When a supermassive star dies, it collapses in on itself to form a dense mass called a singularity. The gravitational field around such an object is so strong that even light cannot escape, so we gave these monstrous space monsters the cute name “black holes.” The corpses of these stars tear apart the gulf in space time, so calling them the densest matter in space is not correct – it is forbidden. If you’re looking for dense matter that’s not covered by a dark shell, you should settle on a low-mass neutron star.
To make a neutron star, you would have to take the mass of the Earth and break it all into a sphere 12 miles in diameter – and then within that sphere, find room to fuse in another 499,999 Earths on top of the first one. It’s very tight there. As you can imagine, a neutron star is a very different type of celestial object than a regular star like our Sun. One such difference? A neutron star has a solid surface called the crust.
In that way, a neutron star has something in common with our dwarf planet. And although the mechanism is different, the drift of a neutron star can move suddenly and violently, not unlike an earthquake. An earthquake. Could they be the source of FRBs?