The fifth state of matter is Bose-Einstein condensation, which is a gaseous superfluid formed by atoms that have been cooled to almost absolute zero. The theory was proposed by Satyndra Bose and Albert Einstein in the 1920s.
Although the theory was proposed in the 1920s, the process was not actually successfully accomplished until 1995 by Eric Cornell and Carl Wieman at the University of Colorado. The experiment was accomplished using a gas of rubidium cooled to 170 nanokelvins. When cooled to this temperature, the atoms collapse into the lowest quantum state, which produces what is called a superfluid. When the atoms get to this temperature, they lose almost all of their energy and cannot move anymore. Since they are unable to move they begin to clump together. The clumping occurs because the atoms can no longer transfer energy and have the same properties and levels. This is sometimes referred to as a super atom as well. This new state of matter has produced a wide range of isotopes, although these isotopes and other creations, like degenerate gases, are very fragile. The slightest increase in temperature can cause them to warm past the threshold and become normal gases once more. These condensates are being proposed for many new applications, like slowing light or anti-stealth technologies.