Aarushhh/wikipedia-simple-splitted huggingface dataset:
Coal is a hard rock which can be burned as a fossil fuel. It is mostly carbon but also contains hydrogen, sulphur, oxygen and nitrogen. It is a sedimentary rock formed from peat, by the pressure of rocks laid down later on top.

Peat, and therefore coal, is formed from the remains of plants which lived millions of years ago in tropical wetlands  (coal swamps), such as those of the late Carboniferous period (the Pennsylvanian).  Charcoal is made by wood heated in an airless space.

Coal can be burned for energy or heat. About two-thirds of the coal mined today is burned in power stations to make electricity. Like oil, when coal is burned its carbon joins with oxygen in the air and makes a lot of carbon dioxide, which causes climate change. Many people die early because of illnesses from air pollution from coal. Most countries are turning to other sources of energy, such as solar power and wind power. But new coal power plants are still being built in some parts of the world, such as China.
Coal can be roasted (heated very hot in a place where there is no oxygen) to produce coke. Coke can be used in smelting to reduce metals from their ores.

History 

Coal was the most important fuel of the Industrial Revolution. Coal was an important part of rail freight in the UK in the 20th century, forming the greater part of several companies' freight volume.  Early in the 21st century most coal fired power stations in the United Kingdom and several other countries were closed to reduce greenhouse gas emissions.

Types of coal
Under suitable conditions, plant material is transformed step by step into
 Peat is not yet coal.
 Lignite (brown coal) is the dirtiest coal, is about 60%-70% carbon, and is used as fuel for electric power generation. Jet is a compact form of lignite that is sometimes polished and has long been used as an ornamental stone.
 Sub-bituminous coal is used as fuel for steam-electric power generation. Also, it is a source of light aromatic hydrocarbons for the chemical synthesis industry.
 Bituminous coal is a dense rock, black but sometimes dark brown. It is a relatively soft coal that breaks and burns readily and quickly.  It used as fuel in power stations, and for heat and power applications in manufacturing, for blacksmithing; and to make coke to make steel.
 Anthracite is a harder, glossy, black coal.  It is longer burning, and used mainly for residential and commercial space heating.
Graphite is difficult to burn and is not so commonly used as fuel. It is still used in pencils, mixed with clay. When powdered, it can be used as a lubricant.
Diamond is commonly believed to be the result of this process, but this is not true. Diamond is carbon but is not formed from coal.

Coal contains impurities. The particular impurities determine the use. Coking coal has little ash or sulfur or phosphorus. Those would spoil the iron made by the blast furnace.

Environmental problems
Coal, when burnt, gives off almost a third more carbon dioxide per unit of energy than oil, and 80% more than natural gas. Almost half of the carbon dioxide from people is because of burning coal so it is the biggest single cause of global warming. Coal contributes to acid rain and smog, especially when burned without scrubbers. Burning coal releases toxic chemicals, including soot, mercury, and carbon monoxide, which contribute to diseases such as cancer and asthma in both humans and wild animals. Coal mining, especially mountaintop removal mining, can damage large areas of land and destroy natural habitats. Higher grades of coal burn more cleanly than lower grades, although they still pollute more than other fuels. In addition to air pollution, burning coal produces toxic coal ash, which can cause water pollution if it is accidentally released into the environment. There are several underground mine fires burning throughout the world
. These underground fires release toxic smoke into the air, and can also cause the ground above to collapse. The city of Centralia, Pennsylvania was evacuated and is now abandoned due to an underground coal mine fire.
Deaths and illness from pollution 
Because of coal every year more than one hundred thousand people die early and millions of people get ill. Coal miners often get pneumoconiosis (black lung disease) from exposure to coal dust.

Protests against coal

Opposition to coal pollution was one of the main reasons the modern environmental movement started in the 19th century.

Peak coal 

Peak coal means the year in which most coal is mined or burned. Many countries have already passed their peak coal years, for example Germany in 1985 and the United States in 2008. Now those countries are mining and burning less coal. But China still mines a lot of coal. The peak coal year for the world may have passed.

Energy 
Compared to other non-renewable sources of energy, coal is inefficient and produces high amounts of greenhouse gases. Coal is commonly found and cheap.

Coal provides about a quarter of the world's heating.

Electricity 
Coal-fired power stations produce 37% of the world's electricity.
Industry 
Almost 70% of world steel production depends on burning coal.

Countries 
The world's top coal producer is China, which produces about four billion tonnes each year. India, the United States, Australia, Indonesia and Russia also produce coal, less than a billion tonnes a year each. The largest exporter by far is Australia and the largest importers are China, India and Japan.

Related pages 

 Coal mining
 Coal forests

References

Other websites 
 Electricity Map countries where more coal is burned are usually darker brown on map
 National Coal Mining Museum for England

Basic English 850 words
Fossil fuels
Sedimentary rocks
Environmental issues
Hydrocarbons
Petroleum, (from Greek πέτρα - rock and έλαιο - oil) also called crude oil, is a thick and black liquid. It is a natural material mainly made of hydrocarbons. The hydrocarbons came from many billions of ancient phytoplankton. When they died, their bodies sank to the bottom. This formed basins of oil in many parts of the world.

Most petroleum is found by drilling down through rocks on land or off-shore on the continental shelf. Major producers are in the Middle East, the Americas, and Russia. It is the most important world fuel source. It supplies 38% of the world's energy and is also used to make petrochemicals.
Crude oil is a mixture of many different chemicals (mostly hydrocarbons), most of which burn well. It is separated into simpler, more useful mixtures by fractional distillation in oil refineries to give separate chemicals such as gasoline (or petrol) for cars, kerosene for airplanes and bitumen for roads. The bitumen gives crude oil its dark black color; most of the other chemicals in crude are slightly yellow or colorless. 

Petroleum can be easily transported by pipeline and oil tanker. Refined petroleum is used as fuels; mainly gasoline (petrol) for cars, diesel fuel for diesel engines used in trucks, trains and ships, kerosene fuel for jets and as lubricants.

Petrochemicals:
 alcohols
 antiseptics
 artificial rubber
 detergents
 drugs
 explosives
 food additives
 insecticides
 perfumes
 plastics
 textile fiber
Problems 
Petroleum resource is limited and non-renewable. Some believe it will run out within 70 years after a peak oil early in the 21st century.
Burning petroleum or other fossil fuel adds the carbon in the oil to the oxygen in the air to create carbon dioxide, which is an air pollutant.  The carbon can be removed from the carbon dioxide by plants.

There is a lot of crude oil left underground. Oil companies quote "reserves" which some people confuse with the actual amount of oil underground, but are more to do with the cost of extracting it by oil wells.
Most of the crude left underground is in the Middle East which is not a politically stable part of the world. Some governments with lots of oil reserves work together through OPEC to keep production low and prices high. People in countries that use oil complain about high oil prices. However, some environmentalists worry about damage being done by using oil as a fuel source (especially global warming) and are therefore happy when prices are kept high so that people use less oil.

Viable alternatives 
There are none as far as we know. The small amounts of uncertain output from all wind and solar energy will not get near what is needed. The person who has proved this is Simon Michaux, an Australian expert. He has shown that the sum total of alternative energy sources comes nowhere near replacing oil. That is where we are at now.

Related pages
 Asphalt
 Coal
 Natural gas
 Oil sands

Other websites
Other websites 

 US Energy Information Administration - Part of the informative website of the US Government's Energy Information Administration.
 Environmental effects of oil extraction 
 BP Statistical Review of World Energy  
 PetroTalk Portal for petro related Articles, Discussion, Links and more
 Oil, petroleum: Development, production, consumption and reserves 
 World oil consumption World oil consumption
 Crude: 2007 Australian Broadcasting Corporation documentary [3 x 30 minutes] about the formation of oil, and humanity's use of it
 Petroleum crude oil Citizendium

Data 
 Department of Energy EIA - World supply and consumption
 Department of Energy EIA - Crude Oil and Total Petroleum Imports to USA
 US petroleum prices  - from US Department of Energy EIA
 European Brent prices  since 1987

References
Natural gas is a mixture of gases. It consists mainly of hydrocarbons. The main component is methane, which is a greenhouse gas. Natural gas is a natural resource, often found in the ground, either alone or together with petroleum. Landfills and natural processes produce a little methane. Usually it is transported to users in a pipeline.

Most natural gas is burnt as a fuel to produce energy. It burns with a blue flame. Like other flames, this can cause pollution with nitrogen oxides.

Natural gas is burned to produce electricity, to cook and to heat buildings. It is also used as fuel for natural gas vehicles for transport. When natural gas is burned in a power station it boils water into steam that spins a steam turbine that turns a generator to make electricity. Some power stations use natural gas in a gas turbine.
Natural gas is also converted into many different industrial chemicals. It is the most common feedstock for making pure hydrogen. Hydrogen is used as fuel in fuel cells, and to make ammonia. Ammonia is used as a fuel, as a fertilizer for crops, and for making many other things. Natural gas is also converted into monomers to make many plastic products.

Related pages

Fossil fuel
Coal
non-renewable resource

References

Other websites 
History of using natural gas from the U.S. Department of Energy

Fossil fuels
Hydrocarbons
Energy can mean various things:

 In physics, energy is a property of matter and space. It can be transferred between objects. It can be converted in its form. It cannot be created or destroyed. 
 In economics it may mean the ‘energy industry’, as in fuel or electric power distribution.
 Energy can be used to heat, move or illuminate.
 In everyday use, the word is used to describe someone acting or speaking in a lively and vigorous way.

Scientific energy 
In physics, energy is a property intrinsic to anything that is able to interact in the universe. The energy of an object is its capability of producing a force that can do work, as well as its capability of transferring heat. When an object does work on another object (changing its momentum), the former’s energy (its capability of doing work) decreases and the latter’s energy increases, by transferring it.
Basic forms of energy include:
 Kinetic energy - energy of an object in motion, which acts as the capacity to undergo change in position over time. 
 Potential energy - the potential a stationary object has to cause a force because it has mass, its position relative to other objects, or stresses within itself (elasticity). Motion is also relative.
 Heat - thermal energy which is used to vibrate atoms and molecules. 
 Electrical energy - energy that relates to electrical interactions.

Conservation of energy 
Energy is a property that is not created or destroyed, although energy can change in detectable form.  This is a rule that is commonly understood as the "conservation law of energy". In respects to this rule, the total amount of energy that exists in an isolated system will always be the same, no matter what changes have been made to it.
In the early 20th century, scientist found that matter itself can be created from energy (energy and matter are interchangeable, in spite of everyday experiences).  This is just another change of form.  After these discoveries, the conservation law of energy was extended to become the conservation law of matter and energy: matter and energy can neither be created from nothing nor destroyed to the point of complete erasure from reality. Albert Einstein was the first to mathematically show this. (E = mc2) 

Matter can be created from energy or converted into energy through processes such as nuclear fission or nuclear fusion.

Types of energy 
Scientists have identified many types of energy, and found that they can be changed from one kind into another. These include:
Chemical energy
 Sound energy
 Renewable energy
 Solar energy
 Nuclear energy
 Elastic energy
 Gravitational potential energy
 Kinetic energy
 Dark energy
 Hamiltonian mechanics
 Internal energy

For example:
For example:

 human throws the stone using energy stored in muscles = chemical energy
 stone moves upwards = kinetic energy
 stone at the highest point = potential energy
 stone falls to ground = kinetic energy
 stone hits ground = thermal energy/sonic energy

Measuring energy 
Energy can be measured. The amount of energy a thing has can be given a number.

As in other kinds of measurements, there are measurement units. The units of measurement for measuring energy are used to make the numbers meaningful.

The SI unit for both energy and work is the joule (J). It is named after James Prescott Joule. 1 joule is equal to 1 newton-metre. In terms of SI base units, 1 J is equal to 1 kg m2 s−2. It is most often used in science, though particle physics often uses the electronvolt.

The measurement for electricity most often uses the kilowatt-hour (kW·h). One kW·h is equivalent to 3,600,000 J (3600 kJ or 3.6 MJ).

Related pages 
 Heat

References 

 
Basic physics ideas
Jewels (or gems or gemstones) are rare minerals. They usually come in colours and sizes. They begin in a rough rock form, but can be cut and polished to turn into a jewellery.

However, some other non-mineral rocks (such as lapis lazuli) or organic materials can also be also used for jewelry and are called gemstones. These include amber or jet. Pearls and coral are sometimes also called gemstones.

Most gemstones are hard. Soft minerals are used in jewelry too, because of their luster that gives them value. 

Being rare or in short supply also makes a gemstone valuable.

History 
The Ancient Greeks began to decide which gems are precious and semi-precious. This continued in other cultures. 

In modern times, the precious stones are diamond, ruby, sapphire and emerald, with all other gemstones being semi-precious.

Types 
 Amethyst
 Aquamarine
 Diamond
 Emerald
 Jade
 Peridot
 Ruby
 Sapphire
 Topaz
 Turquoise
 Opal
 Spinel

References
References

Other websites
 "Book of Royal Gemstones" is a book from 1554 that talks about gemstones.
 "The Blossoms of Thoughts Regarding the Precious Stones" is an old book from the 1600s that is considered one of the most important books about precious stones. It is written in the Arabic language.

Basic English 850 words
Xenon is a non-metal chemical element. It has the chemical symbol Xe and atomic number 54. It is one of the few elements that are a gas at the standard temperature and pressure.

History 
Sir William Ramsay and M. W. Travers discovered this element in 1898. The element's name came from the Greek word xenos, which means 'stranger'.

Chemistry 
Xenon belongs to the group of the noble gases. Noble gases are very unreactive. However, in 1962, chemists have found that xenon can react with fluorine under special conditions, such as high pressure and high temperature. It is not known why xenon behaves differently under these circumstances. There are also some compounds with oxygen. The gas is not very reactive, because if fulfills the octet rule. This means that a lot of energy is needed to remove an electron from xenon. This activation energy for xenon is 1172 kJ/mol. To remove a second electron from xenon, an energy of 2046.4 kJ/mol is needed.
Known oxidation states of xenon are 0, +1, +2, +4, +6 and +8. However, the most stable form is pure xenon, or the xenon's oxidation state of 0. Xenon has 8 stable isotopes and more than 30 unstable isotopes.

Uses 
Xenon gas is used in electron tubes, bactericidal lamps, trobe lamps, and lamps used to excite ruby lasers.
It has the atomic mass of 131.294 and is the 5th inert gas in the inner gas group.

Xenon is also a trace gas in the atmosphere, occurring at 87 ±1 nL/L (parts per billion) or approximately 1 in 11.5 million. It is also emitted from some mineral springs.

Related pages
 Periodic table
 List of common elements

Noble gases
{{Infobox settlement
| name                     = Kuala Lumpur
| settlement_type          = Federal territory and capital city
| official_name            = Federal Territory of Kuala Lumpur{{nobold|Wilayah Persekutuan Kuala Lumpur}}
| translit_lang1           = Other
| translit_lang1_type2     = Burmese
| translit_lang1_info2     = ကွာလာလမ်ပူမြို့
| translit_lang1_type3     = Telugu
| translit_lang1_info3     = 
| image_skyline            = 
| image_caption            = 
| image_flag               = Flag of Kuala Lumpur Malaysia.svg
| image_shield             =
| nickname                 = KL, The Garden City of Lights, City of Contrasts and Diversity
| motto                    = Bersedia Menyumbang Bandaraya Cemerlang| anthem                   = Maju dan Sejahtera 
| image_map                = 
| map_caption              =
| pushpin_map              = Malaysia#Southeast Asia#Asia
| pushpin_map_caption      =
| coordinates              = 
| subdivision_type         = Country
| subdivision_name         = Malaysia
| subdivision_type1        = Administrative areas
| subdivision_name1        = 
| established_title        = Establishment
| established_date         = 1857
| established_title2       = City status
| established_date2        = 1 February 1972
| established_title3       = Transferred to federal jurisdiction
| established_date3        = 1 February 1974
| government_type          = Federal administrationwith local government
| governing_body           = Kuala Lumpur City Hall
| leader_title             = Mayor
| leader_name              = Mahadi bin Che Ngah
| total_type               = Federal territory
| area_footnotes           = 
| area_total_km2           = 243
| area_metro_km2           = 2,243.27
| elevation_footnotes      = 
| elevation_m              = 66
| population_total         = 1,782,500
| population_as_of         = 2019 est.
| population_rank          = 1st
| population_footnotes     = 
| population_density_km2   = 7,802
| population_urban         =
| population_metro         = 7,564,000
| population_density_metro_km2 = 2,708
| population_blank1_title  = Demonym
| population_blank1        = KL-ite / Kuala Lumpurian
| postal_code_type         = Postal code
| postal_code              = 50000 to 60000
| imagesize                = 275px
| timezone                 = MST
| utc_offset               = +8
| blank_name               = Mean solar time
| blank_info               = UTC+06:46:46
| blank1_name              = Area code(s) 
| blank1_info              = 03
| blank2_name              = Vehicle registration
| blank2_info              = V and W (except taxis) HW (for taxis only)
| blank3_name              = ISO 3166-2
| blank3_info              = MY-14
| demographics_type2       = City Index
| demographics2_title1     = HDI 
| demographics2_info1      = 0.867 (very high) (1st)
| demographics2_title2     = GDP 
| demographics2_info2      = RM 244,210 million ($59,831 million) (2nd)
| demographics2_title3     = Per capita 
| demographics2_info3      = RM 129,472 ($31,720) (1st)
| blank5_name              = Official language(s)
| blank5_info              = Malay
English
| website                  = 
| image_seal               = Seal of Kuala Lumpur.svg
| image_blank_emblem       =
| blank_emblem_size        = 280px
| blank_emblem_type        = Logo
}}
Kuala Lumpur () is the capital city it is the largest city of Malaysia and a Federal Territory. After Putrajaya was constructed in the late 1990s, the administrative capital has been moved there. Kuala Lumpur has one of the tallest buildings in the world, the Petronas Twin Towers.

 Climate 
Kuala Lumpur has a tropical rainforest climate (Af'' in the Koeppen climate classification).

The annual range of temperature in Kuala Lumpur is small, only 1°C. There is no distinct seasonal difference in temperature in the city. Kuala Lumpur is hot throughout the year. The annual mean temperature are 26.5 °C (79.7 °F).

The annual rainfall in Kuala Lumpur is high (2393mm). The rainfall distribution is even in the city, with heavy rainfall all the year. In April and November, the monthly rainfall is slightly higher.

Mayors of Kuala Lumpur 
Since Kuala Lumpur became a Federal Territory of Malaysia on February 1, 1972, the city has been led by seven mayors. They are:
Tan Sri Dato' Lokman Yusof (1972)
 Tan Sri Yaakob Latiff (1973 - 1983)
 Tan Sri Dato' Elyas Omar (1983 - 1992)
 Dato' Dr. Mazlan Ahmad (1992 - 1995)
 Tan Sri Dato’ Kamaruzzaman Shariff (1995 - 2001)
 Datuk Mohmad Shaid Mohd Taufek (2001 - 2004)
 Datuk Ruslin Hasan (since 2004)

References

Other websites 

 Kuala Lumpur city location map
 Kuala Lumpur City Hall 
 Maps of Kuala Lumpur
 Kuala Lumpur Travel Guide  - Comprehensive Travel Guide to Kuala Lumpur | City Guide, hotels, attractions and vacations.

Kuala Lumpur
Capital cities in Malaysia
1857 establishments
The speed of light, in any medium,which is usually denoted by , is a physical constant important in many areas of physics.It is denoted by 'c^0' especially in vacuum medium, although the symbol 'c' can be used to refer to that in any medium. It is exactly  by definition. A photon (particle of light) travels at this speed in a vacuum. 

According to special relativity,  is the maximum speed at which all energy, matter, and physical information in the universe can travel. It is the speed of all massless particles such as photons, and associated fields—including electromagnetic radiation such as light—in a vacuum. 

It is predicted by the current theory to be the speed of gravity (that is, gravitational waves). Such particles and waves travel at  regardless of the motion of the source or the inertial frame of reference of the observer. In the theory of relativity,  interrelates space and time, and appears in the famous equation of mass–energy equivalence .
The special theory of relativity is based on the prediction, so far upheld by observations, that the measured speed of light in a vacuum is the same whether or not the source of the light and the person doing the measuring are moving relative to each other. This is sometimes expressed as "the speed of light is independent of the reference frame."

Example explaining how speed does not depend on reference frame 
This behavior is different from our common ideas about motion as shown by this example:

George is standing on the ground next to some train tracks (railroad). There is a train rushing by at . George throws a baseball at  in the direction the train is moving. Tom, a passenger on the train, has a device (like a radar gun) to measure throwing speeds. Because he is on the train, Tom is already moving at  in the direction of the throw, so Tom measures the speed of the ball as only .

In other words, the speed of the baseball, as measured by Tom on the train, depends on the speed of the train.
In the example above, the train was moving at 1/3 the speed of the ball, and the speed of the ball as measured on the train was 2/3 of the throwing speed as measured on the ground.

Now, repeat the experiment with light instead of a baseball; that is, George has a flashlight instead of throwing a baseball. George and Tom both have devices that are the same to measure the speed of light (instead of the radar gun in the baseball example).

George is standing on the ground next to some train tracks. There is a train rushing by at 1/3 the speed of light. George flashes a light beam in the direction the train is moving. George measures the speed of light as . Tom, a passenger on the train, measures the speed of the light beam. What speed does Tom measure?
Intuitively, one may think that the speed of the light from the flashlight as measured on the train should be 2/3 the speed measured on the ground, just like the speed of the baseball was 2/3. But in fact, the speed measured on the train is the full value, , not .

It sounds impossible, but that is what one measures. 

A consequence of this fact that the speed of light is the same for all observers, is that nothing can go faster than the speed of light. Another consequence is that for objects that have mass, no matter how much energy is used to increase the speed of an object, it will get closer and closer, but it will never reach the speed of light. These ideas were discovered in the early 1900s by Albert Einstein, whose work completely changed our understanding of light.

Relation to fundamental electric and magnetic properties of space
Maxwell's equations predicted the speed of light and confirmed Michael Faraday's idea that light was an electromagnetic wave (a way that energy moves). From these equations, we find that the speed of light is related to the inverse of the square root of the permittivity of free space, ε0, and the permeability of free space, μ0:

The index of refraction of a clear material is the ratio between the speed of light in a vacuum and the speed of light in that material.

Measurement
Measurement

Rømer 
Ole Christensen Rømer used an astronomical measurement to make the first quantitative estimate of the speed of light. When measured from Earth, the periods of moons orbiting a distant planet are shorter when the Earth is approaching the planet than when the Earth is receding from it. The distance travelled by light from the planet (or its moon) to Earth is shorter when the Earth is at the point in its orbit that is closest to its planet than when the Earth is at the farthest point in its orbit, the difference in distance being the diameter of the Earth's orbit around the Sun. The observed change in the moon's orbital period is actually the difference in the time it takes light to traverse the shorter or longer distance. Rømer observed this effect for Jupiter's innermost moon Io, and he deduced that light takes 22 minutes to cross the diameter of the Earth's orbit.

Bradley
Another method is to use the aberration of light, discovered and explained by James Bradley in the 18th century. This effect results from the vector addition of the velocity of light arriving from a distant source (such as a star) and the velocity of its observer (see diagram on the right). A moving observer thus sees the light coming from a slightly different direction and consequently sees the source at a position shifted from its original position. Since the direction of the Earth's velocity changes continuously as the Earth orbits the Sun, this effect causes the apparent position of stars to move around. From the angular difference in the position of stars, it is possible to express the speed of light in terms of the Earth's velocity around the Sun. This, with the known length of a year, can be easily converted to the time needed to travel from the Sun to the Earth
. In 1729, Bradley used this method to derive that light travelled 10,210 times faster than the Earth in its orbit (the modern figure is 10,066 times faster) or, equivalently, that it would take light 8 minutes 12 seconds to travel from the Sun to the Earth.
Modern 
Nowadays, the "light time for unit distance"—the inverse of c (1/c), expressed in seconds per astronomical unit—is measured by comparing the time for radio signals to reach different spacecraft in the Solar System. The position of spacecraft is calculated from the gravitational effects of the Sun and various planets. By combining many such measurements, a best fit value for the light time per unit distance is obtained. , the best estimate, as approved by the International Astronomical Union (IAU), is:
light time for unit distance: 
c = 
c =
c = 
c = 
The relative uncertainty in these measurements is 0.02 parts per billion (2), as equivalent to the uncertainty in Earth-based measurements of length by interferometry. Since the metre is defined to be the length travelled by light in a certain time interval, the measurement of the light time for unit distance can also be interpreted as measuring the length of an AU in metres. The metre is considered to be a unit of proper length, whereas the AU is often used as a unit of observed length in a given frame of reference.
Practical effects 
The finite speed of light is a major constraint on long-distance space travel. Supposing a journey to the other side of the Milky Way, the total time for a message and its reply would be about 200,000 years. Even more seriously, no spacecraft could travel faster than light, so all galactic-scale transport would be effectively one-way, and would take much longer than than any modern civilisation has existed.

The speed of light can also be of concern over very short distances. In supercomputers, the speed of light imposes a limit on how quickly data can be sent between processors. If a processor operates at 1 gigahertz, a signal can only travel a maximum of about  in a single cycle. Processors must therefore be placed close to each other to minimize communication latencies; this can cause difficulty with cooling. If clock frequencies continue to increase, the speed of light will eventually become a limiting factor for the internal design of single chips.
Related pages 
Michelson–Morley experiment

References 

Light
Astrophysics
Relativity
Denial is a word used in psychology on defense mechanism. It  means that someone denies that something has happened or is happening although he really knows it is true. Usually this happens because admitting it would cause a lot of pain.

Denial is usually the first state of coping with loss. For example, if someone close to a person dies, the survivor's first feeling might be denial, or refusal to accept the fact that the person is really dead.

Denial, is also when you think that a team (like in football) will win a football match before its even started and refuse to accept the fact thet they could lose

Denial, is also when you refuse to accept the fact that someone else did something (like change something) when you 'think you know' it was a different person

Psychology
Tokyo () is the capital and largest city of Japan. It is on the island of Honshu in the region of Kanto. Tokyo is the center of the Japanese government. The Imperial Palace is in Tokyo, it's not actually public for tourist. Tokyo is the center of business, trade, and industry of Japan. The city is the center of the largest metropolitan area in the world. It faces Tokyo Bay.

It became the capital city of Japan in the middle of 19th century, when its name changed from "Edo" to "Tokyo". Before then, Kyoto was the capital of Japan. The Emperor of Japan, or Tenno, lived in Kyoto. Edo was the place where the Tokugawa Shoguns lived. The city grew up under the control of the shoguns. Before then it was a small town on the sea. Edo means "the mouth of a river" in Japanese.

Tokyo was destroyed by fires started by the Great Kantō earthquake in 1923. It was also badly damaged by bombs during World War II. After Japan lost the war, the city was rebuilt.

History
History

1457-1869
Tokyo began as a small fishing village named Edo. Edo was in the old Musashi Province. 

The Edo clan built walls to protect the town in the late 12th century. In 1457, Ōta Dōkan built Edo Castle. In 1590, Tokugawa Ieyasu made Edo his base. He became shogun in 1603, and the town became the center of his military government. This marked the beginning of the Edo period. During this time, Edo grew into one of the largest cities in the world. More than one million people lived there by the 18th century.

Edo was not the capital of Japan. The emperor lived in the capital, Kyoto. However, since the shogun was more powerful than the emperor throughout Japanese history, Edo had more power. After about 263 years, the Meiji Restoration removed the shogun from power. In 1869, the 17-year-old Emperor Meiji moved to Edo. The old Edo Castle became the Kokyo, the Imperial Palace.

1869-1943

The Tokyo Prefecture and the city of Tokyo were established. This was the capital city until 1943.
1943-present
In 1943, Tokyo City and the "associated municipalities of what was formerly  (1869-1943)" combined into one.

Central Tokyo is built around major railway stations. Suburban railways were built relatively cheaply at street level. There are some expressways.

Tokyo suffered two major catastrophes in the 20th century. The 1923 Great Kantō earthquake left 140,000 dead or missing. World War II was the other disaster for the city. The Bombing of Tokyo from 1944 through 1945 killed between 75,000 and 200,000 people and destroyed half the city. This was almost as much damage as the atomic bombs of Hiroshima and Nagasaki combined.

Tokyo was completely rebuilt after the war. The 1964 Summer Olympics were a major world event. New high-rise developments such as Sunshine 60 started in the 1970s.

Climate
Tokyo has a four-season humid subtropical climate (Köppen climate classification: Cfa) with hot rainy summers and cool dry winters.

Population
Population

As of October 2007 about 8.7 million were living in Tokyo's 23 special wards. The number of people in Tokyo increases to over 15 million during the day. About 2.5 million workers and students enter the city everyday. The three central wards of Chiyoda, Chūō, and Minato increase the most. As of 2005, the regular population in those three areas was only 326,000 at night, but there are 2.4 million in those areas during the day.

Tokyo has many international residents. As of 2005, the most common groups in Tokyo are Chinese (123,661), Koreans (106,697), and Filipinos (31,077). Americans (18,848), British (7,696), Brazilian (5,300) and French (3,000) are less common.

Special wards
Special wards

The 23 special wards of Tokyo are the same area that had been called Tokyo City. On July 1, 1943, Tokyo City was merged with  to become a special government area. This made the wards different from other wards in Japan. Other city wards are part of a larger city government, but these are not.
Each ward is a municipality with its own mayor and assembly like the other cities of Japan. The special wards often use the word city in their official English name, e.g. Chiyoda City.

The wards have a unique administrative relationship with the prefectural government.  The Tokyo Metropolitan Government manages some public works such as water, sewer, and fire-fighting. To pay for these things, the prefecture collects the municipal taxes usually collected by a city.

The special wards of Tokyo are:

Three wards of Tokyo make up the central part of the city. They are Chiyoda, Chūō and Minato.

Landmarks
Landmarks 

Tokyo has many sight-seeing spots, but very few of them are old. There are very few buildings in Tokyo that are more than 50 years old. Popular places for visitors range from Tokyo Tower in the center of the city to Mount Takao out in the western countryside. Tokyo Skytree is a new tower and is the tallest in Japan. Traditional religious sights such as Meiji Shrine and Sensō-ji attract many tourists. The Imperial Palace can be seen in the middle of the city, but is not open to the public.

Transportation 
Tokyo is the cultural, business, and political center of the country. It is also the center of many transport systems. There are many air, rail, sea, and road links in and out of the city. Local subway and bus systems serve every part of the city.

Two commercial airports serve Tokyo. Haneda Airport is in the city limits next to Tokyo Bay. This airport is mostly for domestic travel. Most international flights to and from Tokyo go through Narita Airport in Chiba Prefecture.
Several Shinkansen super-express railway lines begin at Tokyo Station, including the  Tōkaidō Shinkansen going west and Tōhoku Shinkansen going northeast. Tokyo Metro is the city's major subway system.

Tokyo has a busy international and domestic port, but more traffic goes through the nearby port of Yokohama. There are domestic ferries to the islands of Tokyo, but also to other parts of the country such as Hokkaido.

Many highways meet in Tokyo, including: the Chūō, Kan-Etsu, Tōhoku, and Tōmei Expressways. All highway distances in Japan start from zero at a marker in Nihonbashi, Tokyo.

Related pages
 F.C. Tokyo
 Tokyo Metropolis
 Tokyo Verdy
 2020 Summer Olympics

Universities in Tokyo

National Universities

 Hitotsubashi University
 Tokyo Medical and Dental University
 University of Tokyo

Private Universities

 Keio University
 Nihon University
 Tokyo Woman's Christian University
 Waseda University
 Waseda Jitsugyo (Private school attached to Waseda Univ.)

References

Other websites
Other websites 

 Tokyo Convention and Visitors Bureau
 Tokyo Shitamachi Bus

 
Olympic cities
Laozi (Lao Tsu, Lao-Tze) was a Chinese philosopher best known for Taoism, the Tao Te Ching, and becoming a deity of Taoism and Chinese folk religions. A legendary figure of Chinese culture, Laozi may have lived during the Warring States period. Laozi's work influenced anti-authoritarian and Legalist philosophers.

What was his real name? 
Laozi's personal name is supposedly Li Er (李尔). His courtesy name is Boyang (伯阳). A popular posthumous name is Li Dan  Lǐ Dān). During the Tang dynasty, he was called the "Supremely Mysterious and Primordial Emperor"  Tàishàng Xuānyuán Huángdì).

Many people of the Li family say they descended from Laozi. For example, the emperors of the Tang dynasty claimed this. This family was known as the Longxi Li lineage (隴西李氏). Although these are questionable, they show Laozi's impact on Chinese culture.

Who was he?

Was he even real? 

Some philosophers don't think he was real. Some think the Daodejing was "a compilation of Taoist sayings by many hands".
The first mention to Laozi is in the "Records of the Grand Historian" by Sima Qian. In one account, he was an official who lived around the time of Confucius. His name was "Er Li" or "Dan Li", and he wrote some a book with two parts before leaving west. In another, he has the name "Lao Laizi", and the book has 15 parts. In a third, he appears as a royal astrologer named "Lao Dan" living at the time of Duke Xian during the Qin Dynasty. The oldest Daodejing writing comes from around 375 BCE.

According to traditional accounts, Laozi worked as the Keeper of the Archives (librarian) during the Zhou. He was able to study the works of the Yellow Emperor and other classics. Laozi never opened a school but still had many students. There is a story of his meeting with Confucius (most famously in the Zhuangzi ).

Birth 
He may have come from the village of Chu Jen in Chu.
Taoist myths state that Laozi was born when his mother looked at a falling star. He remained in her womb for 62 years while his mother was leaning against a plum tree. The Chinese name Li 李 is the Chinese character for "plum". Laozi was said to have been born as a grown man with a full grey beard and long ears, symbols of wisdom and long life. Other myths state that he was reborn 13 times after his first life during the days of Fuxi. In his last birth as Laozi, he lived 999 years and spent his life traveling to reveal the Tao.
His son Zong 
In accounts where Laozi married, he was said to have had a son named Zong. They are separated when Zong is a child. Zong became a famous soldier and defeated many enemies. Laozi was teaching the Dao, and Zong learns Laozi is his father. Laozi says it is better to treat a beaten enemy with respect and that disrespect to the dead would cause his enemies to seek revenge. So Zong orders his soldiers to bury the enemy dead and hold funeral mournings. Lasting peace is then made.
Buddha and the origin of Daoism 
Sima Qian says Laozi was tired of the moral decay in Chengzhou. The kingdom was declining. He traveled west and lived on the frontier until 80. He was recognized by the guard Yinxi at a western gate. Yinxi asked Laozi to write his wisdom. This became the Daodejing. But the present version of the text includes additions from later periods. In some versions of the tale, Yinxi liked the work so much that he became a student and left with Laozi, never to be seen again. In others, the "Old Master" traveled all the way to India and was the teacher of Siddhartha Gautama, the Buddha. Others say Laozi was the Buddha himself.
A seventh-century work, the Sandong Zhunang ("Pearly Bag of the Three Caverns"), said Laozi pretended to be a farmer when reaching the western gate, but was recognized by Yinxi, who asked to be taught by the great master. Yinxi wanted to find the Tao and said his long study of astrology allowed him to recognize Laozi. Yinxi was accepted by Laozi as a student. This shows the testing a seeker must undergo before being accepted as a student of a master.

Yinxi then trains. After completing the training, the two go to the western lands of the barbarians. They reached the highest religious rank in medieval Taoism called "Preceptor of the Three Caverns". Laozi is the perfect Taoist master and Yinxi is the ideal Taoist student. Laozi is the livingTao personified, teaching others for salvation.
The story of Laozi became religious since the Han dynasty. As Taoism became more popular, Laozi was worshipped as a god. The Way of the Celestial Masters became the first Taoist sect. Later Taoists view Laozi as the Dao in human form. Religious Taoism says that Laozi did not disappear after writing the Daodejing but spent his whole life traveling and revealing the Dao to others.

Daoism

Laozi is traditionally regarded as the founder of Taoism. Popular Taoism typically presents the Jade Emperor as the main deity. Intellectual Taoists, such as the Celestial Masters sect, usually present Laozi (Laojun, 老君, "Lord Lao") and the Three Pure Ones at the main gods.

Daodejing
Daodejing

Laozi is traditionally regarded as the author of the Daodejing, but this is disputed. It is one of the most significant books in Chinese cosmogony. Like other ancient Chinese philosophers, Laozi often explains his ideas using paradox, analogy, ancient sayings, repetition, rhyme, and rhythm. In fact, the whole book can be read as an analogy: the ruler is the self, and the others and empire are the body, senses, and desires.

The Daodejing says the Dao is the source and ideal of all existence: it is unseen, very powerful but also very humble, being the root of all things. People have desires and free will. Many act "unnaturally", breaking the natural balance of the Dao. The Daodejing intends to lead students to "return" to their natural state, in harmony with Tao. Taoism views them language as biased and artificial and shows this through paradoxes.
Another example: technology may give a false sense of progress. Laozi says not to reject technology, but instead seek the calm state of wu wei (無爲), without desires. Laozi says rulers should keep their people ignorant or simple-minded. This may be political advice, but it could also be religious. The text uses terms like "valley spirit" (gushen) and "soul" (po).

Wu wei literally "non-action" or "not acting", is an important concept. The concept is multifaceted, and this is shown by how it can mean many different things and be translated in multiple ways; it can mean "not doing anything", "not forcing", "not acting" (as in movies or drama), "creating nothingness", "acting spontaneously", and "flowing with the moment".
It is used to explain ziran (自然), or harmony with the Tao. It says all ambition originates from the same source. Laozi used the term to mean simplicity and humility as key virtues, in contrast to selfishness. Politically, it means avoiding war, harsh laws and heavy taxes. Some Taoists see a connection between wu wei and esoteric practices, such as zuowang (坐忘, "sitting in oblivion", emptying the mind of thought) found in the Zhuangzi.

Influence: anarchy, libertarianism, and limited government 
Laozi and Zhuangzi influenced many people throughout Chinese history. Zhuangzi was Laozi's most famous follower. Zhuangzi had a great deal of influence on Chinese scholars, bureaucrats, and culture. Politicians have used Laozi's philosophies to deny serving their ruler. They valued humility in leadership and limited government. This was either out of morality or for their own political means. Some anti-authoritarian movements used Laozi teachings to represent the power of the weak.
Laozi supported limited government. Left-libertarians have been influenced by Laozi. In his 1937 book Nationalism and Culture, the anarcho-syndicalist writer Rudolf Rocker praised Laozi's "gentle wisdom" and understanding that sometimes political power opposed culture and the community. In his 1910 article for the Encyclopædia Britannica, Peter Kropotkin said Laozi was one of the earliest supporters for anarchism. Many anarchists like Ursula K. Le Guin have used Laozi to justify their beliefs. Le Guin writes that Laozi "does not see political power as magic. He sees rightful power as earned and wrongful power as usurped... He sees sacrifice of self or others as a corruption of power, and power as available to anyone who follows the Way. No wonder anarchists and Taoists make good friends."
Economist Murray Rothbard suggested that Laozi was the first libertarian, comparing Laozi's ideas to Friedrich Hayek's theory of spontaneous order. James A. Dorn agreed, arguing that Laozi like many liberals "argued that minimizing the role of government and letting individuals develop spontaneously would best achieve social and economic harmony." David Boaz quotes the Daodejing in his 1997 book The Libertarian Reader. Philosopher Roderick Long argues that libertarianism in Taoism actually borrowed from earlier Confucian writers.

References
References

Further reading 
 Article by Bing YeYoung "The Shamanic Origins of Laozi and Confucius" 
 Inspiring thoughts of Lao Tzu
 True Tao Home Page: articles, stories focused on practical applications of Tao teachings.
 A reconstructed portrait of Laozi, based on historical sources, in a contemporary style.
 Lao Tzu Page  that provides teachings on Laozi, his life and philosophical concepts.
 A collection of resources on Laozi by Patrick Jennings: Critical Thinkers: Lao Tse & Daoism.
 Stanford Encyclopedia of Philosophy entry
 老子 Lǎozĭ 道德經 Dàodéjīng - 拼音 Pīnyīn + 王弼 WángBì + 馬王堆 Mǎwángduī + 郭店 Guōdiàn
 

Eastern philosophers
Chinese philosophers
Spiritual teachers
Taoism
This is a list of physicists.

Chile
Nicanor Parra

France
René Descartes

German
Albert Einstein

 Werner Heisenberg

Heinrich Rudolf Hertz

Georg Ohm

Great Britain
 Ernest Rutherford

England
 Michael Faraday

Thomas Young

Stephen Hawking

Robert Hooke

 James Prescott Joule

Isaac Newton

North Ireland
John Stewart Bell

Scotland
 James Clerk Maxwell

Holland
René Descartes

Italy
Galileo Galilei

Alessandro Volta

New Zealand
 Ernest Rutherford

Serbia
Nikola Tesla

United States

Gerard K. O'Neill
Nikola Tesla

Related pages
Physicist
Physics

Lists of scientists