White dwarfs are the final fate of stars that have similar mass to the sun, but were not massive enough to explode in a supernova. They are incredibly dense, with a typical white dwarf having a mass similar to that of the Sun, but compressed to the size of the Earth. Due to their high density, white dwarfs have very faint surfaces with low luminosity. As such, they cool down gradually over time, dimming as they do.

The cooling of a white dwarf is what ultimately leads to its demise. As they lose energy, white dwarfs become less luminous and their surface temperatures drop. Over billions of years, they eventually reach a point where they are not hot enough to sustain nuclear fusion reactions in their cores. At this stage, the white dwarf is said to be "dead."

A dead white dwarf is thought to evolve into a black dwarf. As it continues to cool, its luminosity will diminish further, eventually becoming too faint to be detected by telescopes. At this point, the white dwarf will essentially become invisible, and astronomers refer to it as a black dwarf. However, it is worth noting that the process of a white dwarf becoming a black dwarf is extremely slow and it may take billions of years for this transformation to occur. As a result, there are no known black dwarfs in the universe yet, and they remain purely theoretical objects.