A proton star or a white dwarf is a dense object, but the word compression cannot be used for it. In fact, it can be said that the densest objects have a structure that seems compact, but actually it is not.
In order to show the hardness of Proton in comparison, it can be said that if the hardness of diamond is like the hardness of wood, the hardness of Proton is like steel.
The general result is that all matters in the world can be classified in such a way that some liquid substances such as water are neither dense nor compressed; some are dense but not so compressed such as mercury. In fact, the hardness of a proton star compared to a diamond is like the hardness of steel compared to wood, and if the hardness number of a diamond be 10, a proton star ones would be about 20.
Author: Gh Saleh.