<P> Strange matter is a type of quark matter that is suspected to exist inside some neutron stars close to the Tolman--Oppenheimer--Volkoff limit (approximately 2--3 solar masses), although there is no direct evidence of its existence . In strange matter, part of the energy available manifests as strange quarks, a heavier analogue of the common down quark . It may be stable at lower energy states once formed, although this is not known . </P> <P> Quark--gluon plasma is a very high - temperature phase in which quarks become free and able to move independently, rather than being perpetually bound into particles, in a sea of gluons, subatomic particles that transmit the strong force that binds quarks together . This is analogous to the liberation of electrons from atoms in a plasma . This state is briefly attainable in extremely high - energy heavy ion collisions in particle accelerators, and allows scientists to observe the properties of individual quarks, and not just theorize . Quark--gluon plasma was discovered at CERN in 2000 . Unlike plasma, which flows like a gas, interactions within QGP are strong and it flows like a liquid . </P> <P> At high densities but relatively low temperatures, quarks are theorized to form a quark liquid whose nature is presently unknown . It forms a distinct color - flavor locked (CFL) phase at even higher densities . This phase is superconductive for color charge . These phases may occur in neutron stars but they are presently theoretical . </P> <P> Color - glass condensate is a type of matter theorized to exist in atomic nuclei traveling near the speed of light . According to Einstein's theory of relativity, a high - energy nucleus appears length contracted, or compressed, along its direction of motion . As a result, the gluons inside the nucleus appear to a stationary observer as a "gluonic wall" traveling near the speed of light . At very high energies, the density of the gluons in this wall is seen to increase greatly . Unlike the quark--gluon plasma produced in the collision of such walls, the color - glass condensate describes the walls themselves, and is an intrinsic property of the particles that can only be observed under high - energy conditions such as those at RHIC and possibly at the Large Hadron Collider as well . </P>

Who discovered the 4th and 5th state of matter