thought of as a localized structure, but as a global, topological feature of spacetime. It has been argued that elementary particles are fundamentally not material, either, but are localized properties of spacetime. In quantum gravity, singularities may in fact mark transitions to a new phase of matter. Other proposed states Supersolid A supersolid is a spatially ordered material (that is, a solid or crystal) with superfluid properties. Similar to a superfluid, a supersolid is able to move without friction but retains a rigid shape. Although a supersolid is a solid, it exhibits so many characteristic properties different from other solids that many argue it is another state of matter. String-net liquid In a string-net liquid, atoms have apparently unstable arrangement, like a liquid, but are still consistent in overall pattern, like a solid. When in a normal solid state, the atoms of matter align themselves in a grid pattern, so that the spin of any electron is the opposite of the spin of all electrons touching it. But in a string-net liquid, atoms are arranged in some pattern that requires some electrons to have neighbors with the same spin. This gives rise to curious properties, as well as supporting some unusual proposals about the fundamental conditions of the universe itself. Superglass A superglass is a phase of matter characterized, at the same time, by superfluidity and a frozen amorphous structure. Arbitrary definition Although multiple attempts have been made to create a unified account, ultimately the definitions of what states of matter exist and the point at which states change are arbitrary. Some authors have suggested that states of matter are better thought of as a spectrum between a solid and plasma instead of being rigidly defined. See also Hidden states of matter Classical element Condensed matter physics Cooling curve Phase (matter) Supercooling Superheating Notes and references External links 2005-06-22, MIT News: MIT physicists create new form of matter Citat: "... They have become the first to create a new type of matter, a gas of atoms that shows high-temperature superfluidity." 2003-10-10, Science Daily: Metallic Phase For Bosons Implies New State Of Matter 2004-01-15, ScienceDaily: Probable Discovery Of A New, Supersolid, Phase Of Matter Citat: "...We apparently have observed, for the first time, a solid material with the characteristics of a superfluid...but because all its particles are in the identical quantum state, it remains a solid even though its component particles