Before the discovery of aliens in Australia, reports of aliens were common in the newspapers, and many people claimed to have seen flying saucers, and even seen aliens, and they also took all kinds of photos of flying saucers. Is all this true or false, and do aliens really exist?

According to people who claim to have seen aliens, most of the aliens they see are short, round-headed, narrow, crack-like mouths, and humanoids in tights.

Others are keen to look for traces left by aliens in ancient times. They believe that the round masks of the figures depicted in the murals of the Sahara Desert, the megalithic buildings of Easter Island and South America, and the pyramids, among other unexplained prehistoric wonders, are related to aliens. Other scholars have put forward various ideas such as that humans are descendants of aliens, or that some peoples of mankind (such as the Maya) are descendants of aliens mating with earthlings. But these can only be used as speculations and hypotheses, most of which still lack sufficient evidence.

Scientists have come up with all sorts of possible scenarios for the existence of aliens, which are bold and bizarre, but who can blame the human imagination, and perhaps these fantasies will one day become appreciable. If we rejoice in the large number of 1 million and think that finding aliens is not a problem, it will be too early to rejoice.

For extraterrestrial beings, it only makes sense if you can connect with them. As far as human understanding is concerned, radio signals are the only viable way to establish such a link, and it is therefore necessary to further explore the number of planets inhabited by civilized beings capable of sending such signals.

If they've been sending this kind of signal since their existence, there should be a million planets that are being radioed. But in fact, not to mention algae, even humans did not have this ability more than 100 years ago. On the other hand, neither will life forms that have been destroyed by technology, and that have themselves been destroyed.

Let's not forget that at about the same time as they were able to emit radio signals, humanity also developed massive nuclear weapons that could wipe out all life on Earth. Will aliens destroy themselves at the mercy of a war maniac who has lost their minds?

Let us be optimistic once again that aliens are capable and rational to solve those problems we fear, and assume that they have lived in peace and prosperity for 1 million years. Because of the great development of science and technology and the abundance of life, they will inevitably think of, and fully afford, to spend huge sums of money on groundbreaking research of great significance, including attempts to establish contacts with their counterparts in the outside world. They sent powerful radio signals to the outside world without stopping for 1 million years.

As a result, a small fraction of the 1 million planets are broadcasting this signal, which is 1 million years divided by 4 billion years, or 0.025%. This means that only 250 are sending signals. If they are evenly distributed in the Milky Way, the distance between the two adjacent ones is about 4600 light-years. It would take 4,600 years for human signals to reach our nearest aliens.

If they receive an answer and send an answer right away, we'll have to wait patiently for 9200 years to hear back from them! The contact person of the Ozma Project is only a dozen light-years away from us, and it really doesn't make much sense to do so. For the project to be meaningful, it is necessary to listen to each single sun-like star within 4,600 light-years to see if it is emitting meaningful signals.

To be more realistic, consider that there are only 4,000 years of recorded human history. If aliens were only capable of broadcasting on the radio for a long period of 4,000 years, then there is only one planet broadcasting signals to the outside world today! Therefore, there is at best one more civilized creature in the entire galaxy besides the earth that is sending signals, and our efforts to listen attentively to such signals in the galaxy with radio telescopes are completely futile!

Readers may be deeply disappointed by this conclusion. So how different will the actual situation be from what is estimated here? There are many uncertainties in the above discussion. Is there a planet around every single star? Can life only be born in an environment like Earth? Also, we don't actually know how long a sapient creature can survive and whether they can survive forever? These questions may not be answered definitively for quite some time.

However, how could primitive man have imagined today's large airliners, color televisions, fast electronic computers, and lunar landings? As long as mankind can continue to live in a peaceful and prosperous environment, the development of science will gradually answer these questions. However, even if aliens exist, we will not be able to make effective contact with them for the time being. Therefore, it is probably not credible to associate UFOs with spacecraft from outside the sky.

Some scientists believe that the reason why there are no aliens on Earth is because they were killed by gamma rays before it was possible to reach Earth.

Dr. James Annis of the Fermi Accelerator National Laboratory in Illinois said the reason aliens have not yet reached Earth is that it is only until our galaxy offers the opportunity for life in space to thrive.

Until hundreds of millions of years ago, our galaxy was regularly exposed to gamma-ray bursts, which caused both star collisions and black holes to release large amounts of deadly rays, Annis said. It is only when these collisions become scarce that extraterrestrial life is possible and travel from the planet it inhabits to a considerable distance.

Annis hopes that the theory he presented in the British weekly New Scientist will be able to resolve one of the most famous debates about the existence of extraterrestrial life – the Fermi paradox. The paradox is named after the Italian-origin physicist Enrico Femi, a Nobel laureate. Fermi is said to have proposed this paradox in the 50s, the gist of which is: if aliens do exist, where are they?

This question is convincing because it is based on two facts about our galaxy: the Milky Way is very old, about 10 billion years old, and the Milky Way is only about 100,000 light-years in diameter. So, even if aliens could only travel in space at one-thousandth of the speed of light, it would only take them about 100 million years to cross the Milky Way – a time far shorter than the age of the universe. So, where exactly are the aliens?

Fermi apparently took this reason as evidence that aliens didn't exist at all. Now Annis claims that he has found a loophole in Fermi's inference: aliens are likely to exist, but only until gamma-ray bursts get longer and longer, thus providing enough time for extraterrestrials to travel to the planet.

British scientist Paul Davis discussed the hypothesis of "life provenance transmission", that is, extraterrestrial intelligent beings do not necessarily have to use living organisms for interstellar voyages, and can use highly intelligent robots to carry life provenance (stored in an absolute zero environment) to carry life provenance (stored in an absolute zero environment) on a spacecraft for life propagation colonization, so as to avoid the obstacles of cosmic gamma rays in interstellar travel, the astonishing energy required to travel close to the speed of light, and the limited age of life.

As long as the energy required for navigation is sufficient, this method of "life provenance transmission" can be realized, and it is deduced that in the long time history of the universe, highly intelligent life should be almost all over the entire universe of suitable planets, and there is a wide range of interstellar exchanges, including the earth. However, in fact, the earth has not received information about extraterrestrial life, so some scientists have concluded that the reason why extraterrestrials have not shown up is because extraterrestrial life does not exist.

It can be seen that scientists have not been able to agree on the existence of extraterrestrial life or to come up with definite confirmation or negative evidence. However, extraterrestrial research is no longer science fiction, but an interdisciplinary ——— an important topic of astrobiology with attractive prospects.

According to scientists, there are about 100,000,000,000 stars in the entire galaxy, and about 100,000,000,000 galaxies in the entire universe. If we assume that the probability of life is 1 in 1,000,000,000,000, then there will still be 100,000,000 planets with life.

Many people believe that time travel is impossible to achieve, after all, the distance between stars is measured in light years. However, they ignore the fact that in the mid-19th century, scientists thought that 55 km/h was the maximum speed that humans could achieve, but in this day and age, we have left the speed of sound far behind, and it took less than 200 years. So why can't there be a race on these 100,000,000 planets where life could possibly have invented and mastered the method of interstellar travel beyond human intelligence?

Although scientists have been debating the existence of black holes, after all, from an astronomical point of view, black holes cannot be observed by conventional telescopes, but most astronomers still believe in the results of radio telescope observations, believing that there are indeed such celestial bodies that can absorb light.

Hua Feng knows that many people still don't know what kind of form and what kind of attitude the aliens who may bring them great harm will come to the earth on a large scale, but those extraterrestrial life in Australia has made a possibility in the imagination of human beings.