Birch Planet
A birch planet is an artificial world whose gravity comes from a black hole. There can be extremely big birch planets that can be as large as a light-year in diameter, using a black hole that would have surface gravity like on Earth, but the black hole would need to be 1.5 trillion times heavier than our sun to do that. The concept is like a shellworld Shellworld, but using a black hole. Birch planets can have layers with different gravities and time flows due to the gravity of a black hole. The biggest birch planet could have as many people as a Kardashev 3 civilization Kardashev scale. The name "Birch planet" was coined by an American futurist/YouTuber Isaac Arthur.
References
This article "Birch Planet" is from Wikipedia. The list of its authors can be seen in its historical and/or the page Edithistory:Birch Planet. Articles copied from Draft Namespace on Wikipedia could be seen on the Draft Namespace of Wikipedia and not main one.
