An optical fiber is a flexible, transparent fiber made by drawing glass or plastic to a diameter thicker than that of a human hair. Optical fibers are used most as a means to transmit light between the two ends of the fiber and find wide usage in fiber-optic communications, where they permit transmission over longer distances and at higher bandwidths than electrical cables. Fibers are used instead of metal wires. Fibers are used for illumination and imaging, are wrapped in bundles so they may be used to carry light into, or images out of confined spaces, as in the case of a fiberscope. Specially designed fibers are used for a variety of other applications, some of them being fiber optic sensors and fiber lasers. Optical fibers include a core surrounded by a transparent cladding material with a lower index of refraction. Light is kept in the core by the phenomenon of total internal reflection which causes the fiber to act as a waveguide. Fibers that support many propagation paths or transverse modes are called multi-mode fibers, while those that support a single mode are called single-mode fibers.
Multi-mode fibers have a wider core diameter and are used for short-distance communication links and for applications where high power must be transmitted. Single-mode fibers are used for most communication links longer than 1,000 meters. Being able to join optical fibers with low loss is important in fiber optic communication; this is more complex than joining electrical wire or cable and involves careful cleaving of the fibers, precise alignment of the fiber cores, the coupling of these aligned cores. For applications that demand a permanent connection a fusion splice is common. In this technique, an electric arc is used to melt the ends of the fibers together. Another common technique is a mechanical splice, where the ends of the fibers are held in contact by mechanical force. Temporary or semi-permanent connections are made by means of specialized optical fiber connectors; the field of applied science and engineering concerned with the design and application of optical fibers is known as fiber optics.
The term was coined by Indian physicist Narinder Singh Kapany, acknowledged as the father of fiber optics. Guiding of light by refraction, the principle that makes fiber optics possible, was first demonstrated by Daniel Colladon and Jacques Babinet in Paris in the early 1840s. John Tyndall included a demonstration of it in his public lectures in London, 12 years later. Tyndall wrote about the property of total internal reflection in an introductory book about the nature of light in 1870:When the light passes from air into water, the refracted ray is bent towards the perpendicular... When the ray passes from water to air it is bent from the perpendicular... If the angle which the ray in water encloses with the perpendicular to the surface be greater than 48 degrees, the ray will not quit the water at all: it will be reflected at the surface.... The angle which marks the limit where total reflection begins is called the limiting angle of the medium. For water this angle is 48°27′, for flint glass it is 38°41′, while for diamond it is 23°42′.
In the late 19th and early 20th centuries, light was guided through bent glass rods to illuminate body cavities. Practical applications such as close internal illumination during dentistry appeared early in the twentieth century. Image transmission through tubes was demonstrated independently by the radio experimenter Clarence Hansell and the television pioneer John Logie Baird in the 1920s. In the 1930s, Heinrich Lamm showed that one could transmit images through a bundle of unclad optical fibers and used it for internal medical examinations, but his work was forgotten. In 1953, Dutch scientist Bram van Heel first demonstrated image transmission through bundles of optical fibers with a transparent cladding; that same year, Harold Hopkins and Narinder Singh Kapany at Imperial College in London succeeded in making image-transmitting bundles with over 10,000 fibers, subsequently achieved image transmission through a 75 cm long bundle which combined several thousand fibers. Their article titled "A flexible fibrescope, using static scanning" was published in the journal Nature in 1954.
The first practical fiber optic semi-flexible gastroscope was patented by Basil Hirschowitz, C. Wilbur Peters, Lawrence E. Curtiss, researchers at the University of Michigan, in 1956. In the process of developing the gastroscope, Curtiss produced the first glass-clad fibers. A variety of other image transmission applications soon followed. Kapany coined the term fiber optics, wrote a 1960 article in Scientific American that introduced the topic to a wide audience, wrote the first book about the new field; the first working fiber-optical data transmission system was demonstrated by German physicist Manfred Börner at Telefunken Research Labs in Ulm in 1965, followed by the first patent application for this technology in 1966. NASA used fiber optics in the television cameras. At the time, the use in the cameras was classified confidential, employees handling the cameras had to be supervised by someone with an appropriate security clearance. Charles K. Kao and George A. Hockham of the British company Standard Telephones and Cables were the first, in 1965, to promote the idea that the attenuation in optical fibers could be reduced below 20 decibels per kilometer, making fibers a practical communication medium.
They proposed th
Copper is a chemical element with symbol Cu and atomic number 29. It is a soft and ductile metal with high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkish-orange color. Copper is used as a conductor of heat and electricity, as a building material, as a constituent of various metal alloys, such as sterling silver used in jewelry, cupronickel used to make marine hardware and coins, constantan used in strain gauges and thermocouples for temperature measurement. Copper is one of the few metals; this led to early human use in several regions, from c. 8000 BC. Thousands of years it was the first metal to be smelted from sulfide ores, c. 5000 BC, the first metal to be cast into a shape in a mold, c. 4000 BC and the first metal to be purposefully alloyed with another metal, tin, to create bronze, c. 3500 BC. In the Roman era, copper was principally mined on Cyprus, the origin of the name of the metal, from aes сyprium corrupted to сuprum, from which the words derived and copper, first used around 1530.
The encountered compounds are copper salts, which impart blue or green colors to such minerals as azurite and turquoise, have been used and as pigments. Copper used in buildings for roofing, oxidizes to form a green verdigris. Copper is sometimes used in decorative art, both in its elemental metal form and in compounds as pigments. Copper compounds are used as bacteriostatic agents and wood preservatives. Copper is essential to all living organisms as a trace dietary mineral because it is a key constituent of the respiratory enzyme complex cytochrome c oxidase. In molluscs and crustaceans, copper is a constituent of the blood pigment hemocyanin, replaced by the iron-complexed hemoglobin in fish and other vertebrates. In humans, copper is found in the liver and bone; the adult body contains between 2.1 mg of copper per kilogram of body weight. Copper and gold are in group 11 of the periodic table; the filled d-shells in these elements contribute little to interatomic interactions, which are dominated by the s-electrons through metallic bonds.
Unlike metals with incomplete d-shells, metallic bonds in copper are lacking a covalent character and are weak. This observation explains the low high ductility of single crystals of copper. At the macroscopic scale, introduction of extended defects to the crystal lattice, such as grain boundaries, hinders flow of the material under applied stress, thereby increasing its hardness. For this reason, copper is supplied in a fine-grained polycrystalline form, which has greater strength than monocrystalline forms; the softness of copper explains its high electrical conductivity and high thermal conductivity, second highest among pure metals at room temperature. This is because the resistivity to electron transport in metals at room temperature originates from scattering of electrons on thermal vibrations of the lattice, which are weak in a soft metal; the maximum permissible current density of copper in open air is 3.1×106 A/m2 of cross-sectional area, above which it begins to heat excessively. Copper is one of a few metallic elements with a natural color other than silver.
Pure copper acquires a reddish tarnish when exposed to air. The characteristic color of copper results from the electronic transitions between the filled 3d and half-empty 4s atomic shells – the energy difference between these shells corresponds to orange light; as with other metals, if copper is put in contact with another metal, galvanic corrosion will occur. Copper does not react with water, but it does react with atmospheric oxygen to form a layer of brown-black copper oxide which, unlike the rust that forms on iron in moist air, protects the underlying metal from further corrosion. A green layer of verdigris can be seen on old copper structures, such as the roofing of many older buildings and the Statue of Liberty. Copper tarnishes when exposed to some sulfur compounds, with which it reacts to form various copper sulfides. There are 29 isotopes of copper. 63Cu and 65Cu are stable, with 63Cu comprising 69% of occurring copper. The other isotopes are radioactive, with the most stable being 67Cu with a half-life of 61.83 hours.
Seven metastable isotopes have been characterized. Isotopes with a mass number above 64 decay by β−, whereas those with a mass number below 64 decay by β+. 64Cu, which has a half-life of 12.7 hours, decays both ways.62Cu and 64Cu have significant applications. 62Cu is used in 62Cu-PTSM as a radioactive tracer for positron emission tomography. Copper is produced in massive stars and is present in the Earth's crust in a proportion of about 50 parts per million. In nature, copper occurs in a variety of minerals, including native copper, copper sulfides such as chalcopyrite, digenite and chalcocite, copper sulfosalts such as tetrahedite-tennantite, enargite, copper carbonates such as azurite and malachite, as copper or copper oxides such as cuprite and tenorite, respectively; the largest mass of elemental copper discovered weighed 420 tonnes and was found in 1857 on the Keweenaw Peninsula in Michigan, US. Native copper is a polycrystal
A wage is monetary compensation paid by an employer to an employee in exchange for work done. Payment may be calculated as a fixed amount for each task completed, or at an hourly or daily rate, or based on an measured quantity of work done. Wages are part of the expenses. Payment by wage contrasts with salaried work, in which the employer pays an arranged amount at steady intervals regardless of hours worked, with commission which conditions pay on individual performance, with compensation based on the performance of the company as a whole. Waged employees may receive tips or gratuity paid directly by clients and employee benefits which are non-monetary forms of compensation. Since wage labour is the predominant form of work, the term "wage" sometimes refers to all forms of employee compensation. Wage labour involves the exchange of money for time spent at work; as Moses I. Finley lays out the issue in The Ancient Economy: The idea of wage-labour requires two difficult conceptual steps. First it requires the abstraction of a man's labour from both his person and the product of his work.
When one purchases an object from an independent craftsman... one has not bought his labour but the object, which he had produced in his own time and under his own conditions of work. But when one hires labour, one purchases an abstraction, labour-power, which the purchaser uses at a time and under conditions which he, the purchaser, not the "owner" of the labour-power, determines. Second, the wage labour system requires the establishment of a method of measuring the labour one has purchased, for purposes of payment by introducing a second abstraction, namely labour-time; the wage is the monetary measure corresponding to the standard units of working time. The earliest such unit of time, still used, is the day of work; the invention of clocks coincided with the elaborating of subdivisions of time for work, of which the hour became the most common, underlying the concept of an hourly wage. Wages were paid in the Middle Kingdom of ancient Egypt, ancient Greece, ancient Rome. Depending on the structure and traditions of different economies around the world, wage rates will be influenced by market forces and tradition.
Market forces are more dominant in the United States, while tradition, social structure and seniority play a greater role in Japan. In countries where market forces set wage rates, studies show that there are still differences in remuneration for work based on sex and race. For example, according to the U. S. Bureau of Labor Statistics, in 2007 women of all races made 80% of the median wage of their male counterparts; this is due to the supply and demand for women in the market because of family obligations. White men made about 84% the wage of Asian men, black men 64%; these are overall averages and are not adjusted for the type and quality of work done. Seventy-five million workers earned hourly wages in the United States in 2012, making up 59% of employees. In the United States, wages for most workers are set by market forces, or else by collective bargaining, where a labor union negotiates on the workers' behalf; the Fair Labor Standards Act establishes a minimum wage at the federal level that all states must abide by, among other provisions.
Fourteen states and a number of cities have set their own minimum wage rates that are higher than the federal level. For certain federal or state government contacts, employers must pay the so-called prevailing wage as determined according to the Davis-Bacon Act or its state equivalent. Activists have undertaken to promote the idea of a living wage rate which account for living expenses and other basic necessities, setting the living wage rate much higher than current minimum wage laws require; the minimum wage rate is there to protect the well being of the working class. For purposes of federal income tax withholding, 26 U. S. C. § 3401 defines the term "wages" for chapter 24 of the Internal Revenue Code: "For purposes of this chapter, the term “wages” means all remuneration for services performed by an employee for his employer, including the cash value of all remuneration paid in any medium other than cash. Political science: Labour power Proletarian Working class Wage slavery Galbraith, James Kenneth.
Created Unequal: the Crisis in American Pay, in series, Twentieth Century Fund Book. New York: Free Press, 1998. ISBN 0-684-84988-7 Lebergott, Stanley. "Wages and Working Conditions". In David R. Henderson. Concise Encyclopedia of Economics. Library of Economics and Liberty. OCLC 317650570, 50016270, 163149563 U. S. Bureau of Labor Statistics Wealth of Nations – click Chapter 8 Understanding Capitalism Part III: Wages and Labor Markets – Critical of capitalism U. S. Department of Labor: Minimum Wage Laws – Different laws by State Average U. S. farm and non-farm wage LaborFair Resources – Link to Fair Labor Practices The Truth Behind Wages in Mining – How Wages are measured and Current Standards for Mining Professionals Database Central Europe – Data on average wages in Central Europe and in Emerging Markets Salary and wages data collecti
Human overpopulation occurs when the ecological footprint of a human population in a specific geographical location exceeds the carrying capacity of the place occupied by that group. Overpopulation can further be viewed, in a long term perspective, as existing if a population cannot be maintained given the rapid depletion of non-renewable resources or given the degradation of the capacity of the environment to give support to the population. Changes in lifestyle could reverse overpopulated status without a large population reduction; the term human overpopulation refers to the relationship between the entire human population and its environment: the Earth, or to smaller geographical areas such as countries. Overpopulation can result from an increase in births, a decline in mortality rates, an increase in immigration, or an unsustainable biome and depletion of resources, it is possible for sparsely populated areas to be overpopulated if the area has a meagre or non-existent capability to sustain life.
Advocates of population moderation cite issues like quality of life, carrying capacity, risk of starvation as a basis to argue for population decline. Scientists suggest that the human impact on the environment as a result of overpopulation, profligate consumption and proliferation of technology has pushed the planet into a new geological epoch known as the Anthropocene. Human population has been rising continuously since the end of the Black Death, around the year 1350, although the most significant increase has been since the 1950s due to medical advancements and increases in agricultural productivity; the rate of population growth has been declining since the 1980s, while the absolute total numbers are increasing. Recent rate increases in several countries enjoying steady declines are apparently contributing to continued growth in total numbers; as pointed out by Hans Rosling, the critical factor is that the population is not "just growing", but that the growth ratio reached its peak and the total population is now growing much slower.
The UN population forecast of 2017 was predicting "near end of high fertility" globally and anticipating that by 2030 over ⅔ of world population will be living in countries with fertility below the replacement level. And for total world population to stabilize between 10-12 billion people by year 2100; the United Nations has expressed concerns on continued population growth in sub-Saharan Africa. Recent research has demonstrated; as of April 14, 2019 the world's human population is estimated to be 7.699 billion. Or, 7,622,106,064 on May 14, 2018 and the United States Census Bureau calculates 7,472,985,269 for that same date, and over 7 billion by the United Nations. Most contemporary estimates for the carrying capacity of the Earth under existing conditions are between 4 billion and 16 billion. Depending on which estimate is used, human overpopulation may or may not have occurred; the rapid recent increase in human population is causing some concern. The population is expected to reach between 8 and 10.5 billion between the years 2040 and 2050.
In 2017, the United Nations increased the medium variant projections to 9.8 billion for 2050 and 11.2 billion for 2100. The recent rapid increase in human population over the past three centuries has raised concerns that the planet may not be able to sustain present or future numbers of inhabitants; the InterAcademy Panel Statement on Population Growth, circa 1994, stated that many environmental problems, such as rising levels of atmospheric carbon dioxide, global warming, pollution, are aggravated by the population expansion. Other problems associated with overpopulation include the increased demand for resources such as fresh water and food and malnutrition, consumption of natural resources faster than the rate of regeneration, a deterioration in living conditions. Wealthy but populated territories like Britain rely on food imports from overseas; this was felt during the World Wars when, despite food efficiency initiatives like "dig for victory" and food rationing, Britain needed to fight to secure import routes.
However, many believe that waste and over-consumption by wealthy nations, is putting more strain on the environment than overpopulation. In spite of concerns about overpopulation, widespread in developed countries, the number of people living in extreme poverty globally shows a stable decline though the population has grown seven-fold over the last 200 years. Child mortality has declined, which in turn has led to reduced birth rates, thus slowing overall population growth; the global number of famine-related deaths have declined, food supply per person has increased with population growth. Most countries have no direct policy of limiting their birth rates, but the rates have still fallen due to education about family planning and increasing access to birth control and contraception. Concern about overpopulation is an ancient topic. Tertullian was a resident of the city of Carthage in the second century CE, when the population of the world was about 190 million, he notably said: "What most meets our view is our teeming population.
Our numbers are burdensome to the world, which can hardly support us.... In deed and famine, wars, earthquakes have to be regarded as a remedy for nations, as the means of pruning the luxuriance of the human race." Before that, Plato and others broached the topic as well. Throughout recorded history, population growth has been slow despite high birth rates, due to war and other diseases, high infant mortalit
In demographics, the world population is the total number of humans living, was estimated to have reached 7.6 billion people as of May 2018. It took over 200,000 years of human history for the world's population to reach 1 billion. World population has experienced continuous growth since the end of the Great Famine of 1315–1317 and the Black Death in 1350, when it was near 370 million; the highest population growth rates – global population increases above 1.8% per year – occurred between 1955 and 1975, peaking to 2.06% between 1965 and 1970. The growth rate has declined to 1.18% between 2010 and 2015 and is projected to decline further in the course of the 21st century. However, the global population is still growing and is projected to reach about 10 billion in 2050 and more than 11 billion in 2100. Total annual births were highest in the late 1980s at about 139 million, as of 2011 were expected to remain constant at a level of 135 million, while deaths numbered 56 million per year and were expected to increase to 80 million per year by 2040.
The median age of the world's population was estimated to be 30.4 years in 2018. Six of the Earth's seven continents are permanently inhabited on a large scale. Asia is the most populous continent, with its 4.54 billion inhabitants accounting for 60% of the world population. The world's two most populated countries and India, together constitute about 36% of the world's population. Africa is the second most populated continent, with around 1.28 billion people, or 16% of the world's population. Europe's 742 million people make up 10% of the world's population as of 2018, while the Latin American and Caribbean regions are home to around 651 million. Northern America consisting of the United States and Canada, has a population of around 363 million, Oceania, the least populated region, has about 41 million inhabitants. Though it is not permanently inhabited by any fixed population, Antarctica has a small, fluctuating international population based in polar science stations; this population tends to rise in the summer months and decrease in winter, as visiting researchers return to their home countries.
Estimates of world population by their nature are an aspect of modernity, possible only since the Age of Discovery. Early estimates for the population of the world date to the 17th century: William Petty in 1682 estimated world population at 320 million. More refined estimates, broken down by continents, were published in the first half of the 19th century, at 600 to 1000 million in the early 1800s and at 800 to 1000 million in the 1840s, it is difficult for estimates to be better than rough approximations, as modern population estimates are fraught with uncertainties on the order of 3% to 5%. Estimates of the population of the world at the time agriculture emerged in around 10,000 BC have ranged between 1 million and 15 million. Earlier, genetic evidence suggests humans may have gone through a population bottleneck of between 1,000 and 10,000 people about 70,000 BC, according to the Toba catastrophe theory. By contrast, it is estimated that around 50–60 million people lived in the combined eastern and western Roman Empire in the 4th century AD.
The Plague of Justinian, which first emerged during the reign of the Roman emperor Justinian, caused Europe's population to drop by around 50% between the 6th and 8th centuries AD. The population of Europe was more than 70 million in 1340; the Black Death pandemic of the 14th century may have reduced the world's population from an estimated 450 million in 1340 to between 350 and 375 million in 1400. The population of China decreased from 123 million in 1200 to 65 million in 1393 due to a combination of Mongol invasions and plague. Starting in AD 2, the Han Dynasty of ancient China kept consistent family registers in order to properly assess the poll taxes and labor service duties of each household. In that year, the population of Western Han was recorded as 57,671,400 individuals in 12,366,470 households, decreasing to 47,566,772 individuals in 9,348,227 households by AD 146, towards the End of the Han Dynasty. At the founding of the Ming Dynasty in 1368, China's population was reported to be close to 60 million.
England's population reached an estimated 5.6 million in 1650, up from an estimated 2.6 million in 1500. New crops that were brought to Asia and Europe from the Americas by Portuguese and Spanish colonists in the 16th century are believed to have contributed to population growth. Since their introduction to Africa by Portuguese traders in the 16th century and cassava have replaced traditional African crops as the most important staple food crops grown on the continent; the pre-Columbian North American population numbered somewhere between 2 million and 18 million. Encounters between European explorers and populations in the rest of the world introduced local epidemics of extraordinary virulence. According to the most extreme scholarly claims, as many as 90% of the Native American population of the New World died due to Old World diseases such as smallpox and influenza. Over the centuries, the Europeans had developed high degrees of immunity to these diseases, while the indigenous peoples had no such immunity.
During the European Agricultural and Industrial Revolutions, the life expectancy of children increased dramatically. The percentage of the children born in London who died before the age of five decreased from 74.5% in
Technology is the collection of techniques, skills and processes used in the production of goods or services or in the accomplishment of objectives, such as scientific investigation. Technology can be the knowledge of techniques and the like, or it can be embedded in machines to allow for operation without detailed knowledge of their workings. Systems applying technology by taking an input, changing it according to the system's use, producing an outcome are referred to as technology systems or technological systems; the simplest form of technology is the use of basic tools. The prehistoric discovery of how to control fire and the Neolithic Revolution increased the available sources of food, the invention of the wheel helped humans to travel in and control their environment. Developments in historic times, including the printing press, the telephone, the Internet, have lessened physical barriers to communication and allowed humans to interact on a global scale. Technology has many effects, it has allowed the rise of a leisure class.
Many technological processes produce unwanted by-products known as pollution and deplete natural resources to the detriment of Earth's environment. Innovations have always influenced the values of a society and raised new questions in the ethics of technology. Examples include the rise of the notion of efficiency in terms of human productivity, the challenges of bioethics. Philosophical debates have arisen over the use of technology, with disagreements over whether technology improves the human condition or worsens it. Neo-Luddism, anarcho-primitivism, similar reactionary movements criticize the pervasiveness of technology, arguing that it harms the environment and alienates people; the use of the term "technology" has changed over the last 200 years. Before the 20th century, the term was uncommon in English, it was used either to refer to the description or study of the useful arts or to allude to technical education, as in the Massachusetts Institute of Technology; the term "technology" rose to prominence in the 20th century in connection with the Second Industrial Revolution.
The term's meanings changed in the early 20th century when American social scientists, beginning with Thorstein Veblen, translated ideas from the German concept of Technik into "technology." In German and other European languages, a distinction exists between technik and technologie, absent in English, which translates both terms as "technology." By the 1930s, "technology" referred not only to the study of the industrial arts but to the industrial arts themselves. In 1937, the American sociologist Read Bain wrote that "technology includes all tools, utensils, instruments, clothing and transporting devices and the skills by which we produce and use them." Bain's definition remains common among scholars today social scientists. Scientists and engineers prefer to define technology as applied science, rather than as the things that people make and use. More scholars have borrowed from European philosophers of "technique" to extend the meaning of technology to various forms of instrumental reason, as in Foucault's work on technologies of the self.
Dictionaries and scholars have offered a variety of definitions. The Merriam-Webster Learner's Dictionary offers a definition of the term: "the use of science in industry, etc. to invent useful things or to solve problems" and "a machine, piece of equipment, etc., created by technology." Ursula Franklin, in her 1989 "Real World of Technology" lecture, gave another definition of the concept. The term is used to imply a specific field of technology, or to refer to high technology or just consumer electronics, rather than technology as a whole. Bernard Stiegler, in Technics and Time, 1, defines technology in two ways: as "the pursuit of life by means other than life," and as "organized inorganic matter."Technology can be most broadly defined as the entities, both material and immaterial, created by the application of mental and physical effort in order to achieve some value. In this usage, technology refers to tools and machines that may be used to solve real-world problems, it is a far-reaching term that may include simple tools, such as a crowbar or wooden spoon, or more complex machines, such as a space station or particle accelerator.
Tools and machines need not be material. W. Brian Arthur defines technology in a broad way as "a means to fulfill a human purpose."The word "technology" can be used to refer to a collection of techniques. In this context, it is the current state of humanity's knowledge of how to combine resources to produce desired products, to solve problems, fulfill needs, or satisfy wants; when combined with another term, such as "medical technology" or "space technology," it refers to the state of the respective field's knowledge and tools. "State-of-the-art technology" refers to the high technology available to humanity in any field. Technology can be viewed as an activity that changes culture. Additionally, technology is the application of math, science, an
An oil is any nonpolar chemical substance, a viscous liquid at ambient temperatures and is both hydrophobic and lipophilic. Oils have a high carbon and hydrogen content and are flammable and surface active; the general definition of oil includes classes of chemical compounds that may be otherwise unrelated in structure and uses. Oils may be animal, vegetable, or petrochemical in origin, may be volatile or non-volatile, they are used for food, medical purposes and the manufacture of many types of paints and other materials. Specially prepared oils are used in some religious rituals as purifying agents. First attested in English 1176, the word oil comes from Old French oile, from Latin oleum, which in turn comes from the Greek ἔλαιον, "olive oil, oil" and that from ἐλαία, "olive tree", "olive fruit"; the earliest attested forms of the word are the Mycenaean Greek, e-ra-wo and, e-rai-wo, written in the Linear B syllabic script. Organic oils are produced in remarkable diversity by plants and other organisms through natural metabolic processes.
Lipid is the scientific term for the fatty acids and similar chemicals found in the oils produced by living things, while oil refers to an overall mixture of chemicals. Organic oils may contain chemicals other than lipids, including proteins and alkaloids. Lipids can be classified by the way that they are made by an organism, their chemical structure and their limited solubility in water compared to oils, they have a high carbon and hydrogen content and are lacking in oxygen compared to other organic compounds and minerals. Crude oil, or petroleum, its refined components, collectively termed petrochemicals, are crucial resources in the modern economy. Crude oil originates from ancient fossilized organic materials, such as zooplankton and algae, which geochemical processes convert into oil; the name "mineral oil" is a misnomer, in that minerals are not the source of the oil—ancient plants and animals are. Mineral oil is organic. However, it is classified as "mineral oil" instead of as "organic oil" because its organic origin is remote, because it is obtained in the vicinity of rocks, underground traps, sands.
Mineral oil refers to several specific distillates of crude oil. Several edible vegetable and animal oils, fats, are used for various purposes in cooking and food preparation. In particular, many foods are fried in oil much hotter than boiling water. Oils are used for flavoring and for modifying the texture of foods. Cooking oils are derived either from animal fat, as butter and other types, or plant oils from the olive, maize and many other species. Oils are applied to hair to give it a lustrous look, to prevent tangles and roughness and to stabilize the hair to promote growth. See hair conditioner. Oil has been used throughout history as a religious medium, it is considered a spiritually purifying agent and is used for anointing purposes. As a particular example, holy anointing oil has been an important ritual liquid for Judaism and Christianity. Color pigments are suspended in oil, making it suitable as a supporting medium for paints; the oldest known extant oil paintings date from 650 AD. Oils are used for instance in electric transformers.
Heat transfer oils are used both as coolants, for heating and in other applications of heat transfer. Given that they are non-polar, oils do not adhere to other substances; this makes them useful as lubricants for various engineering purposes. Mineral oils are more used as machine lubricants than biological oils are. Whale oil is preferred for lubricating clocks, because it does not evaporate, leaving dust, although its use was banned in the USA in 1980, it is a long-running myth that spermaceti from whales has still been used in NASA projects such as the Hubble Telescope and the Voyager probe because of its low freezing temperature. Spermaceti is not an oil, but a mixture of wax esters, there is no evidence that NASA has used whale oil; some oils burn in liquid or aerosol form, generating light, heat which can be used directly or converted into other forms of energy such as electricity or mechanical work. To obtain many fuel oils, crude oil is pumped from the ground and is shipped via oil tanker or a pipeline to an oil refinery.
There, it is converted from crude oil to diesel fuel, fuel oils, jet fuel, kerosene and liquefied petroleum gas. A 42-US-gallon barrel of crude oil produces 10 US gallons of diesel, 4 US gallons of jet fuel, 19 US gallons of gasoline, 7 US gallons of other products, 3 US gallons split between heavy fuel oil and liquified petroleum gases, 2 US gallons of heating oil; the total production of a barrel of crude into various products results in an increase to 45 US gallons. Not all oils used as fuels are mineral oils, see biodiesel and vegetable oil fuel. In the 18th and 19th cent