White dwarfs may be the best place to look for extraterrestrial civilizations

For decades, scientists have been listening to the night sky, trying to catch any signals from foreign civilizations. We are looking for mysterious radio signals, Dyson spheres surrounding distant stars, we are looking for traces of life on Mars, but so far we have not found anything.

Return! For a long time, the attention of scientists seeking extraterrestrial life was caught by a mysterious signal recorded in the summer of 1977. Radio astronomer Jerry Eman, who first saw him, marked him on a printout of data from Big Ear Radio Telescope, adding "Wow!" Since then, this signal was known as "Wow Signal!" And many scientists have admitted that his origin is really mysterious.

A few years ago, however, it turned out that its sender was no alien civilization, but only comets flying just across the sky, which was observing the telescope that night. All the charm is broken. We were alone again in the universe, without a single trace of any life outside Earth.

However, nobody stopped the search for extraterrestrial civilizations. One of the many problems faced by scientists from the SETI (Search for Extraterrestrial Intelligence) programs is to decide where to look for signals from foreign civilizations.

In the latest article published on the arXiv website, Jonh Gertz, supported by astronomer and explorer over 70 of the first 100 discovered exoplanets, Geoffrey Marcy, suggests that we should pay more attention to white dwarfs, remnants of stars such as our Sun. Although at first glance this is a fairly original idea, it is not meaningless.

If we know anything about the existence of life in the universe, it is knowledge about Earth.

For example, we know that life can occur on planets orbiting G-class stars, because the Sun is such a star. Therefore, looking for a life at least similar to ours, we should start by reviewing just such stars.

Our current knowledge of G-class stars says that they live about 8-10 billion years. At the end of their lives, they pass successively into the sub-giant, red giant, planetary nebula, and finally end up as white dwarfs. The sun has survived less than 5 billion years, so far nothing threatens it, because it will calmly burn hydrogen inside for a few billion years.

However, any civilization living on a planet orbiting a G-class star will sooner or later have to die or move somewhere else. In a few billion years, when the Sun begins to pass into the red giant stadium, its dimensions will begin to grow. Our star will absorb Mercury and Venus in turn, and its surface will be near the current orbit of the Earth.

One thing is certain - there will be no conditions on Earth for a long time to survive.

Therefore, if our civilization in any form survives to this time, it will have to either look for another planetary system, or manage somehow on the spot.

The problem is that, according to Gertz, there is a great risk that interstellar travel is a challenge too much not only for us, but also for much more advanced civilizations. After all, each of the potentially existing ones will have to face the same laws of physics.

Let's assume for a moment that the Sun is much older than it is now and is slowly beginning to scorch the Earth and we are facing the need to move to anywhere where the survival of the species will be possible.

If we were able to pack a sufficiently large group of people onto a spacecraft and send it at the speed of the Voyager spacecraft, one of the fastest probes ever sent from Earth, in the direction of, say, Barnard's Star, one of the closest stars to us, then this ship would fly there about 100,000 years .

How to build a ship that will survive and feed 4,000 generations in a vacuum of space? It is worth noting here that the Voyager probe weighed 733 kg, and such a ship ...

After all, a much more realistic and immeasurably easier solution would be to move to Mars or even larger bodies of the Planetoid Belt and create there conditions for survival. Moreover, over time, when the red giant rejects its outer layers that will dissolve throughout the planetary system, forming a planetary nebula, a hot white dwarf will remain at the center of the system.

Perhaps then it will be possible to return to Earth and adapt it to re-live. These are all incredibly difficult challenges, but they can still be easier and more realistic than interstellar travel.

It is worth noting another aspect of Gertz's consideration. The evolution of planetary systems indicates that the planets form from a protoplanetary disk relatively quickly after the formation of the star. If we look at Earth, we know that life can arise on a favorable planet quite quickly after the creation of the planet itself (it is worth noting, however, that billions of years may pass from the creation of life to the emergence of technical civilization).

If in other planetary systems these processes occur similarly, then looking towards white dwarfs, we look at planetary systems billions of years older than ours. This, in turn, can mean that if there are any civilizations there, they are much more advanced than us.

All the above data lead the author to say that when looking for signs of extraterrestrial life, we should carefully look at white dwarfs, which constitute 15 percent. of all the stars in our galaxy, because it is around them that advanced civilizations can live that have found that interstellar journeys are out of their reach and have coped with the evolution of their star by traveling within their planetary systems.

White dwarfs may be the best place to look for extraterrestrial civilizations