Strange radio signals coming from the center of the Milky Way, are they sent by aliens? The truth is…

People's curiosity about aliens has never ceased. Novels, movies and TV shows often feature plots of humans fighting aliens.

In real life, many scientific and technological workers have also been searching for aliens. Recently, Chinese student Dr. Wang Ziteng, as the first author, published a new paper in the Astrophysical Journal, which roughly said that scientists have discovered a mysterious radio signal source coming from the center of the Milky Way.

The research team compared all known celestial bodies and could not explain the source of the signal. They thought of several possibilities, including a completely new celestial body or a signal from an alien civilization.

Some people may ask, how can we think of aliens with just such a signal? Do aliens really exist? And how can we discover them?

Today we will talk about extraterrestrial signals and aliens.

Why do we have to hold on to this signal?

The first thing that needs to be made clear is that it is very necessary to hold on to the distinctive radio signals.

In 1967, Jocelyn Bell, a 24-year-old doctoral student, discovered a mysterious periodic signal using a radio telescope. The signal beat strictly according to a period of about 1 second. A few years later, the source of the signal was confirmed to be a rapidly rotating pulsar, and this achievement was awarded the Nobel Prize in Physics in 1974.

Let's go back to the mysterious signal discovered this time. It was first discovered by scientists using the Australian telescope ASKAP, and later discovered again in South Africa using the more sensitive MeerKAT telescope, but only intermittent signals were still obtained. It has five main characteristics:

1. The amplitude of change is large, and the intensity can change more than 100 times within a week;

2. Changes quickly, sometimes lasting for weeks, sometimes disappearing within a day;

3. Very high degree of polarization;

4. There is no pulsation phenomenon (the phenomenon corresponding to pulsars);

5. There are no corresponding celestial bodies in the near-infrared and X-bands.

The strangest property of the newly discovered signal is that it has a very high degree of polarization, meaning that its light oscillates in only one direction, but that direction rotates over time.

The uniqueness of this signal also lies in its changes - it is invisible at first, then gradually becomes brighter from the dark, gradually fades from bright to dark and disappears, then reappears again, repeating this process with many changes. It appears randomly and then becomes brighter and darker.

The polarization is high and changes very quickly. At first glance, it looks like an alien child holding a huge flashlight and waving it around. It is also very similar to the signals emitted by human activities, so it is not ruled out that it was emitted by aliens. However, there is no conclusive evidence to prove this.

What is the significance of this signal?

Now it seems that this signal is beyond human cognition and there is no corresponding known type of celestial body, so what exactly is it? In fact, there is still no clear answer to many questions.

But several contributors to the paper said this is likely a completely new type of celestial body.

A similar new discovery was made five years ago. When China's Sky Eye was put into use in 2016, it received a special signal. Scientists later analyzed and found that the signal might have come from 1,300 light years away.

The night view of the "China Sky Eye" taken on July 24, 2022. Photo by Xinhua News Agency reporter Ou Dongqu

After receiving this signal, scientists were shocked. After analysis, they found that this signal was actually a fast radio burst - a mysterious radio astronomical phenomenon from outside the Milky Way. Once it bursts, it lasts for a very short time, generally only a few milliseconds . The reason why it can be captured by China's Sky Eye is actually because of its amazing energy. Even the energy released by the sun in a day may not be comparable to it.

This new cosmic phenomenon once again demonstrates that the universe is extremely vast, exploration will never end, and new discoveries may open up entirely new areas of research.

How do humans explore alien civilizations?

Since this new radio signal is not necessarily sent by aliens, how can humans explore alien civilizations? There is actually more than one way.

A more direct way is to launch a spacecraft to find aliens!

One of the important missions of many human space exploration programs, including lunar and Mars exploration, is to detect whether there is life and whether there is the basic environment required for life.

More than 50 years ago, scientists launched Voyager 1 and Voyager 2. These two man-made spacecraft have flown out of the edge of the solar system and are heading towards the depths of the vast universe. Unfortunately, more than half a century has passed, and no information about extraterrestrial civilizations has been obtained.

The Voyager spacecraft. Source: NASA

The distance that our aircraft can fly is still relatively limited, so how can we explore more distant places? We can also use radio telescopes to search for signals from alien civilizations.

In 1960, the first Search for Extraterrestrial Intelligence (SETI) experiment was completed by astronomer Frank Drake from Cornell University in the United States.

In 1977, SETI used the Giant Ear radio telescope to receive the famous "Wow!" signal, which was a very strong radio signal lasting 72 seconds. However, this signal has never appeared again.

So how can we judge from radio signals whether the signal is from a living alien? According to the radio signals emitted by human activities, some signals of alien life may have regularity and a certain oscillation frequency.

To this end, scientists are trying to look for some light source signals with narrow bandwidth and fast flashing, which are likely to be emitted by alien activities.

Broadband wireless signals and slower light pulses are generally less likely to be associated with aliens than with pulses from nebulae.

So far, there is no sufficient evidence to prove the existence of aliens. I hope scientists can make some progress in the future.

Planning and production

Author: Liu Yan, Space Application Engineering and Technology Center, Chinese Academy of Sciences

Editor: Yinuo