Even if the probability of life on these exoplanets is extremely small, with such a large base of exoplanets, it is theoretically possible that there could be a great deal of extraterrestrial life in our galaxy, with billions of stars like our sun and countless planets in these star systems. If these potential extraterrestrial beings originated much earlier than earth, then it is possible that their level of technological development far exceeds that of us humans. Even if the spaceships we humans now make fly very slowly, flying for millions or tens of millions of years, they could still reach the far depths of the universe. If it is possible for an alien civilisation to exist and for them to launch probes to explore the universe, why have we not seen any spacecraft from an alien civilisation visit earth for so many years? Why haven't we found them after so many years of exploration?
Some scientists think it may be because the space in the universe is just too big and the distance between alien civilizations and our earth is just too far, so it is very difficult to establish contact between alien civilizations and our earth. There is no way for us to launch spacecraft to reach these exoplanets at this stage, and similarly, those potential alien civilizations may still have relatively limited technology to make the distant interstellar flight to earth.
Although interstellar migration is not possible, there are still many ways to establish contact with these potential alien civilisations, such as by transmitting radio signals, which, after all, travel at the speed of light and take only 100 years to reach a distance of 100 light years, whereas our spacecraft may take millions or tens of millions of years to reach them. So a long time ago, scientists also sent some radio signals towards the depths of the universe, hoping that these radio signals would be picked up by alien civilizations, so that they would know about the existence of our planet and eventually establish interstellar communication with them.
Before the advent of our eye in the sky, the arecibo radio telescope in the united states used to be the largest radio telescope in the world, with a diameter of 350 metres. As the most powerful radio telescope ever built, scientists have achieved many scientific results with the radio arecibo radio telescope over the past decades. In 1974, for example, scientists discovered the first radio-pulsed binary system and finally confirmed the existence of gravitational waves.
The arecibo radio telescope used to send telegrams to aliens
The arecibo radio telescope is oddly shaped to look like a pot. This is because radio signals from the depths of the universe are extremely weak and these signals cannot be picked up by normal equipment when they reach earth. Theoretically, the larger the reflecting surface of a radio telescope, the greater its reception capability, because those radio signals are reflected back once they hit the reflecting surface of the radio telescope and are received centrally by the receiver.
In 1974, when the arecibo radio telescope was renovated, scientists used the once largest "Eye in the sky" To send a telegram, known as the arecibo message, consisting of 1679 binary digits, towards the globular cluster m13, which is about 25,000 light years away from earth. The reason why the radio signal was emitted in this direction is because in this region stars are more dense, there are a large number of exoplanets, there is a possibility that there is alien life, alien life, this signal is a little more likely to be picked up by an alien civilization. Scientists believe that if this arecibo message is picked up by an extraterrestrial civilization, then they may know the basics of the solar system, such as the ten numbers from 1 to 10 using binary representation, the shape of our human race, etc.
In this regard, some of you may be concerned that transmitting signals to an alien civilisation may reveal the location of our planet and therefore bring about its demise. After all, the technological level of those alien civilisations that can reach earth is bound to be far beyond that of us humans, and if they want to destroy our planet, it may be a breeze. There are also some who hold an optimistic view that if advanced alien civilizations do exist deep in the universe, then they may use advanced alien technology to help us develop better and solve various problems that we cannot solve now.
For this issue, we don't really need to worry too much. On the one hand, it is possible that there is no so-called alien life or alien civilisation in this orientation or direction, so naturally it will not be picked up and the earth will not be exposed as a result. Even if there might be alien life, alien civilisations, they might really pick up our signals, and the universe is so dimensional that their level of technology might not be able to achieve interstellar flight to reach earth. On the other hand, the strength of our radio signals is actually relatively weak, and the strength of these radio signals decreases as the distance travels, which means that the farther we travel, the weaker our signals become, and these radio signals may be weakened to a strength that cannot be picked up even before they reach the outer solar system.
What is the status of the arecibo radio telescope?
What has happened to the arecibo radio telescope, once the largest "Eye in the sky" Radio telescope? The arecibo radio telescope has been under construction for many years and much of its equipment has deteriorated, which, combined with a lack of funding for repairs, maintenance and upgrades, has left the arecibo radio telescope rusting away. In 2020, the arecibo radio telescope also had 2 accidents, two cables broke one after another, and the receiver hanging on the reflecting mirror of the radio telescope directly smashed the reflecting surface of the telescope and has collapsed with a bang, literally turning it into a junkyard.
The arecibo radio telescope, once the largest "Eye in the sky", did achieve a lot of scientific research after it was put into use, but due to age and disrepair, it slowly became rusty and eventually collapsed in two accidents, turning it into a junkyard. It's really a shame.