In the latest study, published in the journal Acta Astronautica, scientists hypothesize that aliens 17.6 quadrillion miles away may have used powerful telescopes to observe Earth's ancient civilizations, such as the Romans, Greeks and Egyptians.
The study, led by Zaza Osmanov of the SETI Institute, examines the methods that aliens would use to study Earth. According to scientists, there is a maximum distance of 3,000 light years at which aliens could detect signs of intelligent life.
“The question is whether the artifacts of our technological society can be seen and potentially detected by alien telescopes,” Osmanov says. “Attention should be paid to large ships, buildings, space satellites and other objects that can be easily identified as man-made structures.”
Scientists have hypothesized three types of alien civilizations depending on their level of development. Type I consumes all the energy of the planet with its host star, Type II uses all the energy of the star, and Type III consumes all the galactic energy.
“Highly advanced aliens could deploy multiple telescopes working together or use supercomputers to observe the Earth,” the researchers note. “We have shown that advanced alien societies can use quantum computers based on artificial black holes to record signals from Earth.”
Experts emphasize that in order to recognize us as an intelligent civilization, aliens will most likely pay attention to visible light reflected from relevant objects. Spatial resolution and optical telescopes can identify large artifacts, the scientists say.
“Instead of using large telescopes of astronomical size, optical interferometry can be used using multiple telescopes separated by enormous distances,” the researchers note.
Despite the assumptions of scientists, there is no concrete evidence yet that extraterrestrial civilizations are actually observing the Earth.