressive alien civilization, the death of the Sun and even complete annihilation from quantum collapse. The author describes with humor catastrophic scenarios and considers their probability from the point of view of science. And evaluates the ways that mankind will be able to avoid sudden death.