Researchers claim that the chance of the existence of other civilizations in the universe is slim and that the Earth is probably unique in the combination of conditions that allow life not only to form but also to thrive
By: William Broad, New York Times
You can stop waiting. If until now it was common to think that there are many more developed civilizations in the universe, but the great distance between us and them makes it impossible to make contact with them - two senior scientists claim that the chances of this are very slim.
Relying on recent findings in astronomy, geology and the study of fossils, paleontologist Dr. Peter Ward and astronomer Dr. Donald Brownlee from the University of Washington claim that the composition of the materials on Earth's surface and its relative stability are very rare conditions. According to them, almost everywhere else in the universe conditions prevail that would not allow the development of advanced life: radiation levels that are too high, a lack of chemical substances, or a shower of rocks that would destroy living beings.
The two write in their book "The Rare Earth" that in many places in the universe unicellular life could have developed, but not advanced civilizations. "People think that the sun is a typical Saturday star, but it's not," says Brownlee. "Almost all environments in the universe are terrible for the development of life."
Already in 1960, the American astronomer Dr. Frank Drake began scanning the sky in an attempt to receive radio signals from advanced extraterrestrial civilizations. In 1961 he published the "Drake Equation", a statistical calculation that tried to predict the number of advanced civilizations in the universe. Based on the rate of development of stars, the proportion of stars that may have favorable conditions for life, the estimated duration of existence of an advanced civilization and similar considerations, Drake calculated that in our galaxy alone there are 10,000 civilizations capable of establishing interstellar radio communication. This estimate was later revised by Dr. Carl Sagan to a million. In the entire universe, they estimated, there are about 10 billion developed civilizations.
But the authors of "Rare Earth" claim that many of the basic assumptions of these calculations are unfounded, adding that many astrobiologists share this. According to new research, says Ward, most of the stars in the universe suffer from drastic events - such as the meteor that hit the Earth 65 million years ago and destroyed the dinosaurs - more frequently than the Earth. According to him, if the giant planet Jupiter had not shielded the Earth, the frequency of this type of impact would have been 10,000 times greater "in other solar systems", he added, "the orbits of Jupiter-like planets are too distant to protect the inner stars".
Ward noted that the chances of life in the centers of galaxies are extremely slim. "In the interior of a galaxy you are constantly bombarded," he said. According to him, new studies even show that in these areas there is a very high level of X-ray radiation, gamma rays and ionizing radiation.
Dr. Brownlee explained that the stars on the fringes of the galaxies, on the other hand, suffer from a lack of materials such as iron, magnesium and silicon. These materials are essential, in his opinion, for the formation of Earth-like planets - which has enough gravity to hold the seas and atmosphere, and is characterized by the slow movement of its land plates (on a geological level). These processes contributed to the development of life, because they created the geological diversity on the surface of the earth, the land versus the sea, the different biospheres, and balanced the temperature. According to Brownlee, on a larger or smaller planet these processes could not exist in this way.
Brownlee added that most galaxies lack the metals that allow the creation of planets of the appropriate size, and that if there are metals, they are concentrated in the center of the galaxy, which, as mentioned, is not suitable for the creation of life.
Among the additional rare conditions for life, the researchers included: an appropriate distance from the sun, so that water would exist in a liquid state, and the existence of moons that moderate the climatic changes on the surface of the planet. These conditions are very rare, Ward and Brownlee said. "But it seems many people don't want to hear it," they added.
{Appeared in the Haaretz newspaper, 9/2/2000} At that time, the Hidan site was part of the IOL portal from the Haaretz group.
