10 billion times harder than steel

From a microscopic point of view, the objects we normally see are actually made up of a large number of atoms, and the hardness of the objects varies greatly depending on the type of atom and the way it is bonded, for example, a diamond is made up entirely of carbon atoms, and the way it is bonded is that each carbon atom is bonded to the four carbon atoms next to it through covalent bonds, thus forming a crystal structure like the one shown below.

In this structure, all the "valence electrons" of the carbon atoms are involved in the formation of covalent bonds. Compared to most covalent bonds formed between atoms of the same type, the bond lengths and bond energies of covalent bonds formed between carbon atoms are shorter and higher, and their three-dimensional configuration is very conducive to the rapid distribution of local external forces to all parts of the crystal. Therefore, the hardness of a diamond is quite high.

Diamond has a Mohs hardness of 10, making it the hardest naturally occurring substance on earth. The reason for the "naturally occurring" qualification is that diamond is still not as hard as some synthetic substances, such as polymeric diamond nanorods, artificial Bluestar, carbon alkynes, etc.

Of course, the hardness of these synthetic substances is not much in the universe, so what is the hardest substance in the known universe?

In the known universe, the hardest material should come from the neutron star, according to scientists' calculations, this material is 10 billion times harder than steel. People also gave this substance an interesting name - "nuclear spaghetti", here we come to understand.

Whether it is diamond or synthetic substances, their hardness is limited by the strength of the chemical bond, and the nature of the chemical bond is the interaction between atoms, because the interior of the atom is very empty, so if there is a force to "crush" the atom, and then the neutrons, protons, and electrons that make up the atom tightly pressed together In this way, the hardness of matter can be increased significantly.

Gravity can be such a force, which means that on those objects with very strong gravitational fields, there is likely to be very hard matter.

In the known universe, black holes are the objects with the strongest gravitational fields, but since we know nothing about the interior of black holes, they are not part of the "matter hardness" discussion, and the gravitational fields of neutron stars are undoubtedly the strongest, except for black holes.

It should be noted that neutron stars are not composed entirely of neutrons. According to scientists, the mass of neutrons accounts for about 95% of the total mass of neutron stars, while the rest of the mass is protons and electrons, and there are even a large number of atomic nuclei in the outer structure of neutron stars.

In addition, not all neutron stars are composed of solid matter.

The diagram above shows the internal structure of a neutron star after years of research, from the outside to the inside: "atmosphere", "outer crust", "inner crust", "outer core" and "inner core". The "outer core" and the "inner core".

Scientists believe that the "atmosphere" of a neutron star is only a few millimeters thick and consists mainly of hydrogen, helium, and carbon, whose dynamics are completely controlled by the magnetic field of the neutron star, while the "outer crust" of the neutron star is a solid structure consisting mainly of the nuclei of heavy elements and electrons. The "outer crust" of the neutron star is a solid structure composed mainly of nuclei and electrons of heavy elements.

It should be noted that the nuclei and electrons in the "outer crust" are not combined into complete atoms, so we can simply understand that the "outer crust" of a neutron star is a large pile of nuclei "crushed" by the gravitational field of the neutron star. The "outer crust" of the neutron star is actually a pile of atoms that have been "crushed" by the gravitational field of the neutron star, but the force on them is not enough to crush the electrons into the nucleus, so these "atomic fragments" are pressed tightly together, forming a strange solid structure.

Only the "outer crust" of the neutron star is a solid structure because the matter in the "inner crust" and "outer core" of the neutron star has a fluid nature due to the very high temperature and pressure. As for the matter in the "core" of the neutron star, there is no conclusion yet, but scientists speculate that the matter in this region is probably a "quark-gluon plasma".

We know that only solid matter is hard, which means that only the "outer crust" of the neutron star has the characteristic "hardness".

As the depth increases, the material in the "outer crust" of the neutron star is subjected to more and more pressure, and its hardness increases, so the hardest material on the neutron star is found in the transition region between the "outer crust" and the "inner crust The hardest material on the neutron star is in the transition region between the "outer crust" and the "inner crust" (after all, the material in the "inner crust" is already fluid, and fluid is not "hard").

Interestingly, even more, elaborate names have been given to the different structures, such as "Gnocchi", "Lasagna", "Waffles", etc. "(Waffles), etc.

To test the hardness of "nuclear spaghetti", scientists built a computer model based on the formation conditions of neutron stars, known observational data, and related theories, and after a series of simulations, scientists finally came up with the result that "nuclear spaghetti" is 10 billion times harder than steel!

In addition to black holes, there are no more objects in the known universe than the gravitational field of neutron stars, so "nuclear spaghetti" is also considered to be the hardest material in the known universe.

It is worth mentioning that "nuclear spaghetti" can only exist in the extreme gravitational field of neutron stars, and once it is released from the gravitational bondage of neutron stars, the dense structure of "nuclear spaghetti" will disappear instantly, releasing a large amount of energy.

On the other hand, the density of matter on neutron stars can reach at least 10^11 kg per cubic centimeter (100 billion kilograms), so we can't use "nuclear spaghetti" to make objects (at least in the foreseeable future), even without considering the distance in the universe.