Since the 1960s, astronomers have been conducting SETI activities, hoping to receive radio waves from extraterrestrial civilizations through radio telescopes. SETI also launched radio signals into outer space in the 1970s.
But decades later, human beings still haven’t found alien civilization. So, why haven’t we found aliens? Is it because the universe is so big that they will never come to earth?
In 1995, astronomers discovered the first exoplanet orbiting the main sequence star. Since then, humans have discovered more than 4000 exoplanets, 55 of which may be similar to the environment of the earth. However, the extraterrestrials discovered by human beings are just the tip of the iceberg in the universe.
There are at least 100 billion stars in the galaxy that glow and heat like the sun. There could be a planet around every star. If the planets roaming in interstellar space are included, the number of planets in the galaxy can reach 100 billion.
Given that there are so many alien worlds, and that the universe allows the earth to evolve life, as well as intelligent species like us, there is no reason to think that the earth is special and that alien creatures will not evolve alien life. But the question is, where are these aliens? Why haven’t you found it yet?
One explanation is that the universe is too big. In this world, the scale of light years, such a long distance, is beyond us at present. Today, human beings can’t even fly out of the solar system with a radius of 1 light-year, and it’s even harder to reach the outer planets that are several light-years or even tens of thousands of light-years away. Even if sub light speed flight can be realized in the future, the distance of tens of thousands of light years is still very far away. We can’t go to outer space. Similarly, aliens can’t come to earth. We can’t fly out of the solar system for field exploration, we can only use telescopes on earth to look for extraterrestrial life.
This exoplanet is far away from us. Even with the most powerful astronomical telescope on earth, we can’t see the surface of the exoplanet at all, let alone find the possible aliens on it directly. At this stage, the search for extraterrestrial life can only rely on radio communication.
That is, because of the distance, the strength of radio waves will be greatly attenuated after long-distance propagation, so it is difficult to be detected. The vast universe hinders the effective communication among civilizations. Even if there are aliens, humans have sent signals to the alien world 25000 light years away. Even if there are aliens, they will reply to us after receiving the signals. We will not know their existence until 50000 years later.
Maybe there’s another reason. We can’t find aliens. There may be many civilizations in the galaxy, but alien civilizations that appeared in different periods may be much earlier than human beings, but now they have already been destroyed. Or do alien civilizations know the existence of people on earth, but they don’t want to see us? Moreover, if there were no aliens, there would be only humans in the universe.
If it is only because of distance, we are likely to solve this problem in the future. It takes a long time to fly directly into space. However, if wormholes are used to connect the earth and the alien world, interstellar travel will not be limited by distance and time. We can travel across the galaxy or even between galaxies at will.
What do you think of this? Welcome to leave a message in the comment area!