What are the odds that somewhere in the cosmos, perhaps not far from us, there is a planet similar to Earth and, on its surface, a technologically similar alien civilization?
What are the odds that an Earth-like alien civilization is not far from Earth? What are the odds of finding them?
There are two ways to determine whether we are alone in the universe. One method has been in practice for decades and involves scanning the night sky for radio signals from deep space. We search the night skies in different directions hoping to intercept a signal from an intelligent alien civilization in not-so-distant star systems. So far, we have not received any messages from ET, although one signal, the so-called Wow! signal is the most intriguing.
Searching for Earth-like alien civilizations
The second method involves a relatively new approach, which is something that Professor Avi Loeb from Harvard University and the Galileo project has been speaking about actively. It consists in looking for artificial interstellar objects. These can be either defunct space trash, like our voyager probes will become in the future, or probes that are still active and have traveled vast distances exploring the cosmos. In previous articles, I have made an argument why I consider that some UFOs could be unmanned alien probes that are stuck in our solar system.
But let us return to the first method—the Search for intelligent signals from space. In an interesting essay, astronomer Ethan Siegel pondered whether SETI could detect an Earth-like civilization and how far away such a search could go. When we search for advanced aliens, we search for potential radio signals. So, first, we search for radio waves. This is because, with very long wavelengths, radio waves can pierce through the most light-blocking materials in the cosmos, like dust, gas, and different kinds of ionized atoms. Additionally, radio waves can carry much larger information sets.
Earth is relatively young when it comes to transmitting radio signals. We haven’t been doing this for a long time. And the radio signals we did produce peaked a long time ago. Humankind has been working with radio signals since the 20th century. But these were low-power transmissions that were invisible to potential alien civilizations in outer space. Then, in the 1930s, we had more powerful signals at our disposal, some of which were powerful enough to reach out into the universe. But as explained by experts, these signals peaked a long time ago. Now, fewer and fewer such emissions exist.
During the cold war, powerful military transmissions were produced. These came from a frequency and characteristics that would allow alien civilizations over hundreds of light years from us to detect them. The systems were radar transmissions set up to detect potentially incoming ballistic missiles.
Finding an Earth-like alien civilization
What are the odds that somewhere in the cosmos, there is a planet similar to Earth and, on its surface, a technologically similar civilization? We don’t know but what we do know is that given the signals we have sent out in the last few decades, Siegel assumes it is reasonable to draw an imaginary cosmic sphere up to 60 light-years away and say that if there is an Earth-like civilization out there, it would be able to detect our presence from the transmissions we sent out into the cosmos.