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Kelvin

Kelvin

The kelvin (symbol: K) is the SI unit of temperature, and is one of the seven SI base units. It is defined as the fraction 1/273.16 of the thermodynamic temperature of the triple point of water. A temperature given in kelvins, without further qualification, is measured with respect to absolute zero, where molecular motion stops. It is also common to give a temperature relative to the reference temperature of 273.15 K, approximately the melting point of water under ordinary conditions; this convention is the Celsius temperature scale. The kelvin is named after the British physicist and engineer William Thomson, 1st Baron Kelvin; his barony was in turn named after the River Kelvin, which runs through the grounds of the University of Glasgow.

SI multiples

Typographical conventions

The word kelvin as an SI unit is correctly written with a lowercase k (unless at the beginning of a sentence), and is never preceded by the words degree or degrees, or the symbol °, unlike degrees Fahrenheit, or degrees Celsius. This is because the latter are adjectives, whereas kelvin is a noun. It takes the normal plural form by adding an s in English: kelvins. When the kelvin was introduced in 1954 (10th General Conference on Weights and Measures (CGPM), Resolution 3, CR 79), it was the "degree Kelvin", and written °K; the "degree" was dropped in 1967 (13th CGPM, Resolution 3, CR 104). Note that the symbol for the kelvin unit is always a capital K and never italicised. There is a space between the number and the K, as with all other SI units. Unicode includes the "kelvin sign" at U+212A (in your browser it looks like K). However, the "kelvin sign" is canonically decomposed into U+004B, thereby seen as a (preexisting) encoding mistake, and it is better to use U+004B (K) directly.

Conversion factors

Kelvins and Celsius

The Celsius temperature scale is now defined in terms of the kelvin, with 0 °C corresponding to 273.15 kelvins.
- kelvins to degrees Celsius
- :

\mathrm = \mathrm - 273.15

Temperature and energy

In a thermodynamic system, the energy of the particles of a perfect gas is proportional to the absolute temperature, where the constant of proportionality is the Boltzmann constant. As a result, it is possible to determine the average kinetic energy

\overline

of the gas particles at the temperature T or to calculate the temperature of the gas from the average kinetic energy of the particles: :

\overline = \frac \cdot k_B \cdot \mathrm

External link

- [http://www1.bipm.org/en/si/si_brochure/chapter2/2-1/2-1-1/kelvin.html BIPM brochure on the kelvin] Category:SI base units Category:Units of temperature ko:켈빈 ja:ケルビン simple:Kelvin th:เคลวิน

SI

The International System of Units (abbreviated SI from the French language name Système International d'Unités) is the modern form of the metric system. It is the world's most widely used system of units, both in everyday commerce and in science. The older metric system included several groupings of units. The SI was developed in 1960 from one of these, the metre-kilogram-second (MKS) system, rather than the centimetre-gram-second (CGS) system, which, in turn, had many variants. The SI introduced several newly named units. The SI is not static; it is a living set of standards where units are created and definitions are modified with international agreement as measurement technology progresses. With few exceptions (such as draught beer sales in the United Kingdom), the system is legally being used in every country in the world, and many countries do not maintain official definitions of other units. In the United States, industrial use of SI is increasing, but popular use is still limited. In the United Kingdom, conversion to metric units is official policy but not yet complete. Those countries that still recognize non-SI units (e.g. the US and UK) have redefined most of their traditional, non-SI units in terms of SI units.

History

:See main articles: metre, kilogram, second, ampere, Kelvin, and candela. The metric system was officially adopted in France after the French Revolution. During the history of the metric system a number of variations have evolved and their use spread around the world replacing many traditional measurement systems. By the end of World War II a number of different systems of measurement were still in use throughout the world. Some of these systems were metric system variations whilst others were based on the Imperial and American systems. It was recognised that additional steps were needed to promote a worldwide measurement system. As a result the 9th General Conference on Weights and Measures (CGPM), in 1948, asked the International Committee for Weights and Measures (CIPM) to conduct an international study of the measurement needs of the scientific, technical, and educational communities. Based on the findings of this study, the 10th CGPM in 1954 decided that an international system should be derived from six base units to provide for the measurement of temperature and optical radiation in addition to mechanical and electromagnetic quantities. The six base units recommended were the metre, kilogram, second, ampere, Kelvin degree (later renamed the kelvin), and the candela. In 1960, the 11th CGPM named the system the International System of Units, abbreviated SI from the French name: Le Système International d'Unités. The seventh base unit, the mole, was added in 1970 by the 14th CGPM. The International System is now either obligatory or permissible throughout the world. It is administered by the standards organisation: the Bureau International des Poids et Mesures (International Bureau of Weights and Measures).
Units
:Main articles: SI base unit, SI derived unit, SI prefix The international system of units consists of a set of units together with a set of prefixes. The units of SI can be divided into two subsets. There are the seven base units. Each of these base units are dimensionally independent. From these seven base units several other units are derived. In addition to the SI units there are also a set of non-SI units accepted for use with SI. A prefix may be added to units to produce a multiple of the original unit. All multiples are integer powers of ten. For example, kilo- denotes a multiple of a thousand and milli- denotes a multiple of a thousandth hence there are one thousand millimetres to the metre and one thousand metres to the kilometre. The prefixes are never combined: a millionth of a kilogram is a milligram not a microkilogram.
SI writing style

- Symbols are written in lower case, except for symbols derived from the name of a person. For example, the unit of pressure is named after Blaise Pascal, so its symbol is written "Pa" whereas the unit itself is written "pascal". The one exception is the litre, whose original abbreviation "l" is dangerously similar to "1". The NIST recommends that "L" be used instead, a usage which is common in the U.S., Canada and Australia, and has been accepted as an alternative by the CGPM. The cursive "ℓ" is occasionally seen, especially in Japan, but this is not currently recommended by any standards body. For more information, see Litre.
- Symbols are written without grammatical markers when used with singular numerals: i.e. "25 kg", not "25 kgs". Pluralization would be language dependent; "s" plurals (as in French and English) are particularly undesirable since "s" is the symbol of the second. Other cases may be marked in a language-dependent manner, e.g. Finnish 25 kg:lla = 25 kilogrammalla "with 25 kg".
- Symbols do not have an appended period (.).
- It is preferable to write symbols in upright Roman type (m for metres, L for litres), so as to differentiate from the italic type used for mathematical variables (m for mass, l for length).
- A space should separate the number and the symbol, e.g. "2.21 kg", "7.3×10² m²", "22 °C" [http://physics.nist.gov/Pubs/SP811/sec07.html]. Exceptions are the symbols for plane angular degrees, minutes and seconds (°, ′ and ″), which are placed immediately after the number with no intervening space.
- Spaces should be used to group decimal digits in threes, e.g. 1 000 000 or 342 142 (in contrast to the commas or dots used in other systems, e.g. 1,000,000 or 1.000.000).
- The 10th resolution of CGPM in 2003 declared that "the symbol for the decimal marker shall be either the point on the line or the comma on the line". In practice, the full stop is used in English, and the comma in most other European languages.
- Symbols for derived units formed from multiple units by multiplication are joined with a space or centre dot (·), e.g. N m or N·m.
- Symbols formed by division of two units are joined with a solidus (/), or given as a negative exponent. For example, the "metre per second" can be written "m/s", "m s^-1", "m·s^-1" or $\frac$ . A solidus should not be used if the result is ambiguous, i.e. "kg·m^-1·s^-2" is preferable to "kg/m/s²".
Spelling variations

- Several nations, notably the United States, typically use the spellings 'meter' and 'liter' instead of 'metre' and 'litre' in keeping with standard American English spelling. In addition, the official US spelling for the SI prefix 'deca' is 'deka'.
- The unit 'gram' is also sometimes spelled 'gramme' in English-speaking countries other than the United States, though that is an older spelling and its use is declining.
Cultural issues
The swift worldwide adoption of the metric system as a tool of economy and everyday commerce was based mainly on the lack of customary systems in many countries to adequately describe some concepts, or as a result of an attempt to standardize the many regional variations in the customary system. International factors also affected the adoption of the metric system, as many countries increased their trade. Scientifically, it provides ease when dealing with very large and small quantities because it lines up so well with our decimal numeral system. Cultural differences can be represented in the local everyday uses of metric units. For example, bread is sold in one-half, one or two kilogram sizes in many countries, but you buy them by multiples of one hundred grams in the former USSR. In some countries, the informal cup measurement has become 250 mL, and prices for items are sometimes given per 100 g rather than per kilogram. A profound cultural difference between physicists and engineers, especially radio engineers, existed prior to the adoption of the metre-kilogram-second (MKS) system and hence its descendent, SI. Engineers work with volts, amperes, ohms, farads, and coulombs, which are of great practical utility, while the centimetre-gram-second (CGS) units, which, though appropriate for theoretical physics, can be inconvenient for electrical engineering usage and are largely unfamiliar to householders using appliances rated in volts and watts. People with diabetes test their plasma glucose level regularly. In the U.S., measurement are recorded in milligrams per deciliter (mg/dL); in Europe, the standard is millimole/liter (mmol/L). The fine-tuning that has happened to the metric base units over the past 200 years, as experts have tried periodically to refine the metric system to fit the best scientific research do not affect the everyday use of metric units. Since most non-SI units, such as the U.S. customary units, are nowadays defined in terms of SI units, any change in the definition of the SI units results in a change of the definition of the older units as well.
See also

- Units of measurement
- Weights and measures
- Mesures usuelles
- Metrified English unit
- History of measurement
- Other systems of measurement:
- Imperial units
- U.S. customary units
- Metre-tonne-second system of units
- Chinese system of units
- Planck units
- Atomic units
- Geometrized units
- CODATA
- Metrication
- Metric system in the United States
- Metrology
- UTC (Coordinated Universal Time)
- Binary prefixes - used to quantify large amounts of computer data
- Orders of magnitude
- ISO 31
External links
Official
- [http://www.bipm.fr/en/si/ BIPM (SI maintenance agency)] (home page)
- [http://www.bipm.org/en/si/si_brochure/ BIPM brochure] (SI reference)
- [http://www.iso.ch/iso/en/CatalogueDetailPage.CatalogueDetail?CSNUMBER=5448&ICS1=1 ISO 1000:1992 SI units and recommendations for the use of their multiples and of certain other units], with its price tag of 99 Swiss francs for a 22 page, coverless pamphlet showing why the public is sometimes a little slow to pick up on their recommendations. Information
- [http://physics.nist.gov/cuu/Units/index.html US NIST reference on SI]
- [http://ts.nist.gov/ts/htdocs/200/202/pub814.htm#chart chart]
- [http://www.aticourses.com/international_system_units.htm SI - Its history and use in science and industry]
- [http://www.unc.edu/~rowlett/units/ A Dictionary of Units of Measurement]
- [http://www.unics.uni-hannover.de/ntr/russisch/si-einheiten.html5 Cyrillic transcription of SI symbols]
- Judson, Lewis B., Weights and Measures Standards of the United States: A brief history, NBS Special Publication 447, orig. iss. October 1963, updated March 1976 ([http://ts.nist.gov/ts/htdocs/200/202/SP%20447.pdf 46 page PDF file])
- [http://www.france-property-and-information.com/metric_conversion_table.htm Metric system and conversion tables (courtesy French property advice)]
- [http://www.metre.info metre-info - an encyclopaedia of all metric units] Pro-metric pressure groups
- [http://www.ukma.org.uk/ The UK Metric Association]
- [http://www.metric.org/ The US Metric Association] Pro-customary measures pressure groups
- [http://www.bwmaonline.com/ The British Weights and Measures Association]
Further reading

- I. Mills, Tomislav Cvitas, Klaus Homann, Nikola Kallay, IUPAC: Quantities, Units and Symbols in Physical Chemistry, 2nd ed., Blackwell Science Inc 1993, ISBN 0632035838. Category:SI units Category:Systems of units Category:International standards Category:Dimensional analysis ko:SI 단위계 ja:国際単位系 simple:SI th:หน่วยเอสไอ

Unit

The word unit means any of several things:
- Unit of measurement, a fundamental quantity of measurement
- Units (computer program), a popular program that does unit conversion
- Functional unit, a component of a computer system such as the CPU
- Unit of action, a discrete piece of action (or beat) in a theatrical presentation
- Multiple unit, a passenger train whose carriages have their own motors
- United Nations Intelligence Taskforce, a fictional entity in the Doctor Who television series
- Unit, a rock and roll album by the Australian band Regurgitator
- Unit of alcohol, 10 millilitres of pure ethanol in the UK
- In currency, a unit of money (a monetary unit)
- In a 19-inch rack a rack unit is a standard height of 1.75 inches
- In mathematics:
- Unit vector, a vector with length 1
- Unit circle, the circle with radius 1 centered at the origin
- Unit interval, the interval of all real numbers between 0 and 1
- Imaginary unit, i, whose square is -1
- Root of unity, a complex number, a power of which is 1
- Unit (ring theory), an element that is invertible with respect to ring multiplication
- In category theory, there is a natural transformation called the unit from the identity functor to the composition of two adjoint functors, q.v.
- Military units, including:
- Unit 101, an Israeli special operations unit
- Unit 731, a secret unit of the Japanese army ko:단위 ja:単位 simple:Unit

Temperature

Temperature is the physical property of a system which underlies the common notions of "hot" and "cold"; the material with the higher temperature is said to be hotter. Physically, temperature is a measure of the random agitation of matter and ambiant photons, under the effect of thermal fluctuations. It is a fundamental parameter in thermodynamics and it is conjugate to entropy. More quantitatively, the order of magnitude of the fluctuations of the energy associated with an atom, molecule or another elementary constituant of a physical system is

k_B T

, where

k_B

is Boltzmann's constant, and T is temperature, expressed in Kelvins.

Overview

The formal properties of temperature are studied in thermodynamics and statistical mechanics. The temperature of a system at thermodynamic equilibrium is defined by a relation between the amount of heat

\delta Q

incident on the system during an infinitesimal quasistatic transformation, and the variation

\delta S

of its entropy during this transformation. :

\delta S = \frac

Contrarly to entropy and heat, whose microscopic definitions are valid even far away from thermodynamic equilibrium temperature can only be defined at thermodynamic equilibrium, or local thermodynamic equilibrium (see below). As a system receives heat its temperature rises, similarly a loss of heat from the system tends to decrease its temperature (at the - uncommon - exception of negative temperature, see below). When two systems are at the same temperature, no heat transfer occurs between them. When a temperature difference does exist, heat will tend to move from the higher-temperature system to the lower-temperature system, until they are at thermal equilibrium. This heat transfer may occur via conduction, convection or radiation (see heat for additional discussion of the various mechanisms of heat transfer). Temperature is also related to the amount of internal energy and enthalpy of a system. The higher the temperature of a system, the higher its internal energy and enthalpy are. Temperature is an intensive property of a system, meaning that it does not depend on the system size or the amount of material in the system. Other intensive properties include pressure and density. By contrast, mass and volume are extensive properties, and depend on the amount of material in the system.

Role of temperature in nature

Temperature plays an important role in almost all fields of science, including physics, chemistry, and biology. Many physical properties of materials including the phase (solid, liquid, gaseous or plasma), density, solubility, vapor pressure, and electrical conductivity depend on the temperature. Temperature also plays an important role in determining the rate and extent to which chemical reactions occur. This is one reason why the human body has several elaborate mechanisms for maintaining the temperature at 37 °C, since temperatures only a few degrees higher can result in harmful reactions with serious consequences. Temperature also controls the type and quantity of thermal radiation emitted from a surface. One application of this effect is the incandescent light bulb, in which a tungsten filament is electrically heated to a temperature at which significant quantities of visible light are emitted. Temperature-dependence of the speed of sound in air c, density of air ρ and acoustic impedance Z vs. temperature °C

Temperature measurement

Main article: Temperature measurement Temperature measurement using modern scientific thermometers and temperature scales goes back at least as far as the early 18th century, when Gabriel Fahrenheit adapted a thermometer (switching to mercury) and a scale both developed by Ole Christensen Rømer. Fahrenheit's scale is still in use, alongside the Celsius scale and the Kelvin scale.

Units of temperature

The basic unit of temperature (symbol: T) in the International System of Units (SI) is the kelvin (K). One kelvin is formally defined as 1/273.16 of the temperature of the triple point of water (the point at which water, ice and water vapor exist in equilibrium). The temperature 0 K is called absolute zero and corresponds to the point at which the molecules and atoms have the least possible thermal energy. An important unit of temperature in theoretical physics is the Planck temperature (1.4 × 10³² K). In the field of plasma physics, because of the high temperatures encountered and the electromagnetic nature of the phenomena involved, it is customary to express temperature in electronvolts (eV) or kiloelectronvolts (keV), where 1 eV = 11,605 K. In the study of QCD matter one routinely meets temperatures of the order of a few hundred MeV, equivalent to about 10¹² K. For everyday applications, it is often convenient to use the Celsius scale, in which 0 °C corresponds to the temperature at which water freezes and 100 °C corresponds to the boiling point of water at sea level. In this scale a temperature difference of 1 degree is the same as a 1 K temperature difference, so the scale is essentially the same as the kelvin scale, but offset by the temperature at which water freezes (273.15 K). Thus the following equation can be used to convert from degrees Celsius to kelvins. :

\mathrm

In the United States, the Fahrenheit scale is widely used. On this scale the freezing point of water corresponds to 32 °F and the boiling point to 212 °F. The following formula can be used to convert from Fahrenheit to Celsius: :

\mathrm

See temperature conversion formulas for conversions between most temperature scales. ¹ Only the kelvin, Celsius, Fahrenheit, and Rankine scales are in use today.
² Some numbers in this table have been rounded off.
³ Normal human body temperature is 36.8 °C ±0.7 °C, or 98.2 °F ±1.3 °F.

Negative temperatures

:See main article: Negative temperature. For some systems and specific definitions of temperature, it is possible to obtain a negative temperature. A system with a negative temperature is not colder than absolute zero, but rather it is, in a sense, hotter than infinite temperature (sic).

Articles about temperature ranges:

- 10⁻¹² K = 1 picokelvin (pK)
- 10⁻⁹ K = 1 nanokelvin (nK)
- 10⁻⁶ K = 1 microkelvin (µK)
- 10⁻³ K = 1 millikelvin (mK)
- 10⁰ K = 1 kelvin
- 10¹ K = 10 kelvins
- 10² K = 100 kelvins
- 10³ K = 1,000 kelvin = 1 kilokelvin (kK)
- 10⁴ K = 10,000 kelvins = 10 kK
- 10⁵ K = 100,000 kelvins = 100 kK
- 10⁶ K = 1 megakelvin (MK)
- 10⁹ K = 1 gigakelvin (GK)
- 10¹² K = 1 terakelvin (TK) See Orders of magnitude (temperature).

Theoretical foundation of temperature

Zeroth-law definition of temperature

While most people have a basic understanding of the concept of temperature, its formal definition is rather complicated. Before jumping to a formal definition, let us consider the concept of thermal equilibrium. If two closed systems with fixed volumes are brought together, so that they are in thermal contact, changes may take place in the properties of both systems. These changes are due to the transfer of heat between the systems. When a state is reached in which no further changes occur, the systems are in thermal equilibrium. Now a basis for the definition of temperature can be obtained from the so-called zeroth law of thermodynamics which states that if two systems, A and B, are in thermal equilibrium and a third system C is in thermal equilibrium with system A then systems B and C will also be in thermal equilibrium (being in thermal equilibrium is a transitive relation; moreover, it is an equivalence relation). This is an empirical fact, based on observation rather than theory. Since A, B, and C are all in thermal equilibrium, it is reasonable to say each of these systems shares a common value of some property. We call this property temperature. Generally, it is not convenient to place any two arbitrary systems in thermal contact to see if they are in thermal equilibrium and thus have the same temperature. Also, it would only provide an ordinal scale. Therefore, it is useful to establish a temperature scale based on the properties of some reference system. Then, a measuring device can be calibrated based on the properties of the reference system and used to measure the temperature of other systems. One such reference system is a fixed quantity of gas. The ideal gas law indicates that the product of the pressure and volume (P · V) of a gas is directly proportional to the temperature: :

P \cdot V = n \cdot R \cdot T

(1) where 'T is temperature, n is the number of moles of gas and R is the gas constant. Thus, one can define a scale for temperature based on the corresponding pressure and volume of the gas: the temperature in kelvins is the pressure in pascals of one mole of gas in a container of one cubic metre, divided by 8.31... In practice, such a gas thermometer is not very convenient, but other measuring instruments can be calibrated to this scale. Equation 1 indicates that for a fixed volume of gas, the pressure increases with increasing temperature. Pressure is just a measure of the force applied by the gas on the walls of the container and is related to the energy of the system. Thus, we can see that an increase in temperature corresponds to an increase in the thermal energy of the system. When two systems of differing temperature are placed in thermal contact, the temperature of the hotter system decreases, indicating that heat is leaving that system, while the cooler system is gaining heat and increasing in temperature. Thus heat always moves from a region of high temperature to a region of lower temperature and it is the temperature difference that drives the heat transfer between the two systems.

Temperature in gases

As mentioned previously for a monatomic ideal gas the temperature is related to the translational motion or average speed of the atoms. The kinetic theory of gases uses statistical mechanics to relate this motion to the average kinetic energy of atoms and molecules in the system. For this case 7736 K = 7463 degrees Celsius corresponds to an average kinetic energy of one electronvolt; to take room temperature (300 K) as an example, the average energy of air molecules is 300/7736 eV, or 0.0388 electronvolt. This average energy is independent of particle mass, which seems counterintuitive to many people. Although the temperature is related to the average kinetic energy of the particles in a gas, each particle has its own energy which may or may not correspond to the average. However, after an examination of some basic physics equations it makes perfect sense. The second law of thermodynamics states that any two given systems when interacting with each other will later reach the same average energy. Temperature is a measure of the average kinetic energy of a system. The formula for the kinetic energy of an atom is:
:

K_t = \begin \frac \end mv^2

(Note that a calculation of the kinetic energy of a more complicated object, such as a molecule, is slightly more involved. Additional degrees of freedom are available, so molecular rotation or vibration must be included.)

Thus, particles of greater mass (say a neon atom relative to a hydrogen molecule) will move slower than lighter counterparts, but will have the same average energy. This average energy is independent of the mass because of the nature of a gas, all particles are in random motion with collisions with other gas molecules, solid objects that may be in the area and the container itself (if there is one). A visual illustration of this [http://intro.chem.okstate.edu/1314F00/Laboratory/GLP.htm from Oklahoma State University] makes the point more clear. Not all the particles in the container have different velocities, regardless of whether there are particles of more than one mass in the container, but the average kinetic energy is the same because of the ideal gas law. In a gas the distribution of energy (and thus speeds) of the particles corresponds to the Boltzmann distribution. An electronvolt is a very small unit of energy, approximately 1.602×10^-19 joule.

Temperature of the vacuum

When a satellite in empty space is heated by sunshine and cooled by radiating energy away it is not in thermodynamic equilibrium and has no well-defined temperature. A system in a vacuum will radiate its thermal energy, i.e. convert heat into electromagnetic waves. If vacuum is filled with electromagnetic waves (say, radiation from walls of vacuum chamber, or relic microwave radiation in space) then the system will exchange by energy with these waves and thermally equilibrates at some finite (non zero) temperature. Cosmic microwave background radiation being remnant of radiation of hot early universe when radiation was in thermal equilibrium with matter has Planck spectrum (black body spectrum) with the temperature (at present) of about 2.7 K.

Second-law definition of temperature

In the previous section temperature was defined in terms of the Zeroth Law of thermodynamics. It is also possible to define temperature in terms of the second law of thermodynamics, which deals with entropy. Entropy is a measure of the disorder in a system. The second law states that any process will result in either no change or a net increase in the entropy of the universe. This can be understood in terms of probability. Consider a series of coin tosses. A perfectly ordered system would be one in which every coin toss would come up either heads or tails. For any number of coin tosses, there is only one combination of outcomes corresponding to this situation. On the other hand, there are multiple combinations that can result in disordered or mixed systems, where some fraction are heads and the rest tails. As the number of coin tosses increases, the number of combinations corresponding to imperfectly ordered systems increases. For a very large number of coin tosses, the number of combinations corresponding to ~50% heads and ~50% tails dominates and obtaining an outcome significantly different from 50/50 becomes extremely unlikely. Thus the system naturally progresses to a state of maximum disorder or entropy. Now, we have stated previously that temperature controls the flow of heat between two systems and we have just shown that the universe, and 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: :

\textrm = \frac  = \frac = 1 - \frac

(2) 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: :

\frac = f(T_H,T_C)

(3) 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: :

q_ = \frac

which implies: :

q_13 = f(T_1,T_3) = f(T_1,T_2)f(T_2,T_3)

Since the first function is independent of T₂, this temperature must cancel on the right side, meaning f(T₁,T₃) is of the form g(T₁)/g(T₃) (i.e. f(T₁,T₃) = f(T₁,T₂)f(T₂,T₃) = g(T₁)/g(T₂)· g(T₂)/g(T₃) = g(T₁)/g(T₃)), where g is a function of a single temperature. We can now choose a temperature scale with the property that: :

\frac = \frac

(4) Substituting Equation 4 back into Equation 2 gives a relationship for the efficiency in terms of temperature: :

\textrm = 1 - \frac = 1 - \frac

(5) 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 implies that 0 K is the minimum possible temperature. In fact the lowest temperature ever obtained in a macroscopic system was 20 nK, which was achieved in 1995 at NIST. Subtracting the right hand side of Equation 5 from the middle portion and rearranging gives: :

\frac  - \frac = 0

where the negative sign indicates heat ejected from the system. This relationship suggests the existence of a state function, S, defined by: :

dS = \frac

(6) where the subscript indicates a reversible process. The change of this state function around any cycle is zero, as is necessary for any state function. This function corresponds to the entropy of the system, which we described previously. We can rearranging Equation 6 to get a new definition for temperature in terms of entropy and heat: :

T = \frac

(7) For a system, where entropy S may be a function S(E) of its energy E, the temperature T is given by: :

\frac = \frac

(8) The reciprocal of the temperature is the rate of increase of entropy with energy.

References

External links

- [http://www.unitconversion.org/unit_converter/temperature.html Online Temperature Converter] - convert between various units of temperature, such as kelvin, Celsius, Fahrenheit, Rankine, Reaumur, and even Triple point of water
- [http://www.unitconversion.org/unit_converter/temperature-v.html Interactive Temperature Conversion Table] - convert selected unit to all other units of temperature
- [http://www.indiana.edu/~animal/fun/conversions/temperature.html Temperature Conversions: Celsius, Fahrenheit, Kelvin, Réaumur and Rankine]
- [http://www.unidata.ucar.edu/staff/blynds/tmp.html An elementary introduction to temperature aimed at a middle school audience]
- [http://www.straightdope.com/mailbag/mtempscales.html Why do we have so many temperature scales?]
- [http://thermodynamics-information.net A Brief History of Temperature Measurement] Category:Meteorology Category:Physical quantity Category:Thermodynamics Category:Heat ko:온도 ja:温度 th:อุณหภูมิ

Thermodynamic temperature

To convert celsius into absolute temperature in kelvins, add 273.16 to the original celsius measure. Thermodynamic temperature (formerly called absolute temperature) is a measure, in kelvins (K), of temperature for thermodynamics. A temperature of 0 K is called "absolute zero", and coincides with the minimum molecular activity (i.e., thermal energy) of matter. In practice, the International Temperature Scale of 1990 (ITS-90) serves as an operational definition and the basis for high-accuracy temperature measurements in science and technology.

Derivation of thermodynamic temperature

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. 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: :

\textrm = \frac  = \frac = 1 - \frac

(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: :

\frac = f(T_H,T_C)

(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: :

q_ = \frac

which implies: :

q_13 = f(T_1,T_3) = f(T_1,T_2)f(T_2,T_3)

Since the first function is independent of T₂, this temperature must cancel on the right side, meaning f(T₁,T₃) is of the form g(T₁)/g(T₃) (i.e. f(T₁,T₃) = f(T₁,T₂)f(T₂,T₃) = g(T₁)/g(T₂)×g(T₂)/g(T₃) = g(T₁)/g(T₃)), where g is a function of a single temperature. We can now choose a temperature scale with the property that: :

\frac = \frac

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

\textrm = 1 - \frac = 1 - \frac

(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 implies that 0 K is the minimum possible temperature. In fact the lowest temperature so far obtained in a macroscopic system was 20 nK, which was achieved in 1995 at NIST. Subtracting the right hand side of Equation 4 from the middle portion and rearranging gives: :

\frac  - \frac = 0

where the negative sign indicates heat ejected from the system. This relationship suggests the existence of a state function, S, defined by: :

dS = \frac

(5) where the subscript indicates a reversible process. The change of this state function around any cycle is zero, as is necessary for any state function. This function corresponds to the entropy of the system, which we described previously. We can rearranging Equation 5 to get a new definition for temperature in terms of entropy and heat: :

T = \frac

For a system, where entropy S may be a function S(E) of its energy E, the thermodynamic termperature T is given by: :

\frac = \frac

The reciprocal of the thermodynamic termperature is the rate of increase of entropy with energy. Category:Temperature ja:熱力学温度

Triple point

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. thermodynamic). Note that this is not the phase diagram for water.]] For example, the triple point temperature of mercury is -38.8344 °C at a pressure of 0.2 mPa. The triple point of water is used to define the kelvin, the SI unit of thermodynamic temperature. The number given for the temperature of the triple point of water is an exact definition rather than a measured quantity.

Triple point of water

The single combination of pressure and temperature at which water, ice, and water vapour can coexist in a stable equilibrium occurs at exactly 273.16 kelvins (0.01 °C) and a pressure of 611.73 pascals (ca. 6 millibars). At that point, it is possible to change all of the substance to ice, water, or steam by making infinitesimally small changes in pressure and temperature. (Note that the pressure referred to here is the vapor pressure of the substance, not the total pressure of the entire system.) Water has an unusual and complex phase diagram, although this does not affect general comments about the triple point. At high temperatures, increasing pressure results in first liquid, and then solid water (above around

10^9

Pa a crystalline form of ice which is denser than water forms). At lower temperatures the liquid state ceases to appear with compression causing the state to pass directly from gas to solid. It is, however, possible to melt ice by increasing pressure under specific conditions. At a constant pressure higher than the triple point, heating ice necessarily passes from ice to liquid then to steam. In pressures below the triple point, such as in outer space where the pressure is low, liquid water cannot exist: Ice skips the liquid stage and becomes steam on heating, in a process known as sublimation.

External links

- [http://www1.bipm.org/en/si/base_units/ Definition of the kelvin] at BIPM
- [http://www.lsbu.ac.uk/water/phase.html Phase diagram of water] Category:Chemical properties Category:Thermodynamics ja:三重点

Absolute zero

In physics, absolute zero is a fundamental lower bound on the temperature of a macroscopic system. In practice it is believed to be unachievable but its existence has been inferred from extrapolation from observed physical phenomena and from kinetic theory. Today it is defined as the temperature at which all motion of particles would theoretically cease. The Kelvin and Rankine temperature scales are defined so that absolute zero is 0 kelvins (K) or 0 degrees Rankine (°R). The Celsius and Fahrenheit scales are defined so this is −273.15 °C or −459.67 °F.

History

A state of absolute zero was first proposed by Guillaume Amontons in 1702. Amontons was investigating the relationship between pressure and temperature in gases though he lacked accurate and precise thermometers. Though his results were at best semi-quantitative, he established that the pressure of a gas increases by roughly one-third between the temperatures of "cold" and the boiling point of water. His work led him to speculate that a sufficient reduction in temperature would lead to the disappearance of pressure. Though absolute zero can be defined in this way, such a definition has practical and conceptual limitations as any real gas will liquefy before attaining a temperature of absolute zero. In 1848, William Thomson, 1st Baron Kelvin proposed an absolute temperature scale in which equal reduction in measured temperature gave rise to equal reduction in the heat of a body. This freed the concept from the constraints of the gas laws and established an absolute zero as the temperature at which no further heat could be transferred from a body. Absolute zero has never been reached.

Kinetic theory

According to kinetic theory there would be no movement of individual particles at absolute zero, and thus any material at this temperature would be solid. This contradicts experimental evidence. A more practical definition of absolute zero is as the temperature where no further energy may be extracted. For the case of free atoms at temperatures approaching absolute zero, most of the energy is in the form of translational motion and the temperature can be measured in terms of the distribution of this motion, with slower speeds corresponding to lower temperatures. In fact because of quantum mechanical effects, the speed at absolute zero is not exactly zero, but depends, as does the energy, on the volume within which the atom is confined. At absolute zero, the molecules and atoms in a system are all in the ground state (i.e., the lowest possible energy state) and the system has the least possible amount of kinetic energy allowed by the laws of physics. This minimum energy corresponds to the zero-point energy encountered in the quantum mechanical particle in a box problem. As emphasised above, the lowest possible energy is not necessarily zero energy, owing to the ramifications of quantum theory.

Cryogenics

It can be shown from the laws of thermodynamics that absolute zero can never be achieved, though it is possible to achieve temperatures arbitrarily close to it through the use of cryocoolers. This is the same principle that ensures no system may be 100% efficient. At very low temperatures in the vicinity of absolute zero, matter exhibits many unusual properties including superconductivity, superfluidity, and Bose-Einstein condensation. In order to study such phenomena, scientists have worked to obtain ever lower temperatures. As of 2005:
- The lowest temperature Bose-Einstein condensate achieved was 450 pK, or 4.5 × 10^-10 K. This was performed by Wolfgang Ketterle and colleagues at the Massachusetts Institute of Technology.
- The Boomerang Nebula, with a temperature of 1 K, is the coldest place known outside a laboratory. The nebula is 5000 light-years from Earth and is in the constellation Centaurus.
- The coldest temperature ever produced was 100 pK during an experiment on nuclear magnetic ordering in the Helsinki University of Technology's Low Temperature Lab.

Thermodynamics and Absolute Zero

The third law of thermodynamics states that the entropy of a perfect crystal at absolute zero or 0K is zero. This means that in a perfect crystal, at 0K, nearly all molecular motion should cease in order to achieve ΔS=0. A perfect crystal is one in which the internal lattice structure is the same at all times; in other words, it is fixed and non-moving, and does not have rotational or vibrational energy. This means that there is only one way in which this order can be attained: when every particle of the structure is in its proper place. However, the equation for predicting quantized vibrational levels shows that even when the vibrational quantum number is 0, the molecule still has vibrational energy. This means that no matter how cold the temperature gets, the molecule will always have vibration. This is in keeping with the Heisenberg uncertainty principle, which states that both the position and the momentum of a particle cannot be known precisely, at a given time.

E_v

h(v_0)[v+(1/2)]

, where h = Planck's constant,

v_0

= characteristic frequency of the vibration, and v = the vibrational quantum number. Note that even when v = 0 (the zero-point energy),

E_v

does not equal 0

(v_0

≠ 0). Since all molecules will have some vibrational energy at all times, the entropy of such a molecule will not be 0. However, the third law of thermodynamics requires the entropy of a perfect crystal to be 0, at absolute zero. Since, perfect crystal configuration can never physically be reached, many have used this as an argument against the possibility of attaining absolute zero temperature.

Absolute temperature scales

Absolute or thermodynamic temperature is conventionally measured in kelvins, and now rarely in degrees Rankine. An object's absolute temperature therefore describes how much warmer the object is than absolute zero. While temperature is a measure of the heat of an object, heat itself is simply a highly abstract consideration of the kinetic energy of the molecular particles of the object. At absolute zero, we have reached the baseline. The absolute temperature measures the movement among the particles of an object by comparing it to the state of an object at absolute zero.

Negative temperatures

Certain situations can give rise to "negative" temperatures, though this phenomenon is very much an artifact of the definition of thermodynamic temperature, rather than a system "colder" than absolute zero. Category:Temperature ko:절대 영도 ja:絶対零度 simple:Absolute zero

Celsius

The degree Celsius (°C) is a unit of temperature named after the Swedish astronomer Anders Celsius (1701–1744), who first proposed a similar system in 1742. The Celsius scale sets 0.01 °C to be at the triple point of water and a degree Celsius to be 1/273.16 of the difference in temperature between the triple point of water and absolute zero. Until 1954 the scale was defined with the freezing point of water at 0 °C and the boiling point at 100 °C at standard atmospheric pressure, this definition is still a close approximation to the actual definition and is for that reason commonly (but wrongly) used to refer to the scale.

History

The Celsius temperature scale was originally designed so that the freezing point of water is 100 degrees, and its boiling point is 0 degrees at standard atmospheric pressure. This was reversed to its modern order some time after his death, in part at the instigation of Daniel Ekström, the manufacturer of most of the thermometers used by Celsius. Several other people, including Per Elvius the Elder from Sweden (1710) and Christian of Lyons (1743), independently invented the same temperature scale. The oft-quoted claim that the botanist Carolus Linnaeus (1740) is amongst those is unsubstantiated. The Delisle scale was another temperature scale that ran "downward". Since there are one hundred graduations between these two reference points, the original term for this system was centigrade (100 parts) or centesimal. In 1948 the system's name was officially changed to Celsius (a third name which had also been in use before then) by the 9th General Conference on Weights and Measures (CR 64), both in recognition of Celsius himself and to eliminate confusion caused by conflict with the use of the SI centi- prefix. While the values for freezing and boiling of water remain approximately correct, they are no longer suitable as reference points for a formal standard. The current official definition of the Celsius scale sets 0.01 °C to be at the triple point of water and a degree to be 1/273.16 of the difference in temperature between the triple point of water and absolute zero. This definition was adopted in 1954 at the 10th General Conference on Weights and Measures, the very same definition given for the kelvin. For the practical calibration of thermometers, the International Temperature Scale of 1990 defines many additional reference points.

Naming

The degree Celsius is the only SI unit whose full unit name ("degree Celsius", not "Celsius") in English includes an upper case letter. That is a quirk of English, because it is a proper adjective rather than a noun (before the name was changed from "degree Kelvin" to "kelvin" in 1967, that was another SI unit containing a capital letter in English). While SI prefixes could be applied in principle, as in "12 m°C", they are not used in practice (ISO 1000).

Application

The Celsius scale is the world's most commonly used temperature scale. It has been adopted by virtually all the countries of the world, with the notable exceptions of the United States of America and Jamaica. In broadcast media it was still frequently referred to as centigrade until the late 1980s or early 1990s, particularly by weather forecasters on European networks such as the BBC, ITV, and RTÉ. In the United States and Jamaica, Fahrenheit remains the preferred scale for everyday temperature measurement, although Celsius or kelvin is used for aeronautical and scientific applications. In the United Kingdom, Celsius is the official scale used by the government and the media. It is also the only scale used in British cooking and temperature controllers (for example, room thermostats). Some of the British media, however, still provide Fahrenheit equivalents since many in Britain, especially older people, still use the Fahrenheit scale. Even so, many that do still switch to the use of Celsius for low temperatures.

Trivia

- The Unicode character set contains a dedicated precomposed degrees Celsius character (℃, U+2103). This character was only intended for compatibility mapping of legacy character sets that contain it as well. It should not be used in new texts. Category:SI derived units Category:Units of temperature zh-min-nan:Liap-sī ko:섭씨 ja:セルシウス度

Barony

Baron is a specific title of nobility or a more generic feudal qualification. The word baron comes from French baron, itself from Frankish baro meaning "freeman, warrior"; it merged with cognate Old English beorn meaning "nobleman." Ultimately it seems to mean a burden bearer.

Western European Feudal Titles

The British Isles

In the British peerage system, barons rank lowest, coming after viscounts. A female of baronial rank has the honorific baroness. A baron may hold a barony (plural baronies). William the Conqueror introduced "baron" as a rank into England to distinguish the men who had pledged their loyalty to him (see Feudalism). Previously, in the Anglo-Saxon kingdom of England, the king's companions held the title of earls and in Scotland, the title of thane. All who held their barony "in chief of the king" (i.e. directly from William and his successors) became alike barones regis (barons of the king), bound to perform a stipulated service, and welcome to attend his council. Before long, the greatest of the nobles, especially in the marches, such as the Earls of Chester or the Bishops of Durham, might refer to their own tenants as "barons", where lesser magnates spoke simply of their "men" (homines). Initially those who held land direct of the crown by military service, from earls downwards, all alike bore the title of baron, but under Henry II, the Dialogus de Scaccario already distinguishes greater or lesser baronies. Within a century of the Norman Conquest, as in Thomas Becket's case (1164), there arose the practice of sending to each greater baron a special summons to the council that evolved into the House of Lords, while the lesser barons, Magna Carta (1215) stipulated, would receive summons only in general, through the sheriffs. Thus appeared a definite distinction, which eventually had the effect of restricting to the greater barons the rights and privileges of peerage. The King of England could create a new barony in one of two ways: by a writ of summons directing someone to Parliament, or by letters patent. Writs of summons featured in medieval times, but creation by letters patent has become the norm. Baronies thus no longer directly relate to land ownership. In Scotland, the rank of baron refers to the holder of a feudal barony, which does relate to the feudal jurisdiction over the territorial entity. Scottish (feudal) barony is a dignity of honour ranked as titled nobility, as HM Lyon Court ruled 26th February 1943 and thereafter confirmed by the Court of Session. Curiously, but in the UK this normal continental style (titled nobility) in almost meaningless (confused with Peerage of the Realm), and in use in Scotland only where the nobiliary Law system is very different from English one. Therefore the rank of Scottish baron is in absolutely similarity with the Freiherr in the Holy Roman Empire, and fell into the category Uradel (old feudal nobility). By the Feudal Law, a Scottish barony erected by the Crown makes its holders full equivalent of Reichsfreiherr (in old German sense). If such a barony was granted together with a "coronatoris regalitatis" (regality – the semi-sovereign power of justice) the holder of such a barony is equivalent of Hochadel ( high semi-sovereign noble in old German sense). All Scottish baronies were erected with remainder "to heirs and assignees of feudal right over the territorial entity". But with the end of feudalism in Scotland, after 28 November 2004 the dignity of a Scottish Baron became a purely hereditary title of honour, ranking (curiously) below all baronets(!) and above all Clan Chiefs (who are not peers of the Realm). This table of precedence is based on Baronetcy Warrant by King Charles I, and is contradicts to a number of constitutional norm of legislation which confirms for all (feudal) baronies of Scotland pre-dated 1707 status amongst the Peerage of Scotland.The Scots system does not have baronies as in England, but "Lordships of Parliament".But, at least one of Scottish feudal barony was recognised by the Crown and House of Lords as a Lordship in the Peerage of Scotland, without any Writ of Summons or Letters Patent granting peerage. It is Barony of Torphichen, granted on 24 January1564 by Crown Charter for James Sandilands, his heirs and assignees of feudal right over territorial entity. Generally, the more modern baronies pass only to male heirs. However, in the cases of Scottish Lordships of Parliament and of English baronies by writ a daughter can inherit provided she has no brothers. In the English case, if there are multiple daughters, they jointly inherit the barony as coheirs, which then falls into abeyance until there is only one heir again. The Scottish equivalent of the English baron is Lord of Parliament. In the late twentieth century Britain introduced the concept of non-hereditary life peers. All appointees to this distinction have taken place at the rank of baron, though in principle nothing prevents the creation of a life peerage of higher rank. Baronies are often subsidiary titles, thus being used as courtesy titles by eldest sons.

Style of address

Non-Scottish barons are styled The Right Honourable The Lord [Barony]. Baron's wives are titled The Right Honourable The Lady [Barony]. Baronesses in their own right are either titled The Right Honourable The Baroness [Barony] or The Right Honourable The Lady [Barony], mainly based on personal preference (for an example of the former, see Margaret Thatcher). Right Honourable is frequently abbreviated to Rt. Hon. When referred to by the Sovereign in public instruments, The Right Honourable is changed to Our right trusty and well-beloved cousin (even if the said baron is not their blood cousin), with and counsellor attached if they are a Privy Counsellor. Courtesy barons are styled simply Lord [Barony], and their wives are Lady [Barony]. The style of Right Honourable is not used for them. Normally one refers to or addresses Baron X as Lord X and his wife as Lady X. In the case of women who hold baronies in their own right, they can be referred to as Baroness X as well as Lady X. In direct address, they can also be referred to as My Lord or My Lady. The husband of a Baroness in her own right does not receive a style. Children of Barons and Baronesses in their own right, whether hereditary or for life, have the style The Honourable [Forename] [Surname]. After the death of the father or mother, the child may continue to use the style Honourable.

Germany

In Germany all the knightly families (distinguished by the prefix "von") eventually were recognised as of baronial rank. Families which had always held this status were called Uradel or Original Nobility, and were heraldically entitled to a seven pointed coronet. Families which had been ennobled at a definite point in time had only five points on their coronet. These families held their titles from their lord. The holder of an allodial (ie free-standing) barony was thus called a Free Lord, Freiherr and its various variations occupy the same rank as a foreign Baron, exclusively (as in the Holy Roman Empire) or concurrently. The non-allodial barony, whether original or created, is of small value because it descends to all sons and daughters of the male line. The holders of original titles distinguish themselves from the newcomers by abbreviating "von" as "v."

In other languages

The title was quite common in most European countries, in various languages (whether Germanic, Romance, Slavonic or other), often in a slightly modified form. The following list includes the male and female forms and (sometimes) the territorial domain. Notice, especially for the 'alternative' Freiherr-type titles, that the existence of a word does not always implies the actual use : it is a mere rendering of foreign realities.

Elsewhere

In some republics of continental Europe, the title of "Baron" retains a purely social prestige, with no particular political privileges. In the Polynesian island monarchy of Tonga, as opposed to the situation in Europe, barons are granted this imported title (in English), and continue to hold and exercise some political power.

References

- Category:Titles Category:Peerage
- ja:男爵

University of Glasgow

The University of Glasgow, founded in 1451, is the largest of the three universities in Glasgow, Scotland. It is a renowned centre for teaching and research and one of the ancient universities of Scotland and is amongst the largest and most prestigious in the United Kingdom.

History

It was founded in 1451 by papal bull of Pope Nicholas V, at the suggestion of King James II, giving Bishop William Turnbull permission to add the university to the city's cathedral. Its founding came about as a result of King James II's wish that Scotland have two Universities to equal Oxford and Cambridge of England. It is the second oldest university in Scotland (the 4th oldest in the United Kingdom), the oldest being the University of St Andrews (founded in 1413). The Universities of St Andrews, Glasgow and Aberdeen are ecclesiastical foundations, while Edinburgh is a city foundation. Glasgow has enjoyed a (usually friendly) rivalry with the University of St Andrews since its creation, and with Edinburgh University since its foundation in 1583. Of all the universities and tertiary education establishments in Scotland, only Glasgow and Edinburgh offer a complete range of professional studies including law, medicine, dentistry, and engineering, combined with a comprehensive range of academic studies including science, social science, ancient and modern languages, literature, and history.

Present

Glasgow has the fourth largest financial endowment among UK universities at £120m, and the fifth largest endowment per student, according to the Sutton Trust (2002). In 2003 the university had around 17,000 students and 4,500 members of staff. Over 3,600 of these are postgraduate students, while around 2,600 are foreign students. The university is a member of the Russell Group of elite British Universities and is a founding member of the organisation Universitas 21, an international grouping of universities dedicated to setting world-wide standards for higher education.

Facilities

Universitas 21 Universitas 21 The university's initial accommodations were part of the complex of religious buildings in the precincts of Glasgow Cathedral. This coexistence became increasingly uneasy with time, particularly following the protestant reformation, after which Glasgow became a predominantly Protestant city. In the 17th century this, combined with the university's growth and the broadening and secularisation of its curriculum, led it to establish its own two-quadrangled building outside the cathedral precincts, on the nearby medieval High Street. Over the following centuries, the university's size and scope continued to expand. It was a centre of the Scottish Enlightenment and subsequently of the industrial revolution, and its expansion in the High Street was constrained by the density of the burgeoning mercantile district. Consequently in 1870, it moved to a (then a greenfield site) on the Gilmorehill in the West End of the city (around three miles west of its prior location), enclosed by a large loop of the River Kelvin. Its accommodations there were a number of custom-made buildings, designed by Sir George Gilbert Scott in the Gothic revival style. The largest of these (now called the Gilbert Scott Building) echoed (in a far grander scale) the High Street campus' twin quadrangle layout. Between the two quadrangles Scott built an open cloister, above which are his grand Bute Hall (used for examinations and graduation ceremonies), and the buildings' signature Gothic bell tower. The sandstone cladding and Gothic design of the buildings' exterior belie the modernity of its Victorian construction — Scott's building is hung on a (then cutting-edge) riveted iron frame, with a lightweight wooden-beam roof. Even these enlarged premises could not contain the ever-growing university, which quickly spread across much of Gilmorehill. The 1930s saw the construction of the award-winning round reading room (it is now a grade-A listed building) and an aggressive programme of house purchases, in which the university (fearing the surrounding district of Hillhead was running out of suitable building land) acquired several terraces of Victorian houses and joined them together internally. The departments of Psychology, Computing Science, and Eastern European Languages continue to be housed in these terraces. More buildings were built beside the main buildings, filling the land between University Avenue and the river with natural science buildings and the faculty of medicine. The medical school spread into neighbouring Partick and joined with the Western General Infirmary. The growth and prosperity of the city, which had forced the university's relocation to Hillhead, again proved problematic when more real estate was required. The school of veterinary medicine, which was founded in 1862, moved to a new campus in the leafy suburb of Garscube in 1954. The university later moved its sports ground and associated facilities to Anniesland (around two miles west of the main campus) and built student halls of residence in both Anniesland and Maryhill. 1954 The growth of tertiary education from the 1960s led the university to build numerous modern buildings across the hill, including several brutalist concrete blocks: the Maclaurin building (housing the department of mathematics, named after university graduate Colin Maclaurin); the Boyd Orr building (a squat grey concrete tower housing lecture rooms and laboratories); and the Adam Smith building (housing the social science faculty, named after university graduate Adam Smith). Other additions around this time, including the glass-lined library tower and the amber-brick geology building were more in keeping with the Gilmorehill's leafy suburban architecture. Interestingly, the erection of these buildings around 1968 also involved the demolition of a large number of houses in Ashton Road, and rerouting the west end of University Avenue to its current position. The University's Hunterian Museum resides in the Gilbert Scott Building, and the related Hunterian Gallery is housed in buildings attached to the University Library. The latter includes "The Mackintosh House", a rebuilt terraced house designed by, and furnished after, architect Charles Rennie Mackintosh. The university opened a campus in the borders town of Dumfries. The Crichton campus, designed to meet the needs for tertiary education in an area far from major concentrations of population, is jointly operated by the University of Glasgow, the University of Paisley, Bell College, and the Open University. It offers a modular curriculum, leading to one of a small number of liberal arts degrees. In October 2001 the century-old Bower Building (home to the university's botany department and biological museum) was gutted by fire. Manuscripts by naturalist Charles Darwin, together with a large number of samples obtained on his expeditions, were destroyed. The interior and roof of the building were largely destroyed, although the main facade remained intact. After a £10.8 million refit, the building re-opened to staff and students in November 2004. The Wolfson Medical School Building, with its award-winning glass-fronted atrium, opened in 2002 [http://www.gla.ac.uk/faculties/medicine/medschool.html]. The university is currently over a number of different campuses. The main one is the Gilmorehill campus, in Hillhead. As well as this there is the Vet School at the top of Maryhill Road, on the Garscube Estate. The University also operates a Dental School in the city centre; as well as the aforementioned Crichton campus in Dumfries; and in 2003 they opened their new Education Faculty Building (the St Andrews Building, replacing Bearsden's St Andrews Campus) in the Woodlands area of the city on the site of the former Queens College, which had in turn been bought by Glasgow Caledonian University, from whom the university acquired the site. As well as these teaching campuses the university has halls of residence in and around the North-West of the city. They have the Murano Street halls in Maryhill; the Wolfson halls, also in Maryhill; Queen Margaret halls, in Kelvinside; and Kelvinhaugh Gate, in Yorkhill. In recent years, Dalrymple and Horselethill halls in Dowanhill, Reith halls in North Kelvinside and the Maclay halls in Park Circus (near Kelvingrove Park), have closed and been sold, as the development value of such property increased. The university also has a large sports complex in their Garscube Estate, beside their Wolfson Halls and Vet School. This is a new facility. They sold their previous sports ground (Westerlands) which was in the Anniesland area of Glasgow. The university also has a boathouse situated on the River Clyde. It is out of here that Glasgow University Boat Club train. Glasgow University Boat Club Glasgow University Boat Club

Governance and administration

In common with the other Ancient universities of Scotland the University's constitution is laid out in the Universities (Scotland) Acts. These Act create a tripartite structure of bodies - the University Court (governing body), the Academic Senate (academic affairs) and the General Council (advisory). There is also a clear separation between governance and executive administration.

University Court

The governing body of the University is the University Court, which is responsible for contractual matters; employing staff; and all other matters relating to finance and administration. The Court takes decisions about the deployment of resources as well as formulating strategic plans for the university. The Court is chaired by the Rector (see below for more information), who is elected by all the matriculated students at the university.

Academic Senate

The Academic Senate (or University Senate) is the body which is responsible for the management of academic affairs, and the awarding of all degrees. The Senate consists of various academics and is chaired by the Prinicpal of the university.

Committees

There are also a number of committees of both the Court and Senate that make important decisions and investigate matters referred to them. As well as these bodies there is a General Council made up of the university graduates that is involved in the running of the university. The graduates also elect the Chancellor of the university. A largely honorific post, the current Chancellor is Sir William Kerr Fraser, a former Principal of Glasgow University.

Executive administration

However, day to day management of the University is undertaken by the University Principal (who is also Vice-Chancellor) and the Secretary of Court. The current principal is Sir Muir Russell who replaced Professor Sir Graeme Davies in October, 2003. The current secretary of court is David Newall. There are also five Vice-Principals, each with a specific remit. There is a Vice-Principal in charge of Learning and Teaching (who also acts as the Clerk to Senate); a Vice-Principal Estates; a Vice-Principal Research; a Vice-Principal External Relations; and a Vice-Principal Staffing. They each play a major role in the day to day management of the university.

Faculties

There are currently nine faculties at Glasgow University. They are Arts; Biomedical and Life Sciences; Education (formed when the university merged with St Andrews College of Education); Engineering; Information and Mathematical Sciences; Law, Business and Social Sciences; Medicine (includes Dentistry and Nursing); Physical Sciences; and Veterinary Medicine. The Veterinary School is perhaps Glasgow's most famous Faculty, having wrought the personalities of James Herriot (aka Alf Wight), Eddie Straiton ("The TV Vet"), Sir William Weipers, among many others and has the distinction of having its degree recognised not only by the UK, but also the USA, Australia, Canada, New Zealand, as well as most other countries in the world, an honour shared by only a handful of other institutions. The Medical Faculty is also one of Glasgow's greatest strengths. Traditionally considered one of the top schools in the UK, it placed first in The Times' 2004 ranking of UK university medical departments.

Students

Unlike the majority of Scotland's universities, the students at the University of Glasgow are not members of the National Union of Students - membership has been rejected on a number of occasions on both economic (the costs of membership would exceed £70,000 per year for an institution of this size) and political grounds. Neither does their representative body take the form of a Students' Association, as it does at the other Scottish universities. However, every student is automatically represented by the Glasgow University Students' Representative Council (SRC) and has the right to stand for election to this body and elect its members. The President of the SRC, along with one other SRC member, the Court Assessor, sits on the University Court and a number of SRC members sit on the Academic Senate (which also has the responsibility of overseeing student discipline). Each student has the right to opt out of being a SRC member, although this very rarely happens. Students also elect a Rector (officially styled "Lord Rector") who holds office for a three year term and is legally entitled to chair the university court. This position is in practice largely an honorary and ceremonial one, and has been held by political figures including William Gladstone, Benjamin Disraeli, Andrew Bonar Law, Robert Peel, Raymond Poincaré, Arthur Balfour, and 1970s union activist Jimmy Reid, and latterly by celebrities such as TV presenters Arthur Montford and Johnny Ball, musician Pat Kane, and actors Richard Wilson, Ross Kemp and Greg Hemphill. In the past, few Rectors have actually been present to perform the duties of their office, although in recent years there has been a trend to elect people on the expectation that they will be working rectors. Ross Kemp was asked to resign by the SRC (which he did) for what they felt was a failure to act as a working rector. In 2004, for the first time in its history, the University was left without a Rector as no nominations were received. When the elections were run in December, Israeli whistleblower Mordechai Vanunu was chosen for the post [http://news.bbc.co.uk/1/hi/scotland/4100119.stm], even though he is unable to attend due to restrictions placed upon him by the Israeli government. Mordechai Vanunu Students can also be members of one of the university's two students' unions, Glasgow University Union (GUU) and the Queen Margaret Union (QMU). These are largely social institutions, providing their members with facilities for dining, recreation, socialising, and drinking, and both have a number of meeting rooms available for rental to members. Students are currently barred from holding membership of both unions (by the GUU's bye-laws which state that members cannot be members of other unions, but this is frequently breached), although they can use most of the facilities of both provided they are a member of one. A significant attempt was made to introduce Automatic Joint Student Membership at the end of the 2003/2004 session, which would see all matriculated students automatically become a member of both unions. However, this ran out of time due to a technical failing in the tabling of a resolution to make the necessary constitutional changes at a Special General Meeting of the GUU. Towards the end of the 2004/2005 academic year a motion was put to the SRC suggesting a referendum on whether the student bodies should merge into a single Students Association. The motion was withdrawn but is likely to reappear in the future. Sporting affairs are regulated by the Glasgow University Sports Association (GUSA) (previously the Glasgow University Athletics Club). Students who join one of the sports clubs affiliated with the university, such as the Glasgow University Shinty Club club, must join GUSA. There is also an active student media scene at Glasgow University, part of, but editorially independent from, the SRC. There is a newspaper, the Glasgow University Guardian; a magazine, Glasgow University Magazine (GUM); a television station, Glasgow University Student Television (GUST); and a radio station, Subcity. In recent years, independent of the SRC, the Queen Margaret Union has published a fortnightly magazine, qmunicate, and Glasgow University Union has produced the GUUi.

Alumni and faculty

See: List of Alumni and Faculty of the University of Glasgow Famous scholars associated with the university include Lord Kelvin, Adam Smith, James Watt, John Logie Baird, Colin Maclaurin, and Joseph Lister. Philosopher Francis Hutcheson studied at Glasgow, and protestant reformer John Knox may also have done so. In more recent times, the university boasts of having Europe's largest collection of life scientists, etc.

External links

- [http://www.gla.ac.uk/ University of Glasgow website]
- [http://www.glasgowstudent.net Glasgow University Students' Representative Council]
- [http://www.guu.co.uk/ Glasgow University Union]
- [http://www.qmu.org.uk/ Queen Margaret Union]
- [http://www.gla.ac.uk/student/gusa/ Glasgow University Sports Association (GUSA)]
- [http://www.subcity.org/ Subcity Radio]
- [http://www.src.gla.ac.uk/gust/ Glasgow University Student Television (GUST)] Category:Glasgow Category:Visitor attractions in Glasgow Category:Buildings and structures in Glasgow Glasgow, University of Glasgow, University of ja:グラスゴー大学

Lowercase

Minuscule, or lower case, is the smaller form (case) of letters (in the Roman alphabet: a, b, c, ...). Originally alphabets were written entirely in majuscule (capital) letters which were spaced between well-defined upper and lower bounds. When written quickly with a pen, these tended to rounder and simpler forms, like uncials. It is from these that the first minuscule hands developed, the half-uncials and cursive minuscule, which no longer stay bound between a pair of lines. These in turn formed the foundations for carolingian minuscule, developed by Alcuin for use in the court of Charlemagne, which quickly spread across Europe. Here for the first time it became common to mix both majuscule and minuscule letters in a single text. The word itself is often spelt miniscule, by association with the unrelated word miniature and the prefix mini. This is traditionally regarded as a spelling mistake, but is now so common that dictionaries tend to accept it as a spelling variation. However, miniscule is still less likely to be used for minuscule letters. The term "lower case" comes from manual typesetting. Since minuscules were more frequent in text than majuscules, typesetters often stored them on the lower shelf of a desk to keep them in easy reach.

History

Traditionally, more important letters - those beginning sentences or nouns - were made larger; now they were written in a different script, although there was no fixed capitalization system until the early 18th century (and even then all nouns were capitalized, a system still followed in German but not in English). Similar developments have taken place in other alphabets. The minuscule script for the Greek alphabet has its origins in the seventh century and acquired its quadrilinear form in the eighth century. Over time, uncial letter forms were increasingly mixed into the script. The earliest dated Greek minuscule text is the Uspenski Gospels (MS 461) in the year 835. The modern practice of capitalizing every sentence seems to be imported (and is commonly not used when printing Ancient Greek materials even today). The Samaritan alphabet has also had minuscule letters, which makes it relatively unusual among abjads, which—including Hebrew, Syriac and Arabic—tend to be written without case.

Usage

In scripts with a case distinction, minuscules are generally used in most texts, and for most of any given text, with majuscules reserved for emphasis and special contexts.

Degree (temperature)

:This article describes "degree" as a unit of temperature. For alternative meanings, see Degree (disambiguation). The term degree is used in several scales of temperature. The symbol ° is usually used, followed by the initial letter of the unit, for example °C for degree(s) Celsius. (For temperature differences, the usage is sometimes reversed; then 100 C°, or "100 Celsius degrees", is a temperature difference, while 100 °C, or "100 degrees Celsius", is an actual temperature.) These include:
- degree Celsius (°C)
- degree Delisle (°De)
- degree Fahrenheit (°F)
- degree Newton (°N)
- degree Rankine (°R or °Ra)
- degree Réaumur (°R)
- degree Rømer(°Rø)
- The degree Kelvin (°K) is a former name for the SI unit of temperature. Since 1967 it has been known simply as the kelvin, with symbol K.

Degree symbol

In Unicode, the "degree sign" is U+00B0 (°). The HTML character entity reference for it is °. The Alt+ Code is Alt+0176. Due to a similar appearance in some fonts in print and on computer screens, some other characters may be mistakenly substituted for it: the "masculine ordinal indicator" (U+00BA,