Thermodynamic temperature is the absolute measure of temperature and is one of the principal parameters of thermodynamics. Thermodynamic temperature is an “absolute” scale because it is the measure of the fundamental property underlying temperature: its null or zero point, absolute zero, is the lowest possible temperature where nothing could be colder and no heat energy remains in a substance.

Thermodynamics (from the Greek thermos meaning heat and dynamics meaning power) is a branch of physics that studies the effects of changes in temperature, pressure, and volume on physical systems at the macroscopic scale by analyzing the collective motion of their particles using statistics. ... Absolute zero is the lowest possible temperature where nothing could be colder and no heat energy remains in a substance. ... In physics, heat, symbolized by Q, is defined as energy in transit. ...

The Z machine at Sandia National Laboratories in Albuquerque, New Mexico, U.S.A., set a record man-made temperature for a bulk quantity of matter of greater than two billion kelvin. Courtesy, Sandia National Laboratories.

Image File history File links Z-machine480. ... Image File history File links Z-machine480. ... Zork universe Zork games Zork Anthology Zork trilogy Zork I   Zork II   Zork III Beyond Zork   Zork Zero   Planetfall Enchanter trilogy Enchanter   Sorcerer   Spellbreaker Other games Wishbringer   Return to Zork Zork: Nemesis   Zork Grand Inquisitor Zork: The Undiscovered Underground Topics in Zork Encyclopedia Frobozzica Characters   Kings   Creatures Timeline   Magic   Calendar... It has been suggested that Sandia Base be merged into this article or section. ...

Overview

Fig. 1 The translational motion of particles gives a substance its temperature.  Here, the size of helium atoms relative to their spacing is shown to scale under 136 atmospheres of pressure. These room-temperature atoms have a certain, average speed (slowed down here two trillion fold). At any given instant however, a particular helium atom may be moving much faster than average while another may be nearly motionless.

Temperature arises from the random submicroscopic vibrations of the particle constituents of matter. These motions comprise the kinetic energy in a substance. More specifically, the thermodynamic temperature of any bulk quantity of matter is the measure of the average kinetic energy of a certain kind of vibrational motion of its constituent particles called translational motions. Translational motions are ordinary, whole-body movements in 3D space whereby particles move about and exchange energy in collisions. Fig. 1 at right shows translational motion in gases; Fig. 4 below shows translational motion in solids. Thermodynamic temperature’s null point, absolute zero, is the temperature at which the particle constituents of matter have minimal motion (retaining only quantum mechanical motion) and zero heat energy remains in a substance.^[1] Image File history File links Translational_motion. ... Image File history File links Translational_motion. ... General Name, Symbol, Number helium, He, 2 Chemical series noble gases Group, Period, Block 18, 1, s Appearance colorless Atomic mass 4. ... Standard atmosphere (symbol: atm) is a unit of pressure. ... This article or section does not cite its references or sources. ... Kinetic energy is the energy by virtue of the motion of an object. ... The space we live in is three-dimensional space. ... Fig. ...

Throughout the scientific world where measurements are made in SI units, thermodynamic temperature is measured in kelvins (symbol: K). Many engineering fields in the U.S. measure thermodynamic temperature using the Rankine scale. Cover of brochure The International System of Units. ... The Kelvin scale is a thermodynamic (absolute) temperature scale where absolute zero—the lowest possible temperature where nothing could be colder and no heat energy remains in a substance—is defined as zero kelvin (0 K). ... Motto: (Out Of Many, One) (traditional) In God We Trust (1956 to date) Anthem: The Star-Spangled Banner Capital Washington D.C. Largest city New York City None at federal level (English de facto) Government Federal constitutional republic  - President George Walker Bush (R)  - Vice President Dick Cheney (R) Independence from... See Rankine cycle for the idealized thermodynamic cycle for a steam engine. ...

By international agreement, the unit “kelvin” and its scale are defined by two points: absolute zero, and the triple point of specially prepared (VSMOW) water. Absolute zero is defined as being precisely 0 K and −273.15 °C. The triple point of water is defined as being precisely 273.16 K and 0.01 °C. This definition does three things: 1) it fixes the magnitude of the kelvin unit as being precisely 1 part in 273.16 parts the difference between absolute zero and the triple point of water; 2) it establishes that one kelvin has precisely the same magnitude as a one-degree increment on the Celsius scale; and 3) it establishes the difference between the two scales’ null points as being precisely 273.15 kelvins (0 K = −273.15 °C and 273.16 K = 0.01 °C). Conversion from kelvins to degrees Rankine (°R) is accomplished as follows: T_K × 1.8 = T_°R. In physics, the triple point of a substance is the temperature and pressure at which three phases (gas, liquid, and solid) of that substance may coexist in thermodynamic equilibrium. ... VSMOW, or Vienna Standard Mean Ocean Water, is an isotopic water standard defined in 1968 by the International Atomic Energy Agency. ... Celsius relates to the Celsius or centrigrade temperature scale. ... Celsius relates to the Celsius or centrigrade temperature scale. ...

Table of thermodynamic temperatures

The full range of the thermodynamic temperature scale and some notable points along it are shown in the table below.

^A For Vienna Standard Mean Ocean Water at one standard atmosphere (101.325 kPa) when calibrated strictly per the two-point definition of thermodynamic temperature.
^B The 2500 K value is approximate. The 273.15 K difference between K and °C is rounded to 300 K to avoid false precision in the Celsius value.
^C For a true blackbody (which tungsten filaments are not). Tungsten filaments’ emissivity is greater at shorter wavelengths which makes them appear whiter.
^D Effective photosphere temperature. The 273.15 K difference between K and °C is rounded to 273 K to avoid false precision in the Celsius value.
^E The 273.15 K difference between K and °C is ignored to avoid false precision in the Celsius value.
^F For a true blackbody (which the plasma was not). The Z machine’s dominant emission originated from 40 MK electrons (soft x–ray emissions) within the plasma. The metre, or meter (U.S.), is a measure of length. ... ... The boiling point of a substance is the temperature at which it can change its state from a liquid to a gas throughout the bulk of the liquid at a given pressure. ... An incandescent light bulb and its glowing filament. ... ... The Sun is the star at the center of the Solar System. ... Color is an important part of the visual arts. ... Lightning is an atmospheric discharge of electricity, usually, but not always, during a rain storm. ... The solar corona as seen in deep ultraviolet light at 17. ... The Sun is the star at the center of the Solar System. ... In the NATO phonetic alphabet, X-ray represents the letter X. An X-ray picture (radiograph) taken by Röntgen An X-ray is a form of electromagnetic radiation with a wavelength approximately in the range of 5 pm to 10 nanometers (corresponding to frequencies in the range 30 PHz... The mushroom cloud of the atomic bombing of Nagasaki, Japan, 1945, rose some 18 kilometers (11 mi) above the hypocenter. ... This article is about electromagnetic radiation. ... Zork universe Zork games Zork Anthology Zork trilogy Zork I   Zork II   Zork III Beyond Zork   Zork Zero   Planetfall Enchanter trilogy Enchanter   Sorcerer   Spellbreaker Other games Wishbringer   Return to Zork Zork: Nemesis   Zork Grand Inquisitor Zork: The Undiscovered Underground Topics in Zork Encyclopedia Frobozzica Characters   Kings   Creatures Timeline   Magic   Calendar... In astrophysics, silicon burning is a nuclear fusion reaction which occurs in massive stars. ... A neutron star is one of the few possible endpoints of stellar evolution. ... The Relativistic Heavy Ion Collider at Brookhaven National Laboratory. ... In physics, the Planck time (tP), is the natural unit of time. ... According to the Big Bang, the universe emerged from an extremely dense and hot state (bottom). ... The Planck temperature, named after German physicist Max Planck, is the natural unit of temperature, denoted by TP. The Planck units, in general, represent limits of quantum mechanics. ... The Planck length, denoted by , is the unit of length in the system of units known as Planck units. ... VSMOW, or Vienna Standard Mean Ocean Water, is an isotopic water standard defined in 1968 by the International Atomic Energy Agency. ... This article or section does not cite its references or sources. ...

The relationship of temperature, motions, conduction, and heat energy

The nature of kinetic energy, translational motion, and temperature

At its simplest, “temperature” is the measure of the kinetic energy resulting from the motions of matter’s particle constituents (molecules, atoms, and subatomic particles). The full variety of these kinetic motions contribute to the total heat energy in a substance. The relationship of kinetic energy, mass, and velocity is given by the formula E_k = ¹/₂m • v ².^[11] Accordingly, those particles with one unit of mass moving at one unit of velocity have the same kinetic energy—and the same temperature—as those with twice the mass but only 70.7% of the velocity. Kinetic energy is the energy by virtue of the motion of an object. ... This article or section does not cite its references or sources. ... In chemistry, a molecule is an aggregate of two or more atoms in a definite arrangement held together by chemical bonds [1] [2] [3] [4] [5]. Chemical substances are not infinitely divisible into smaller fractions of the same substance: a molecule is generally considered the smallest particle of a pure... Atomic redirects here. ... A subatomic particle is a particle smaller than an atom: it may be elementary or composite. ... In physics, heat, symbolized by Q, is defined as energy in transit. ...

Fig. 2 The translational motions of helium atoms occurs across a range of speeds. Compare the shape of this curve to that of a Planck curve in Fig. 5 below.

The thermodynamic temperature of any bulk quantity of a substance (a statistically significant quantity of particles) is directly proportional to the average—or “mean”—kinetic energy of a specific kind of particle motion known as translational motion. These simple movements in the three x, y, and z–axis dimensions of space means the particles move in the three spatial degrees of freedom.^[12] Translational motion is but one form of heat energy and is what gives gases not only their temperature, but also their pressure and the vast majority of their volume. This relationship between the temperature, pressure, and volume of gases is established by the ideal gas law’s formula pV = nRT. Image File history File linksMetadata Download high-resolution version (600x700, 150 KB) This graph shows the Maxwell distribution of helium atom speeds at 5500 kelvin. ... Image File history File linksMetadata Download high-resolution version (600x700, 150 KB) This graph shows the Maxwell distribution of helium atom speeds at 5500 kelvin. ... Degrees of freedom is a general term used in explaining dependence on parameters, and implying the possibility of counting the number of those parameters. ... Isotherms of an ideal gas The ideal gas law is the equation of state of a hypothetical ideal gas. ...

The relationship between thermodynamic temperature and the kinetic energy of the translational motion of a given particle is given by the Boltzmann constant (symbol: K_b). The Boltzmann constant also relates the thermodynamic temperature of a bulk quantity of a substance to the mean energy of the translational motions of its constituent particles as follows: Ludwig Boltzmann The Boltzmann constant (k or kB) is the physical constant relating temperature to energy. ...

E_mean = 3/2K_bT

where…

E_mean = joules (symbol: J)

K_b = 1.380 6505(24) × 10⁻²³ J/K

T = thermodynamic temperature in kelvins

While the Boltzmann constant is useful for finding the mean kinetic energy of particles, it’s important to note that even when a substance is isolated and in thermodynamic equilibrium (all parts are at a uniform temperature and no heat is going into or out of it), the translational motions of individual atoms and molecules occurs across a wide range of speeds (see animation in Fig. 1 above). At any one instant, the proportion of particles moving at a given speed within this range is determined by probability as described by the Maxwell–Boltzmann distribution. The graph shown here in Fig. 2  shows the speed distribution of 5500 K helium atoms. They have a most probable speed of 4.780 km/s (0.2092 s/km). However, a certain proportion of atoms at any given instant are moving faster while others are moving relatively slowly; some are momentarily at a virtual standstill (off the x–axis to the right). This graph uses inverse speed for its x–axis so the shape of the curve can easily be compared to the curves in Fig. 5 below. In both graphs, zero on the x–axis represents infinite temperature. Additionally, the x and y–axis on both graphs are scaled proportionally. A joule is the work done or energy required to exert a force of one newton for a distance of one metre, so the same quantity may be referred to as a newton metre or newton-metre with the symbol N·m. ... In thermodynamics, a thermodynamic system is said to be in thermodynamic equilibrium when it is in thermal equilibrium, mechanical equilibrium, and chemical equilibrium. ... The introduction to this article provides insufficient context for those unfamiliar with the subject matter. ...

The high speeds of translational motion

Although very specialized laboratory equipment is required to directly detect translational motions, the resultant collisions by atoms or molecules with small particles suspended in a fluid produces Brownian motion that can be seen with an ordinary microscope. The translational motions of elementary particles are very fast^[13] and temperatures close to absolute zero are required to directly observe them. For instance, when scientists at the NIST achieved a record-setting cold temperature of 700 nK (billionths of a kelvin) in 1994, they used optical lattice laser equipment to adiabatically cool cesium atoms. They then turned off the entrapment lasers and directly measured atom velocities of 7 mm per second to in order to calculate their temperature.^[14]  Formulas for calculating the velocity and speed of translational motion are given in the following footnote.^[15] A fluid is defined as a substance that continually deforms (flows) under an applied shear stress regardless of the magnitude of the applied stress. ... Three different views of Brownian motion, with 32 steps, 256 steps, and 2048 steps denoted by progressively lighter colors. ... Absolute zero is the lowest possible temperature where nothing could be colder and no heat energy remains in a substance. ... NIST logo The National Institute of Standards and Technology (NIST, formerly known as The National Bureau of Standards) is a non-regulatory agency of the United States Department of Commerce’s Technology Administration. ... An optical lattice is formed by using counterpropagating laser beams to create a periodic (in space) intensity pattern. ... In thermodynamics, an adiabatic process is a process in which no heat is transferred to or from working fluid. ... General Name, Symbol, Number Caesium, Cs, 55 Series Alkali metals Group, Period, Block 1(IA), 6, s Density, Hardness 1879 kg/m3, 0. ...

The internal motions of molecules and specific heat

Fig. 3 Molecules have internal structure because they are composed of atoms that have different ways of moving within molecules. The heat energy stored in these internal degrees of freedom does not contribute to the temperature of a substance.

There are other forms of heat energy besides the kinetic energy of translational motion. As can be seen in the animation at right, molecules are complex objects; they are a population of atoms and thermal agitation can strain its internal chemical bonds in three different ways: via rotation, bond length, and bond angle movements. These are all types of internal degrees of freedom. This makes molecules distinct from monatomic substances (consisting of individual atoms) like the noble gases helium and argon, which have only the three translational degrees of freedom.^[12] Heat energy is stored in molecules’ internal degrees of freedom, which gives them an internal temperature.  Even though these motions are called “internal,” the external portions of molecules still move—rather like the jiggling of a stationary water balloon. This permits the two-way exchange of kinetic energy between internal motions and translational motions with each molecular collision. Accordingly, as heat is removed from molecules, both their internal and translational kinetic energies (temperatures) simultaneously diminish in equal proportions. Image File history File links Thermally_Agitated_Molecule. ... Image File history File links Thermally_Agitated_Molecule. ... In chemistry, a molecule is an aggregate of two or more atoms in a definite arrangement held together by chemical bonds [1] [2] [3] [4] [5]. Chemical substances are not infinitely divisible into smaller fractions of the same substance: a molecule is generally considered the smallest particle of a pure... A chemical bond is the physical phenomenon (or phenomena) responsible for the attractive interactions between atoms that confers stability to di- and polyatomic chemical compounds. ... In physics and chemistry, monatomic is a combination of the words mono and atomic, and means single atom. ... For the musical band, see Noble Gas (band) The noble gases are the chemical elements in group 18 (old-style Group 0) of the periodic table. ... General Name, Symbol, Number helium, He, 2 Chemical series noble gases Group, Period, Block 18, 1, s Appearance colorless Atomic mass 4. ... General Name, Symbol, Number argon, Ar, 18 Chemical series noble gases Group, Period, Block 18, 3, p Appearance colorless Atomic mass 39. ... A water bomb, or water balloon, is a simple small latex rubber balloon filled with tap water. ...

The heat energy stored internally in molecules does not contribute to the temperature of a substance (nor to the pressure or volume of gases). This is because any kinetic energy that is, at a given instant, bound in internal motions is not at that same instant contributing to the molecules’ translational motions. Since the internal temperature of the molecules in any bulk quantity of a substance in equilibrium is, on average, equal to the temperature of their translational motions, the distinction is usually of interest only in the detailed study of certain thermodynamic phenomenon such as the sublimation of solids and the diffusion of hot gases in a partial vacuum. Sublimation of an element or substance is a conversion between the solid and the gaseous phases of matter, with no intermediate liquid stage. ... This article or section does not cite its references or sources. ...

Different molecules absorb different amounts of heat energy for each incremental increase in temperature. Water for instance, can absorb a large amount of heat energy per mole (specific number of particles) with only a modest temperature change. This property is known as a substance’s specific heat capacity. High specific heat capacity arises, in part, because a substance’s molecules possess more internal degrees of freedom than others. For instance, nitrogen, which is a diatomic molecule, has five active degrees of freedom: the three comprising translational motion plus two rotational degrees of freedom internally. Not surprisingly, nitrogen has five-thirds the molar heat capacity as do the monatomic gases.^[16] Larger, more complex molecules can have dozens of internal degrees of freedom. The mole (symbol: mol) is the SI base unit that measures an amount of substance. ... Specific heat capacity, also known simply as specific heat (Symbol: C or c) is the measure of the heat energy required to raise the temperature of a specific quantity of a substance (thus, the name “specific” heat) by certain amount, usually one kelvin. ... General Name, Symbol, Number nitrogen, N, 7 Chemical series nonmetals Group, Period, Block 15, 2, p Appearance colorless Atomic mass 14. ... A computer rendering of the Nitrogen Molecule, which is a diatomic molecule. ...

The diffusion of heat energy: Entropy, phonons, and mobile conduction electrons

Fig. 4 The temperature-induced translational motion of particles in solids takes the form of phonons. Shown here are phonons with identical amplitudes but with wavelengths ranging from 2 to 12 molecules.

Heat conduction is the diffusion of heat energy from hot parts of a system to cold. A “system” can be either a single bulk entity or a plurality of discrete bulk entities. The term “bulk” in this context means a statistically significant quantity of particles (which can be a microscopic amount). Anytime heat energy diffuses within an isolated system, temperature differences within the system decrease (entropy increases). Image File history File links 1D_normal_modes_(280_kB). ... Image File history File links 1D_normal_modes_(280_kB). ... Normals modes of vibration progression through a crystal. ... Amplitude is a nonnegative scalar measure of a waves magnitude of oscillation, that is, magnitude of the maximum disturbance in the medium during one wave cycle. ... The wavelength is the distance between repeating units of a wave pattern. ... Heat flow along greatly perfectly insulated wire Heat conduction is the transmission of heat across matter. ... Ice melting - classic example of entropy increasing[1] described in 1862 by Rudolf Clausius as an increase in the disgregation of the molecules of the body of ice. ...

One particular heat conduction mechanism occurs when translational motion—the particle motion underlying temperature—transfers momentum from particle to particle in collisions. In gases, these translational motions are of the nature shown above in Fig. 1. As can be seen in that animation, not only does momentum (heat) diffuse throughout the volume of the gas through serial collisions, but entire molecules or atoms can advance forward into new territory, bringing their kinetic energy with them. Consequently, heat diffuses through gases rather easily; especially for light atoms or molecules. Convection speeds this process even more. In classical mechanics, momentum (pl. ... Convection is the internal movement of currents within fluids (i. ...

Translational motion in solids however, takes the form of phonons (see Fig. 4 at right). Phonons are constrained, quantized wave packets traveling at the speed of sound for a given substance. The manner in which phonons interact within a solid determines a variety of its properties, including its thermal conductivity. In electrically insulating solids, phonon-based heat conduction is usually inefficient^[17] and such solids are considered to be thermal insulators (such as glass, plastic, rubber, ceramic, and rock). This is because in solids, atoms and molecules are locked into place relative to their neighbors and are not free to roam. Normals modes of vibration progression through a crystal. ...

Metals however, are not restricted to only phonon-based heat conduction. Heat energy conducts through metals extraordinarily quickly because instead of direct molecule-to-molecule collisions, the vast majority of heat energy is mediated via very light, mobile conduction electrons. This is why there is a near-perfect correlation between metals’ thermal conductivity and their electrical conductivity.^[18] Conduction electrons imbue metals with their extraordinary conductivity because they are delocalized, i.e. not tied to a specific atom, and behave rather like a sort of “quantum gas” due to the effects of zero-point energy (for more on ZPE, see Note 1 below). Furthermore, electrons are relatively light with a rest mass only ¹/₁₈₃₆th that of a proton. This is about the same ratio as a .22 Short bullet (29 grains or 1.88 g) compared to the rifle that shoots it. As Sir Isaac Newton once wrote with his third law of motion: Hot metal work from a blacksmith In chemistry, a metal (Greek: Metallon) is an element that readily forms positive ions (cations) and has metallic bonds. ... The electron is a fundamental subatomic particle that carries an electric charge. ... In physics, thermal conductivity, k, is the intensive property of a material that indicates its ability to conduct heat. ... Electrical conductivity is a measure of a materials ability to conduct an electric current. ... In chemistry, delocalized electrons are electrons in a molecule that do not belong to a single atom or a covalent bond. ... In physics, the zero-point energy is the lowest possible energy that a quantum mechanical physical system may possess; it is the energy of the ground state of the system. ... Thermodynamic temperature is the absolute measure of temperature and is one of the principal parameters of thermodynamics. ... // For alternative meanings see proton (disambiguation). ... .22 Short is a variety of . ... A grain is a unit of mass equal to 0. ... BIC pen cap, about 1 gram. ... Sir Isaac Newton, (4 January 1643 – 31 March 1727) [ OS: 25 December 1642 – 20 March 1727][1] was an English physicist, mathematician, astronomer, alchemist, and natural philosopher, regarded by many as the greatest figure in the history of science. ... Newtons First and Second laws, in Latin, from the original 1687 edition of the Principia Mathematica. ...

“Law #3: All forces occur in pairs, and these two forces

 are equal in magnitude and opposite in direction.”

However, a bullet accelerates faster than a rifle given an equal force. Since kinetic energy increases as the square of velocity, nearly all the kinetic energy goes into the bullet, not the rifle, even though both experience the same force from the expanding propellant gases. In the same manner—because they are much less massive—heat energy is readily borne by mobile conduction electrons. Too, because they’re delocalized and very fast, kinetic heat energy conducts extremely quickly through metals with abundant conduction electrons.

The diffusion of heat energy: Black-body radiation

Fig. 5 The spectrum of black-body radiation has the form of a Planck curve. A 5500 K black body has a peak emittance wavelength of 527 nm. Compare the shape of this curve to that of a Maxwell distribution in Fig. 2 above.

Thermal radiation is a byproduct of the collisions arising from atoms’ various vibrational and rotational motions. These collisions cause atoms to emit thermal photons (known as black-body radiation). Photons are emitted anytime an electric charge is accelerated (as happens when two atoms’ electron clouds collide). Even individual molecules with internal temperatures greater than absolute zero also emit black-body radiation from their atoms. In any bulk quantity of a substance at equilibrium, black-body photons are emitted across a range of wavelengths in a spectrum that has a bell curve–like shape called a Planck curve (see graph in Fig. 5 at right). The top of a Planck curve—the peak emittance wavelength—is located in particular part of the electromagnetic spectrum depending on the temperature of the black body. Substances at extreme cryogenic temperatures emit at long radio wavelengths whereas extremely hot temperatures produce short gamma rays (see Table of thermodynamic temperatures, above). Black body spectrum as a function of wavelength. ... Black body spectrum as a function of wavelength. ... Thermal radiation is electromagnetic radiation emitted from the surface of an object which is due to the objects temperature. ... The word light is defined here as electromagnetic radiation of any wavelength; thus, X-rays, gamma rays, ultraviolet light, microwaves, radio waves, and visible light are all forms of light. ... As the temperature decreases, the peak of the black body radiation curve moves to lower intensities and longer wavelengths. ... The wavelength is the distance between repeating units of a wave pattern. ... Black body spectrum In physics, Plancks law of black body radiation predicts the spectral intensity of electromagnetic radiation at all wavelengths from a black body at temperature  : where the following table provides the definition and SI units of measure for each symbol: The wavelength is related to the frequency... Wiens displacement law is a law of physics that states that there is an inverse relationship between the wavelength of the peak of the emission of a black body and its temperature. ... Legend: γ = Gamma rays HX = Hard X-rays SX = Soft X-Rays EUV = Extreme ultraviolet NUV = Near ultraviolet Visible light NIR = Near infrared MIR = Moderate infrared FIR = Far infrared Radio waves: EHF = Extremely high frequency (Microwaves) SHF = Super high frequency (Microwaves) UHF = Ultra high frequency VHF = Very high frequency HF = High... Cryogenics is a branch of physics (or engineering) that studies the production of very low temperatures (below –150 °C, –238 °F or 123 K) and the behavior of materials at those temperatures. ... This article is about electromagnetic radiation. ...

Black-body photons diffuse heat energy as they are absorbed by neighboring atoms, transferring momentum in the process. Black-body photons also easily escape from a substance and can be absorbed by the ambient environment; kinetic energy is lost in the process. The intensity of black-body radiation increases as the fourth power of absolute temperature. Thus, a black body at 824 K (just short of glowing dull red) emits 60 times the radiant heat energy as it does at 296 K (room temperature). This is why one can so easily feel the radiant heat from hot objects at a distance. At higher temperatures, such as those found in an incandescent lamp, black-body radiation can be the principal mechanism by which heat energy escapes a system. An incandescent light bulb and its glowing filament. ...

Heat energy and absolute zero

As a substance cools, many forms of heat energy and their related effects simultaneously decrease in magnitude: the translational motions of atoms diminish, both the internal and translational motions of molecules diminish, conduction electrons (if the substance is an electrical conductor) travel somewhat slower,^[19] and black-body radiation’s wavelength increases (the photons’ energy decreases). When no more heat energy remains in a substance and the molecules are as close as possible to complete rest (retaining only quantum mechanical motion), the substance is at absolute zero.^[1] The wavelength is the distance between repeating units of a wave pattern. ...

The heat of phase changes

Fig. 6 Water’s temperature does not change during phase transitions as heat flows into our out of it. The total heat capacity of a mole of water in its liquid phase (the green line) is 7.5507 kJ.

The kinetic energy of motion is just one contributor to the total heat energy in a substance. Another is the potential energy of molecular bonds that can yet form in a substance as it cools (such as during condensing and freezing). This concept may be more easily grasped by visualizing it in the reverse direction: as the heat energy required to break molecular bonds (such as during evaporation and melting). These processes are known as phase transitions. The heat energy required for a phase transition is called latent heat. Anyone who has compared the 100 °C air from a hair dryer to 100 °C steam knows that the steam can cause severe burns whereas the air can not. The burn occurs because a large amount of heat energy is liberated as steam condenses into liquid water on the skin. Even though heat energy is liberated or absorbed during phase transitions, pure chemical elements, compounds, and eutectic alloys exhibit no temperature change whatsoever while they undergo them (see Fig. 6, at right). Image File history File linksMetadata Download high-resolution version (960x620, 216 KB) This graph shows how water’s temperature does not change during phase transitions as heat energy flows in or out of it. ... Image File history File linksMetadata Download high-resolution version (960x620, 216 KB) This graph shows how water’s temperature does not change during phase transitions as heat energy flows in or out of it. ... In the physical sciences, potential energy is energy which is captured within a physical system by virtue of the relative positions or configurations of objects, and which has the potential to be released when the system is allowed to attain a configuration with a lower energy state. ... Water vapor condensing over a cup of hot tea Condensation is the change in matter of a substance to a denser phase, such as a gas (or vapor) to a liquid. ... In physics and chemistry, freezing is the process of cooling a liquid to the temperature (called freezing point) where it turns solid. ... This article or section is in need of attention from an expert on the subject. ... In physics, melting is the process of heating a solid substance to a point (called the melting point) where it turns into a liquid. ... In physics, a phase transition, (or phase change) is the transformation of a thermodynamic system from one phase to another. ... This article or section does not cite its references or sources. ... A 1900 blowdryer (France) Modern-day blowdryer A blowdryer is an electromechanical device designed to blow cool or hot air over wet or damp hair, in order to accelerate the evaporation of water particles and dry the hair. ... In physical chemistry, and in engineering, steam refers to vaporized water. ... The periodic table of the chemical elements (this version outdated on October 13, 2006) A chemical element, often called simply an element, is a substance that cannot be decomposed or transformed into other chemical substances by ordinary chemical processes. ... A chemical compound is a chemical substance consisting of two or more different chemically bonded chemical elements, with a fixed ratio determining the composition. ... A eutectic or eutectic mixture is a mixture of two or more phases at a composition that has the lowest melting point, and where the phases simultaneously crystallise from molten solution at this temperature. ... An alloy is a combination, either in solution or compound, of two or more elements, at least one of which is a metal, and where the resulting material has metallic properties. ...

This phenomenon can be readily understood by examining one particular type of phase transition: the melting of a solid. When a solid melts, crystal lattice chemical bonds break apart; the substance has gone from what is known as a more ordered state to a less ordered state (see Topological order). In Fig. 6, the melting of ice is shown within the lower left box heading from blue to green. At one specific thermodynamic point, the melting point (which is 0 °C across a wide pressure range in the case of water), all the atoms or molecules are—on average—at the maximum energy threshold the lattice bonds can withstand without breaking and jumping to a higher quantum energy state. Quantum transitions are a complete jump from one energy level to another; no intermediate values are possible. Consequently, when a substance is at its melting point, every joule of heat energy that is added to it only causes the bonds of a specific quantity of its atoms or molecules to release from the crystal lattice and become liquid; no kinetic energy is added to translational motion (which is what gives substances their temperature). The effect is rather like popcorn: at a certain temperature, additional heat energy can’t make the kernels any hotter until the transition (popping) is complete. If the process is reversed (as in the freezing of a liquid), heat energy must be removed from a substance. Enargite crystals In mineralogy and crystallography, a crystal structure is a unique arrangement of atoms in a crystal. ... A chemical bond is the physical phenomenon (or phenomena) responsible for the attractive interactions between atoms that confers stability to di- and polyatomic chemical compounds. ... In physics, topological order is a new kind of order (a new kind of organization of particles) in a quantum state that is beyond the Landau symmetry-breaking description. ... The melting point of a crystalline solid is the temperature at which it changes state from solid to liquid. ... Fig. ... A joule is the work done or energy required to exert a force of one newton for a distance of one metre, so the same quantity may be referred to as a newton metre or newton-metre with the symbol N·m. ... Popcorn Popcorn or popping corn is a type of maize which explodes from the kernel and puffs up when it is heated in oil or by dry heat. ...

As stated above, the heat energy required for a phase transition is called latent heat. In the specific cases of melting and freezing, it’s called enthalpy of fusion or heat of fusion. If the molecular bonds in a crystal lattice are strong, the heat of fusion can be relatively great, typically in the range of 6 to 30 kJ per mole for water and most of the metallic elements.^[20] If the substance is one of the monatomic gases, (which have little tendency to form molecular bonds) the heat of fusion is more modest, ranging from 0.021 to 2.3 kJ per mole.^[21] Relatively speaking, phase transitions can be truly energetic events. To completely melt ice at 0 °C into water at 0 °C, one must add roughly 80 times the heat energy as is required to increase the temperature of the same mass of liquid water by one degree Celsius. The metals’ ratios are even greater, typically in the range of 400 to 1200 times.^[22] And the phase transition of boiling is much more energetic than freezing. For instance, the energy required to completely boil or vaporize water (what is known as enthalpy of vaporization) is roughly 540 times that required for a one-degree increase.^[23] Water’s sizable enthalpy of vaporization is why one’s skin can be burned so quickly as steam condenses on it (heading from red to green in Fig. 6 above). In the opposite direction, this is why one’s skin feels cool as liquid water on it evaporates (a process that occurs at a sub-ambient wet-bulb temperature that is dependent on relative humidity). Standard enthalpy change of fusion of period three. ... Boiling is the rapid vaporization of a liquid, which typically occurs when a liquid is heated to a temperature such that its vapor pressure is above that of the surroundings, such as air pressure. ... The standard enthalpy change of vaporization, ΔvHo, also (less correctly) known as the heat of vaporization is the energy required to transform a given quantity of a substance into a gas. ... Wet-bulb temperature ... This does not cite its references or sources. ...

The origin of heat energy

Earth’s proximity to the Sun is why most everything near Earth’s surface is warm with a temperature substantially above absolute zero.^[24] The Sun constantly replenishes heat energy the Earth loses into space. Because matter is everywhere in the natural world, and because of the wide variety of heat diffusion mechanisms (one of which is black-body radiation which occurs at the speed of light), objects on Earth rarely vary too far from the global mean surface and air temperature of 287 to 288 K (14 to 15 °C). The more an object’s or system’s temperature varies from this average, the more rapidly it tends to come back into equilibrium with the ambient environment. Earth (IPA: , often referred to as the Earth, Terra, the World or Planet Earth) is the third planet in the solar system in terms of distance from the Sun, and the fifth largest. ... The Sun is the star at the center of the Solar System. ... Solar irradiance spectrum at top of atmosphere. ...

History of thermodynamic temperature

• 1702–1703: Guillaume Amontons (1663 – 1705) published two papers that credit him with being the first researcher to deduce the existence of a fundamental (thermodynamic) temperature scale featuring an absolute zero. He made the discovery while endeavoring to improve upon the air-thermometers in use at the time. His J-tube thermometers comprised a mercury column that was supported by a fixed mass of air entrapped within the sensing portion of the thermometer. In thermodynamic terms, his thermometers relied upon the volume / temperature relationship of gas under constant pressure. His measurements of the boiling point of water and the melting point of ice showed that regardless of the mass of air trapped inside his thermometers or the weight of mercury the air was supporting, the reduction in air volume at the ice point was always the same ratio. This observation lead him to posit that a sufficient reduction in temperature would reduce the air volume to zero. In fact, his calculations projected that absolute zero was equivalent to −240 degrees on today’s Celsius scale—only 33.15 degrees short of the true value of −273.15 °C.

• 1742: Anders Celsius (1701 – 1744) created a “backwards” version of the modern Celsius temperature scale whereby zero represented the boiling point of water and 100 represented the melting point of ice.

• 1744: Coincident with the death of Anders Celsius, the famous botanist Carolus Linnaeus (1707 – 1778) effectively reversed ^[25] Celsius’s scale upon receipt of his first thermometer featuring a scale where zero represented the melting point of ice and 100 represented water’s boiling point. His custom-made “linnaeus-thermometer,” for use in his greenhouses, was made by Daniel Ekström, Sweden’s leading maker of scientific instruments at the time. For the next 204 years, the scientific and thermometry communities world-wide referred to this scale as the “centigrade scale.” Temperatures on the centigrade scale were often reported simply as “degrees” or, when greater specificity was desired, “degrees centigrade.” The symbol for temperature values on this scale was °C (in several formats over the years). Because the term “centigrade” was also the French-language name for a unit of angular measurement (one-hundredth of a right angle) and had a similar connotation in other languages, the term “centesimal degree” was used when very precise, unambiguous language was required by international standards bodies such as the Bureau international des poids et mesures (BIPM). The 9th CGPM (Conférence générale des poids et mesures) and the CIPM (Comité international des poids et mesures) formally adopted “degree Celsius” (symbol: °C) in 1948.^[26]

• 1777: In his book Pyrometrie (Berlin: Haude & Spener, 1779) completed four months before his death, Johann Heinrich Lambert (1728 – 1777)—sometimes incorrectly referred to as Joseph Lambert—proposed an absolute temperature scale based on the pressure / temperature relationship of a fixed volume of gas. This is distinct from the volume / temperature relationship of gas under constant pressure that Guillaume Amontons discovered 75 years earlier. Lambert stated that absolute zero was the point where a simple straight-line extrapolation reached zero gas pressure and was equal to −270 °C.

• Circa 1787: Notwithstanding the work of Guillaume Amontons 85 years earlier, Jacques Alexandre César Charles (1746 – 1823) is often credited with “discovering”, but not publishing, that the volume of a gas under constant pressure is proportional to its absolute temperature. The formula he created was V₁/T₁ = V₂/T₂.

• 1802: Joseph Louis Gay-Lussac (1778 – 1850) published work (acknowledging the unpublished lab notes of Jacques Charles fifteen years earlier) describing how the volume of gas under constant pressure changes linearly with its absolute (thermodynamic) temperature. This behavior is called Charles’s Law and is one of the gas laws. His are the first known formulas to used the number “273” for the expansion coefficient of gas relative to the melting point of ice (indicating that absolute zero was equivalent to −273 °C).

• 1848: William Thomson, (1824 – 1907) also known as “Lord Kelvin,” wrote in his paper, On an Absolute Thermometric Scale, of the need for a scale whereby “infinite cold” (absolute zero) was the scale’s null point, and which used the degree Celsius for its unit increment. As did Gay-Lussac, Thomson calculated that absolute zero was equivalent to −273 °C on the air–thermometers of the time. This absolute scale is known today as the Kelvin thermodynamic temperature scale. It’s noteworthy that Thomson’s value of “−273” was actually derived from 0.00366, which was the accepted expansion coefficient of gas per degree Celsius relative to the ice point. The inverse of −0.00366 expressed to four significant digits is −273.2 °C which is remarkably close to the true value of −273.15 °C.

• 1859: William John Macquorn Rankine (1820 – 1872) proposed a thermodynamic temperature scale similar to William Thomson’s but which used the degree Fahrenheit for its unit increment. This absolute scale is known today as the Rankine thermodynamic temperature scale.

• Circa 1930s: Gas thermometry experiments carefully calibrated to the melting point of ice and boiling point of water showed that absolute zero was equivalent to −273.15 °C.

• 1948: Resolution 3 of the 9th CGPM (Conférence Générale des Poids et Mesures, also known as the General Conference on Weights and Measures) fixed the triple point of water at precisely 0.01 °C. At this time, the triple point still had no formal definition for its equivalent kelvin value, which the resolution declared “will be fixed at a later date.” The implication is that if the value of absolute zero measured in the 1930s was truly −273.15 °C, then the triple point of water (0.01 °C) was equivalent to 273.16 K. Also, both the CIPM (Comité international des poids et mesures, also known as the International Committee for Weights and Measures) and the CGPM formally adopted the name “Celsius” for the “degree Celsius” and the “Celsius temperature scale.” ^[26]

• 1954: Resolution 3 of the 10th CGPM gave the Kelvin scale its modern definition by choosing the triple point of water as its second defining point and assigned it a temperature of precisely 273.16 kelvin (what was actually written 273.16 “degrees Kelvin” at the time). This defined absolute zero as being precisely zero kelvin and −273.15 °C.

• 1967/1968: Resolution 3 of the 13th CGPM created the unit increment of thermodynamic temperature (as distinct from the scale) and gave it the name “kelvin”, symbol K, instead of “degree Kelvin”, symbol °K. In so doing, feeling it useful to explicitly define the magnitude of this new unit increment, 13th CGPM also decided in Resolution 4 that “The kelvin, unit of thermodynamic temperature, is the fraction 1/273.16 of the thermodynamic temperature of the triple point of water.”

• 2005: The CIPM (Comité International des Poids et Mesures, also known as the International Committee for Weights and Measures) affirmed that for the purposes of delineating the temperature of the triple point of water, the definition of the Kelvin thermodynamic temperature scale would refer to water having an isotopic composition defined as being precisely equal to the nominal specification of VSMOW water.

Guillaume Amontons (August 31, 1663 - October 11, 1705) was a French instrument inventor and physicist. ... Anders Celsius The observatory of Anders Celsius, from a contemporary engraving. ... Carolus Linnaeus, also known after his ennoblement as  , (May 23, 1707 – January 10, 1778), was a Swedish botanist, physician and zoologist[1] who laid the foundations for the modern scheme of nomenclature. ... The International Bureau of Weights and Measures is the English name of the Bureau international des poids et mesures (BIPM, often written in English Bureau International des Poids et Mesures), a standards organisation, one of the three organizations established to maintain the International System of Units (SI) under the terms... The General Conference on Weights and Measures is the English name of the Conférence générale des poids et mesures (CGPM, never GCWM). ... The International Committee for Weights and Measures is the English name of the Comité international des poids et mesures (CIPM, sometimes written in English Comité International des Poids et Mesures). ... Johann Heinrich Lambert Johann Heinrich Lambert (August 26, 1728 – September 25, 1777), was a mathematician, physicist and astronomer. ... Jacques Alexandre César Charles, 1820. ... Joseph Louis Gay-Lussac. ... Wikibooks has more about this subject: Constructing school science lab equipment/Making Charles law tubes AARON IS SO COOL!!!!! Charles law (sometimes called the Law of Charles) is one of the gas laws. ... The gas laws are a set of laws that describe the relationship between thermodynamic temperature (T), pressure (P) and volume (V) of gases. ... William Thomson, 1st Baron Kelvin OM GCVO PC PRS FRSE (26 June 1824 – 17 December 1907) was a mathematical physicist, engineer, and outstanding leader in the physical sciences of the 19th century. ... William John Macquorn Rankine (July 2, 1820 - December 24, 1872) was a Scottish engineer and physicist. ... Fahrenheit is a temperature scale named after the German physicist Daniel Gabriel Fahrenheit (1686–1736), who proposed it in 1724. ... See Rankine cycle for the idealized thermodynamic cycle for a steam engine. ... The General Conference on Weights and Measures is the English name of the Conférence générale des poids et mesures (CGPM, never GCWM). ... The International Committee for Weights and Measures is the English name of the Comité international des poids et mesures (CIPM, sometimes written in English Comité International des Poids et Mesures). ... VSMOW, or Vienna Standard Mean Ocean Water, is an isotopic water standard defined in 1968 by the International Atomic Energy Agency. ...

Derivations of thermodynamic temperature

Strictly speaking, the temperature of a system is well-defined only if its particles (atoms, molecules, electrons, photons) are at equilibrium, and so obey a Boltzmann distribution (or its quantum mechanical counterpart). There are many possible scales of temperature, derived from a variety of observations of physical phenomena. The thermodynamic temperature can be shown to have special properties, and in particular can be seen to be uniquely defined (up to some constant multiplicative factor) by considering the efficiency of idealized heat engines. Thus the ratios of temperatures, T₂/T₁, are the same in all absolute scales. Atomic redirects here. ... In chemistry, a molecule is an aggregate of two or more atoms in a definite arrangement held together by chemical bonds [1] [2] [3] [4] [5]. Chemical substances are not infinitely divisible into smaller fractions of the same substance: a molecule is generally considered the smallest particle of a pure... The electron is a fundamental subatomic particle that carries an electric charge. ... The word light is defined here as electromagnetic radiation of any wavelength; thus, X-rays, gamma rays, ultraviolet light, microwaves, radio waves, and visible light are all forms of light. ... In thermodynamics, a thermodynamic system is said to be in thermodynamic equilibrium when it is in thermal equilibrium, mechanical equilibrium, and chemical equilibrium. ... In physics, the Boltzmann distribution predicts the distribution function for the fractional number of particles Ni / N occupying a set of states i which each has energy Ei: where is the Boltzmann constant, T is temperature (assumed to be a sharply well-defined quantity), is the degeneracy, or number of... Fig. ... Look up Up to on Wiktionary, the free dictionary In mathematics, the phrase up to xxxx indicates that members of an equivalence class are to be regarded as a single entity for some purpose. ... Energy conversion efficiency is the ratio between the useful output of an energy conversion machine and the input, in energy terms. ... In engineering and thermodynamics, a heat engine performs the conversion of heat energy to mechanical work by exploiting the temperature gradient between a hot source and a cold sink. Heat is transferred from the source, through the working body of the engine, to the sink, and in this process some... A ratio is a dimensionless, or unitless, quantity denoting an amount or magnitude of one quantity relative to another. ...

Loosely stated, temperature controls the flow of heat between two systems and the Universe, as we would expect any natural system, tends to progress so as to maximize entropy. Thus, we would expect there to be some relationship between temperature and entropy. In order to find this relationship let's first consider the relationship between heat, work and temperature. A heat engine is a device for converting heat into mechanical work and analysis of the Carnot heat engine provides the necessary relationships we seek. The work from a heat engine corresponds to the difference between the heat put into the system at the high temperature, q_H and the heat ejected at the low temperature, q_C. The efficiency is the work divided by the heat put into the system or: Universe is a word derived from the Old French univers, which in turn comes form the Latin roots unus (one) and versus (a form of vertere, to turn). Physicists concept of the Universe is motivated[] by the attempt to describe the whole of space-time, including all matter and energy... Ice melting - classic example of entropy increasing[1] described in 1862 by Rudolf Clausius as an increase in the disgregation of the molecules of the body of ice. ... Mechanical work is a force applied through a distance, defined mathematically as the line integral of a scalar product of force and displacement vectors. ... A Carnot heat engine is a hypothetical engine that operates on the reversible Carnot cycle. ...

(1)

where w_cy is the work done per cycle. We see that the efficiency depends only on q_C/q_H. Because q_C and q_H correspond to heat transfer at the temperatures T_C and T_H, respectively, q_C/q_H should be some function of these temperatures:

(2)

Carnot's theorem states that all reversible engines operating between the same heat reservoirs are equally efficient. Thus, a heat engine operating between T₁ and T₃ must have the same efficiency as one consisting of two cycles, one between T₁ and T₂, and the second between T₂ and T₃. This can only be the case if: A Carnot heat engine is a hypothetical engine that operates on the reversible Carnot cycle. ...

Consequently, we have:

where T₁ is the temperature of the triple point of water. So we can define the thermodynamic temperature as:

This temperature scale has the property that:

(3)

Substituting Equation 3 back into Equation 1 gives a relationship for the efficiency in terms of temperature:

(4)

Notice that for T_C=0 K the efficiency is 100% and that efficiency becomes greater than 100% below 0 K. Since an efficiency greater than 100% violates the first law of thermodynamics, this requires that 0 K must be the minimum possible temperature. This makes intuitive sense; since temperature is the motion of particles, no system can, on average, have less motion than the minimum permitted by quantum physics. In fact, as of June 2006, the coldest man-made temperature was 450