Scientific units named after people
Encyclopedia
This is a list of scientific units named after people. For other lists of eponyms (names derived from people) see eponym
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Note that by convention, the name of the unit is properly written in all-lowercase, but its abbreviation is capitalized.
SI base unit
SI derived unit
Natural unit
Eponym
An eponym is the name of a person or thing, whether real or fictitious, after which a particular place, tribe, era, discovery, or other item is named or thought to be named...
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Note that by convention, the name of the unit is properly written in all-lowercase, but its abbreviation is capitalized.
SI base unitSI base unitThe International System of Units defines seven units of measure as a basic set from which all other SI units are derived. These SI base units and their physical quantities are:* metre for length...
s
- ampereAmpereThe ampere , often shortened to amp, is the SI unit of electric current and is one of the seven SI base units. It is named after André-Marie Ampère , French mathematician and physicist, considered the father of electrodynamics...
(A), electric current – André-Marie AmpèreAndré-Marie AmpèreAndré-Marie Ampère was a French physicist and mathematician who is generally regarded as one of the main discoverers of electromagnetism. The SI unit of measurement of electric current, the ampere, is named after him.... - kelvinKelvinThe kelvin is a unit of measurement for temperature. It is one of the seven base units in the International System of Units and is assigned the unit symbol K. The Kelvin scale is an absolute, thermodynamic temperature scale using as its null point absolute zero, the temperature at which all...
(K), thermodynamic temperature – Lord Kelvin
SI derived unitSI derived unitThe International System of Units specifies a set of seven base units from which all other units of measurement are formed, by products of the powers of base units. These other units are called SI derived units, for example, the SI derived unit of area is square metre , and of density is...
- becquerelBecquerelThe becquerel is the SI-derived unit of radioactivity. One Bq is defined as the activity of a quantity of radioactive material in which one nucleus decays per second. The Bq unit is therefore equivalent to an inverse second, s−1...
(Bq), radioactivity – Henri BecquerelHenri BecquerelAntoine Henri Becquerel was a French physicist, Nobel laureate, and the discoverer of radioactivity along with Marie Curie and Pierre Curie, for which all three won the 1903 Nobel Prize in Physics.-Early life:... - degree CelsiusCelsiusCelsius is a scale and unit of measurement for temperature. It is named after the Swedish astronomer Anders Celsius , who developed a similar temperature scale two years before his death...
(°C), temperature – Anders CelsiusAnders CelsiusAnders Celsius was a Swedish astronomer. He was professor of astronomy at Uppsala University from 1730 to 1744, but traveled from 1732 to 1735 visiting notable observatories in Germany, Italy and France. He founded the Uppsala Astronomical Observatory in 1741, and in 1742 he proposed the Celsius... - coulomb (C), electric charge – Charles-Augustin de CoulombCharles-Augustin de CoulombCharles-Augustin de Coulomb was a French physicist. He is best known for developing Coulomb's law, the definition of the electrostatic force of attraction and repulsion. The [SI unit] of charge, the coulomb, was named after him....
- faradFaradThe farad is the SI unit of capacitance. The unit is named after the English physicist Michael Faraday.- Definition :A farad is the charge in coulombs which a capacitor will accept for the potential across it to change 1 volt. A coulomb is 1 ampere second...
(F), capacitance – Michael FaradayMichael FaradayMichael Faraday, FRS was an English chemist and physicist who contributed to the fields of electromagnetism and electrochemistry.... - grayGray (unit)The gray is the SI unit of absorbed radiation dose of ionizing radiation , and is defined as the absorption of one joule of ionizing radiation by one kilogram of matter ....
(Gy), absorbed dose of radiation - Louis Harold GrayLouis Harold GrayLouis Harold Gray was a British physicist who worked mainly on the effects of radiation on biological systems, inventing the field of radiobiology as he went. A summary of his work is given below... - henry (H), inductance – Joseph HenryJoseph HenryJoseph Henry was an American scientist who served as the first Secretary of the Smithsonian Institution, as well as a founding member of the National Institute for the Promotion of Science, a precursor of the Smithsonian Institution. During his lifetime, he was highly regarded...
- hertzHertzThe hertz is the SI unit of frequency defined as the number of cycles per second of a periodic phenomenon. One of its most common uses is the description of the sine wave, particularly those used in radio and audio applications....
(Hz), frequency – Heinrich Rudolf HertzHeinrich Rudolf HertzHeinrich Rudolf Hertz was a German physicist who clarified and expanded the electromagnetic theory of light that had been put forth by Maxwell... - jouleJouleThe joule ; symbol J) is a derived unit of energy or work in the International System of Units. It is equal to the energy expended in applying a force of one newton through a distance of one metre , or in passing an electric current of one ampere through a resistance of one ohm for one second...
(J), energy, work, heat – James Prescott JouleJames Prescott JouleJames Prescott Joule FRS was an English physicist and brewer, born in Salford, Lancashire. Joule studied the nature of heat, and discovered its relationship to mechanical work . This led to the theory of conservation of energy, which led to the development of the first law of thermodynamics. The... - newton (N), force – Isaac NewtonIsaac NewtonSir Isaac Newton PRS was an English physicist, mathematician, astronomer, natural philosopher, alchemist, and theologian, who has been "considered by many to be the greatest and most influential scientist who ever lived."...
- ohm (Ω) , electrical resistance – Georg OhmGeorg OhmGeorg Simon Ohm was a German physicist. As a high school teacher, Ohm began his research with the recently-invented electrochemical cell, invented by Italian Count Alessandro Volta. Using equipment of his own creation, Ohm determined that there is a direct proportionality between the potential...
- pascalPascal (unit)The pascal is the SI derived unit of pressure, internal pressure, stress, Young's modulus and tensile strength, named after the French mathematician, physicist, inventor, writer, and philosopher Blaise Pascal. It is a measure of force per unit area, defined as one newton per square metre...
(Pa), pressure – Blaise PascalBlaise PascalBlaise Pascal , was a French mathematician, physicist, inventor, writer and Catholic philosopher. He was a child prodigy who was educated by his father, a tax collector in Rouen... - siemensSiemens (unit)The siemens is the SI derived unit of electric conductance and electric admittance. Conductance and admittance are the reciprocals of resistance and impedance respectively, hence one siemens is equal to the reciprocal of one ohm, and is sometimes referred to as the mho. In English, the term...
(S), electrical conductance – Werner von Siemens - sievertSievertThe sievert is the International System of Units SI derived unit of dose equivalent radiation. It attempts to quantitatively evaluate the biological effects of ionizing radiation as opposed to just the absorbed dose of radiation energy, which is measured in gray...
(Sv), radiation dose equivalent – Rolf SievertRolf Maximilian SievertProfessor Rolf Maximilian Sievert was a medical physicist whose major contribution was in the study of the biological effects of radiation.Professor Sievert was born in Stockholm, Sweden... - teslaTesla (unit)The tesla is the SI derived unit of magnetic field B . One tesla is equal to one weber per square meter, and it was defined in 1960 in honour of the inventor, physicist, and electrical engineer Nikola Tesla...
(T), magnetic flux density – Nikola TeslaNikola TeslaNikola Tesla was a Serbian-American inventor, mechanical engineer, and electrical engineer... - voltVoltThe volt is the SI derived unit for electric potential, electric potential difference, and electromotive force. The volt is named in honor of the Italian physicist Alessandro Volta , who invented the voltaic pile, possibly the first chemical battery.- Definition :A single volt is defined as the...
(V), electric potential, electromotive force – Alessandro VoltaAlessandro VoltaCount Alessandro Giuseppe Antonio Anastasio Gerolamo Umberto Volta was a Lombard physicist known especially for the invention of the battery in 1800.-Early life and works:... - wattWattThe watt is a derived unit of power in the International System of Units , named after the Scottish engineer James Watt . The unit, defined as one joule per second, measures the rate of energy conversion.-Definition:...
(W), power, radiant flux – James WattJames WattJames Watt, FRS, FRSE was a Scottish inventor and mechanical engineer whose improvements to the Newcomen steam engine were fundamental to the changes brought by the Industrial Revolution in both his native Great Britain and the rest of the world.While working as an instrument maker at the... - weberWeber (unit)In physics, the weber is the SI unit of magnetic flux. A flux density of one Wb/m2 is one tesla.The weber is named for the German physicist Wilhelm Eduard Weber .- Definition :...
(Wb), magnetic flux – Wilhelm Eduard WeberWilhelm Eduard WeberWilhelm Eduard Weber was a German physicist and, together with Carl Friedrich Gauss, inventor of the first electromagnetic telegraph.-Early years:...
Centimeter-gram-second system of units
- biot (Bi), electric current – Jean-Baptiste BiotJean-Baptiste BiotJean-Baptiste Biot was a French physicist, astronomer, and mathematician who established the reality of meteorites, made an early balloon flight, and studied the polarization of light.- Biography :...
- debyeDebyeThe debye is a CGS unit of electric dipole momentElectric dipole moment is defined as charge times displacement: Historically the debye was defined as the dipole moment resulting from two charges of opposite sign but an equal magnitude of 10-10 statcoulomb10-10 statcoulomb is approximately 0.2083...
(D), electric dipole moment – Peter DebyePeter DebyePeter Joseph William Debye FRS was a Dutch physicist and physical chemist, and Nobel laureate in Chemistry.-Early life:... - eotvosEotvos (unit)The eotvos is a unit of acceleration divided by distance that was used in conjunction with the older centimeter-gram-second system of units. The eotvos is defined as 1/1,000,000,000 galileo per centimetre...
(E), gravitational gradient – Loránd EötvösLoránd EötvösBaron Loránd Eötvös de Vásárosnamény , more commonly called Baron Roland von Eötvös in English literature, was a Hungarian physicist. He is remembered today largely for his work on gravitation and surface tension.-Life:... - galileo (Gal), acceleration – Galileo GalileiGalileo GalileiGalileo Galilei , was an Italian physicist, mathematician, astronomer, and philosopher who played a major role in the Scientific Revolution. His achievements include improvements to the telescope and consequent astronomical observations and support for Copernicanism...
- gaussGauss (unit)The gauss, abbreviated as G, is the cgs unit of measurement of a magnetic field B , named after the German mathematician and physicist Carl Friedrich Gauss. One gauss is defined as one maxwell per square centimeter; it equals 1 tesla...
(G or Gs), magnetic flux density – Carl Friedrich GaussCarl Friedrich GaussJohann Carl Friedrich Gauss was a German mathematician and scientist who contributed significantly to many fields, including number theory, statistics, analysis, differential geometry, geodesy, geophysics, electrostatics, astronomy and optics.Sometimes referred to as the Princeps mathematicorum... - gilbert (Gb), magnetomotive force – William Gilbert
- goeppert-mayer (GM), two-photon absorption cross section – Maria Goeppert-Mayer
- kayserWavenumberIn the physical sciences, the wavenumber is a property of a wave, its spatial frequency, that is proportional to the reciprocal of the wavelength. It is also the magnitude of the wave vector...
(kayser), wavenumber – Heinrich KayserHeinrich KayserHeinrich Gustav Johannes Kayser was a German physicist.He was born at Bingen am Rhein. Kayser's early work was concerned with the characteristics of acoustic waves. He discovered the occurrence of helium in the Earth's atmosphere. Together with Carl Runge, he examined the spectra of chemical... - maxwellMaxwell (unit)The maxwell, abbreviated as Mx, is the compound derived CGS unit of magnetic flux. The unit was previously called a line. The unit name honours James Clerk Maxwell, who presented the unified theory of electromagnetism, and was established by the IEC in 1930.In a magnetic field of strength one...
(Mx), magnetic flux – James Clerk MaxwellJames Clerk MaxwellJames Clerk Maxwell of Glenlair was a Scottish physicist and mathematician. His most prominent achievement was formulating classical electromagnetic theory. This united all previously unrelated observations, experiments and equations of electricity, magnetism and optics into a consistent theory... - oerstedOerstedOersted is the unit of magnetizing field in the CGS system of units.-Difference between cgs and SI systems:...
(Oe), magnetic field strength – Hans Christian ØrstedHans Christian ØrstedHans Christian Ørsted was a Danish physicist and chemist who discovered that electric currents create magnetic fields, an important aspect of electromagnetism... - poisePoiseThe poise is the unit of dynamic viscosity in the centimetre gram second system of units. It is named after Jean Louis Marie Poiseuille ....
(P), dynamic viscosity – Jean Louis Marie PoiseuilleJean Louis Marie PoiseuilleJean Louis Marie Poiseuille was a French physician and physiologist.Poiseuille was born in Paris, France.From 1815 to 1816 he studied at the École Polytechnique in Paris. He was trained in physics and mathematics. In 1828 he earned his D.Sc... - raylRaylA rayl is one of two units of specific acoustic impedance.When sound waves pass through any physical substance the pressure of the waves causes the particles of the substance to move....
, acoustic impedance – Lord Rayleigh - stokes (S or St), kinematic viscosity – George Gabriel StokesGeorge Gabriel StokesSir George Gabriel Stokes, 1st Baronet FRS , was an Irish mathematician and physicist, who at Cambridge made important contributions to fluid dynamics , optics, and mathematical physics...
No longer in use
- franklinStatcoulombThe statcoulomb or franklin or electrostatic unit of charge is the physical unit for electrical charge used in the centimetre-gram-second system of units and Gaussian units. It is a derived unit given by...
(Fr), electric charge – Benjamin FranklinBenjamin FranklinDr. Benjamin Franklin was one of the Founding Fathers of the United States. A noted polymath, Franklin was a leading author, printer, political theorist, politician, postmaster, scientist, musician, inventor, satirist, civic activist, statesman, and diplomat... - clausius (Cl), entropy – Rudolf ClausiusRudolf ClausiusRudolf Julius Emanuel Clausius , was a German physicist and mathematician and is considered one of the central founders of the science of thermodynamics. By his restatement of Sadi Carnot's principle known as the Carnot cycle, he put the theory of heat on a truer and sounder basis...
Others
- ångströmÅngströmThe angstrom or ångström, is a unit of length equal to 1/10,000,000,000 of a meter . Its symbol is the Swedish letter Å....
(Å), distance – Anders Jonas ÅngströmAnders Jonas ÅngströmAnders Jonas Ångström was a Swedish physicist and one of the founders of the science of spectroscopy.-Biography:... - BaudBaudIn telecommunications and electronics, baud is synonymous to symbols per second or pulses per second. It is the unit of symbol rate, also known as baud rate or modulation rate; the number of distinct symbol changes made to the transmission medium per second in a digitally modulated signal or a...
, symbol rate – Emile BaudotÉmile BaudotJean-Maurice-Émile Baudot , French telegraph engineer and inventor of the first means of digital communication Baudot code, was one of the pioneers of telecommunications... - Bark scaleBark scaleThe Bark scale is a psychoacoustical scale proposed by Eberhard Zwicker in 1961. It is named after Heinrich Barkhausen who proposed the first subjective measurements of loudness....
, psychoacoustical scale – Heinrich BarkhausenHeinrich BarkhausenHeinrich Georg Barkhausen , born at Bremen, was a German physicist.Born into a patrician family in Bremen, he showed interest in natural sciences from an early age... - brewster (B), stress optic coefficient – David BrewsterDavid BrewsterSir David Brewster KH PRSE FRS FSA FSSA MICE was a Scottish physicist, mathematician, astronomer, inventor, writer and university principal.-Early life:...
- centimorganCentimorganIn genetics, a centimorgan or map unit is a unit of recombinant frequency for measuring genetic linkage, defined as that distance between chromosome positions for which the expected average number of intervening chromosomal crossovers in a single generation is 0.01. It is often used to infer...
, recombinantion frequency – Thomas Hunt MorganThomas Hunt MorganThomas Hunt Morgan was an American evolutionary biologist, geneticist and embryologist and science author who won the Nobel Prize in Physiology or Medicine in 1933 for discoveries relating the role the chromosome plays in heredity.Morgan received his PhD from Johns Hopkins University in zoology... - curieCurieThe curie is a unit of radioactivity, defined asThis is roughly the activity of 1 gram of the radium isotope 226Ra, a substance studied by the pioneers of radiology, Marie and Pierre Curie, for whom the unit was named. In addition to the curie, activity can be measured using an SI derived unit,...
(Ci), radioactivity – Marie and Pierre CuriePierre CuriePierre Curie was a French physicist, a pioneer in crystallography, magnetism, piezoelectricity and radioactivity, and Nobel laureate. He was the son of Dr. Eugène Curie and Sophie-Claire Depouilly Curie ... - daltonAtomic mass unitThe unified atomic mass unit or dalton is a unit that is used for indicating mass on an atomic or molecular scale. It is defined as one twelfth of the rest mass of an unbound neutral atom of carbon-12 in its nuclear and electronic ground state, and has a value of...
(Da), atomic mass – John DaltonJohn DaltonJohn Dalton FRS was an English chemist, meteorologist and physicist. He is best known for his pioneering work in the development of modern atomic theory, and his research into colour blindness .-Early life:John Dalton was born into a Quaker family at Eaglesfield, near Cockermouth, Cumberland,... - darcyDarcyA darcy and millidarcy are units of permeability, named after Henry Darcy. They are not SI units, but they are widely used in petroleum engineering and geology. Like other measures of permeability, a darcy has the same units as area.-Definition:Permeability measures the ability of fluids to...
(D), permeability, – Henry DarcyHenry DarcyHenry Philibert Gaspard Darcy was a French engineer who made several important contributions to hydraulics.-Biography:... - decibelDecibelThe decibel is a logarithmic unit that indicates the ratio of a physical quantity relative to a specified or implied reference level. A ratio in decibels is ten times the logarithm to base 10 of the ratio of two power quantities...
(dB) dimensionless proportions and ratios, e.g. relative power levels – Alexander Graham BellAlexander Graham BellAlexander Graham Bell was an eminent scientist, inventor, engineer and innovator who is credited with inventing the first practical telephone.... - degree Rankine (°R), temperature – William John Macquorn RankineWilliam John Macquorn RankineWilliam John Macquorn Rankine was a Scottish civil engineer, physicist and mathematician. He was a founding contributor, with Rudolf Clausius and William Thomson , to the science of thermodynamics....
- Dobson unitDobson unitThe Dobson unit is a unit of measurement of atmospheric ozone columnar density, which is dominated by ozone in the stratospheric ozone layer. One Dobson unit refers to a layer of ozone that would be 10 µm thick under standard temperature and pressure. For example, 300 DU of ozone brought...
, atmospheric ozone – Gordon Dobson - Erlang unitErlang unitThe erlang is a dimensionless unit that is used in telephony as a statistical measure of offered load or carried load on service-providing elements such as telephone circuits or telephone switching equipment. It is named after the Danish telephone engineer A. K...
(erl), dimensionless volume of telecommunications traffic – Agner Krarup ErlangAgner Krarup ErlangAgner Krarup Erlang was a Danish mathematician, statistician and engineer, who invented the fields of traffic engineering and queueing theory.... - degree FahrenheitFahrenheitFahrenheit is the temperature scale proposed in 1724 by, and named after, the German physicist Daniel Gabriel Fahrenheit . Within this scale, the freezing of water into ice is defined at 32 degrees, while the boiling point of water is defined to be 212 degrees...
(°F), temperature – Daniel Gabriel Fahrenheit - fermi (fm), distance – Enrico FermiEnrico FermiEnrico Fermi was an Italian-born, naturalized American physicist particularly known for his work on the development of the first nuclear reactor, Chicago Pile-1, and for his contributions to the development of quantum theory, nuclear and particle physics, and statistical mechanics...
- Hounsfield scaleHounsfield scaleThe Hounsfield scale, named after Sir Godfrey Newbold Hounsfield, is a quantitative scale for describing radiodensity.-Definition:The Hounsfield unit scale is a linear transformation of the original linear attenuation coefficient measurement into one in which the radiodensity of distilled water at...
, radiodensity – Godfrey Newbold Hounsfield - janskyJanskyThe flux unit or jansky is a non-SI unit of spectral flux density equivalent to 10−26 watts per square metre per hertz...
(Jy), electromagnetic flux – Karl Jansky - langley (ly), solar radiation – Samuel Pierpont LangleySamuel Pierpont LangleySamuel Pierpont Langley was an American astronomer, physicist, inventor of the bolometer and pioneer of aviation...
- langmuir (L), gas exposure dose – Irving LangmuirIrving LangmuirIrving Langmuir was an American chemist and physicist. His most noted publication was the famous 1919 article "The Arrangement of Electrons in Atoms and Molecules" in which, building on Gilbert N. Lewis's cubical atom theory and Walther Kossel's chemical bonding theory, he outlined his...
- Mach numberMach numberMach number is the speed of an object moving through air, or any other fluid substance, divided by the speed of sound as it is in that substance for its particular physical conditions, including those of temperature and pressure...
(Ma), relative speed – Ernst MachErnst MachErnst Mach was an Austrian physicist and philosopher, noted for his contributions to physics such as the Mach number and the study of shock waves... - neperNeperThe neper is a logarithmic unit for ratios of measurements of physical field and power quantities, such as gain and loss of electronic signals. It has the unit symbol Np. The unit's name is derived from the name of John Napier, the inventor of logarithms...
(Np), relative power level – John NapierJohn NapierJohn Napier of Merchiston – also signed as Neper, Nepair – named Marvellous Merchiston, was a Scottish mathematician, physicist, astronomer & astrologer, and also the 8th Laird of Merchistoun. He was the son of Sir Archibald Napier of Merchiston. John Napier is most renowned as the discoverer... - degree ÖchsleÖchsle scaleThe Oechsle Scale is a hydrometer scale measuring the density of grape must, which is an indication of grape ripeness and sugar content used in wine-making. It is named for Ferdinand Oechsle and it is widely used in the German, Swiss and Luxembourgish wine-making industries...
(°Oe), density – Ferdinand Öchsle - Rockwell scaleRockwell scaleThe Rockwell scale is a hardness scale based on the indentation hardness of a material. The Rockwell test determines the hardness by measuring the depth of penetration of an indenter under a large load compared to the penetration made by a preload. There are different scales, denoted by a single...
(HR), indentation hardness – Stanley Rockwell - röntgenRöntgenThe roentgen is a unit of measurement for exposure to ionizing radiation , and is named after the German physicist Wilhelm Röntgen...
(R), dosage of X-rays or gamma radiation – Wilhelm Röntgen - Richter magnitudeRichter magnitude scaleThe expression Richter magnitude scale refers to a number of ways to assign a single number to quantify the energy contained in an earthquake....
, earthquakeEarthquakeAn earthquake is the result of a sudden release of energy in the Earth's crust that creates seismic waves. The seismicity, seismism or seismic activity of an area refers to the frequency, type and size of earthquakes experienced over a period of time...
power – Charles Francis RichterCharles Francis RichterCharles Francis Richter , was an American seismologist and physicist. Richter is most famous as the creator of the Richter magnitude scale which, until the development of the moment magnitude scale in 1979, quantified the size of earthquakes... - siegbahnX unitThe x unit is a unit of length approximately equal to 0.1 pm . It is used to quote the wavelength of X-rays and gamma rays....
(xu), distance, – Manne SiegbahnManne SiegbahnKarl Manne Georg Siegbahn FRS was a Swedish physicist who was awarded the Nobel Prize in Physics in 1924 "for his discoveries and research in the field of X-ray spectroscopy".... - Scoville unitsScoville scaleThe Scoville scale is a measurement of the spicy heat of a chili pepper. The number of Scoville heat units indicates the amount of capsaicin present. Capsaicin is a chemical compound that stimulates chemoreceptor nerve endings in the skin, especially the mucous membranes.The scale is named after...
, capsaicin content of chili peppers – Wilbur ScovilleWilbur ScovilleWilbur Lincoln Scoville was an American pharmacist and is best known for his creation of "The Scoville Organoleptic Test", now standardized as the Scoville scale. He devised the test and scale in 1912 while working at the Parke-Davis pharmaceutical company to measure piquancy, or "hotness", of... - svedbergSvedbergA svedberg is a non-SI physical unit used for sedimentation coefficients. It characterizes the behaviour of a particle type in sedimentation processes, notably centrifugation. The svedberg is technically a measure of time, and is defined as exactly 10-13 seconds A svedberg (symbol S, sometimes...
(S or Sv), sedimentation rate – Theodor SvedbergTheodor SvedbergTheodor H. E. Svedberg was a Swedish chemist and Nobel laureate, active at Uppsala University. His work with colloids supported the theories of Brownian motion put forward by Einstein and the Polish geophysicist Marian Smoluchowski... - sverdrupSverdrupThe sverdrup, named in honour of the pioneering oceanographer Harald Sverdrup, is a unit of measure of volume transport. It is used almost exclusively in oceanography, to measure the transport of ocean currents. Its symbol is Sv. Note that the sverdrup is not an SI unit, and that its symbol...
(Sv), volume transport rate – Harald SverdrupHarald SverdrupHarald Ulrik Sverdrup was a Norwegian oceanographer and meteorologist who made a number of important theoretical discoveries in these fields. Having first worked in Bergen and Leipzig he was the scientific director of the North Polar expedition of Roald Amundsen aboard the Maud from 1918 to 1925... - torrTorrThe torr is a non-SI unit of pressure with the ratio of 760 to 1 standard atmosphere, chosen to be roughly equal to the fluid pressure exerted by a millimetre of mercury, i.e., a pressure of 1 torr is approximately equal to 1 mmHg...
(Torr), pressure – Evangelista TorricelliEvangelista TorricelliEvangelista Torricelli was an Italian physicist and mathematician, best known for his invention of the barometer.-Biography:Evangelista Torricelli was born in Faenza, part of the Papal States... - trolandTrolandThe troland , named after Leonard T. Troland, is a unit of conventional retinal illuminance. It is meant as a method for correcting photometric measurements of luminance values impinging on the human eye by scaling them by the effective pupil size.The troland typically refers to the ordinary or...
(Td), luminance (human eye) – Leonard Troland
Natural unitNatural unitsIn physics, natural units are physical units of measurement based only on universal physical constants. For example the elementary charge e is a natural unit of electric charge, or the speed of light c is a natural unit of speed...
systems
- Planck unitsPlanck unitsIn physics, Planck units are physical units of measurement defined exclusively in terms of five universal physical constants listed below, in such a manner that these five physical constants take on the numerical value of 1 when expressed in terms of these units. Planck units elegantly simplify...
– Max PlanckMax PlanckMax Karl Ernst Ludwig Planck, ForMemRS, was a German physicist who actualized the quantum physics, initiating a revolution in natural science and philosophy. He is regarded as the founder of the quantum theory, for which he received the Nobel Prize in Physics in 1918.-Life and career:Planck came... - Stoney units – George StoneyGeorge Johnstone StoneyGeorge Johnstone Stoney was an Irish physicist most famous for introducing the term electron as the "fundamental unit quantity of electricity"....
- Schrödinger units – Erwin SchrödingerErwin SchrödingerErwin Rudolf Josef Alexander Schrödinger was an Austrian physicist and theoretical biologist who was one of the fathers of quantum mechanics, and is famed for a number of important contributions to physics, especially the Schrödinger equation, for which he received the Nobel Prize in Physics in 1933...
No longer in use
- Mercalli intensity scaleMercalli intensity scaleThe Mercalli intensity scale is a seismic scale used for measuring the intensity of an earthquake. It measures the effects of an earthquake, and is distinct from the moment magnitude M_w usually reported for an earthquake , which is a measure of the energy released...
, earthquake effects – Giuseppe MercalliGiuseppe MercalliGiuseppe Mercalli was an Italian volcanologist. He is best remembered today for his Mercalli scale for measuring earthquakes which is still used today.-Biography:... - degree Réaumur (°R), temperature – René Antoine Ferchault de RéaumurRené Antoine Ferchault de RéaumurRené Antoine Ferchault de Réaumur was a French scientist who contributed to many different fields, especially the study of insects.-Life:Réaumur was born in a prominent La Rochelle family and educated in Paris...
- degree DelisleDelisle scaleThe Delisle scale is a temperature scale invented in 1732 by the French astronomer Joseph-Nicolas Delisle . Delisle was the author of Mémoires pour servir à l'histoire et aux progrès de l'Astronomie, de la Géographie et de la Physique .He had been invited to Russia by Peter the Great...
(°D), temperature – Joseph-Nicolas DelisleJoseph-Nicolas DelisleJoseph-Nicolas Delisle was a French astronomer.-Life:He was one of the 11 sons of Claude Delisle . Like many of his brothers, among them Guillaume Delisle, he initially followed classical studies. Soon however, he moved to astronomy under the supervision of Joseph Lieutaud and Jacques Cassini... - degree NewtonNewton scaleThe Newton scale is a temperature scale devised by Isaac Newton around 1700. Applying his mind to the problem of heat, he elaborated a first qualitative temperature scale, comprising about twenty reference points ranging from "cold air in winter" to "glowing coals in the kitchen fire". This...
(°N), temperature – Isaac NewtonIsaac NewtonSir Isaac Newton PRS was an English physicist, mathematician, astronomer, natural philosopher, alchemist, and theologian, who has been "considered by many to be the greatest and most influential scientist who ever lived."... - degree RømerRømer scaleRømer is a temperature scale named after the Danish astronomer Ole Christensen Rømer, who proposed it in 1701.In this scale, the zero was initially set using freezing brine. The boiling point of water was defined as 60 degrees...
(°Rø), temperature – Ole Rømer - degree BauméBaumé scaleThe Baumé scale is a pair of hydrometer scales developed by French pharmacist Antoine Baumé in 1768 to measure density of various liquids. The unit of the Baumé scale has been notated variously as degrees Baumé, B°, Bé° and simply Baumé . One scale measures the density of liquids heavier than water...
(°Bé), density – Antoine BauméAntoine BauméAntoine Baumé was a French chemist.He was born at Senlis. He was apprenticed to the chemist Claude Joseph Geoffroy, and in 1752 was admitted a member of the École de Pharmacie, where in the same year he was appointed professor of chemistry... - einsteinEinstein (unit)An einstein is a unit used in irradiance and in photochemistry. One einstein is defined as one mole of photons, regardless of their frequency. Therefore, the number of photons in an einstein is Avogadro's number, 6.022×1023. Irradiance might be measured in einsteins per square metre per second, if...
(E), photochemistry – Albert EinsteinAlbert EinsteinAlbert Einstein was a German-born theoretical physicist who developed the theory of general relativity, effecting a revolution in physics. For this achievement, Einstein is often regarded as the father of modern physics and one of the most prolific intellects in human history... - ponceletPonceletThe poncelet is an obsolete unit of power, once used in France and replaced by cheval vapeur . The unit was named after Jean-Victor Poncelet....
(p), power – Jean-Victor PonceletJean-Victor PonceletJean-Victor Poncelet was a French engineer and mathematician who served most notably as the commandant general of the École Polytechnique... - faraday (Fd), electrical charge – Michael FaradayMichael FaradayMichael Faraday, FRS was an English chemist and physicist who contributed to the fields of electromagnetism and electrochemistry....
- hartleyBan (information)A ban, sometimes called a hartley or a dit , is a logarithmic unit which measures information or entropy, based on base 10 logarithms and powers of 10, rather than the powers of 2 and base 2 logarithms which define the bit. As a bit corresponds to a binary digit, so a ban is a decimal digit...
(Hart), information – Ralph HartleyRalph HartleyRalph Vinton Lyon Hartley was an electronics researcher. He invented the Hartley oscillator and the Hartley transform, and contributed to the foundations of information theory.-Biography:...