AcharyaChanakya/simple-wikipedia huggingface dataset:
In 1905, Albert Einstein used Planck's idea to show that a beam of light is made up of a stream of particles called photons. The energy of each photon depends on its frequency. Einstein's idea is the beginning of the idea in quantum mechanics that all subatomic particles like electrons, protons, neutrons, and others are both waves and particles at the same time. (See picture of atom with the electron as waves at atom.) This led to a theory about subatomic particles and electromagnetic waves called "wave-particle duality". This is where particles and waves were neither one nor the other, but had certain properties of both.
In 1913, Niels Bohr came up with the idea that electrons could only take up certain orbits around the nucleus of an atom. Under Bohr's theory, the numbers called m and n in the equation above could represent orbits. Bohr's theory said electrons could begin in some orbit m and end up in some orbit n, or an electron could begin in some orbit n and end up in some orbit m so if a photon hits an electron, its energy will be absorbed, and the electron will move to a higher orbit because of that extra energy. Under Bohr's theory, if an electron falls from a higher orbit to a lower orbit, then it will have to give up energy in the form of a photon. The energy of the photon will equal the energy difference between the two orbits, and the energy of a photon makes it have a certain frequency and color. Bohr's theory provided a good explanation of many aspects of subatomic phenomena, but failed to answer why each of the colors of light produced by glowing hydrogen (and by glowing neon or any other element) has a brightness of its own, and the brightness differences are always the same for each element.
By the time Niels Bohr came out with his theory, most things about the light produced by a hydrogen lamp were known, but scientists still could not explain the brightness of each of the lines produced by glowing hydrogen.
Werner Heisenberg took on the job of explaining the brightness or "intensity" of each line. He could not use any simple rule like the one Balmer had come up with. He had to use the very difficult math of classical physics that figures everything out in terms of things like the mass (weight) of an electron, the charge (static electric strength) of an electron, and other tiny quantities. Classical physics already had answers for the brightness of the bands of color that a hydrogen lamp produces, but the classical theory said that there should be a continuous rainbow, and not four separate color bands. Heisenberg's explanation is:
There is some law that says what frequencies of light glowing hydrogen will produce. It has to predict spaced-out frequencies when the electrons involved are moving between orbits close to the nucleus (center) of the atom, but it also has to predict that the frequencies will get closer and closer together as we look at what the electron does in moving between orbits farther and farther out. It will also predict that the intensity differences between frequencies get closer and closer together as we go out. Where classical physics already gives the right answers by one set of equations the new physics has to give the same answers but by different equations.
Classical physics uses the methods of the French mathematician Fourier to make a math picture of the physical world, and it uses collections of smooth curves that go together to make one smooth curve that gives, in this case, intensities for light of all frequencies from some light. But it is not right because that smooth curve only appears at higher frequencies. At lower frequencies, there are always isolated points and nothing connects the dots. So, to make a map of the real world, Heisenberg had to make a big change. He had to do something to pick out only the numbers that would match what was seen in nature. Sometimes people say he "guessed" these equations, but he was not making blind guesses. He found what he needed. The numbers that he calculated would put dots on a graph, but there would be no line drawn between the dots. And making one "graph" just of dots for every set of calculations would have wasted lots of paper and not have gotten anything done. Heisenberg found a way to efficiently predict the intensities for different frequencies and to organize that information in a helpful way.
Just using the empirical rule given above, the one that Balmer got started and Rydberg improved, we can see how to get one set of numbers that would help Heisenberg get the kind of picture that he wanted:
The rule says that when the electron moves from one orbit to another it either gains or loses energy, depending on whether it is getting farther from the center or nearer to it. So we can put these orbits or energy levels in as headings along the top and the side of a grid. For historical reasons the lowest orbit is called n, and the next orbit out is called n - a, then comes n - b, and so forth. It is confusing that they used negative numbers when the electrons were actually gaining energy, but that is just the way it is.
Since the Rydberg rule gives us frequencies, we can use that rule to put in numbers depending on where the electron goes. If the electron starts at n and ends up at n, then it has not really gone anywhere, so it did not gain energy and it did not lose energy. So the frequency is 0. If the electron starts at n-a and ends up at n, then it has fallen from a higher orbit to a lower orbit. If it does so then it loses energy, and the energy it loses shows up as a photon. The photon has a certain amount of energy, e, and that is related to a certain frequency f by the equation e = h f. So we know that a certain change of orbit is going to produce a certain frequency of light, f. If the electron starts at n and ends up at n - a, that means it has gone from a lower orbit to a higher orbit. That only happens when a photon of a certain frequency and energy comes in from the outside, is absorbed by the electron and gives it its energy, and that is what makes the electron go out to a higher orbit. So, to keep everything making sense, we write that frequency as a negative number. There was a photon with a certain frequency and now it has been taken away.
So we can make a grid like this, where f(a←b) means the frequency involved when an electron goes from energy state (orbit) b to energy state a (Again, sequences look backwards, but that is the way they were originally written.):
Grid of f
Heisenberg did not make the grids like this. He just did the math that would let him get the intensities he was looking for. But to do that he had to multiply two amplitudes (how high a wave measures) to work out the intensity. (In classical physics, intensity equals amplitude squared.) He made an odd-looking equation to handle this problem, wrote out the rest of his paper, handed it to his boss, and went on vacation. Dr. Born looked at his funny equation and it seemed a little crazy. He must have wondered, "Why did Heisenberg give me this strange thing? Why does he have to do it this way?" Then he realized that he was looking at a blueprint for something he already knew very well. He was used to calling the grid or table that we could write by doing, for instance, all the math for frequencies, a matrix. And Heisenberg's weird equation was a rule for multiplying two of them together. Max Born was a very, very good mathematician. He knew that since the two matrices (grids) being multiplied represented different things (like position (x,y,z) and momentum (mv), for instance), then when you multiply the first matrix by the second you get one answer and when you multiply the second matrix by the first matrix you get another answer. Even though he did not know about matrix math, Heisenberg already saw this "different answers" problem and it had bothered him. But Dr. Born was such a good mathematician that he saw that the difference between the first matrix multiplication and the second matrix multiplication was always going to involve Planck's constant, h, multiplied by the square root of negative one, i. So within a few days of Heisenberg's discovery they already had the basic math for what Heisenberg liked to call the "indeterminacy principle." By "indeterminate" Heisenberg meant that something like an electron is just not pinned down until it gets pinned down. It is a little like a jellyfish that is always squishing around and cannot be "in one place" unless you kill it. Later, people got in the habit of calling it "Heisenberg's uncertainty principle," which made many people make the mistake of thinking that electrons and things like that are really "somewhere" but we are just uncertain about it in our own minds. That idea is wrong. It is not what Heisenberg was talking about. Having trouble measuring something is a problem, but it is not the problem Heisenberg was talking about.
Heisenberg's idea is very hard to grasp, but we can make it clearer with an example. First, we will start calling these grids "matrices," because we will soon need to talk about matrix multiplication.
Suppose that we start with two kinds of measurements, position (q) and momentum (p). In 1925, Heisenberg wrote an equation like this one:
He did not know it, but this equation gives a blueprint for writing out two matrices (grids) and for multiplying them. The rules for multiplying one matrix by another are a little messy, but here are the two matrices according to the blueprint, and then their product:
Matrix of p
Matrix of q
The matrix for the product of the above two matrices as specified by the relevant equation in Heisenberg's 1925 paper is:
A=p(n←n-a)*q(n-a←n-b)+p(n←n-b)*q(n-b←n-b)+p(n←n-c)*q(n-c←n-b)+...
B=p(n-a←n-a)*q(n-a←n-c)+p(n-a←n-b)*q(n-b←n-c)+p(n-a←n-c)*q(n-c←n-c)+...
C=p(n-b←n-a)*q(n-a←n-d)+p(n-b←n-b)*q(n-b←n-d)+p(n-b←n-c)*q(n-d←n-d)+...
and so forth.
If the matrices were reversed, the following values would result:
A=q(n←n-a)*p(n-a←n-b)+q(n←n-b)*p(n-b←n-b)+q(n←n-c)*p(n-c←n-b)+...
B=q(n-a←n-a)*p(n-a←n-c)+q(n-a←n-b)*p(n-b←n-c)+q(n-a←n-c)*p(n-c←n-c)+...
C=q(n-b←n-a)*p(n-a←n-d)+q(n-b←n-b)*p(n-b←n-d)+q(n-b←n-c)*p(n-d←n-d)+...
Note how changing the order of multiplication changes the numbers, step by step, that are actually multiplied.
The work of Werner Heisenberg seemed to break a log jam. Very soon, many different other ways of explaining things came from people such as Louis de Broglie, Max Born, Paul Dirac, Wolfgang Pauli, and Erwin Schrödinger. The work of each of these physicists is its own story. The math used by Heisenberg and earlier people is not very hard to understand, but the equations quickly grew very complicated as physicists looked more deeply into the atomic world.
In the early days of quantum mechanics, Albert Einstein suggested that if it were right then quantum mechanics would mean that there would be "spooky action at a distance." It turned out that quantum mechanics was right, and that what Einstein had used as a reason to reject quantum mechanics actually happened. This kind of "spooky connection" between certain quantum events is now called "quantum entanglement".
When an experiment brings two things (photons, electrons, etc.) together, they must then share a common description in quantum mechanics. When they are later separated, they keep the same quantum mechanical description or "state." In the diagram, one characteristic (e.g., "up" spin) is drawn in red, and its mate (e.g., "down" spin) is drawn in blue. The purple band means that when, e.g., two electrons are put together the pair shares both characteristics. So both electrons could show either up spin or down spin. When they are later separated, one remaining on Earth and one going to some planet of the star Alpha Centauri, they still each have both spins. In other words, each one of them can "decide" to show itself as a spin-up electron or a spin-down electron. But if later on someone measures the other one, it must "decide" to show itself as having the opposite spin.
Einstein argued that over such a great distance it was crazy to think that forcing one electron to show its spin would then somehow make the other electron show an opposite characteristic. He said that the two electrons must have been spin-up or spin-down all along, but that quantum mechanics could not predict which characteristic each electron had. Being unable to predict, only being able to look at one of them with the right experiment, meant that quantum mechanics could not account for something important. Therefore, Einstein said, quantum mechanics had a big hole in it. Quantum mechanics was incomplete.
Later, it turned out that experiments showed that it was Einstein who was wrong.
In 1925, Werner Heisenberg described the Uncertainty principle, which says that the more we know about where a particle is, the less we can know about how fast it is going and in which direction. In other words, the more we know about the speed and direction of something small, the less we can know about its position. Physicists usually talk about the momentum in such discussions instead of talking about speed. Momentum is just the speed of something in a certain direction times its mass.
The reason behind Heisenberg's uncertainty principle says that we can never know both the location and the momentum of a particle. Because light is an abundant particle, it is used for measuring other particles. The only way to measure it is to bounce the light wave off of the particle and record the results. If a high energy, or high frequency, light beam is used, we can tell precisely where it is, but cannot tell how fast it was going. This is because the high energy photon transfers energy to the particle and changes the particle's speed. If we use a low energy photon, we can tell how fast it is going, but not where it is. This is because we are using light with a longer wavelength. The longer wavelength means the particle could be anywhere along the stretch of the wave.
The principle also says that there are many pairs of measurements for which we cannot know both of them about any particle (a very small thing), no matter how hard we try. The more we learn about one of such a pair, the less we can know about the other.
Even Albert Einstein had trouble accepting such a bizarre concept, and in a well-known debate said, "God does not play dice".
To this, Danish physicist Niels Bohr famously responded, "Einstein, don't tell God what to do".
Electrons surround every atom's nucleus. Chemical bonds link atoms to form molecules. A chemical bond links two atoms when electrons are shared between those atoms. Thus quantum mechanics is the physics of the chemical bond and of chemistry. Quantum mechanics helps us understand how molecules are made, and what their properties are.
quantum mechanics can also help us understand big things, such as stars and even the whole universe. Quantum mechanics is a very important part of the theory of how the universe began called the Big Bang.
Everything made of matter is attracted to other matter because of a fundamental force called gravity. Einstein's theory that explains gravity is called the theory of general relativity. A problem in modern physics is that some conclusions of quantum mechanics do not seem to agree with the theory of general relativity.
quantum mechanics is the part of physics that can explain why all electronic technology works as it does. Thus quantum mechanics explains how computers work, because computers are electronic machines. But the designers of the early computer hardware of around 1950 or 1960 did not need to think about quantum mechanics. The designers of radios and televisions at that time did not think about quantum mechanics either. However, the design of the more powerful integrated circuits and computer memory technologies of recent years does require quantum mechanics.
quantum mechanics has also made possible technologies such as:
quantum mechanics is a challenging subject for several reasons:
quantum mechanics describes nature in a way that is different from how we usually think about science. It tells us how likely to happen some things are, rather than telling us that they certainly will happen.
One example is Young's double-slit experiment. If we shoot single photons (single units of light) from a laser at a sheet of photographic film, we will see a single spot of light on the developed film. If we put a sheet of metal in between, and make two very narrow slits in the sheet, when we fire many photons at the metal sheet, and they have to go through the slits, then we will see something remarkable. All the way across the sheet of developed film we will see a series of bright and dark bands. We can use mathematics to tell exactly where the bright bands will be and how bright the light was that made them, that is, we can tell ahead of time how many photons will fall on each band. But if we slow the process down and see where each photon lands on the screen we can never tell ahead of time where the next one will show up. We can know for sure that it is most likely that a photon will hit the center bright band, and that it gets less and less likely that a photon will show up at bands farther and farther from the center. So we know for sure that the bands will be brightest at the center and get dimmer and dimmer farther away. But we never know for sure which photon will go into which band.
One of the strange conclusions of quantum mechanics theory is the "Schrödinger's cat" effect. Certain properties of a particle, such as their position, speed of motion, direction of motion, and "spin", cannot be talked about until something measures them (a photon bouncing off of an electron would count as a measurement of its position, for example). Before the measurement, the particle is in a "superposition of states," in which its properties have many values at the same time. Schrödinger said that quantum mechanics seemed to say that if something (such as the life or death of a cat) was determined by a quantum event, then its state would be determined by the state that resulted from the quantum event, but only at the time that somebody looked at the state of the quantum event. In the time before the state of the quantum event is looked at, perhaps "the living and dead cat (pardon
the expression) [are] mixed or smeared out in equal parts."
People often use the symbol formula_6, which is called "h-bar." formula_7 . H-bar is a unit of angular momentum. When this new unit is used to describe the orbits of electrons in atoms, the angular momentum of any electron in orbit is always a whole number.
The particle in a 1-dimensional well is the most simple example showing that the energy of a particle can only have specific values. The energy is said to be "quantized."
The well has zero potential energy inside a range and has infinite potential energy everywhere outside that range. For the 1-dimensional case in the formula_8 direction, the time-independent Schrödinger equation can be written as:
Using differential equations, we can figure out that formula_10 can be written as
or as
The walls of the box mean that the wavefunction must have a special form. The wavefunction of the particle must be zero anytime the walls are infinitely tall. At each wall:
Consider "x" = 0
Now consider: formula_15
We can see that formula_22 must be an integer. This means that the particle can only have special energy values and cannot have the energy values in between. This is an example of energy "quantization."
Duisburg
Duisburg (; Westphalian: "Duisborg", Ripuarian: "Duisburch", Low Franconian: "Duusbörg") is a German city in the state of North Rhine-Westphalia. It is where the Rhine and the Ruhr rivers meet. About 500,000 people live in Duisburg.
Kuopio
Kuopio is a city in Northern Savonia, Finland. It is the biggest city and cultural center of Eastern Finland. In November 2015 the population was about 112.000. It is the 8th biggest city in Finland.
The city is surrounded by lake Kallavesi. Many parts of the city are built on islands. Kuopio has always been a city of education. Two important schools are the University of Eastern Finland and the Savonia University of Applied Sciences.
In 2011 the town of Karttula merged with Kuopio. In 2013 Nilsiä merged as well. In 2015, Maaninka merged with the city. In 2017 Juankoski merged with the city.
Kuopio is twinned with:
A hammer is a tool for putting nails into objects such as wood. It has a long handle, and a tip with a flat end for hitting nails. The most common type of hammer (sometimes called a "claw hammer") has a curved end (on the other side of the hitting end) for pulling nails out.
A sledgehammer is a hammer that has a longer shaft, and a more massive head. The user can swing it with two hands and apply more force.
Hammers were used around 3.3 million years ago. The first hammers were made without handles. Stones attached to sticks with strips of leather or animal sinew were being used. Hammers with handles were made in 30,000 BCE during the middle of the Paleolithic Stone Age. The hammer was used for building, food and protection.
Hammers can be classified into two. They are:
Hand-powered hammers are hammers that are used with the hand. Examples include:
Mechanically-powered hammers are hammers that are used with a machine. Examples include:
Big hammers were sometimes used as weapons. A tiny hammer is also used inside most small arms.
Feces (or faeces), also called poo (generally British English), poop, shit, dookie, stool, or number 2 is the body's solid waste left over from eating food. Human feces leave the intestinal tract and are removed from the body through the anus. Feces are known for their unpleasant odor. The color, which can range from dark green through brown (the most common color) to bright yellow, depends on a lot of different things; for example, different foods can change the color of feces, as can some illnesses, like diarrhea. The consistency of feces changes too. In humans it is measured using the Bristol stool scale, a system for separating feces into 7 different types. It is used for medical diagnosis.
Although feces are generally considered waste, they actually have many uses. Feces are used by some scientists to follow animal populations. Feces from animals and humans can be used to create fertilizers for plant crops. Some feces are also used as a fuel for fires.
In informal language, there are many words for feces. These are often offensive or even vulgar. Examples include "shit", "poop", and "crap".
Catholicism is the traditions and beliefs of Catholic Churches. It refers to their theology, liturgy, morals and spirituality. The term usually refers to churches, both western and eastern, that are in full communion with the Holy See.
In 2012, there were more than 1.1 billion Catholics worldwide. This makes up more than 17% of the world population.
The word "Catholicism" comes from the Greek word "catholikismos" (). This means "according to the whole".
The word "Catholicism" refers to many things, including its religious beliefs (called theologies and "doctrines"), and its form of religious worship (called liturgies). The word also refers to Catholic religious beliefs about ethics (things that are right and wrong). It also refers to the ways that members of the Catholic religion live and practice their religion.
Many people use the word Catholicism to talk about religious beliefs of the Catholic Church, whose leader is called the "Bishop of Rome" and often called the "Pope". The Catholic Church is based in the Vatican City, a small independent country in the city of Rome, Italy. Sometimes the word also refers to beliefs of other Christian churches, including the Eastern Orthodox Churches, who have many beliefs similar to the Catholic Church, but do not believe the Bishop of Rome is their leader.
The word Catholicism is often used to tell the difference between the beliefs of Catholic Christians and the beliefs of others called Protestant Christians. Catholic and Orthodox churches use church leaders, called bishops, to determine beliefs. Protestants, however, often use each member's own understanding of the Bible to determine beliefs. Protestants use guidelines from the 16th-century Protestant Reformation to understand the Bible. It is the world's second largest religious denomination after Sunnism.
The oldest document that uses the name "Catholic Church" is a letter written by a man named Ignatius. Ignatius lived in the ancient city of Antioch. In the year 107, Ignatius wrote a letter addressed to the Christian community in the ancient city of Smyrna. In this letter, Ignatius encouraged the Christian Community to be loyal to their leader, the Bishop. Ignatius wrote:
"Wherever the bishop shall appear, there let the multitude of the people also be; even as, wherever Jesus Christ is, there is the Catholic Church."
Many different denominations (groups) of Christians call themselves "catholic". Often these groups have special beliefs about their leaders, called bishops. They believe Jesus of Nazareth (whom Christians believe is the Son of God) appointed the first bishops, who appointed future bishops, who eventually appointed each community's current bishops. This appointing of leaders is called "Apostolic Succession".
The groups that use the term "Catholic" to talk about themselves are the:
Not all communities believe that other communities use the term "catholic" properly. Also, not all communities believe that the other communities have apostolic succession either. For example, the Catholic Church believes that the Eastern Orthodox have apostolic succession. However, the Catholic Church does not believe that the Anglicans or Lutherans have it.
Eastern Orthodox have similar beliefs about Anglicans and Lutherans. Not all Eastern Orthodox believe that the Catholic Church has apostolic succession. Different members of the Eastern Orthodox churches have different opinions.
However, the Anglicans and Lutherans generally believe that all Christians are part of the "catholic" church. These groups have a very different understanding of the term "Catholic".
Catholicism was started as a result of Jesus of Nazareth, a Jewish man whom Christians believe is the Son of God, a Christian belief known as the Trinity (Father, Son, and Holy Spirit). Catholics believe Jesus to be a descendant of David, a Jewish king from a long time ago. Jesus was crucified by the Romans in the year 33 AD. Catholics believe Jesus rose from the dead, and spoke to his followers, called the twelve Apostles. They also believe that Jesus rose into Heaven, and then sent the Holy Spirit to guide his followers at an event known as Pentecost.
One of his followers, the apostle named Saint Peter, was appointed leader by Jesus and later became recognized as the first Pope, or Bishop of Rome, soon after that he was captured and was martyred in Rome. Catholics believe that Saint Peter was given the "keys of the Kingdom of Heaven," meaning that Jesus made him and the apostles in charge of forgiving sins. Catholics believe that Saint Peter passed the Apostolic Power (the ability to ordain priests and consecrate the Eucharist), given to him by Christ, to the Popes, who continue to pass the power through the papacy to this day. At the current time, the pope is Pope Francis, who is the leader of the Catholic Church. The word "pope" comes from the Latin word for "father."
In 325, the First Council of Nicaea agreed on how to organize the church. The council agreed the Church had five patriarchs (patriarch was the highest type of church leader). The five leaders were the archbishops of Rome (the Pope), Alexandria, Antioch, Constantinople, and Jerusalem. The Patriarch of Rome, was honored as "first among equals."
In time, several groups split off from the Catholic Church because of differing opinions of theology. This caused breaks from the Church called schisms. Most schisms happened because people had different beliefs about what is true.
In 451, a church division happened when all the church leaders meeting at the Church Council in the city of Chalcedon excommunicated (cut off) three leaders, because they held to monophysitism and would not accept the view that Jesus had two natures (fully divine and fully human). These three were the bishops of Egypt, Syria, and Armenia. Of course, these three bishops did not accept being excommunicated either, so the churches under them are still known today as Oriental Orthodox Churches.
In 1054, an Eastern part of the Catholic Church severed itself, in the East-West Schism. The church in Western Europe which followed the Pope, became known as the Roman Catholic Church. The churches in the rest of the world, which did not think that the Pope should lead all Christians, became known as the Orthodox Church. "Orthodox" means "correct belief;" as they believe that they have kept the teachings of the early church, and the Roman Catholics have not.
The next big secession was the Protestant Reformation. Protestants resisted the valid central authority of the Church in Rome and rejected many practices, beliefs and disciplines. The Reformation started in Germany, where Martin Luther sent his demands for change to the Church. Because of politics in Europe, many nations supported Luther. The Lutheran Church was started. Later the Calvinist or Presbyterian Church started.
In England, King Henry VIII started the Anglican church. He wanted to divorce his first wife; but the Pope wouldn't allow it, as the marriage was valid. At first, the church of King Henry VIII, the Church of England, was very similar to the Catholic Church. The major difference was that the king was head of the church, instead of the Pope. Later, under his son, Edward VI, the Anglican Church became more reformed or Protestant. Anglicans, and several other Protestant denominations, still believe they are reformed Catholics. Puritanism arose among Anglicans who thought the reforms didn't go far enough.
After the Reformation, many other Churches began because of disagreements over beliefs and practices of earlier Protestant doctrine. According to the 2010 U.S. Religious Congregations and Membership Study, this accounts for most of the Protestant denominations in the United States. There are about 314,000 of these. Two examples of these Protestant (or Reformed) churches are Methodist and Baptist.
A nail is a metal object with a flat head and a long, sharp tip. A hammer or nail gun is used to put it into another object. It is often used to join two objects together.
The history of the nail came in three periods:
Nails date back at least to Ancient Egypt – bronze nails found in Egypt have been dated 3400 BC. The Bible has references to nails. King David gave iron to make nails for what would become Solomon's Temple.
The Romans made extensive use of nails. The Roman army left behind seven tons of nails when it evacuated the fortress of Inchtuthil in Perthshire, Scotland, in 86 or 87 AD.
A dictatorship is a form of government, where one person effectively has all the power to run a country. In very few cases, a small group of people holds this power. This person is called a dictator. A dictatorship that is ruled by soldiers is called a military dictatorship or junta. An absolute monarchy (the system where there are Kings and Queens who have full power over their country) can be considered to be a dictatorship, but the people are usually not called dictators.
Roman dictators were temporary rulers appointed to protect the state during a war or other emergency. Many countries have laws that allow a similarly time-limited dictatorship, to fight against such problems. Karl Marx has the idea of the Dictatorship of the proletariat. When they became independent in the 1960s and 1970s, many African states changed to be dictatorships, run by one person. Karl Popper distinguished between two different forms of government, "Those where it is possible to change the government without bloodshed, in a popular vote, and those where it isn't." He said that this was the key difference, and not how the forms of government are named.
Dictators often come to power in times of difficulty, such as massive unemployment, inflation, and unrest among the population. Dictators are normally backed by powerful groups, such as landowners, private company owners, bank owners and in some cases institutions like the Roman Catholic Church to put in place law and order by force. This force may be directed at the poorer parts of society, such as unemployed workers, ethnic minorities, working class areas andshanty towns. Examples of this are the dictatorships in Latin America and the prosecution of the Jewish community in 1940s Germany.
Dictators normally need to do a number of things to put in place their dictatorships: they need to get rid of their opponents (which may be political or religious) - some are imprisoned, exiled (sent outside their country) or killed. Dictators will then need to prohibit (or not allow) political parties that oppose their rule. They will confiscate the political parties' property or offices and such things. Dictators may suppress or persecute some religious groups or institutions. Dictators will also need to undo or close down democratic institutions such as parliament and in some cases the congress.
Some social organizations, such as civil rights groups, human rights organisations, legal aid centers, students' unions, teachers' federations, trade or workers unions are also undone and those who persist with such activities may be killed. Dictators often rewrite an existing constitution or put in place a completely new one. This makes their power constitutional (which then cannot be disputed). Dictators then maintain their rule with state terrorism, which normally involves a secret police, death squads, random or night curfew, indefinite arrest without trial and a network of torture centers and concentration camps. Some dictatorships create a fictional (or non existent) internal (inside their country) enemy which they claim to be at war with to justify (give reason for) their use of much military violence against their people.
Electricity is the presence and flow of electric charge. Using electricity we can transfer energy in ways that allow us to do simple chores. Its best-known form is the flow of electrons through conductors such as copper wires.
The word "electricity" is sometimes used to mean "electrical energy". They are not the same thing: electricity is a transmission medium for electrical energy, like sea water is a transmission medium for wave energy. An item which allows electricity to move through it is called a conductor. Copper wires and other metal items are good conductors, allowing electricity to move through them and transmit electrical energy. Plastic is a bad conductor (also called an insulator) and doesn’t allow much electricity to move through it so it will stop the transmission of electrical energy.
Transmission of electrical energy can happen naturally (such as lightning), or be made by people (such as in a generator). It can be used to power machines and electrical devices. When electrical charges are not moving, electricity is called static electricity. When the charges are moving they are an electric current, sometimes called 'dynamic electricity'. Lightning is the most known - and dangerous - kind of electric current in nature, but sometimes static electricity causes things to stick together in nature as well.
Electricity can be dangerous, especially around water because water is a form of good conductor as it has impurities like salt in it. Salt can help electricity flow. Since the nineteenth century, electricity has been used in every part of our lives. Until then, it was just a curiosity seen in the lightning of a thunderstorm.
Electrical energy can be created if a magnet passes close to a metal wire. This is the method used by a generator. The biggest generators are in power stations. Electrical energy can also be released by combining chemicals in a jar with two different kinds of metal rods. This is the method used in a battery. Static electricity can be created through the friction between two materials - for instance a wool cap and a plastic ruler. This may make a spark. Electrical energy can also be created using energy from the sun, as in photovoltaic cells.
Electrical energy arrives at homes through wires from the places where it is made. It is used by electric lamps, electric heaters, etc. Many appliances such as washing machines and electric cookers use electricity. In factories, electrical energy powers machines. People who deal with electricity and electrical devices in our homes and factories are called "electricians".
The idea of electricity, or the fact that amber acquires the power to attract light objects when rubbed, may have been known to the Greek philosopher Thales of Miletus, who lived about 600 B.C.
Another Greek philosopher, Theophrastus, stated in a treatise that this power is possessed by other substances.
The first scientific study of electrical and magnetic phenomena, however, did not appear until A.D. 1600, from research done by the English physician William Gilbert. Gilbert was the first to apply the term "electric" (Greek, "elektron", "amber") to the force that substances exerted after being rubbed. He also distinguished between magnetic and electric action.
Ben Franklin spent much time in electrical research. His famous kite experiment proved that the atmospheric electricity (that causes the phenomena of lightning and thunder) is identical with the electrostatic charge on a Leydan jar. Franklin developed his theory that electricity is a single "fluid" existing in all matter, and that its effects can be explained by excesses and shortages of this fluid.
There are two types of electric charges that push and pull on each other: positive charges and negative charges. Electric charges push or pull on each other if they are not touching. This is possible because each charge makes an electric field around itself. An electric field is an area that surrounds a charge. At each point near a charge, the electric field points in a certain direction. If a positive charge is put at that point, it will be pushed in that direction. If a negative charge is put at that point, it will be pushed in the exact opposite direction.
It works like magnets, and in fact, electricity creates a magnetic field, in which similar charges repel each other and opposite charges attract. This means that if you put two negatives close together and let them go, they would move apart. The same is true for two positive charges. But if you put a positive charge and a negative charge close together, they would pull towards each other. A short way to remember this is the phrase opposites attract likes repel.
All the matter in the universe is made of tiny particles with positive, negative or neutral charges. The positive charges are called protons, and the negative charges are called electrons. Protons are much heavier than electrons, but they both have the same amount of electric charge, except that protons are positive and electrons are negative. Because "opposites attract," protons and electrons stick together. A few protons and electrons can form bigger particles called atoms and molecules. Atoms and molecules are still very tiny. They are too small to see. Any big object, like your finger, has more atoms and molecules in it than anyone can count. We can only estimate how many there are.
Because negative electrons and positive protons stick together to make big objects, all big objects that we can see and feel are electrically neutral. "Electrically" is a word meaning "describing electricity", and "neutral" is a word meaning "balanced." That is why we do not feel objects pushing and pulling on us from a distance, as they would if everything was electrically charged. All big objects are electrically neutral because there is the same amount of positive and negative charge in the world. We could say that the world is exactly balanced, or neutral. Scientists still do not know why this is so.
The electrons can move all around the material. Protons never move around a solid object because they are so heavy, at least compared to the electrons. A material that lets electrons move around is called a conductor. A material that keeps each electron tightly in place is called an insulator. Examples of conductors are copper, aluminum, silver, and gold. Examples of insulators are rubber, plastic, and wood. Copper is used very often as a conductor because it is a very good conductor and there is so much of it in the world. Copper is found in electrical wires. But sometimes, other materials are used.
Inside a conductor, electrons bounce around, but they do not keep going in one direction for long. If an electric field is set up inside the conductor, the electrons will all start to move in the direction opposite to the direction the field is pointing (because electrons are negatively charged). A battery can make an electric field inside a conductor. If both ends of a piece of wire are connected to the two ends of a battery (called the "electrodes"), the loop that was made is called an electrical circuit. Electrons will flow around and around the circuit as long as the battery is making an electric field inside the wire. This flow of electrons around the circuit is called electric current.
A conducting wire used to carry electric current is often wrapped in an insulator such as rubber. This is because wires that carry current are very dangerous. If a person or an animal touched a bare wire carrying current, they could get hurt or even die depending on how strong the current was and how much electrical energy the current is transmitting. You should be careful around electrical sockets and bare wires that might be carrying current.
It is possible to connect an electrical device to a circuit so that electrical current will flow through a device. This current will transmit electrical energy to make the device do something that we want it to do. Electrical devices can be very simple. For example, in a light bulb, current carries energy through a special wire called a filament, which makes it glow. Electrical devices can also be very complicated. Electrical energy can be used to drive an electric motor inside a tool like a drill or a pencil sharpener. Electrical energy is also used to power modern electronic devices, including telephones, computers, and televisions.
Here are a few terms that a person can come across when studying how electricity works. The study of electricity and how it makes electrical circuits possible is called electronics. There is a field of engineering called electrical engineering, where people come up with new things using electricity. All of these terms are important for them to know.
Electrical energy is mostly generated in places called power stations. Most power stations use heat to boil water into steam which turns a steam engine. The steam engine's turbine turns a machine called a 'generator'. Coiled wires inside the generator are made to spin in a magnetic field. This causes electricity to flow through the wires, carrying electrical energy. This process is called electromagnetic induction. Michael Faraday discovered how to do this.
Many sources of heat can be used to boil water for generators. Heat sources may use renewable energy resources in which the supply of heat energy never runs out and non-renewable energy resources in which the supply will be eventually used up.
Sometimes a natural flow, such as wind power or water power, can be used directly to turn a generator so no heat is needed.
Pretty Soldier Sailor Moon or Sailor Moon is a shojo manga by Naoko Takeuchi. It was adapted to an anime series by Toei Animation CO., LTD. "Sailor Moon" was one of the most popular anime/manga series during the 1990s, spanning five seasons, four movies, and multiple video games. It continues to hold a strong fanbase with many fansites devoted to it.
Usagi (Serena in English) is an eighth grader who is clumsy, a crybaby and who also gets bad grades. One day, she meets a talking cat named Luna, who tells her that she is Sailor Moon, a superhero. She has to fight monsters to save people from getting their energy stolen by evil beings. Usagi has some friends who fight evil along with her. They are named Sailor Mercury, Sailor Venus, Sailor Mars, and Sailor Jupiter. They make up a team called the Sailor Senshi ("Senshi" means "soldier" or "guardian in Japanese"). The Sailor Senshi are named after different planets in the solar system. Each of the Sailor Senshi uses magical powers to become a Sailor Senshi. They are also young Japanese girls. Their real names are not Sailor Mercury, Sailor Venus, Sailor Mars, and Sailor Jupiter. For example, when Sailor Mercury is not fighting evil, her name is Ami Mizuno (Amy in English). The name of Sailor Venus is Minako Aino (Mina in English). The name of Sailor Mars is Rei Hino (Raye in English). The name of Sailor Jupiter is Makoto Kino (Lita in English). Each of them has a transformation sequence where they turn into their Sailor Senshi form, with many colourful effects.
Mamoru Chiba (called Darien Chiba in the English manga and Darien Shields in the English anime) is Usagi's boyfriend. He uses magic powers to transform into a man named Tuxedo Mask, who fights evil along with the Sailor Senshi. In the future, Usagi and Mamoru get married and become the king and queen of the earth. Their daughter, named Chibiusa (Rini in the English version), travels through time to help them and the Sailor Senshi.
Usagi has a cat named Luna, named after the Latin word for moon. Minako has a cat named Artemis after the Greek goddess of the moon (although Artemis is a male cat). Luna and Artemis are not ordinary cats. They can talk, and they have moon symbols on their foreheads. They can also turn into humans in the manga, and Luna turns into a human in one of the anime movies. In the future, they have a kitten named Diana (Diana is the name of the Roman moon goddess).
Later on there are some other Sailor Senshi. They are named after the planets Saturn, Uranus, Neptune, and Pluto (now a dwarf planet). Sailor Saturn's real name is Hotaru Tomoe. Sailor Uranus' real name is Haruka Tenoh (Amara in English). Sailor Neptune's real name is Michiru Kaioh (Michelle in English). Sailor Pluto's real name is Setsuna Meioh (Trista in English). In the manga and anime series, Haruka and Michiru are lesbians, but in the English anime they were changed to cousins. This is because the English anime was made for younger children than the anime series.
Each Sailor Senshi has different powers. Sailor Moon has powers of love and healing. Sailor Mercury has powers of water and ice. Sailor Mars has fire powers, Sailor Jupiter has electricity and plant powers, and Sailor Venus has light and energy powers. Sailor Chibi Moon, (called Sailor Mini Moon in the English version) has love and sugar powers. Sailor Saturn is death and rebirth, Sailor Neptune is water, Sailor Uranus is earth, and Sailor Pluto has time and death powers. Tuxedo Mask can throw roses against enemies.
In the manga there are five series: "Bishoujo Senshi Sailor Moon", "Bishoujo Senshi Sailor Moon R(eturn/omance)", "Bishoujo Senshi Sailor Moon Super" "Bishoujo Senshi Sailor Moon SuperS" "Bishoujo Senshi Sailor Moon Stars". Sailor Moon was originally serialized in the Japanese manga magazine by Kodansha. Afterwards Kodansha published the completed series in volumes. There are eighteen volumes total.
The anime stayed close to the story from the manga. However, due to its popularity, Toei made more seasons and produced movies. Sailor Moon was licensed to be aired in the United States by DIC Entertainment (a company that makes TV and film). DIC cut out some scenes and changed some of the dialogue to make it more acceptable for children. Many anime fans did not like the changes. Due to their complaints, ADV Films and later Pioneer Inc. made uncut versions.
The following TV series and movies were made:
Anesthetic
An anesthetic or anaesthetic is a substance that stops pain. It makes people either stop hurting, or go completely to sleep during surgery. Anesthetic can be rubbed onto the skin, given by injection ("shot"), or given as a gas to breathe. The use of an anesthetic is called anaesthesia. Anaesthesia blocks the pain during operations. This lets patients undergo surgery and other procedures without the distress and pain they would normally feel. It comes from Greek roots an-, "without" and aesthetos, "perceptible, able to feel".