At a press conference held last week, Israeli-American astrophysicist Avi Leib, head of Harvard University's astronomy department, announced the "Galileo" project, whose stated goal is to search for technological signs of extraterrestrial civilizations in the solar system and even on Earth. In a series of scientific articles and lectures at international conferences published in recent years, I presented an opposite thesis: apparently the chance of probes or transmissions from other cultures arriving to explore the Earth is extremely low, even if many extraterrestrial cultures exist.
The astronomical event that was the motive for the "Galileo" project, as well as Prof. Leib's spoken word book "Extraterrestrial", which was published this year and translated into 25 languages, is a near-sun transit of the first object identified as coming from outside the solar system. The mysterious object that was nicknamed "Uomuamua" (a remote messenger in Hawaiian) passed through the inner solar system in 2017.
Leib then proposed the controversial hypothesis that it was not just an interstellar rock, but a probe sent by an advanced civilization to investigate us. The reasons for this hypothesis are the elongated shape of the object (like a cigar) and more importantly its acceleration - the speed of Omama's distance from the sun was increasing (albeit at a small rate), while due to the sun's gravity it should actually have slowed down.
Later, natural explanations for Umama's shape and acceleration were put forward, but the media's interest in the extraterrestrial probe hypothesis did not stop. Is there a scientific basis for this hypothesis, and for the Galileo project in general? Apparently, any research outside the box or consensus is appropriate and may even yield surprising results, but most astronomers tend to dismiss this interpretation, as well as the belief that the origin of UFOs is extraterrestrial civilizations studying us.
The reason for this is called 'Ockham's Razor' - if there are several explanations for a phenomenon, one should choose the simplest one, which requires fewer hypotheses and complex assumptions. The fact that we do not understand a certain phenomenon (such as UFOs, for which there is a detailed report Published by the Pentagon in June of this year, does not necessarily mean that its origin is an extraterrestrial culture or aliens. The "Galileo" project and the "extraterrestrial" explanation for the UFO phenomenon are similar in this sense to a modern version of the well-known book by Erich von Daniken "Chariots of the Gods", which tries to explain archaeological mysteries around the world as visits by advanced civilizations from other worlds.
In the article Published in 2015 in the International Journal of Astrobiology, as well as in a follow-up article in 2017 and in a lecture at the International Space Conference (International Astronautical Congress) in Jerusalem (2015) I presented an assessment of the very low chance of intentional radio transmissions from extraterrestrial civilizations arriving on Earth in the present or the near future. Also at the international space conference that will be held in October 2021 in Dubai I will talk about this issue.
This assessment is even more valid for the proposition that objects such as Omama and UFOs are research probes of alien civilizations. This estimate is based on the high prevalence of planets with environmental conditions suitable for life, found by NASA's Kepler space telescope mission. Kepler discovered that planets similar to Earth in size and temperature are extremely common, probably tens of billions in the Milky Way, our home galaxy.
This conclusion, which seemingly supports the existence of extraterrestrial civilizations, claims that precisely due to the high frequency of planets similar to the Earth in terms of life inventions, the Earth and the solar system are not unique or "interesting" enough, and therefore extraterrestrial civilizations find no reason to direct transmissions to us (and all the more not research probes, whose cost is high and their speed is lower than radio transmissions that travel at the speed of light).
Although it is possible that technological civilizations like ours are a rarer and more interesting phenomenon than planets with simple biological life, and extraterrestrial civilizations may (or may) be interested in the technological culture that appeared about a century ago on Earth, but the information about the Earth being home to a technological culture has not yet reached existing cultures At a distance that exceeds several decades of light years from us, since this information - the first radio and radar transmissions from Earth - began to spread in space less than a century ago, with the first shortwave radio transmissions and the use of radar before World War II.
Even if an advanced civilization picked up these transmissions and sent a reply as soon as the first signals from Earth arrived, in order for the transmissions to reach the solar system now, the civilization must be less than 50 light years away. This distance seems great, but in fact it is very small compared to the dimensions of the galaxy (about one hundred thousand light years), and even if there are thousands of cultures in the galaxy, the chance that such an extraterrestrial culture will find itself so close to us is extremely small.
For example, if there are a thousand civilizations in the Milky Way, the average distance between neighboring civilizations is about 3,000 light years and the chance that a civilization will be found less than 50 light years away from us is about 0.03%. As for a probe, whose speed is obviously significantly lower than the speed of light, the chance is much smaller. For example, if the advanced civilization sends a probe at a speed of 20% of the speed of light (similar to the speed expected in the project Breakthrough Starshot headed by Prof. Leib), in order for the probe to reach the solar system in 2017, the civilization must be at a distance of up to 16 light years (16 years the transit time of the radio transmissions from Earth to the civilization and more/0.2 16 = 80 years the flight time of the probe from the civilization to the solar system a total of about a hundred years) and the chance of such a close civilization (again, assuming a thousand civilizations in the galaxy) is 0.003%.
In addition, for 60 years astronomers have been listening to space in an attempt to locate intelligent radio transmissions originating from technological civilizations (the SETI project). If there were such civilizations close to us, it is likely that we would have discovered their radio and radar transmissions a long time ago, but the SETI project has not yet found anything.
Despite the very low chance of a technological civilization existing at a relatively small distance of a few light years from us, if such a neighboring civilization did exist, it could have received the first radio transmissions from Earth and sent probes and research means, which might have been able to explain the observed UFO phenomenon Since the middle of the last century, however, there is still the question of why the SETI project did not notice its radio transmissions, and why, despite the abundance of UFOs, they choose to hide from our eyes. According to the principle of "Occam's Razor", it is much more likely that UFOs can be explained as natural phenomena that we still do not understand, or artificial objects of earthly origin, as for Umama's apparently mysterious properties, explanations were offered that are much more prosaic than the alien probe speculation.
Prof. Omri Vandel is an astrophysicist, astrobiologist, researcher of black holes and life in the universe at the Rakeh Institute of Physics at the Hebrew University. Not long ago his book appeared "Astrophysics and life in the universe” published by “Akadmon”.
