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Final curtain for Europe's deep-space telescope

The deep-space telescope Herschel took its final bow on Monday, climaxing a successful four-year mission to observe the birth of stars and galaxies, the European Space Agency (ESA) said.

Space & Earth - Astronomy

Jun 17, 2013

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Absolute zero

Absolute zero is a temperature marked by a 0 entropy configuration. It is the coldest temperature theoretically possible and cannot be reached by artificial or natural means. Temperature is an entropically defined quantity that effectively determines the number of thermodynamically accessible states of a system within an energy range. Absolute zero physically possesses quantum mechanical zero-point energy. Having a limited temperature has several thermodynamic consequences; for example, at absolute zero all molecular motion does not cease but does not have enough energy for transference to other systems, it is therefore correct to say that at 0 kelvin molecular energy is minimal. In addition, any particle with zero energy would violate Heisenberg's Uncertainty Principle, which states that the location and momentum of a particle cannot be known at the same time. A particle at absolute zero would be at rest, so both its position, and momentum (0), would be known simultaneously.

By international agreement, absolute zero is defined as precisely 0 K on the Kelvin scale, which is a thermodynamic (absolute) temperature scale, and −273.15° on the Celsius scale. Absolute zero is also precisely equivalent to 0 R on the Rankine scale (same as Kelvin but measured in Fahrenheit intervals), and −459.67° on the Fahrenheit scale. Though it is not theoretically possible to cool any substance to 0 K, scientists have made great advancements in achieving temperatures close to absolute zero, where matter exhibits quantum effects such as superconductivity and superfluidity. For the kinematics of the molecules, on a larger scale, which is easier to understand see kinetic energy.

This text uses material from Wikipedia, licensed under CC BY-SA

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