Astronomy
The Evolution of White Dwarfs into Black Dwarfs
Quick fact
Black dwarfs are purely theoretical—no black dwarf has ever been observed because the universe is only about 13.8 billion years old, far younger than the trillions of years needed for a white dwarf to cool completely.
Why this is interesting
You've heard of white dwarfs—the dense cinders of dead stars. But what happens when they finally cool down? Welcome to the black dwarf, a star that has yet to exist in our universe.