If someone asks, do alien civilisations exist in the universe? I believe that the vast majority of people would give an affirmative answer. Because of this, in the process of exploring the universe, humans also look for those alien civilisations that may exist. In the past, apart from using various observation devices to search around, humans have also taken the initiative to expose their position in the universe, expecting alien civilisations to notice the earth and give a response.
As early as 1974, humans sent a radio message to the m13 globular cluster through the arecibo radio telescope - the "Arecibo message", which was the message is powerful, easy to decode and contains important information about earth civilisation, which could be easily accessed by an alien civilisation if it exists in the m13 globular cluster, as long as they are at a similar level of technology to earth.
"The arecibo message was just the beginning, and in 2015, astrobiologist douglas wacoch, formerly of the seti institute, set up a research organisation called meti "A research organization dedicated to sending powerful and easily decodable radio messages to areas near earth where extraterrestrial civilizations may exist.
Such a situation begs the question of whether other intelligent civilisations, if they do exist in the universe, would do the same thing as humans do.
Would alien civilizations actively reveal their location?
According to this theory, intelligent civilizations in the universe would be careful to hide themselves in the darkness, but this is only a hypothesis.
So we can also assume that when intelligent civilisations in the universe develop to a certain extent, they may well be as eager to find other intelligent civilisations as humans are, and if they can't, they may also actively reveal their position in the universe and expect other intelligent civilisations to give a response.
But the question is, if this is the case, then why have we not received any information from alien civilisations until now?
One plausible explanation for this question is that alien civilisations may not be using radio to send messages, but rather other methods, such as by deliberately creating abnormal macroscopic phenomena in the universe and hoping to draw the attention of other intelligent civilisations. Interestingly, we may have found one such example.
355 light-years away, an abnormal star appears, evocatively
About 355 light-years away in the direction of centaurus, there is a star called "Hd101065". Observations show that this star, with a radius of about 1.9 times that of the sun and a mass of about 4 times that of the sun, is a rapidly oscillating ap star whose luminosity changes dramatically in a short period of time. The photovariation period is about 12.15 minutes.
The reason why "Hd101065" Is considered an anomalous star is that its elemental abundances are very different from the normal case. Spectroscopic analysis shows that "Hd101065" Is lower in iron than the sun, but it contains a significantly higher proportion of lanthanides (e.g. Yttrium, caesium, scandium, neodymium, promethium, niobium, thorium and ytterbium) and actinides (e.g. Actinium, neptunium, plutonium, americium, curium, einsteinium and berkelium).
Importantly, many of these elements are radioactive, and some of them have very short half-lives, such as einsteinium, where the longest half-life among its isotopes is only about 472 days, while the shortest half-life is only about 20 seconds.
Scientists estimate the age of "Hd101065" To be about 56.6 (±27.9) million years, which means that even if, by coincidence, the star was born in a region rich in lanthanides and actinides, after such a long period of time, those elements with short half-lives would have decayed. After such a long period of time, those elements with short half-lives would have decayed to such an insignificant extent that they could not have been detected by us.
However, the fact that we did detect these "Undetectable elements" On "Hd101065", how can this be explained?
Imagine if there was an alien civilisation there, and if they were interested in revealing their location, they could send a lot of "Undetectable elements" To nearby stars, hoping to attract the attention of other intelligent civilisations. The first of these would be to send large amounts of "Undetectable elements" To nearby stars in the hope of attracting the attention of other intelligent civilisations.
This method seems to be more suitable for intelligent civilisations to announce their presence in the universe than radio messages sent by humans, because it is a method of "Broadcasting" Through space and can be observed by intelligent civilisations in all directions, whereas radio signals can only be sent in a specific direction.
Of course, scientists do not generally use the term "Alien civilisation" To explain this unusual star without conclusive evidence, but there are two speculations.
One view is that there may be some unknown, very high atomic number, super-heavy elements in the star that are slowly decaying, making the abundance of elements in "Hd101065" Abnormal.
Another view is that this may be due to the presence of a neutron star in the vicinity of hd101065, which continues to produce a variety of heavy elements under the constant bombardment of the high-speed particle streams it releases.