Aliens don't visit Earth because they think they're not intelligent
The universe is so vast that it is unimaginable that it would seem reasonable to have a civilization equal to or better than ours, but so far there has been no contact from extraterrestrial intelligence, let alone extraterrestrial intelligence. No signs of civilization even exist. As an answer to this mystery, a hypothesis was proposed that ``since aliens do not seem to have intelligent life forms on Earth, they may not bother to contact us.''
[2211.16505] The Fermi Paradox revisited: Technosignatures and the Contact Era
Maybe we don't see aliens because they're waiting to hear a signal from us first
The contradiction that ``the probability of the existence of extraterrestrial civilizations in space is high, but there is no contact from aliens at all'' is called the Fermi paradox , and it troubles scientists who challenge the search for extraterrestrial intelligence. I am letting you. As one of the answers to these arguments, a new theory appeared in October 2022 that ``the solar system is considered worthless because the lifespan of the sun is relatively short.''
The theory that extraterrestrial life does not appear on the earth is ``because it is not worth visiting the solar system''-GIGAZINE
Amri Wandel of the Hebrew University of Jerusalem's Laka Institute of Physics, who is working on the issue, said in a paper published on the preprint server arXiv, 'Earth may not be interested in aliens.' put forward a hypothesis.
This hypothesis consists of two major assumptions. The first is that ``actually, life is common in the universe, and the existence of living things alone does not pay much attention.'' Recent observations have discovered a series of planets located in the habitable zone where life can be nurtured like the Earth, raising expectations that extraterrestrial life may exist.
Aliens may also become aware of the existence of these planets, but sending probes to all candidate sites would be a heavy burden even for highly advanced civilizations. Therefore, it is thought that aliens will first try to make contact with radio waves, which can be done with much less energy than physical exploration, but it is meaningless to send a message to a planet where there are only single-celled organisms and primitive animals. There is none.
The second assumption that appears here is that ``aliens will be interested in evidence of the existence of intelligent life if they can obtain it.'' If a signal that seems to be a radio communication arrives from a planet that has a high probability of having life, it will be proof of the existence of an advanced civilization there.
Theoretically, it is believed that since the invention of full-scale radio communication on Earth until today, radio waves emitted by Earthlings have reached as many as 15,000 planetary systems. However, even if an alien were to observe Earth's radio waves and then send a message back, it would take time for it to arrive, so we can only expect responses from 1,300 planetary systems within a range of 50 light years from Earth. Only, Wandel calculated.
To make matters worse, the radio waves emitted in the early days of humankind were not intentional messages, but rather radio waves from television and radio broadcasts that accidentally leaked into space, making them indistinguishable from noise even a light-year away. It's gone. Therefore, even if aliens receive radio waves from the Earth, there is a high possibility that they will not notice it and will not think that there is intelligent life on Earth.
Because of these problems, Mr. Wandel concluded, ``Unless a civilization that can communicate lasts at least thousands of years, civilizations cannot communicate with each other.''
in Science, Posted by log1l_ks