Absolute zero is the lowest possible temperature where nothing could be colder, and no heat energy remains in a substance. Temperature is a physical property of a system that underlies the common notions of hot and cold something that is hotter generally has the greater temperature In Physics, heat, symbolized by Q, is Energy transferred from one body or system to another due to a difference in Temperature Absolute zero is the point at which molecules do not move (relative to the rest of the body) more than they are required to by a quantum mechanical effect called zero-point energy. Quantum mechanics is the study of mechanical systems whose dimensions are close to the Atomic scale such as Molecules Atoms Electrons In Physics, the zero-point energy is the lowest possible Energy that a Quantum mechanical Physical system may possess and is the energy of the It is a theoretical limit and cannot be achieved with the current technology available.

By international agreement, absolute zero is defined as precisely 0 K on the Kelvin scale, which is a thermodynamic (absolute) temperature scale, and −273. The kelvin (symbol K) is a unit increment of Temperature and is one of the seven SI base units The Kelvin scale is a thermodynamic Thermodynamic temperature is the absolute measure of Temperature and is one of the principal parameters of Thermodynamics. 15 on the Celsius (centigrade) scale. The Celsius Temperature scale was previously known as the centigrade scale. ^[1] Absolute zero is also precisely equivalent to 0 °R on the Rankine scale (also a thermodynamic temperature scale), and −459. Rankine is a thermodynamic (absolute temperature scale named after the Scottish Engineer and Physicist William John Macquorn Rankine 67 degrees on the Fahrenheit scale. Fahrenheit is a temperature scale named after Daniel Gabriel Fahrenheit (1686–1736 a German Physicist who proposed it in 1724 Though it is not possible to cool any substance to 0 K,^[2] scientists have made great advancements in achieving temperatures close to absolute zero, where matter exhibits quantum effects such as superconductivity and superfluidity. A Bose–Einstein condensate (BEC is a State of matter of Bosons confined in an external Potential and cooled to Temperatures very near to Superconductivity is a phenomenon occurring in certain Materials generally at very low Temperatures characterized by exactly zero electrical resistance Superfluidity is a phase of matter or description of Heat capacity in which unusual effects are observed when Liquids, typically of Helium-4 In 2000 the Helsinki University of Technology has reported reaching temperatures of 100 pK (1×10⁻¹⁰K). Helsinki University of Technology ( TKK) ( Finnish: Teknillinen korkeakoulu; Swedish: Tekniska högskolan) is the premier technical The kelvin (symbol K) is a unit increment of Temperature and is one of the seven SI base units The Kelvin scale is a thermodynamic

Contents 1 History 1.1 Limit to the 'degree of cold' 1.2 Lord Kelvin's work 2 Additional Information 3 Thermodynamics near absolute zero 4 Relation with Bose Einstein Condensates 5 Absolute temperature scales 6 Negative temperatures 7 See also 8 Notes 9 References 10 External links

History

One of the first to discuss the possibility of an "absolute cold" on such a scale was Robert Boyle who in his 1665 New Experiments and Observations touching Cold, stated the dispute which is the primum frigidum is very well known among naturalists, some contending for the earth, others for water, others for the air, and some of the moderns for nitre, but all seeming to agree that:

“

There is some body or other that is of its own nature supremely cold and by participation of which all other bodies obtain that quality. Robert Boyle was a Natural philosopher, chemist physicist inventor and early Gentleman scientist, noted for his work in Physics and Chemistry Niter (US or nitre (UK is the mineral form of Potassium nitrate, KNO3 also known as saltpeter (US or saltpetre (UK

”

Limit to the 'degree of cold'

The question whether there is a limit to the degree of cold possible, and, if so, where the zero must be placed, was first attacked by the French physicist Guillaume Amontons in 1702, in connection with his improvements in the air thermometer and in his instrument temperatures were indicated by the height at which a column of mercury was sustained by a certain mass of air, the volume or "spring" which of course varied with the heat to which it was exposed. Amontons therefore argued that the zero of his thermometer would be that temperature at which the spring of the air in it was reduced to nothing. On the scale he used, the boiling-point of water was marked at +73 and the melting-point of ice at 51, so that the zero of his scale was equivalent to about −240 on the Celsius scale.

This remarkably close approximation to the modern value of −273. 15 °C for the zero of the air-thermometer was further improved on by Johann Heinrich Lambert, who gave the value −270 °C and observed that this temperature might be regarded as absolute cold. Johann Heinrich Lambert ( August 26, 1728 &ndash September 25 1777) was a Swiss Mathematician, Physicist and ^[3]

Values of this order for the absolute zero were not, however, universally accepted about this period. Pierre-Simon Laplace and Antoine Lavoisier, in their 1780 treatise on heat, arrived at values ranging from 1,500 to 3,000 below the freezing-point of water, and thought that in any case it must be at least 600 below. John Dalton in his Chemical Philosophy gave ten calculations of this value, and finally adopted −3,000 °C as the natural zero of temperature. John Dalton FRS (6 September 1766 &ndash 27 July 1844 was an English Chemist, Meteorologist and Physicist.

Since temperature is the measure of the average kinetic energy in a system, it is possible that some molecules reach a state of no kinetic energy while others have more kinetic energy than the measured energy. Since the difference between the lower and higher measurements give us the temperature we read, it is quite possible for some molecules to reach zero Kelvin.

Lord Kelvin's work

After J.P. Joule had determined the mechanical equivalent of heat, Lord Kelvin approached the question from an entirely different point of view, and in 1848 devised a scale of absolute temperature which was independent of the properties of any particular substance and was based solely on the fundamental laws of thermodynamics. James Prescott Joule FRS (ˈdʒuːl December 24, 1818 &ndash October 11, 1889) was an English Physicist William Thomson 1st Baron Kelvin (or Lord Kelvin) OM, GCVO, PC, PRS, FRSE, (26 June 1824 &ndash 17 December 1907 The laws of thermodynamics, in principle describe the specifics for the transport of Heat and work in Thermodynamic processes. It followed from the principles on which this scale was constructed that its zero was placed at −273. 150 °C, at almost precisely the same point as the zero of the air-thermometer. ^[4]

Additional Information

It can be shown from the laws of thermodynamics that absolute zero can never be achieved artificially, though it is possible to reach temperatures close to it through the use of cryocoolers. In Physics, thermodynamics (from the Greek θερμη therme meaning " Heat " and δυναμις dynamis meaning " Cryocoolers are the devices used to reach cryogenic temperatures This is the same principle that ensures no machine can be 100% efficient. A machine is any device that uses Energy to perform some activity

At very low temperatures in the vicinity of absolute zero, matter exhibits many unusual properties including superconductivity, superfluidity, and Bose-Einstein condensation. Superconductivity is a phenomenon occurring in certain Materials generally at very low Temperatures characterized by exactly zero electrical resistance Superfluidity is a phase of matter or description of Heat capacity in which unusual effects are observed when Liquids, typically of Helium-4 A Bose–Einstein condensate (BEC is a State of matter of Bosons confined in an external Potential and cooled to Temperatures very near to In order to study such phenomena, scientists have worked to obtain ever lower temperatures. A phenomenon (from Greek φαινόμενoν, pl φαινόμενα - phenomena) is any observable occurrence A scientist, in the broadest sense refers to any person that engages in a systematic activity to acquire Knowledge or an individual that engages in such practices

• In 1994, researchers at NIST achieved a then-record cold temperature of 700 nK (billionths of a kelvin). The kelvin (symbol K) is a unit increment of Temperature and is one of the seven SI base units The Kelvin scale is a thermodynamic

• In November 2000, nuclear spin temperatures below 100 pK were reported for an experiment at the Helsinki University of Technology's Low Temperature Lab. Helsinki University of Technology ( TKK) ( Finnish: Teknillinen korkeakoulu; Swedish: Tekniska högskolan) is the premier technical However, this was the temperature of one particular degree of freedom—a quantum property called nuclear spin—not the overall average thermodynamic temperature for all possible degrees of freedom. ^[5][6]

• In February 2003, the Boomerang Nebula, was found to be −272. The Boomerang Nebula (also called the Bow Tie Nebula) is a Protoplanetary nebula located 5000 light-years away from Earth in the Centaurus constellation 15 °C; 1 K, the coldest place known outside a laboratory. The nebula is 5,000 light-years from Earth and is in the constellation Centaurus. A nebula (from Latin: "mist" pl nebulae or nebulæ, with ligature or nebulas) is an Interstellar cloud of EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001 Centaurus ( Centaur) is a bright constellation of the southern hemisphere. ^[7]

Thermodynamics near absolute zero

At temperatures near 0 K, nearly all molecular motion ceases and ΔS = 0 for any adiabatic process. This article covers adiabatic processes in Thermodynamics. For adiabatic processes in Quantum mechanics, see Adiabatic process (quantum mechanics Pure substances can (ideally) form perfect crystals as T0. In Materials science, a crystal is a Solid in which the constituent Atoms Molecules or Ions are packed in a regularly ordered repeating Max Planck's strong form of the third law of thermodynamics states the entropy of a perfect crystal vanishes at absolute zero. The third law of Thermodynamics is a statistical law of nature regarding Entropy and the impossibility of reaching Absolute zero of Temperature In Thermodynamics (a branch of Physics) entropy, symbolized by S, is a measure of the unavailability of a system ’s Energy However, this cannot be true if the lowest energy state is degenerate, or more than one microstate. This article refers to physical states having the same energy In Statistical mechanics, a microstate describes a specific detailed microscopic configuration of a system that the system visits in the course of its thermal fluctuations The original Nernst heat theorem makes the weaker and less controversial claim that the entropy change for any isothermal process approaches zero as T0

The implication is that the entropy of a perfect crystal simply approaches a constant value. Walther Hermann Nernst ( June 25, 1864 &ndash November 18, 1941) was a German Physicist who is known for his theories

The Nernst postulate identifies the isotherm T = 0 as coincident with the adiabat S = 0, although other isotherms and adiabats are distinct. The third law of Thermodynamics is a statistical law of nature regarding Entropy and the impossibility of reaching Absolute zero of Temperature As no two adiabats intersect, no other adiabat can intersect the T = 0 isotherm. In Euclidean geometry, the Intersection of a line and a line can be the Empty set, a point, or a line Consequently no adiabatic process initiated at nonzero temperature can lead to zero temperature. (≈ Callen, pp. 189-190)

An even stronger assertion is that It is impossible by any procedure to reduce the temperature of a system to zero in a finite number of operations. (≈ Guggenheim, p. 157)

A perfect crystal is one in which the internal lattice structure extends uninterrupted in all directions. In Mathematics, especially in Geometry and Group theory, a lattice in R n is a Discrete subgroup of The perfect order can be represented by translational symmetry along three (not usually orthogonal) axes. Symmetry generally conveys two primary meanings The first is an imprecise sense of harmonious or aesthetically-pleasing proportionality and balance such that it reflects beauty or In Mathematics, two Vectors are orthogonal if they are Perpendicular, i In Mathematics, the Cartesian coordinate system (also called rectangular coordinate system) is used to determine each point uniquely in a plane Every lattice element of the structure is in its proper place, whether it is a single atom or a molecular grouping. For substances which have two (or more) stable crystalline forms, such as diamond and graphite for carbon, there is a kind of "chemical degeneracy". A chemical substance is a Material with a definite chemical composition. In Mineralogy, diamond is the allotrope of carbon where the carbon atoms are arranged in The Mineral graphite, as with Diamond and Fullerene, is one of the Allotropes of carbon. Carbon (kɑɹbən is a Chemical element with the symbol C and its Atomic number is 6 The question remains whether both can have zero entropy at T = 0 even though each is perfectly ordered.

Perfect crystals never occur in practice; imperfections, and even entire amorphous materials, simply get "frozen in" at low temperatures, so transitions to more stable states do not occur.

Using the Debye model, the specific heat and entropy of a pure crystal are proportional to T ³, while the enthalpy and chemical potential are proportional to T ⁴. Peter Joseph William Debye ( March 24 1884 &ndash November 2 1966) was a Dutch physicist and physical chemist Specific heat capacity, also known simply as specific heat, is the measure of the heat energy required to increase the Temperature of a unit quantity In Thermodynamics and molecular chemistry, the enthalpy (denoted as H, h, or rarely as χ) is a quotient or description of In Thermodynamics and Chemistry, chemical potential, symbolized by μ, is a term introduced by the American engineer chemist and mathematical (Guggenheim, p. 111) These quantities drop toward their T = 0 limiting values and approach with zero slopes. For the specific heats at least, the limiting value itself is definitely zero, as borne out by experiments to below 10 K. Even the less detailed Einstein model shows this curious drop in specific heats. Albert Einstein ( German: ˈalbɐt ˈaɪ̯nʃtaɪ̯n; English: ˈælbɝt ˈaɪnstaɪn (14 March 1879 – 18 April 1955 was a German -born theoretical In fact, all specific heats vanish at absolute zero, not just those of crystals. Likewise for the coefficient of thermal expansion. Thermal Expansion is the tendency of matter to change in Volume in response to a change in temperature Maxwell's relations show that various other quantities also vanish. Maxwell's relations are a set of equations in Thermodynamics which are derivable from the definitions of the Thermodynamic potentials. These phenomena were unanticipated. A phenomenon (from Greek φαινόμενoν, pl φαινόμενα - phenomena) is any observable occurrence

Since the relation between changes in the Gibbs energy, the enthalpy and the entropy is

thus, as T decreases, ΔG and ΔH approach each other (so long as ΔS is bounded). In Thermodynamics, the Gibbs free energy ( IUPAC recommended name Gibbs energy or Gibbs function) is a Thermodynamic potential which Experimentally, it is found that all spontaneous processes (including chemical reactions) result in a decrease in G as they proceed toward equilbrium. In scientific inquiry an experiment ( Latin: Ex- periri, "to try out" is a method of investigating particular types of research questions or A chemical reaction is a process that always results in the interconversion of Chemical substances The substance or substances initially involved in a chemical reaction are called In Thermodynamics, a thermodynamic system is said to be in thermodynamic equilibrium when it is in thermal equilibrium Mechanical equilibrium, and If ΔS and/or T are small, the condition ΔG < 0 may imply that ΔH < 0, which would indicate an exothermic reaction that releases heat. In Thermodynamics, the word exothermic "outside heating" describes a process or reaction that releases Energy usually in the form of Heat, but However, this is not required; endothermic reactions can proceed spontaneously if the TΔS term is large enough. In Thermodynamics, the word endothermic "within-heating" describes a process or reaction that absorbs Energy in the form of Heat.

More than that, the slopes of the temperature derivatives of ΔG and ΔH converge and are equal to zero at T = 0, which ensures that ΔG and ΔH are nearly the same over a considerable range of temperatures, justifying the approximate empirical Principle of Thomsen and Berthelot, which says that the equilibrium state to which a system proceeds is the one which evolves the greatest amount of heat, i. In Philosophy, empiricism is a theory of Knowledge which asserts that knowledge arises from Experience. e. , an actual process is the most exothermic one. (Callen, pp. 186-187)

Relation with Bose Einstein Condensates

A Bose-Einstein Condensate is a substance that behaves very unusually but only at extremely low temperatures, maybe a few billionths above absolute zero. A Bose–Einstein condensate (BEC is a State of matter of Bosons confined in an external Potential and cooled to Temperatures very near to It is at this point the laws of thermodynamics become very important. The laws of thermodynamics, in principle describe the specifics for the transport of Heat and work in Thermodynamic processes.

Absolute temperature scales

Absolute or thermodynamic temperature is conventionally measured in kelvins (Celsius-scaled increments), and increasingly rarely in the Rankine scale (Fahrenheit-scaled increments). Thermodynamic temperature is the absolute measure of Temperature and is one of the principal parameters of Thermodynamics. The kelvin (symbol K) is a unit increment of Temperature and is one of the seven SI base units The Kelvin scale is a thermodynamic The Celsius Temperature scale was previously known as the centigrade scale. Rankine is a thermodynamic (absolute temperature scale named after the Scottish Engineer and Physicist William John Macquorn Rankine Fahrenheit is a temperature scale named after Daniel Gabriel Fahrenheit (1686–1736 a German Physicist who proposed it in 1724 Absolute temperature is uniquely determined up to a multiplicative constant which specifies the size of the "degree", so the ratios of two absolute temperatures, T₂/T₁, are the same in all scales. The most transparent definition comes from the classical Maxwell-Boltzmann distribution over energies, or from the quantum analogs: Fermi-Dirac statistics (particles of half-integer spin) and Bose-Einstein statistics (particles of integer spin), all of which give the relative numbers of particles as (decreasing) exponential functions of energy over kT. The Maxwell–Boltzmann distribution is a Probability distribution with applications in Physics and Chemistry. In Statistical mechanics, Fermi-Dirac statistics is a particular case of Particle statistics developed by Enrico Fermi and Paul Dirac that In Quantum mechanics, spin is a fundamental property of atomic nuclei, Hadrons and Elementary particles For particles with non-zero spin In Statistical mechanics, Bose - Einstein statistics (or more colloquially B-E statistics determines the statistical distribution of The exponential function is a function in Mathematics. The application of this function to a value x is written as exp( x) On a macroscopic level, a definition can be given in terms of the efficiencies of "reversible" heat engines operating between hotter and colder thermal reservoirs. Macroscopic is commonly used to describe physical objects that are measurable and observable by the Naked eye. A heat engine is a physical or theoretical device that converts Thermal energy to mechanical output

Negative temperatures

Main article: Negative temperature

Certain semi-isolated systems, such as a system of non-interacting spins in a magnetic field, can achieve negative temperatures; however, they are not actually colder than absolute zero. In Physics, certain systems can achieve negative temperatures; that is their Thermodynamic temperature can be of a negative quantity They can be however thought of as "hotter than T = ∞", as energy will flow from a negative temperature system to any other system with positive temperature upon contact.

See also

Notes

References

• Herbert B. Callen (1960). "Chapter 10", Thermodynamics. New York: John Wiley & Sons, Inc. OCLC 535083. The OCLC Online Computer Library Center is according to its website a "nonprofit membership computer library service and research organization dedicated to the public purpose  
• Herbert B. Callen (1985). Thermodynamics and an Introduction to Thermostatistics, Second Edition, New York: John Wiley & Sons, Inc. ISBN 0-471-86256-8.  
• E. A. Guggenheim (1967). Thermodynamics: An Advanced Treatment for Chemists and Physicists, Fifth Edition, Amsterdam: North Holland Publishing. OCLC 324553. The OCLC Online Computer Library Center is according to its website a "nonprofit membership computer library service and research organization dedicated to the public purpose  
• George Stanley Rushbrooke (1949). Introduction to Statistical Mechanics. Oxford: Clarendon Press. OCLC 531928. The OCLC Online Computer Library Center is according to its website a "nonprofit membership computer library service and research organization dedicated to the public purpose  

External links

• Lansing state journal

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