The vaporized crust of Earth-like planets is found in the atmosphere of white dwarfs.

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The vaporized crust of Earth-like planets is found in the atmosphere of white dwarfs. 

The researchers have observed four nearby white dwarfs and found remainings of vaporized earth-like planets around them. So that tells that rocky planets are very common in the universe. The distance between stars and those rocky planets is unknown, but that thing is interesting because white dwarfs are remainings of the Sun-like stars. Or rather saying sun-mass stars. The thing is that this kind of information is interesting from the point of view of the SETI-program. 

The white dwarfs are born in nova-eruptions, and if there was some kind of intelligent race around that star, they must leave their home or they will destroy when nova will crush their home planet. The thing that makes that kind of thing easier is that before nova erupts the star will grow to a red giant. And the civilization must move farther from it. The reason why researchers believe that the intelligent lifeform is leaving their solar system is all species living on land have an innate instinct for self-preservation, causing all beings to fight to the end. And that means that the suicide of the species is impossible if we are we look at this issue from the perspective of our evolution. The will of surviving would drive the civilization to move away from their solar system when their sun will explode. 

The sun-type or little bit brighter stars are the places, where could be mankind lifeforms. But then we must realize, that mankind doesn't necessarily mean, that the lifeform is intelligent. When we are talking about similar lifeforms that are living on Earth we are meaning similar lifeforms that are found on Earth. That means carbon-based lifeform, which is not necessarily intelligent. 

But when we are talking about Earth-like planets we are forgetting that the surface temperature of the planet has also an effect on lifeforms and the possibility that there can be lifeforms on that planet. The clouds and chemical structure of the atmosphere along with the size of the water layer are determining the surface temperature of the planet. But when we are thinking about the lifeforms of the Earth-type rocky planets, we must remember that those lifeforms that are living on some planet are fully adapted to their world. 

Same way deep-sea fishes and all other animals are adapted to their environment on Earth. The environment where the snow leopard or asps lives are extremely hostile to humans. Without clothes, we would get skin cancer in high mountains. Or at the desert of Sahara, we would dry to death without a shovel and tent, which we can use to get water and use as a shield against burning sunlight. On most of Earth, humans need clothes and houses to survive against nature. 

So that means that if those lifeforms live on the rocky planet what gravity is about 4 times to Earth that means the planet is not hostile to the endemic lifeforms that are living on its surface. The fact is that if we want to search the intelligent super civilizations the white dwarfs are giving us tips on where we must or where we should turn our telescopes. 

If we are thinking about the civilization of the Kardashev's scale III what means galactic scale civilization requires time to advance to that level. And the beginning of those hypothetical super civilizations is most likely at the rocky planet, which orbits the Sun-like star. But creating the technology, that makes the interstellar traveling routine requires time, and we might think that the civilization would go a similar path every time until it reaches the  Kardashev's scale. And that thing involves crisis, but if the civilization would not destroy itself it would face a bright future.

https://en.wikipedia.org/wiki/Kardashev_scale

https://scitechdaily.com/vaporized-crusts-of-earth-like-planets-discovered-in-dying-stars/

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