Radio communication with extraterrestrial intelligence, reality or imagination?

The article summarizes the issue of making radio contact with aliens, or with alien technology - in science, popular science literature and science fiction

If Carl Sagan, a well-known astrophysicist who died in 1996, were alive with us today, he would surely be disappointed that the year 2000 has passed, and we still have not received radio signals originating from extraterrestrial intelligence, since in his book Contact (based on which the film of the same name was also produced, starring Jodie Foster), he described such an event, which took place towards the year 2000 and everything that happened after it.

Little Green Men or on pulsars and quasars

Jocelyn Bell, a PhD student at the Jodrell Bank Astronomical Observatory, England, in 1967 picked up a radio signal in incredibly precise bursts that lasted about one second. At that time there were many satellites in the sky that broadcast beep...beep..., so she believed that the source of the signal was in one of those satellites.

However, once it was determined that the source of the signals was in distant space and other similar signal sources were found, there was no escaping the conclusion that the source of the signals is developed beings living on distant planets, somewhere in the galaxy.

The researchers at the observatory called the phenomenon - little green people. Not many months passed and it became clear that the origin of the transmissions was in neutron stars, which were not known to astronomers until then. These are massive stars with a small volume, having a magnetic field as large as one million millionths of the Earth's magnetic field and rotating around their axis with a cycle time of a fraction of a second to several seconds. As usual in these cases, Anthony Hewish, the supervisor of the same doctoral student who worked so hard on the establishment of the antenna field and the other technical activities in the research, won the Nobel Prize (he and not Jocelyn) for the discovery of those stars also known as pulsars.

Several years before, in the early XNUMXs, Soviet astronomers detected a radio signal of intense intensity from a distant celestial source. It was the first time I detected a radio signal from such a distant source and the unique thing about it, unlike the one-second cycles of the first pulsar, the one with the little green men, was that its cycle was once every hundred days. The Soviet scientists were sure that the source of the signal was in a technological culture with enormous energy resources and this received a lot of publicity in the public and the press. This was even immortalized in a song recorded by the Bird Band (anyone remember?).

Indeed, these were radio transmissions from a distant source, but not from a technological culture. After some time, the astronomers coined the term quasar (QUASi stellAR object), one of whose characteristics is the same electromagnetic radiation that jumped the Russian astronomers at the time.

In the cases described above, these were signals picked up during astronomical studies and mistakenly attributed to extraterrestrial technology. Not long after these events, we began an activity aimed at receiving artificial signals from space.

The Earth is a planet that orbits the Sun. Our galaxy has several hundred billion suns. According to observations and estimates - half of the suns have planets orbiting them. Even if we assume that only around one in a hundred million suns, life developed similar to ours, then only in our galaxy there are, or were, millions of intelligent civilizations (and in the entire universe - this number is twice a hundred billion, as the number of galaxies in the universe).

are we alone

Over a century ago, at the time when the Suez and Panama canals were mined, they thought they could see canals on the surface of Mars. As a result, a theory was developed about creatures that dug canals to transport water from the polar glaciers of Mars to the arid deserts. Carl Sagan in his television program Cosmos said: "There is no doubt that the ascensions on Mars indicated the existence of intelligence: the question is only at which end of the telescope..."

In our century, the century in which radio and electronics began to develop, we aimed the antennas into space as well. We receive natural radio signals from the various celestial bodies, signals that help to complete what we see in the optical telescopes, but we try in various research programs, starting in 1960, to also receive artificial transmissions carrying information originating from distant stars. Does the intelligence here exist only on the receiving side (and we are the only intelligence in the universe and some will say - alas for that intelligence), or are there millions of cultures after all and we have not received them until today because:-

A. We are limited in listening to certain frequencies at a given time. It is possible that the broadcasts are on other frequencies.
B. If only one out of a hundred million stars is transmitting, our antennas have most likely been pointed at other stars and we have missed the transmitting stars, even if they are millions in number.
third. The window of time in which they broadcast was too short - in the meantime they continued to develop and stopped showing interest in interstellar communication or they discovered another method of communication that is not based on electromagnetic radiation and the most alarming possibility - they simply ceased to exist and therefore this may also be our fate.
Even if a million cultures in the galaxy transmitted continuously for 100 years each, the transmissions were spread over billions of years (our galaxy is about ten billion years old). Our chance of receiving broadcasts precisely in the forty years in which we are trying to do so, is extremely slim.
d. We have surrounded ourselves with such electromagnetic pollution that it is difficult for us to receive weak signals coming from afar.
God. They do not broadcast at all, because their norm forbids any involvement in the development of foreign cultures, or they are afraid to broadcast, lest a hostile culture discover them and come to attack them. In connection with this last possibility - it is known of at least one time when we transmitted a message into space with the intention that it would be picked up by intelligent beings outside the earth, but this act received a lot of criticism for the aforementioned reason.
and. The pace of life of those creatures is of a different magnitude than ours, therefore a typical message that lasts seconds for us, takes years or microseconds for them and so far we have not designed our reception computers to distinguish such a message.
G. The communicating cultures are much more advanced than us and have no interest in communicating with us or their communication or information technology is not within our current knowledge.
H. There is something simple and basic that we haven't given (or we can't give) attention to, because of which we don't perceive anything.

There are opinions that even if life is a broken vision in the universe, intelligent life is another matter. According to the theory of evolution, the formation of life and its development is a natural and necessary thing. On the other hand, there is no evidence that intelligence has an adaptive value on a universal scale - that is, it is very possible that there is life in the universe, but it does not transmit.

More than that - even if intelligence has an adaptive value (in other words intelligent beings are more successful in surviving), some believe that technological intelligence, as we have reached it in the last hundred years, inevitably leads to extinction, whether due to a catastrophe such as a nuclear war or due to prolonged damage to the quality of the environment that leads to gradual extinction.

Marconi - the radio pioneer, Coconi - the interstellar radio pioneer

Institutionalized searches for extraterrestrial intelligence, or as this topic is called in English - SETI, the acronym for Search for Extraterrestrial Intelligence, began in 1959, when Kokoni and Morrison published an article in the British journal NATURE about the possibility of transmissions from somewhere in the galaxy and our ability to receive them. "It's hard to know what the chances of success are," they said, "but if we don't try, we certainly won't succeed." Inspired by the article, the American astronomer Frank Drake pointed a 26 m diameter radio-telescope dish at the stars Tau-Stei and Epsilon-Aridani and listened... He continued to listen to hundreds more stars using even larger dishes, but in vain.

Since then, many dozens of projects have been conducted in radio research of extraterrestrial intelligence. NASA - the American National Space Agency - has also started a very comprehensive program for combined searches - a general scan of the sky at the Jet Propulsion Laboratory and a careful examination of hundreds of suns at the Ames Research Center. The NASA project was stopped after about a year, according to the decision of the Congress. However, various research programs continue today on behalf of various bodies. These programs mobilize all technological innovations. The reception techniques include huge antennas, sensitive receivers, chunks of spectrum and computers capable of scanning millions of frequencies and locking onto significant signals.

The latest technologies of radio reception components as well as heavy decoding algorithms were also mobilized for this effort. These techniques simplify and visualize the scanning of radio channels, while increasing the chance of automatically subtracting artificial signals from the noise.

Answer in 100,000 years

The main problem with two-way radio communication with distant stars is the time it takes for the radio waves to travel through space. When we talked to the astronomers about the moon, it took the radio waves a second and a quarter to arrive, meaning at least two and a half seconds between the end of the transmission and receiving an answer about it. The research spacecraft that patrol the solar system transmit images to us and receive commands - it takes many minutes and even about an hour for the radio waves to make their way from the ground station to the spacecraft and vice versa. Therefore, the accepted concept of NASA speaks of autonomous navigation of those spacecraft.

The sun closest to our sun is more than four light years away, which means that a two-way radio connection with a body located near it will last about nine years for each transmission. The size of our galaxy is 120 thousand light years and we are quite on its edge. Radio waves emanating from a star in another part of the galaxy will reach us after tens of thousands of years. However, in terms of the universe (15 billion light years), it's really close. To overcome the barrier of being able to communicate two-way in a reasonable amount of time, the idea of ​​automated radio stations was developed and possible and scattered in space by intelligent civilizations (and may be launched by us within the next few decades). These stations are able to receive and diagnose information-carrying signals, transmit information and most importantly - store it.

Several ideas have been proposed on how to overcome the enormous interstellar distance that does not allow for direct two-way radio communication.

Contact

Carl Sagan, astrophysicist and popular science writer, was personally involved in radio searches for alien civilizations. He wrote a fictional book called "Contact" in which success in creating such a relationship is described. One day radio astronomy observatory computers noticed an artificial transmission that included series of prime numbers.

In the second layer of the received transmission and with a modulation method that is not acceptable in our radio technology (binary modulation of the wave polarization), images were discovered. To everyone's astonishment, it was found out that the photos were nothing but television broadcasts broadcast in 1936 on the occasion of the Berlin Olympics.

In the third layer of the broadcast, the main message was hidden - a huge text including drawings, which were nothing but instructions for building a huge machine.

In the fourth layer and show modulation, was the key to deciphering the text. It turns out that our first television broadcasts were picked up by an automatic radio station which attached the information to them and sent them back to us. The machine was nothing but a spaceship with a technology unknown to us, which allowed travel and meeting, albeit not directly, with the culture that placed the station.

The hostile Andromeda

In the science fiction number "A is Andromeda" (by Fred Hoyle and John Eliot) it is described how an intelligent culture many light years away from us, which seeks to spread its culture to distant worlds, sends an omnidirectional radio transmission (by the way, it has already been proven that an omnidirectional transmission of this kind , unlike transmission using a highly directional antenna, requires energy resources that far exceed the total energy on earth and therefore this kind of transmission is not possible according to our physical understanding).

Here the problem of the transmission transit time and receiving a response to it was solved, in that the transmission was intended to be essentially one-way. The initiators of the broadcast, residents of Andromeda, did not expect an answer to him at all: whoever receives - will receive...

The broadcast was received at a radio-astronomical observatory on Earth and after it was decoded it was found that it contained information for the construction and programming of a giant computer. Unlike in Sagan's book, the intention of the senders of the message was not pure. The computer was supposed to take over the earth and its activation almost caused a holocaust on our world.

Galactic Internet and Space Odyssey

Timothy Ferriss, a science writer, came up with the idea of ​​a galactic or even cosmic network of automatic radio stations that communicate with each other and exchange information from different cultures. Such stations are capable of replicating themselves. They can land on a planet or an asteroid and using robotic facilities, utilize the materials at the landing site and build another station. In this way they can multiply and spread far and wide. If we extrapolate our technological progress, we too will be able to build such stations in a few decades.

If such a station is near us, we can call it, retrieve information from it, and load our own information into it. The information found in it, if found, was loaded many years ago by cultures that may no longer exist. But since the automatic station is near us, we can talk to her beyond the barrier of distance and time - almost in a direct dialogue. And perhaps such a station is already inside our solar system and for the time being is only listening and not transmitting - so that we don't come to investigate and dismantle it, but a day will come and depending on the nature of the transmissions it receives, it will decide to contact us. This is the idea expressed in the book of Arthur C. Clark (originator of the idea of ​​communication satellites) "2001 Space Odyssey".

Virtual reality and completely non-local communication networks

Timothy Ferris continues his ideas and claims that it is likely that the type of information we will receive from such a station will be what we call Virtual Reality, something that will allow us to experience, experience and see the distant worlds, just as if we were there.

Another idea is that the network of automatic stations, despite all the distances between them, will become the most intelligent entity in the galaxy, because such a large processing capacity and such a huge memory - they are intelligence in its embodiment. And since eternity is at the disposal of these networks - there is no obstacle for networks in different galaxies to communicate with each other despite the millions of light years separating them.

The idea is that a sufficiently large computer can think by itself... and we humans, like other animals, have nervous systems, we are nothing but a computer...

For human sex life

Everything written here, as fictional as it may seem, receives serious attention among the scientific community. Radio searches for extraterrestrial intelligence are conducted in universities, research institutes, private parties and also by government authorities.

Although we are developing different technologies for this purpose, these searches are more in terms of voyages of discovery than scientific research. Just as years ago we crossed oceans and discovered new continents and cultures, so we try to do today. Thanks to radio technologies, we stay in the armchair at the astronomical observatory and the radio waves cross the oceans of space for us. Some refer to this phenomenon as a religion, as we expect to encounter beings, ideas, physical laws and technologies that are superior to us at the moment. These searches have various philosophical implications and above all they have an impact on how we see the future of the human race. If we make contact with a foreign culture, we can expect to reach its level as well. This will have far reaching effects on our world and maybe even wars will stop.

But if it becomes clear to us that technological civilizations are destroying themselves or that maybe we are alone - it will be even more so, our duty towards the universe and ourselves to take care and protect the earth and all life on it.

Carl Sagan (1934 - 1996): "One and only message from space will prove to us that it is possible to continue to exist even after technological maturity. It is hard to think of another enterprise that holds such great promise for the future of humanity; It is very possible that the future of human civilization depends on the reception of interstellar messages. In the deepest sense, the search for extraterrestrial intelligence is a search for ourselves."

The water window of the galaxy

At what frequencies do they try to receive intelligent transmissions from distant stars? If we examine the history of radio searches for extraterrestrial intelligence, it appears that the dominant frequency tested is 1,420 MHz (1.42 GHz). This frequency is the resonance frequency of the hydrogen molecule. This frequency has high permeability through clouds of interstellar matter and vice versa. It spreads better than other frequencies. At this frequency, radio-astronomical observations that follow natural radio sources are conducted anyway. Hydrogen is also the most common element in the universe and is the parent of all other elements. For all these reasons it is likely that a technological culture that wants to broadcast to another culture will choose this frequency. A similar frequency in its characterization is the frequency 1.667 GHz, which is the resonance frequency of the hydroxyl molecule (OH - hydrogen atom and oxygen atom), which is also abundant in interstellar space. These frequencies are called the water window of the galaxy (remember - water = H2O) and in the frequency allocations of the International Telecommunication Organization (ITU), they are assigned (the first, exclusively and the second on a preliminary basis) to space exploration and radio astronomy. Of course, this is not about a single frequency, but about the frequency ranges 1,400 to 1,427 MHz and 1,660.5 to 1,668.4 MHz. If we pay attention, it seems that the resonance frequencies of the hydrogen and the hydroxyl are at the upper end of the assigned domains and not in the middle. This reflects the desire of radio astronomers to receive signals from distant galaxies as well. As we know, the galaxies are moving away from each other and the farther the galaxy is from us, the greater its speed relative to us. This is where the Doppler effect comes into play, according to which the frequency received from a moving source will be lower than the transmitted frequency. This phenomenon is known and taken into account in certain types of communication satellites. In optical astronomy this is called redshift and it is used to calculate the distances of galaxies from us.

Other frequency ranges assigned to deep space listening are 2.7 and 10.7 GHz, which also excel in transgressions in the interstellar medium, a feature that makes them suitable for radio-astronomy purposes and receiving distant signals.

Congressman Proxmeyer: "Why do we need to invest millions in radio searches for aliens and UFOs; Aren't those within us enough?"

The search for extraterrestrial intelligence - SETI (Search for Extraterrestrial Intelligence), is an attempt to use a large radio telescope, sophisticated receivers and modern data analysis tools to discover hypothetical signals sent towards us by advanced civilizations residing on planets orbiting other suns. Inevitably, there are large uncertainties in choosing the appropriate wavelength, bandwidth, polarization, time constant, and decoding algorithm with which to search for these signals. Nevertheless, radio technology is not expensive, is probably discovered at an early stage in the technological development of civilization, can be detected (and not only from distances inside the solar system as the Galileo probe did - but also from vast interstellar distances) and is capable of transmitting enormous amounts of information. The first large-scale systematic search program, which covered large portions of the wavelengths considered optimal for interstellar communication, was initiated by NASA on October 12, 1992. Congress canceled the program a year later, but it will soon be revived using private funding. Meanwhile, a number of more modest projects have turned up tantalizing findings.

A promising project is META (Megachannel Extraterrestrial Array), which is directed by Paul Horowitz, a professor of physics at Harvard University and is primarily funded by the Planetary Society, the world's largest space interest group. The antenna used in the META project is shown in the picture. After five years of continuous sky-scanning and two years of re-scanning, Horowitz and myself have found a handful of candidate radio signals, of extremely narrow bandwidth, whose origin does not appear to orbit the Earth and which cannot be attributed to specific sources of noise or interference. Also other projects such as OZMA - the first purposeful radio search for extraterrestrial intelligence) and the SERENDIP project of the University of California, found unusual signals from space that seemed to have an intelligent origin. The only trouble is that none of those sources were repeated and in science, data that is not repeated is usually not worth much. The tantalizing nature of the META findings is that the five strongest signals all come from the plane of the Milky Way. The probability that this coordination is coincidental is something like half a percent, meaning that there is a high probability that their origin in our galaxy is artificial. We believe that more comprehensive searches should be conducted.

These words were written by Carl Sagan, a scientist and science educator who was more involved than anyone else in radio searches for extraterrestrial civilizations. The words were written in 1994, two years before his untimely death.