Humanity has not yet met a single form of life outside our planet. If we ignore the tales of "Area 51" and "eyewitness encounters with UFOs and their pilots", we still have not received any extraterrestrial signals, even remotely trying to resemble an attempt by some intelligent civilization to establish interstellar or intergalactic communication with us. All in all, no Ewoks and ETs
Considering what an amazing level of technology development we have reached over the past 100 years, it would be safe to assume that any other highly developed civilization that mastered space flights and appeared even several hundred years earlier than ours could currently have even more advanced technologies.
Humanity has come up with many ways to transmit messages through space. Some are in use now, while others will come. If one day super-advanced aliens want to communicate with us, then they will have a real choice.
Good old radio waves
This is what first comes to people's minds when they discuss the topic of communication with aliens. Receiving and transmitting messages using this method has become the object of interest in many science fiction books and films such as "Contact" and "Independence Day". After all, we have been working with radio waves for almost a hundred years now and have achieved a pretty good level of efficiency in their use. Many serious scientists and organizations, such as SETI, still use radio waves as their main tool for finding extraterrestrial civilizations.
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With the help of the same radio waves in the late 70s, the famous "WOW signal!" - an unexpected and abrupt emission of radiation from a nearby star cluster, which for many years so no one could really explain. Until recently. Although, according to the latest information, some astronomers still doubt that the real source of this signal has been determined.
Be that as it may, the radio detection method has several critical disadvantages. And the first of them is that the farther you are from the source of radio waves, the weaker they are. In this case, the radio waves that we sent into space over the last hundred years will actually dissipate in just a few light years, becoming completely elusive.
The solution to this problem may be the use of larger transmitting radio dishes, but in this case we will have to face many difficult engineering challenges. One of them - will require the construction of a truly gigantic plate, up to the size of the Earth itself. Theoretically, some super-developed space civilization could already solve this problem due to the high level of development of its technologies, but for some reason I want to believe that it was able to come to a more efficient and less resource-intensive method from the list below.
Lasers
Where radio waves fail and become useless, lasers can be a more efficient way to communicate over long distances. Their plus is integrity and density. The sent laser message from a galaxy far, far away will continue to be clearly visible upon arrival.
In addition, the directionality of the laser messages is beneficial. Even a single target can be selected as the delivery target of a message, thereby increasing the effectiveness of such a message. In this regard, lasers noticeably outperform radio waves. Sufficiently advanced civilizations could send messages using laser transmission to other systems located hundreds of light years away. And one of these messages could be caught here on Earth.
However, there is a question: what frequency should the laser signal be used for transmission?
If civilization turns out to be sufficiently developed, then it could use gamma rays for this. This type of radiation can be transmitted over truly gigantic distances. Of course, this will require colossal energy expenditures, but if we assume that a developed civilization will not have a shortage of these very resources, then problems should not arise.
For us, a potentially more realistic option under current conditions is the use of infrared or microwave lasers. If only simply because they require less energy. And, by the way, we are already slowly beginning to adapt this method of messaging.
star Light
You may have heard of the Kepler Telescope, NASA's space observatory, which searches for exoplanets by observing the change in stellar brightness that occurs as a planet passes by a star.
Now let's imagine that some advanced cosmic civilization has found a way to place an artificially created giant rectangular or triangular object, or maybe some 1258-gon (object with 1258 sides), into orbit of its star. In this case, we just need to find out how this object will be displayed in the telescope data, which, in principle, will be doable in practice, although it will take some tinkering.
What's even more interesting is that an extraterrestrial civilization doesn't even need to be super-advanced to be able to do this. Even in a couple of hundred years we will be capable of such an adventure. All you need to do is make the object very thin, deliver it into space and assemble it in orbit.
Dyson sphere
The method will be very similar to the previous one, with the only exception that only a really very technologically advanced civilization will be capable of this. And the main goal will not be explained by a simple desire to contact us. Rather, the main task here will be to collect the energy that the star produces.
The idea is this: why put ordinary pieces of iron in orbit when you can put billions of solar panels there to collect stellar energy? Sounds crazy, we understand. But given our current technological level, humanity will be able to achieve this level of technology in a few hundred, and in a less optimistic case, a thousand years.
With the ability to manually alter the starlight, an advanced civilization could send us sane-looking messages. And it would be much easier for us to catch and understand such messages than to sit and decipher the effects caused by an object of a complex geometric shape located in orbit, as in the paragraph above.
The collected energy from the star could also be used to power other communications equipment and technologies described in this article. Any civilization that will be able to create such structures will automatically be higher than us in development. And if we can somehow be the first to detect such activity, then sending a response to such a message will not be the best idea for us.
Unusual phenomena
If we imagine that somewhere out there there is a civilization that surpasses us by several million years in technological development, then why not also imagine that such a civilization will be able to manipulate the movement of space objects inside at least its own galaxy?
Let's say it could control the behavior of a nearby star or other objects to attract our attention. Let's say you first accelerate objects to near light speed and then slow them down. Do it over and over again. In the end, somebody will notice.
Or you can very quickly change the properties of a star, for example, its brightness, and thus send encrypted messages, say, prime numbers or pi digits. Of course, such opportunities will definitely require colossal energy costs, and the technologies themselves that allow you to do this can now be imagined only in science fiction.
Nevertheless, Earth astronomers every night continue to peer into the depths of space in the hope of finding something extraordinary that could definitely attract our attention. The features described above would certainly seem godlike to us.
Gravitational waves
More recently, humanity has confirmed the existence of gravitational waves (rapid changes in the curvature of space-time). In 2015, scientists at the Laser Interferometric Gravitational Wave Observatory (LIGO) conducted an experiment and announced the first ever real observation of a ripple in spacetime, which was predicted by Einstein.
A highly developed civilization, using neutron stars and black holes (the main sources of gravitational waves), could send us strange, but at the same time clearly reasonable signals. A little "cheat" with the frequency and amplitude of these waves - and with the help of them you can transmit encoded information.
All of this will undoubtedly require technological superiority in development. But the good news is that even our current sensors are capable of picking up gravitational waves launched from billions of light-years away. Therefore, any civilization that decides to use them as a means of transmitting messages will immediately "appear on our radar."
In fact, these distortions of space-time are so small that we are talking about distances less than the diameter of some proton. But if the aliens really want to get our attention, they could zoom in on these waves so that we can get a clearer message from them. Although the option in which they could use these waves in such a way that they will be able to kill all living things is also possible in theory.
Highly charged particle bombardment
The earth is exposed to a colossal amount of radiation every day. But if aliens know a way to further change its volume, then, most likely, with the help of this radiation they can also send signals that we can detect. All that is needed is to send an increased by only a couple of percent of the total volume of highly charged particles, and our scientists will definitely notice this. And the very change in the number of particles can be used as an encoding for messages.
Of course, you can think of a more ecological way. But who among highly developed civilizations will take care of some kind of safety of several billion erectus monkeys?
In general, this method of communication is still unknown to our science. In addition, it is not known how at all using this method it is possible to transmit more or less targeted messages. In fact, from our point of view, this method does not seem to be the most suitable and effective for interstellar communication. But if aliens have already mastered it, then why not?
Destruction of something big in space
If the civilization turns out to be technologically advanced enough, then this is really possible. Destroying large objects in ways that will definitely grab our attention, and then sending messages with other methods, will clearly not be left out of our eyes and ears. For example, aliens can launch a huge swarm of nanorobots, disintegrating large objects and turning them into elementary particles, or use black holes as a kind of intergalactic eraser, erasing everything in their path from reality. Fun, isn't it?
More reasonable, of course, would be to change the decay rate of some cosmic object like a red dwarf (a star that can burn for trillions of years), quickly "extinguishing" it. Our scientists have never seen the death of a red dwarf star. Probably because the universe itself exists less than the potentially equal life cycle of such stars. We would be surprised!
Wormholes
We do not really know if such objects are actually physically possible. But if it turns out that wormholes are not only our hypotheses, but also a completely real reality, then we still do not know how (natural or artificial) they can be created.
But just from this moment the fun begins. Perhaps the aliens have already found a way to place a wormhole near us in the manner of "Interstellar" and use it as a kind of portal for the transmission of both physical objects and radio messages.
Maybe someday a wormhole will open up next to us, and a whole fleet of ships will emerge from it, wanting to make the first contact. Or those who want to harvest …
Changing the laws of physics
When we look into space, we think that the laws of physics apply to the entire Universe, they are constant and never change. It seems to us that this is actually the case, but what if we are wrong?
What if incredibly technologically advanced aliens have found a way to manipulate physics in a way that makes it much easier to use the techniques described above?
When you are subject to the laws of physics, you are able to control everything. If our tiny, albeit developed monkey brains are not yet able to understand many things that happen even in those parts of the Universe that our eyes have reached, then what can we say about technologies that can not just ignore, but actually change the laws of physics for themselves?
Just imagine that somewhere there may be technologies that can not only destroy large objects, but literally bring them beyond the brink of being. And instead of simply destroying us in a fiery hyena, these technologies can deprive us as such of the possibility of existence.
NIKOLAY KHIZHNYAK