the-french-artist/wikipedia_20220301.simple_sentence_split huggingface dataset:
The prevailing Big Bang model accounts for many of the experimental observations described above, such as the correlation of distance and redshift of galaxies, the universal ratio of hydrogen:helium atoms, and the ubiquitous, isotropic microwave radiation background.
As noted above, the redshift arises from the metric expansion of space; as the space itself expands, the wavelength of a photon traveling through space likewise increases, decreasing its energy.
The longer a photon has been traveling, the more expansion it has undergone; hence, older photons from more distant galaxies are the most red-shifted.
Determining the correlation between distance and redshift is an important problem in experimental physical cosmology.
Other experimental observations can be explained by combining the overall expansion of space with nuclear physics and atomic physics.
As the Universe expands, the energy density of the electromagnetic radiation decreases more quickly than does that of matter, since the energy of a photon decreases with its wavelength.
Thus, although the energy density of the Universe is now dominated by matter, it was once dominated by radiation; poetically speaking, all was light.
As the Universe expanded, its energy density decreased and it became cooler; as it did so, the elementary particles of matter could associate stably into ever larger combinations.
Thus, in the early part of the matter-dominated era, stable protons and neutrons formed, which then associated into atomic nuclei.
At this stage, the matter in the Universe was mainly a hot, dense plasma of negative electrons, neutral neutrinos and positive nuclei.
Nuclear reactions among the nuclei led to the present abundances of the lighter nuclei, particularly hydrogen, deuterium, and helium.
Eventually, the electrons and nuclei combined to form stable atoms, which are transparent to most wavelengths of radiation; at this point, the radiation decoupled from the matter, forming the ubiquitous, isotropic background of microwave radiation observed today.
Other observations are not clearly answered by known physics.
According to the prevailing theory, a slight imbalance of matter over antimatter was present in the Universe's creation, or developed very shortly thereafter.
Although the matter and antimatter mostly annihilated one another, producing photons, a small residue of matter survived, giving the present matter-dominated Universe.
Several lines of evidence also suggest that a rapid cosmic inflation of the Universe occurred very early in its history (roughly 10−35 seconds after its creation).
Recent observations also suggest that the cosmological constant (Λ) is not zero, and that the net mass-energy content of the Universe is dominated by a dark energy and dark matter that have not been characterized scientifically.
They differ in their gravitational effects.
Dark matter gravitates as ordinary matter does, and thus slows the expansion of the Universe; by contrast, dark energy serves to accelerate the Universe's expansion.
Multiverse hypothesis
Some people think that there is more than one universe.
They think that there is a set of universes called the multiverse.
By definition, there is no way for anything in one universe to affect something in another.
The multiverse is not yet a scientific idea because there is no way to test it.
An idea that cannot be tested or is not based on logic is not science.
So it is not known if the multiverse is a scientific idea.
The future of the Universe is a mystery.
However, there has a couple of theories based on the possible shapes of the Universe:
If the Universe is a closed sphere, it will stop expanding.
The Universe will do the opposite of that and become a singularity for another Big Bang.
This is the Big Crunch or Big Bounce theory.
If the Universe is an opened sphere, it will speed up the expansion.
After 22,000,000,000 (22 billion) years, the Universe will rip apart with the force.
This is the Big Rip theory.
If the Universe is flat, it will expand forever.
All stars will lose their energy for that and become a dwarf star.
After a googol years, the black holes will also be gone.
This is the Heat Death or Big Freeze theory.
A chance "Boltzmann's brain" may appear, and random quantum fluctuations and quantum tunnelling could generate a new Big Bang after an incredible amount of time.
Over an infinite time there could also be an entropy decrease by Poincaré recurrence theorem or by thermal fluctuations.
Edward Robert Harrison 2000.
Cosmology 2nd ed.
The classic text for a generation.
For lay readers.
-------- 2008.
Challenging.
Antiverse
Age of the Universe at Space.
Stephen Hawking's Universe  – Why is the universe the way it is?
Cosmology FAQ
Cosmos – An "illustrated dimensional journey from microcosmos to macrocosmos"
Illustration comparing the sizes of the planets, the sun, and other stars
Logarithmic Maps of the Universe
My So-Called Universe  – Arguments for and against an infinite and parallel universes
Parallel Universes  by Max Tegmark
The Dark Side and the Bright Side of the Universe Princeton University, Shirley Ho
Richard Powell: An Atlas of the Universe – Images at various scales, with explanations
Multiple Big Bangs
Universe – Space Information Centre
Exploring the Universe  at Nasa.gov
The Known Universe created by the American Museum of Natural History
Units of measurement give standards so that the numbers from our measurements refer to the same thing.
Measurement is a process that uses numbers to describe a physical quantity.
We can measure how big things are, how warm they are, how heavy they are, and many other features.
For example, the metre is a standard unit to measure length.
Before 1982, one meter was defined as the distance between two markers on a special metal rod.
During that time, saying that something had a length of two meters meant that it was exactly twice as long as the rod used to define the meter.
Now scientists define the meter by using the speed of light.
In the past, different units were used in different countries.
Today, most units of measure fall into one of three systems:
The older two, the British imperial system and the closely related US customary system use the foot as a measure of length, the pound as a measure for weight, and the second as a measure for time.
They use other units as well.
The number of smaller units that make the bigger units in these two systems varies: For example, there are 12 inches in a foot and 16 ounces in a pound.
The newest and most used of the three systems is the metric system or SI system which use 10, 100 or 1000 of a smaller unit to make a bigger one.
For instance, there are 100 centimetres in one metre or 1000 grams in one kilogram.
This system uses the metre for length and kilogram for mass.
The common, non-metric measurement of time does not follow this pattern.
The second is the basis for time measurement, and it is based on the sexagesimal system: 60 seconds make one minute, and 60 minutes make one hour.
Number and unit of measurement
The property of the thing being measured is given as a number of units of measure.
The number only has sense when the unit of measurement is also given.
By that number it represents a measurement of something.
For example, The Eiffel Tower in Paris, France is  tall.
That is, the distance from the top to the bottom of the Eiffel Tower is 300 metres.
The property of the Eiffel Tower being measured is a distance.
The number measured is 300.
300 of what?
The unit of measurement is the metre.
Measurement standards
Standards are usually special objects used to make measurements.
A metre stick is an example of a standard.
When you measure something with a metre stick, you can compare that measurement to anything else that is also measured with a metre stick.
This makes measurement easier and comparisons between measurements easier.
Science, medicine and engineering use smaller units of measurement to measure small things with less error.
It is easy to measure large things using larger units of measurement.
Astronomical measurements like the width of a galaxy use light years and parsecs.
Systems of units of measurement
There are many different standards and units used all over the world.
Some became less used during the 19th and 20th centuries.
Metric System
The metric system is a system of measurement used in most of the world.
It is also called the International System of Units, or SI.
The units of length or linear size are based on the metre.
They include the kilometre (km) which is 1,000 metres, the centimetre (cm), and the millimetre (mm) which is 1/1,000th of a metre.
The unit of volume is the litre.
It is used for measuring an amount of liquid.
A millilitre (abbreviated as mL) is the amount of liquid that would fill up a cube that measures 1 centimetre on each side.
One litre of liquid would fill up a cube that is 10 cm on each side.
The unit of mass is the kilogram.
A kilogram (kg) is the mass of 1 litre of water (at  temperature and  pressure).
1 gram (g) is the mass of 1 millilitre of water at .
The metric tonne is 1,000 kilograms or a million grams.
Imperial units were defined in the United Kingdom in 1824.
These units were based on similar units that were in use before 1824.
Imperial units were used in countries that were part of the British Empire.
While many of these countries, including the United Kingdom, have officially adopted SI, the older system of units are still used.
US customary units
US customary units are the official units used in the US.
These are similar to the British imperial units and also based on the units used in the United Kingdom from before American Independence.
Some of the units are different to the British ones.
For example, there are 20 imperial fluid ounces in an imperial pint, but 16 US fluid ounces in a US pint.
Additionally, the US fluid ounce is slightly bigger than the imperial fluid ounce.
The result is that US pints and gallons are smaller than imperial pints and gallons.
In the United States, the metric system has been legal for trade since 1866 but other measurements such as the gallon, inch, and the pound are still widely used.
Length - inch (in), foot (ft), yard (yd), and mile.
1 foot = 12 inches
1 yard = 3 feet (plural of foot) = 36 inches
1 mile = 1760 yards = 5280 feet
Imperial volume - imperial fluid ounce (fl oz), imperial pint (pt), and imperial gallon (gal).
1 imperial pint = 20 imperial fluid ounces
1 imperial gallon = 8 imperial pints
US volume - US fluid ounce (fl oz), US cup (cp), US pint (pt), US quart (qt), and US gallon (gal).
1 US cup = 8 US fluid ounces
1 US pint = 2 US cups = 16 US fluid ounces
1 US quart = 2 US pints = 4 US cups = 32 US fluid ounces
1 US gallon = 4 US quarts = 8 US pints = 16 US cups
Weight and mass - ounce (oz), pound (lb), and stone (st).
1 pound = 16 ounces
1 stone = 14 pounds
The ounces for weight and volume are different.
Even when measuring water, the number of ounces of weight is not the same as the number of fluid ounces.
Converting between systems
Metric to US
1 metre = 1.09 yards = 39.37 inches.
1 litre = 33.3 fluid ounces = 1.76 pints = .26 US gallons.
1 kilogram = 35.32 ounces = 2.2 pounds
US to metric
1 inch = 2.54 centimetres
1 foot = 30.48 centimetres
1 yard = 0.9144 metres
1 mile = 1.609344 kilometres
1 fluid ounce = 29.6 millilitres
1 pint = 473.1 millilitres
1 gallon = 3.79 litres
1 cup = 236.55 millilitres
1 ounce = 28.35 grams
1 pound = 0.45359237 kilograms
Other units of measurement
The unit of time is the second.
The minute (60 seconds) and hour (60 minutes or 3600 seconds) are larger units.
A day is defined as 24 hours, but the Earth’s rotation has slowed.
The difference is corrected at the end of some years with what is called a leap second.
A week (7 days) and month are also standard units.
A unit of measurement that applies to money is called a unit of account.
This is normally a currency issued by a country.
For instance, the United States use dollars.
Each dollar is 100 cents.
The United Kingdom uses pounds.
Each pound is 100 pennies or pence.
The European Union uses the Euro.
There are 100 cents in the Euro.
The units for electricity, magnetism and radiation were mostly invented in the 19th century when scientists learned how to measure them.
Most were originally given imperial systems, but it is usual to use metric systems for them today.
ar:قياسات
tr:Ölçüm
U.S. customary units is the system of units of measurement used to measure things in the United States and U.S. territories.
The system of Imperial units is similar and in some parts identical.
Temperature is measured in degrees Fahrenheit (°F).
Here is a formula to convert from °C to °F:
Units of weight and mass include the pound (453.6 grams), which contains 16 ounces.
This should not be confused with the British pound which is a type of money.
The different uses of the word pound can cause confusion.
Different sizes of ounce are also in use.
Some people have been trying to replace these units with the metric system since the 1820s.
Much infrastructure in the United States and British Empire was built in past centuries using the old measures.
During the 20th century some sectors such as science, medicine and the military of the United States converted to metric but Americans still use the old units for daily purposes.
On the other hand, world trade is conducted using the metric system and except for the US, the world uses the metric system for almost all purposes.
Mass and weight
Uranus is the seventh planet from the Sun in the Solar System.
It is an ice giant as Neptune.
It is the third largest planet in the solar system.
The planet is made of ice, gases and liquid metal.
Its atmosphere contains hydrogen (1H), helium (2He) and methane.
The temperature on Uranus is  near the top of its atmosphere, but its small solid core (about 55% the mass of Earth) is probably about .
The planet is tilted on its axis so much that it is sideways.
It has five big moons, many small ones, and a small system of 13 planetary rings.
The distance between Uranus and the Sun is about 2.8 billion km.
Uranus completes its orbit  around the Sun in 84 earth years.
It completes a spin around itself in 17 hours and 14 minutes.
This means there are about 43,000 Uranian days in one Uranian year.
Uranus was discovered in 1781.
This planet can be seen with the naked eye under perfect conditions.
John Flamsteed saw it decades earlier but mistook it for a star (34 Tauri).
Uranus  has been observed many times through a telescope, and even through the naked eye, but was mistaken for a star due to its slow orbit.
Sir William Herschel observed Uranus on 13 March 1781 from the garden of his house at 19 New King Street in Bath, Somerset, England (now the Herschel Museum of Astronomy), and first reported it (on 26 April 1781) as a comet.
With a homemade 6.2-inch reflecting telescope, Herschel "engaged in a series of observations on the parallax of the fixed stars."
Herschel wrote in his journal: "In the quartile near ζ Tauri ... either [a] Nebulous star or perhaps a comet."
On 17 March he noted: "I looked for the Comet or Nebulous Star and found that it is a Comet, for it has changed its place."
When he presented his discovery to the Royal Society, he continued to assert that he had found a comet, but also implicitly compared it to a planet:
Herschel notified the Astronomer Royal Nevil Maskelyne of his discovery and received this reply from him on 23 April 1781: "I don't know what to call it.
It is as likely to be a regular planet moving in an orbit nearly circular to the sun as a Comet moving in a very eccentric ellipsis.
I have not yet seen any coma or tail to it."
Although Herschel continued to describe his new object as a comet, other astronomers had already begun to think otherwise.
Finnish-Swedish astronomer Anders Johan Lexell, working in Russia, was the first to calculate the orbit of the new object.
Its nearly circular orbit led him to a conclusion that it was a planet rather than a comet.
Berlin astronomer Johann Elert Bode described Herschel's discovery as "a moving star that can be deemed a hitherto unknown planet-like object circulating beyond the orbit of Saturn".
Bode concluded that its near-circular orbit was more like a planet's than a comet's.
The object was soon universally accepted as a new planet.
By 1783, Herschel acknowledged this to Royal Society president Joseph Banks: "By the observation of the most eminent Astronomers in Europe it appears that the new star, which I had the honour of pointing out to them in March 1781, is a Primary Planet of our Solar System."
In recognition of his achievement, King George III gave Herschel an annual stipend of £200 on condition that he move to Windsor so that the Royal Family could look through his telescopes ().
They are named for characters from the works of Shakespeare and Alexander Pope.
The five biggest moons are Miranda, Ariel, Umbriel, Titania and Oberon.
Many moons have yet to be discovered.
In 1986, NASA's Voyager 2 visited Uranus.
This is the only space probe that tried to investigate the planet from a short distance.
The spacecraft studied the atmosphere of the planet.
Uranus is covered in blue clouds.
The top clouds, made of methane, are difficult to see.
Lower clouds are thought to be frozen water.
There are also violent storms.
Wind speeds can reach .
Scientists are studying the clouds to try to understand the storms on the planet.
The planet Uranus has a system made of 13 rings which is far fewer than the rings of Saturn but more than those around Jupiter and Neptune.
The rings of Uranus were discovered in 1977.
More than 200 years ago, William Herschel also reported observing rings, but modern astronomers do not believe that he saw them, because they are very dark and faint.
Two additional rings were discovered in 1986 in images taken by Voyager 2, and two outer rings were found in 2003–2005 by the Hubble Space Telescope.
The rings are probably mainly composed of frozen water.
The rings of Uranus are thought to be relatively young, not more than 600 million years old.
The Uranian ring system probably began from the collisional fragmentation of moons that once existed around the planet.
After colliding, the moons probably broke up into many particles, which survived as narrow, optically dense rings only in zones of maximum stability.
General properties
The ring system of Uranus has thirteen distinct rings.
In order of increasing distance from the planet they are: 1986U2R/ζ, 6, 5, 4, α, β, η, γ, δ, λ, ε, ν, μ rings.
They can be divided into three groups: nine narrow main rings (6, 5, 4, α, β, η, γ, δ, ε), two dusty rings (1986U2R/ζ, λ) and two outer rings (μ, ν).
The rings of Uranus   consist mainly of macroscopic particles and  little dust, although dust is known to be present in 1986U2R/ζ, η, δ, λ, ν and μ rings.
In addition to these well-known rings, there may be numerous optically thin dust bands and faint rings between them.
These faint rings and dust bands may exist only temporarily.
Some of them became visible during a series of ring plane-crossing events in 2007.
A number of dust bands between the rings were observed in forward-scattering  geometry by Voyager 2.
All rings of Uranus show azimuthal brightness variations.
The rings are made of an extremely dark material.
The rings are slightly red in the ultraviolet and visible parts of the spectrum and grey in near-infrared.
They show no identifiable spectral features.
The chemical composition of the ring particles is not known.
However, they cannot be made of pure water ice like the rings of Saturn because they are too dark, darker than the inner moons of Uranus.
This shows that they are probably a mixture of the ice and a dark material.
The nature of this material is not clear, but it may be organic compounds considerably darkened by the charged particle irradiation from the Uranian magnetosphere.
The rings' particles may consist of a heavily processed material which was initially similar to that of the inner moons.
As a whole, the ring system of Uranus is unlike either the faint dusty rings of Jupiter or the broad and complex rings of Saturn, some of which are composed of very bright material—water ice.
However, there are similarities with some parts of the latter ring system; the Saturnian F ring and the ε ring are both narrow, relatively dark and are shepherded by a pair of moons.
The newly discovered outer rings of Uranus are similar to the outer G and E rings of Saturn.
Narrow ringlets existing in the broad Saturnian rings also resemble the narrow rings of Uranus.
In addition, dust bands observed between the main rings of Uranus may be similar to the rings of Jupiter.
In contrast, the Neptunian ring system is quite similar to that of Uranus, although it is less complex, darker and contains more dust.
The Neptunian rings are also positioned further from the planet.
Uranus revolves around the Sun once every 84 Earth years.
Its average distance from the Sun is roughly 3 billion km (about 20 AU).
The intensity of sunlight on Uranus is about 1/400 that on Earth.
Its orbital elements were first calculated in 1783 by Pierre-Simon Laplace.
With time, discrepancies began to appear between the predicted and observed orbits, and in 1841, John Couch Adams first proposed that the differences might be due to the gravitational tug of an unseen planet.
In 1845, Urbain Le Verrier began his own independent research into Uranus's orbit.
On September 23, 1846, Johann Gottfried Galle found a new planet, later called Neptune, at nearly the position predicted by Le Verrier.
The rotational period of the interior of Uranus is 17 hours, 14 minutes, clockwise (retrograde).
As on all giant planets, its upper atmosphere experiences very strong winds in the direction of rotation.
At some latitudes, such as about two-thirds of the way from the equator to the south pole, visible features of the atmosphere move much faster, making a full rotation in as little as 14 hours.
NASA's Uranus fact sheet
Uranus Profile  by NASA's Solar System Exploration
Keck pictures of Uranus show best view from the ground  — Press release with some photographs showing rings, satellites and clouds
News reports of December 22, 2005 rings and moons discovery
New Moons and Rings found at Uranus, SPACE.com
Two more rings discovered around Uranus , MSNBC
Planets—Uranus A kid's guide to Uranus.
Uranus (planet) -Citizendium
A university is a higher learning institution.
The word university comes from the Latin universitas magistrorum et scholarium, roughly meaning "community of teachers and scholars".
Students can go to university to get an academic degree.
Unlike the schooling they have done before, the courses at university are specialised.
A person studying biology at university has many courses about biology and fewer courses in other fields such as languages or history.
To get a higher degree, people must do some research.
Not all subjects are offered at universities.
Mainly, universities offer courses which are about knowledge.
They usually do not offer courses in practical trades.
In some cases such as law, where there are both knowledge and practical issues, the university does mainly the theoretical side of the subject.
Practical qualifications are done elsewhere.
The universities were born in Europe during the Middle Ages.
The first institution of this type was the University of Bologna, which later became a model for other centres of education.
At first, the universities had formed themselves according to the model of the professional groups and like almost everything in the Middle Ages, they remained tied to the Catholic Church.
At the beginning, they had worked to teach the so-called "seven liberal arts" (the trivium and the quadrivium):
Trivium: grammar, logic and rhetoric.
Quadrivium: arithmetic and geometry, astronomy and music.
That earliest division caused the present divisions between literary and scientific fields.
From one point of view, the world's oldest university is Qarawiyyin university.
However, teaching religion is not the definition used by most people.
A university should in theory teach every subject.
The university is generally regarded as a formal institution that has its origin in the Medieval Christian tradition.
European higher education took place for hundreds of years in cathedral schools or monastic schools (scholae monasticae).
There, monks and nuns taught classes: evidence of these dates back to the 6th century.
The Universities of Paris and Oxford were founded by members of the church.
Later universities were founded by kings.
In the early medieval period, most new universities were founded from pre-existing schools, usually when these schools became mainly sites of higher education.
Pope Gregory VII promoted the concept of modern university as his 1079 Papal Decree.
He ordered the establishment of cathedral schools, which eventually turned into the first European universities.
A university can include several campuses or different places where classes are taught by professors.
In each campus there are several faculties and university schools (mainly for teaching), and also laboratories, departments and institutes of research.
Many campuses also have housing for students in buildings called dormitories and structures like libraries, study rooms and gymnasiums for students that live there.
Each school offers many courses that students take to earn a degree.
The person with the highest right to control and to command in a university is the rector, who governs the university with the help of the party of vice-rectors and of other organs such as the social council and the governing body.
Notable universities
University of New Brunswick
University of Chile (Universidad de Chile)
Catholic University of Chile (Universidad Católica de Chile)
Metropolitan Technologic University (Universidad Tecnológica Metropolitana)
Åbo Akademi University
Aalto University
University of Kyoto
University of Osaka
University of Malaya
UNAM, Universidad Nacional Autónoma de México.
The biggest and most important university in Mexico and Latin America
UdG, University of Guadalajara.
It is the second oldest university in Mexico, regarded as one of the most significant universities in Mexico.
IPN, Instituto Politécnico Nacional
ITESM, Instituto Tecnológico y de Estudios Superiores de Monterrey
ITAM, Instituto Tecnoloógico Autónomo de México
Open University of the Netherlands
Wageningen University & Research
Naval Academy "Mircea cel Batran" (ANMB)
Chalmers University
Royal Institute of Technology
Galatasaray University (İstanbul)
Queens University, Belfast
Durham University
There is a group of famous universities called the Ivy League.
Massachusetts Institute Of Technology
History of the Universities
Value is how much something is worth.
Often the best way to find the value of something is to use the price that it can be sold for.
However Oscar Wilde wrote that 'people know the price of everything but the value of nothing'- in other words true value does not depend on money alone.
In math, a value is a number which is concrete, something everyone can agree upon.
However people may disagree on the value of water, depending if you live in a desert or next to a river.
Disagreements on the value of things can create fights between nations, political parties, religions, etc.
Volapük is a constructed language created in 1880 by Johann Martin Schleyer.
Schleyer was a Catholic priest from Germany.
He felt that God had told him in a dream to make an international language.
Volapük conventions took place in 1884, 1887, and 1889.
The aim was to help people from different cultures speak to each other.
Volapük became less popular after 1887 when Esperanto was published.
Part of the reason was that Esperanto is easier to learn with a simpler grammar.
There are believed to only be 20-30 Volapük speakers in the world today.
"Vol" and "pük" come from the English words "world" and "speech".
The grammar is based on Indo-European languages.
An example of Volapük is the translation of the Lord's prayer:
Basic course in Volapük, in English
Basic grammar of Volapük, in Esperanto
Volapop: A site about popular culture written in Volapük
Discussion group on the vocabulary and grammar of Volapük
A complete Italian grammar of Volapük (1888) by V. Amoretti
Una grammatica completa di Volapük in lingua italiana (1888) a cura di V. Amoretti
General Volapük discussion group
Flenef bevünetik Volapüka / International Friendship of The World Language
The vocabulary a person uses is all the words that person knows and uses.
In general, a person who is five knows about 4,000 to 5,000 words.
Adults who have gone to college may know 20,000 words.
A hearing vocabulary and reading vocabulary are bigger than a speaking vocabulary or writing vocabulary, as people understand some words that they do not use.
The number of words in a language is more than the words listed in one dictionary.
One dictionary may have a list of 500,000 (half a million) words.
Another dictionary may have some other words that the other dictionary does not have.
When you add all the words in those dictionaries, there are about 750,000 words in English.
There may be more words than that.
You may think to yourself, "If there are 750,000 words, how can we talk with only 3000 words?"
Because, we do not need to know all the words.
You can say most things with around 3,000 words.
The most used words are short words.
That is true in all languages.
The 50 most common words in English have fewer than seven letters.
Half of these words have fewer than four letters.
The vocabulary of a language is always changing.
New words are made or words change their meaning.
Words about computers, like "download" are new to the English language.
The new word "bling" came from hip hop.
Words like "cool" have developed new meanings.
Complicated vocabulary detector
Simplevocab - A multi-word dictionary
Vegetable oils are triglyceride oils made from plants.
They are used in food and for cooking.
In past centuries they were much used as fuel in oil lamps.
Some kinds of plant oils that people use are palm oil, maize, olive, peanut, rapeseed, soy, and sunflower.
Cooking oils
A verb is a kind of word (part of speech) that tells about an action or a state.
It is the main part of a sentence:  every sentence has a verb.
In English, verbs are the only kind of word that changes to show past or present tense.
Every language in the world has verbs, but they are not always used in the same ways.
In some other languages (Chinese & Indonesian, for example) verbs do not change for past and present tense.
This means the definition above only works well for English verbs.
There are sixteen verbs used in Basic English.
They are: be, do, have, come, go, see, seem, give, take, keep, make, put, send, say, let, get.
The word 'verb'
The word verb originally comes from *were-, a Proto-Indo-European word meaning "a word".
It comes to English through the Latin verbum and the Old French verbe.
Verbal phrase
In simple sentences, the verb may be one word: The cat sat on the mat.
However, the verb may be a phrase: The cat will sit on the mat.
Verbal phrases can be extremely difficult to analyse: I'm afraid I will need to be going soon.
There seem to be three verbal phrases here, which mean something like Sorry, I must go soon.
Verb forms
In English and many other languages, verbs change their form.
This is called inflection.
Most English verbs have six inflected forms (see the table), but be has eight different forms.
You should notice that some of the verb forms look the same.
You can say they have the same shape.
For example, the plain present and the plain form of walk have the same shape.
The same is true for the past and the past participle.
But these different forms can have different shapes in other verbs.
For example, the plain present of be is usually are but the plain form is be.
Also, the past of eat is ate, but the past participle is eaten.
When you look for a verb in the dictionary, it is usually the plain form that you look for.
An English sentence must have at least one primary-form verb.
Each main clause can only have one primary-form verb.
Kinds of Verbs
English has two main kinds of verbs: normal verbs (called lexical verbs) and auxiliary verbs.
The difference between them is mainly in where they can go in a sentence.
Some verbs are in both groups, but there are very few auxiliary verbs in English.
There are also two kinds of auxiliary verbs: modal verbs and non-modal verbs.
The table below shows most of the English auxiliaries and a small number of other verbs.
To do (do, does, did)
To be (am, is, are, was, were): Creates a progressive tense
To have (have, has, had): Creates a perfect tense
The following verbs are modal auxiliaries.
Auxiliary verbs also inflect for negation.
Usually this is done by adding not or n't.
Use of the auxiliary do
Sometimes the verb do is used with other verbs.
It does not really change the meaning, but it can be used to make a strong statement.
I do talk (Present)
I did go (Past)
I don't talk (Present)
I didn't go (Past)
Sometimes it comes before the subject.
This is called inversion and it usually means the sentence is a question.
Do you talk? (
Present)
Did you go? (
Past)
Many other languages do not use the verb do as an auxiliary verb.
They use the simple present for do, and the simple past or perfect for did.
Tense, aspect, and mood
Tense is mainly used to say when the verb happens: in the past, present, or future.
In order to explain and understand tense, it is useful to imagine time as a line on which past tense, present tense and future tense are positioned.
Some languages have all three tenses, some have only two, and some have no tenses at all.
English and Japanese for example have only two tenses: past and present.
Chinese and Indonesian verbs do not show tense.
Instead they use other words in the sentence to show when the verb happens.
Aspect usually shows us things like whether the action is finished or not, or if something happens regularly.
English has two aspects: progressive and perfect.
In English, aspect is usually shown by using participle verb forms.
Aspect can combine with present or past tense.
Progressive aspect
English uses the gerund-participle, usually together with the auxiliary be (and its forms am, is, are, was, and were) to show the progressive aspect.
I'm sleeping. (
present progressive)
He was studying English last night. (
past progressive)
He will be going to the store tomorrow (future progressive)
I've seen him twice. (
present perfect)
I had lived there for three years. (
past perfect)
He had intended to bake a cake but ran out of flour.
She had wanted  to buy him a gift but he refused.
If only I had been born standing up!
I wish you had told me that before.
I would rather you had gone somewhere else.
Finally, English mood is now usually shown by using modal verbs.
In the past, English had a full mood system but that has almost completely disappeared.
The subjunctive mood now uses the plain form.
There is also a form of be that is used in conditionals to show that something is not true (e.g., If I were a bird, I would fly to California.)
Sentence parts that go with verbs
Certain parts of a sentence naturally come before verbs or after them, but these are not always the same for all verbs.
The main sentence parts are: subject, object, complement, and modifier.
Almost all English sentences have subjects, but sentences that are orders (called imperatives) usually do not have any subjects.
A subject usually comes before a verb, but it can also come after auxiliary verbs.
In the following examples, the subject is underlined and the primary verb is in bold.
The food was good.
The small boy with red hair is sleeping.
Can you see the car?
Come here. (
no subject)
Many verbs can be followed by an object.
These verbs are called transitive verbs.
In fact, some verbs must have an object (e.g., take), but some verbs never take an object (e.g., sleep).
Verbs that do not take an object are called intransitive verbs.
Some verbs can even have two objects.
They are called ditransitive verbs.
In the following examples, the object is underlined and the primary verb is in bold.
no object)
I took the book from him.
I gave him the book. (
2 objects)
I am happy. (
I became a teacher. (
complement, no object)
I slept in my bed (1 object)
Complements
Some verbs can or must be followed by a complement.
These verbs are called linking verbs or copula.
In the following examples, the complement is underlined and the verb is in bold.
He is a boy.
She became sick.
She became a manager.
Verbs can be modified by various modifiers, mainly adverbs.
Note that verbs generally do not need modifiers; it's usually a choice.
In the following examples, the adverb is underlined and the verb is in bold.
The boy ran quickly.
The freely swinging rope hit him.
Differences between verbs and other words
Sometimes a verb and another word can have the same shape.
In these cases you can usually see the difference by looking at various properties of the words.
Verbs vs. adjectives
Sometimes a verb and an adjective can have the same shape.
Usually this happens with participles.
For example, the present participle interesting and the adjective interesting look the same.
Verbs are different from adjectives, though, because they cannot be modified by very, more, or most.
For example, you can say "That is very interesting," so you know interesting is an adjective here.
But you cannot say "My teacher is very interesting me in math" because in this sentence interesting is a verb.
On the other hand, if you cannot change the 'be' verb to 'seem' or 'become', it is probably a verb.
He was isolated / He became isolated (isolated is an adjective)
The door was opening / *The door became opening (opening is a verb)
Verbs vs. nouns
The gerund-particle sometimes looks like a noun.
This is especially true when it is used as a subject, as in the following example:
Running is good for you.
Verbs cannot generally be modified by adjectives and nouns cannot generally be modified by adverbs.
So, in "Running regularly is good for you", running is a verb because it is modified by regularly, an adverb.
Verbs cannot change for number, so if you can make the word plural, it is a noun, not a verb.
For example, "this drawing is nice" can change to "these drawings are nice", so drawing is a noun.
But "drawing trees is fun" cannot change to "drawings trees is fun", so it is a verb here.
Object/complement
Many verbs can take objects or complements, but nouns cannot.
So, in "parking the car is hard", parking is a verb because it takes the object the car.
But, if you say, "there's no parking", parking may be a noun because it does not have an object.
Verbs vs. prepositions
Some verbs have become prepositions.
Again, usually these share a shape with participles.
Given the problems, I do not think we should go.
We have many helpers, including John.
According to the map, we are here.
He went to hospital following the fight.
The main difference between verbs and prepositions is that verbs have a subject.
Even if the subject is not written, you can understand what it is.
Prepositions do not have a subject.
This article is about physical object; for meaning from audio field, see loudness.
The volume of an object is a measure of the amount of space occupied by that object, and is not to be confused with mass.
The volume of a mountain is much larger than the volume of a rock, for instance.
The length is the longest distance between the object's extremities.
The width (or breadth) refers to the size of the object in a direction perpendicular to its length.
The height (or depth) stands for the size of that object in the direction perpendicular to both the length and the width.
For objects at or near the Earth's surface, height or depth often refers to the dimension of the object along the local vertical.
All physical objects occupy a volume, even if some are so thin that they appear to be two-dimensional, like a sheet of paper.
The unit of volume in the International System of Units is the cubic meter, which is represented by the symbol m3.
In some fields or applications, one often uses different units to simplify the discussions or writings.
For instance:
Everyday quantities of liquids are often measured in units of a litre, written as L, which is the volume occupied by a cubic decimetre.
Large quantities of liquids, such as oil, and sometimes other materials, may be measured and traded in units of barrels.
There are many different reference volumes called barrels, depending on the nature of the content.
Traditional units are still in encountered in some countries: Imperial units such as the gallon or the fluid ounce were in widespread use within the British Empire.
Some of them are still popular in the United States, which also uses units like the bushel, the quart, the cup and the teaspoon (in cooking recipes, for example).
See U.S. customary units for more examples.
Non-conservation of volume
Measuring a volume
In mathematics, the volume of simple geometric objects, written , can often be calculated on the basis of their shape and dimensions:
The volume of a perfect cube of side c is c3.
The volume of a rectangular box is the product of its three linear dimensions: length, width and length.
The volume of a parallelepiped of sides a, b and c is a × b × c.
The volume of a sphere of radius r is (4/3) π r3.
The volume of a gas is typically that of its container, but it could be ill-defined, as in the case of the atmosphere, which has no clear upper limit.
The volume of a liquid is often measured by pouring it into a graduated container.
The volume of a small solid can be estimated by immersing it into a graduated container partially filled with a known amount of liquid, provided the solid is not soluble in the liquid.
It has a day longer than a year.
The year length of Venus is 225 Earth days.
The day length of Venus is 243 Earth days.
Venus is a terrestrial planet because it has a solid, rocky surface like other planets in the inner solar system.
Astronomers have known Venus for thousands of years.
The ancient Romans named it after their goddess Venus, goddess of love and beauty.
Venus is the brightest thing in the night sky except for the Moon.
It is sometimes called the morning star or the evening star as at some elongations it is easily seen just before the sun comes up in the morning.
At other times, it can be seen just after the sun goes down in the evening.
Venus comes closer to the Earth than any other planet does.
Venus is sometimes called the sister planet of Earth as they are quite similar in size and gravity.
In other ways the planets are very different.
Venus' atmosphere (air) is mostly carbon dioxide with clouds of sulphuric acid.
Sulphuric acid is a chemical that is poisonous to life.
The thick atmosphere makes it hard to see the surface.
Until the late twentieth century many thought there might be life there.
The pressure on Venus' surface is 92 times that of Earth.
Venus spins very slowly on its axis and it spins in the opposite direction to the other planets.
Physical properties
Venus is a terrestrial planet so, like the Earth, its surface is made of rock.
Venus is much hotter than Earth.
All the carbon dioxide in the atmosphere acts like a blanket, trapping heat from the Sun.
This effect is called the greenhouse effect and it is very strong on Venus.
This makes the surface of Venus the hottest of any planet's surface in the Solar System with an estimated average temperature of .
This is hot enough to melt lead or zinc.
Venus has no oceans because it is much too hot for water.
Venus' surface is a dry desert.
Because of the clouds, only radar can map the surface.
It is about 80% smooth, rocky plains, made mostly of basalt.
Two higher areas called continents make up the north and south of the planet.
The north is called Ishtar Terra and the south is called Aphrodite Terra.
They are named after the Babylonian and Greek goddesses of love.
The surface of Venus looks like it has been shaped by volcanic activity.
Venus has a lots of volcanoes.
The surface of Venus is estimated to be 300–600 million years old.
Unlike Earth or Mars, Venus does not have defined highlands or lowlands, and it does not have tectonic plates.
Venus' atmosphere is mostly carbon dioxide and nitrogen gas with clouds of sulphuric acid.
Because the atmosphere is so thick or dense the pressure is very high.
The pressure is 92 times the pressure on Earth, enough to crush many things.
It is impossible to see the planet's surface from space as the thick cloud layer reflects 60% of the light that hits it.
The only way scientists are able to see it is by using infrared and ultraviolet cameras and radar.
Scientists believe that billions of years ago, the atmosphere of Venus could have been like Earth's atmosphere.
There may have been lots of water on the surface of Venus.
But after 600 million to several billion years, the evaporation of the water put greenhouse gases into its atmosphere.
In 1967, Venera 4 found that the magnetic field of Venus was much weaker than that of Earth.
This magnetic field is induced by an interaction between the ionosphere and the solar wind.
Venus' magnetosphere is not strong enough to protect the atmosphere from cosmic rays.
Venus can sometimes be seen passing between the Sun and Earth.
Venus looks like a black dot when seen through a special telescope.
These passages are called "transits".
These "transits" happen in pairs eight years apart.
Then it is more than a hundred years to the next pair.
Venus orbits the Sun at an average distance of about 108 million km (67 million mi).
It completes an orbit every 224.7 days.
The rotation of Venus is slow.
A Venusian sidereal day is longer than a Venusian year.
List of satellites sent to Venus
Many man-made satellites have been sent to Venus to study it.
Mariner 2 was launched on August 27, 1962.
It was made to study the atmosphere of Venus, its magnetic field, and mass.
The last radio signal from Mariner 2 was received on January 3, 1963.
Mariner 2 is still orbiting around the Sun today.
Venera 4
Venera 4 was a probe made by the Soviet Union to explore Venus.
The probe had a two probes.
One was designed to enter the atmosphere of Venus and use a parachute to land on the surface.
Another received the information from the probe on Venus to mission controllers on Earth.
Venera 4 was launched on June 12, 1967.
The last radio signal from Venera 4 was received on October 18, 1967.
Mariner 5
Mariner 5 was a spacecraft of the Mariner program.
Mariner 5 was launched on June 14, 1967.
The last radio signal from Mariner 5 was on October 14, 1968.
Mariner 5 was made to study the magnetic field of Venus and to measure the hard ultraviolet spectrum, of the Venusian atmosphere.
Venera 9
Venera 9 was a spacecraft made by the Soviet Union.
It consisted of a probe to orbit Venus which was called an orbiter and another probe that will land on Venus which was called a lander.
It was launched on June 8, 1975.
The last radio signal from the orbiter was on March 22, 1976.
The last radio signal was on October 22, 1975.
The orbiter was the first spacecraft to orbit Venus, while the lander was the first to return pictures from the surface of another planet.
Venera 10 was a spacecraft made by the Soviet Union.
It was launched on June 14, 1975.
Venera 13
Venera 13 was a probe in the Soviet Venera program.
It was made to explore Venus.
It was launched on October 30, 1981.
The last radio signal from the lander was on March 1, 1982.
The last radio signal from the spacecraft that took the lander to Venus was on April 25, 1983.
Venera 14
Venera 14 was a probe in the Soviet Venera program.
It was launched on November 4, 1981.
The last radio signal from the lander was on March 5, 1982.
The last radio signal from the spacecraft that took the lander to Venus was on April 9, 1983.
Venera 15
Venera 15 was a spacecraft sent to Venus by the Soviet Union.
It was made to map the surface of Venus.
It was launched on June 2, 1983.
The last radio signal from Venera 15 was on January 5, 1985.
Venera 16
Venera 16 was a      spacecraft sent to Venus by the Soviet Union.
It was launched on June 7, 1983.
Its last radio signal from Venera 16 was on June 13, 1985.
References and Notes
Nine Planets: Venus
Images of Venus
Vatican City (; officially Vatican City State, ) is an independent sovereign state and the smallest country in the world by size, at 0.49 km².
Its territory is completely surrounded by Italy and it is only one of three countries in the world that are enclaves of another country (the others being San Marino, also in Italy, and Lesotho in southern Africa).