Absolute zero is the theoretical temperature as it can never be reached. The laws of thermodynamics state that absolute zero cannot be reached because this would require a thermodynamic system to be fully removed from the rest of the universe. A system at absolute zero would still possess quantum mechanical zero-point energy. While molecular motion would not cease entirely at absolute zero, the system would not have enough energy for transference to other systems. It is therefore correct to say that molecular kinetic energy is minimal at absolute zero. By international agreement, absolute zero is defined as 0K on the Kelvin scale and as −273.15°C on the Celsius scale. Scientists have achieved temperatures very close to absolute zero, where matter exhibits quantum effects such as superconductivity and superfluidity. One of the unexpected results of cooling matter very close to absolute zero was the discovery of a new state of matter. Solid, liquid, and gas are the common states of matter, but when matter, particularly a fluid such as liquid helium, reaches these incredibly low temperatures, it loses all its viscosity, and becomes a superfluid. These strange fluids exhibit the ability to flow against gravity, and to a degree, move from their containers into others. Another phase of matter, called a Bose-Einstein condensate, can be produced at temperatures approaching absolute zero. Bose-Einstein condensates can only be seen when the temperature of a specimen is brought to within one billionth of one degree of absolute zero. Consequently, only the most specialized laboratories can attempt to study this fragile state of matter. Also, Bose-Einstein condensates have so far only been made from microscopically small amounts of matter, on the order of about 10,000 or fewer atoms. They are related to superfluids and behave in somewhat similar ways, but are usually produced from matter in a gaseous state. The laws of physics which govern Bose-Einstein condensates are not fully understood, and seem to challenge the things we know about the nature of matter. The best way to understand these condensates without an in-depth knowledge of physics is to understand that when matter reaches this point, the atoms in it "collapse" into the lowest possible state of energy, and also begin to behave as if they were no longer discreet particles, but rather waves. Physicists have much more study and research ahead of them in order to fully understand this state of matter, which was only first observed in 1995.
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