“Visible only near”. How the aliens learn about the existence of people
MOSCOW, 3 Dec — RIA Novosti, Tatiana Pichugina. Astronomers believe that a tenth of the planets of our Galaxies potentially habitable. If at least one of them has a highly developed civilization, then it, scans the cosmos in search of brothers in mind. What is the probability that we will find — in the material RIA Novosti.
In the book “the universe. Life. Mind” Soviet astronomer Iosif Shklovsky described a thought experiment in which a sound Martians observe Earth. Scientist have proven that they would not have noticed or agricultural activities or large-scale deforestation, no lights of cities or even nuclear tests. The presence of free oxygen in the atmosphere would have told the Martians just what on the planet is the biosphere.
By itself, oxygen is definitely not a sign of life. In the atmosphere must be gases that are produced in the process of life.Eugene Samankaltaisia researcher of the Special astrophysical Observatory of RAS
In addition to the oxygen, markers of life in the atmosphere are ozone, water, methane and carbon dioxide. And all at the same time. The Martians would be able to register them by sending the orbit of the Earth probes, but a distant civilization, being on a similar level of technological development, is unlikely. In any case, our tools are not enough to determine whether the atmosphere at Proxima Centauri b — our nearest exoplanet, which is 4.22 light years.
Century radio
Shklovsky argued that the best way to learn about people — listen to the airwaves of the Earth in the meter range. In 1960-1970, when he wrote his book, live TV, experienced the peak of activity. The radio signal is distributed freely in space at the speed of light is not absorbed by cosmic dust, clouds and not dissipated.
So our television now can watch aliens located at a distance of not more fifty light-years from Earth.
In recent decades, the share of terrestrial television is shrinking, developing digital broadcasting, Internet. Electromagnetic radiation, encoder signals, hidden in underground cables, securely screened plastic casing.
Over time, becoming more technically advanced civilization, to an outside observer, we will be less noticeable. To capture signs of our activity is possible only near the Ground.Eugene Samankaltaisia researcher of the Special astrophysical Observatory of RAS
For example, the Martians could catch a powerful radio telescope signal from the mobile phone. Beyond the Solar system this will not happen. If only we are not talking about a deliberate signal.
However, the very first messages that are sent to the nearest potentially habitable star systems in the framework of the SETI project to search for extraterrestrial intelligence, is not gone from us at a distance of more than thirty light-years.
It is theoretically possible to signal light, by setting the laser beacon on the Ground or orbit. Modern sources are able to generate a beam which will fly a few dozen light years. But he would be too weak compared to the Sun and, most likely, lost.