Nuclear Pasta

Pasta. Nuclear pasta. Although pasta sounds soft and squishy, nuclear pasta is the strongest theoretical material in the whole universe. It is a billion billion times stronger than steel, with density around a whopping 10^14 g/cm^3! This theoretical material is predicted to be found in neutron stars, with a typical layer thickness of 100 m.

https://astrobites.org/2017/10/05/nuclear-pasta-in-neutron-stars/

"It's so dense that, as far as [neutron stars] are concerned, normal matter is a slightly polluted vacuum." ---CrashCourse

Why is nuclear pasta so so strong?

The strength of a material is determined by its atomic structure. Nuclear pasta, on the other hand, doesn't really have an atomic structure. It is a gigantic nucleus itself. Nuclear pasta is a form of degenerate matter, and it is prevented compression by the outward push of neutron degeneracy pressure.

Degeneracy pressure is the pressure caused by two fermions (such as neutrons) refusing to get too close together. Or more formally, degeneracy pressure is a result of Pauli's exclusion principle, which states that fermions cannot simultaneously occupy the same quantum state (such as spin, momentum, position).

Additionally, nuclear pasta are also held together by the strong nuclear force - the strongest of the four fundamental forces of the universe. The strong force is 100 trillion trillion trillion times stronger than the gravitational force, but it has such a short range that we cannot feel it daily. The strong nuclear force binds neutrons and protons, and they also hold nucleon themselves together.

Where is nuclear pasta and how is it formed?

Nuclear pasta forms the transition region between the “normal” iron on the surface of the neutron star and the ultra dense material at the core (could be superfluids, or quark-gluon plasma, for what we know).

The surface of the neutron star consist of conventional matter of iron with metallic bonding, where the positive nucleus forms a lattice with a sea of electrons flowing around. Going deeper, as the pressure increases, the distance between the electrons and the nucleus decrease, and, eventually, the electrons and protons in the nucleus merge to form neutrons (and neutrinos). This process is called “electron capture”.

As pressure gets even higher, the neutrons get closer and closer, forming shapes resembling typical pasta - from “gnocchi”, to “spaghetti”, and as the nucleons get even closer - it forms “waffles” and “lasagna”. Eventually they are so close that they are categorized as defects, then “antispaghetti” and “antignocchi” (like Swiss cheese).

Mmmm, tasty.

Here are some lovely photos of edible gnocchi and lasagna.