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In 1995 Edward Witten started what has been called the "Second Superstring Revolution" by introducing M-theory to the world. This theory combines the 5 different string theories (along with a previously abandoned attempt to unify General Relativity and Quantum Mechanics called 11D-Supergravity) into one theory. What Witten actually did was to predict that the fact that all these different theories were connected was a result of there being some underlying theory of which they were all approximations. This theory is somewhat vague in nature and has not yet been pinned down.
Additionally, it was found that the equations that required string theory to exist in 10 dimensions were actually approximations as well. The proposed M-theory would need one extra dimension and instead be a theory that takes place in "11 dimensions". Witten has himself compared this idea in simple terms to a general who takes up a position on a hilltop, the extra space-coordinate, to get a better view of the battlefield's two other dimensions.
The combination is accomplished by knitting together a web of relationships between each of the string theories called dualities (specifically, S-duality, T-duality, and U-duality). Each of these dualities provides a way of converting one of the string theories into another. T-duality is probably the most easily explained of the dualities. It has to do with the size, written as R, of the curled up dimensions of the string theories. It was discovered that by taking a Type IIA string theory that has a size R and changing the radius to 1/R the result will end up being what is equivalent to a Type IIB theory of size R. This duality, along with the others, creates connections between all 5 (or 6, if supergravity is counted) theories. The fact that these dualities existed had been known before Witten came up with the idea of M-theory.
Additional amusement has come for many in guessing what the M might stand for (possibilities include Matrix, Magic, Muffin, Mystery, Mother and Membrane). Regardless of what the M might possibly mean, M-theory has become one of the most interesting and active areas of research in theoretical physics today.
"For a more technical explanation, see w:M-theory (simplified explanation)."
Jaguar Cars
Jaguar Cars is a brand of automobiles made by Jaguar Land Rover. This is a British car builder, owned by the Indian builder Cans Tata Motors since the beginning of 2008. It was established in 1922 by William Lyons. It was renamed Jaguar in 1935. Jaguar is owned by the Indian automobile manufacturer Tata Motors Ltd. Jaguar is known for its luxury saloons and sportscars.
Jaguar was a private company until it became part of the British Motor Corporation in 1966. The new company was called British Motor Holdings. In 1968 that company joined with Leyland Motors to became British Leyland. In 1975 British Leyland was nationalised. In 1984 Jaguar was made private again by Margaret Thatcher. Ford bought Jaguar in 1989. In 1999 it was made part of Ford's "Premier Automotive Group" along with Aston Martin, Land Rover, Volvo and Lincoln. In 2008, Ford sold Jaguar and Land Rover to Tata Motors. Jaguar is now a brand of the merged company called Jaguar Land Rover (JLR).
The company was originally in Blackpool, but moved to Coventry. Today Jaguar automobiles are made at the JLR factory in Castle Bromwich in Birmingham. In late 2018 was open new plant in Slovakia.
Jaguar owns the Daimler brand (not Daimler-Benz). Jaguar bought the British Daimler Company in 1960. Daimler became a brand for some of Jaguar's saloon automobiles, but is not used now.
As of 2017, JLR sells the following different Jaguar automobile ranges: XJ, XF, XE, XK, F-Pace, E-Pace, iPace, and the F-Type.
Jaguar has won many sports car races, like the Le Mans 24 Hours and other races.
Scientific method
Scientific method refers to ways to investigate phenomena, get new knowledge, correct errors and mistakes, and test theories.
The Oxford English Dictionary says that scientific method is: "a method or procedure that has characterized natural science since the 17th century, consisting in systematic observation, measurement, and experiment, and the formulation, testing, and modification of hypotheses".
A scientist gathers empirical and measurable evidence, and uses sound reasoning. New knowledge often needs adjusting, or fitting into, previous knowledge.
What distinguishes a scientific method of inquiry is a question known as 'the criterion'. It is an answer to the question: is there a way to tell whether a concept or theory is science, as opposed to some other kind of knowledge or belief? There have been many ideas as to how it should be expressed. Logical positivists thought a theory was scientific if it could be verified; but Karl Popper thought this was a mistake. He thought a theory was not scientific unless there was some way it might be refuted. On the other hand, Paul Feyerabend thought there was no criterion. For him, "anything goes", or whatever works, works.
Scientists try to let reality speak for itself. They support a theory when its predictions are confirmed, and challenge it when its predictions prove false. Scientific researchers offer hypotheses as explanations of phenomena, and design experiments to test these hypotheses. Since big theories cannot be tested directly, it is done by testing predictions derived from the theory. These steps must be repeatable, to guard against mistake or confusion by any particular experimenter.
Scientific inquiry is generally intended to be as objective as possible. To reduce biased interpretations of results, scientists publish their work, and so share data and methods with other scientists.
Science and things that are not science (such as pseudoscience) are often distinguished by whether they use the scientific method. One of the first people to create an outline of the steps in the scientific method was John Stuart Mill.
There is no one scientific method. Some fields of science are based on mathematical models, such as physics and climate science. Other fields, such as many fields of social science, have rough theories and rely more on patterns that emerge from their data. Sometimes scientists focus on testing and confirming hypotheses, but open-ended exploration is also important. Some scientific fields use laboratory experiments. Others collect observations from real-world situations. Many areas of science are quantitative, emphasizing numerical data and mathematical analysis. But some areas, especially in social science, use qualitative methods, such as interviews or detailed observations of human or animal behavior. Focusing too much one kind of method can lead us to ignore knowledge produced using other methods.
Some textbooks focus on a single, standard "scientific method." This idea of a single scientific method is largely based on experimental, hypothesis-testing, quantitative areas of science. It doesn't apply very well to other areas of science. It is often written as a number of steps:
Although written as a list, scientists may go back and forth between different steps a number of times before being satisfied with the answer.
Not all scientists use the above "scientific method" in their day-to-day work. Sometimes the actual work of science looks nothing like the above.
Let's say we are going to find out the effect of temperature on the way sugar dissolves in a glass of water. Below is one way to do this, following the scientific method step by step.
Does sugar dissolve faster in hot water or cold water? Does the temperature affect how fast the sugar dissolves? This is a question we might want to ask.
One simple experiment would be to dissolve sugar in water of different temperatures and to keep track of how much time it takes for the sugar to dissolve. This would be a test of the idea that the rate of dissolving varies according to the kinetic energy of the solvent.
We want to make sure to use exactly the same amount of water in each trial, and exactly the same amount of sugar. We do this to make sure that the temperature alone causes the effect. It might be, for example, that the ratio of sugar to water is also a factor in the rate of dissolving. To be extra careful, we might also run the experiment so that the water temperature does not change during the experiment.
This is called "isolating a variable". This means that, of the factors which might have an effect, only one is being changed in the experiment.
We will do the experiment in three trials, which are exactly the same, except for the temperature of the water.
One way that makes it easy to see results is to make a table of them, listing all of the things that changed each time we ran the experiment. Ours might look like this:
If every other part of the experiment was the same (we did not use more sugar one time than the other, we did not stir one time or the other, etc.), then this would be very good evidence that heat affects how fast sugar is dissolved.
We cannot know for sure, though, that there is not something else affecting it. An example of a "hidden cause" might be that sugar dissolves faster each time more sugar is dissolved into the same pot. This is probably not true, but if it were, it could make the results exactly the same: three trials, and the last one would be fastest. We have no reason to think that this is true at this time, but we might want to note it as another possible answer.
The replication crisis (or replicability crisis) refers to a crisis in science. Very often the result of a scientific experiment is difficult or impossible to replicate later, either by independent researchers or by the original researchers themselves. While the crisis has long-standing roots, the phrase was coined in the early 2010s as part of a growing awareness of the problem.
Since the reproducibility of experiments is an essential part of the scientific method, the inability to replicate studies has potentially grave consequences.
The replication crisis has been particularly widely discussed in the field of psychology (and in particular, social psychology) and in medicine, where a number of efforts have been made to re-investigate classic results, and to attempt to determine both the validity of the results, and, if invalid, the reasons for the failure of replication.
Recent discussions have made this problem better known.
Elements of scientific method were worked out by some early students of nature.
Gas
A gas is one of the four most common states of matter. In a gas the molecules move freely and are independent of each other. This makes it different from a liquid where the molecules are loosely attached. It is also different from a solid where the bonds are strong and hold the molecules together.
In a pure gas, each molecule may be made of an individual atom. It may be elemental, where each molecule is made of more than one of the same atom bound together. It may be compounds where molecules are made of many types of atoms together. An example of a monoatomic gas is neon, an example of an elemental gas is hydrogen and an example of a compound gas is carbon dioxide.
A gas mixture contains a mix of any of the above types, for example air which is 87% nitrogen, 0.2% oxygen and 13.7% argon and carbon dioxide.<0.0009></33.3456333>
Poison gases were used as chemical weapons in War I but were later banned. gas is a natural mixture of methane and other gases.
All gases can flow, like liquids. This means the molecules move about independently of each other. Most gases are colourless, like hydrogen. Gas particles will spread about, or diffuse, in order to fill all the space in any container such as a bottle or a room. Compared to liquids and solids, gases have a very low density and viscosity. We cannot directly see most gases since they aren't coloured. However it is possible to measure their density, volume, temperature and pressure.
Pressure is the measure of how much pushing force something is putting on another object. In a gas, this is usually the gas pushing on the container of the object or, if the gas is heavy, something inside the gas. Pressure is measured in pascals. Because of Newton's third law, we can change the pressure of a gas by putting force on the object containing it. For example, squeezing a bottle with air inside pressurises (gives more pressure) to the air inside.
When talking about gas, pressure is often related to the container. A lot of gas in a small container would have very high pressure. A small amount of a gas in a big container would have low pressure.
Gas can create pressure itself when there is a lot of it. The weight of the gas creates pressure on anything underneath it, including other gas. On a planet, this is called atmospheric pressure.
The temperature of a gas is how hot or cold it is. In physics it is usually measured in kelvins although degrees Celsius are used more elsewhere. In a gas, the average velocity (how fast they move) of the molecules is related to the temperature. The faster the gas molecules are moving, the more they collide, or smash into each other. These collisions release energy, which in a gas comes in the form of heat. Conversely if the temperature around the gas becomes hotter then the gas particles will convert the thermal energy to kinetic energy, making them move faster and making the gas hotter.
A gas can go through two different state changes. If the temperature is low enough the gas can condense and turn into a liquid. Sometimes, if the temperature is low enough it can go through deposition, where it changes straight to a solid. Normally a gas must first condense to a liquid, and then freeze to become a solid, but if the temperature is very low it can skip the liquid stage and instantly become solid. Frost on the ground in winter is caused by this. Water vapour (a gas) goes into the air which is very cold, and instantly becomes ice due to deposition.
Family
A family is a group of people who, in most cases, live together. They share their money and food and are supposed to take care of one another. Its members are either genetically related (like brother and sister) or legally bound to each other, for example by marriage. In many cultures, the members of a family have the same or a similar surname.
The family in accordance to the Catholic doctrine is treated in many articles of the Catechism of the Catholic Church starting from the article 2201.
A family is said to be society's smallest unit, its nucleus. Family life is more private and intimate than public life. But in most countries there are laws for it. For example, there are restrictions for marrying within the family and bans for having a sexual relationship with relatives, especially with children.
Three types of family 0n the basic of size
are: "nuclear family", "single-parent family" and "extended family".
Both the "nuclear family" and the "single-parent family" are also called the "immediate family".
Foster families are families where a child lives with and is cared for by people who are not his or her parents.
Some family members are related closer to each other. Consanguinity is a way of measuring this closeness.
Notes:
Wave (physics)
A wave is a kind of oscillation (disturbance) that travels through space and matter. Wave motions transfer energy from one place to another.
Waves are found everywhere in the natural world. Examples of waves are:
Waves have properties that can be measured. All waves can be pictured by adding sine waves.
Sine waves can be measured too. The shape of a sine wave is given by its amplitude, phase, wavelength and frequency. The speed that the sine wave moves can be measured. The amplitude and wavelength of the sine wave are shown in the picture.
The highest point on a wave is called the crest. The lowest point is called the trough. The crest of a wave and the trough of a wave are always twice the wave's amplitude apart from each other. The part of the wave halfway in between the crest and the trough is called the baseline.
Complicated waveforms (like the sound waves of music) can be made by adding up sine waves of different frequencies. This is how mp3 audio files are converted from their compressed form into the music we can hear. Complex waves can be separated into sine waves by Fourier analysis.
Some waves can move through matter while others cannot. For instance, some waves can move through empty space, light waves for example. Sound waves, on the other hand, cannot move through empty space. Inherently, all waves carry energy from one place to another when they move. In some applications of technology, waves may carry meaningful information from one place to another, such as news on the radio.
Usually, after a wave moves through matter, the matter is the same as it was before the wave was introduced, though in some cases, matter can be affected by waves traveling through it. In 1922, Louis de Broglie found out that all waves are also particles, and all particles are also waves.
In matter:
Weapon
A weapon is an object that can be used to attack or injure a person or animal. People have used weapons since very ancient times. While other animals use weapons, in most cases they are attached to the animal (teeth, claws, tusks, etc.). In man's case they are detached and constantly selected for the purpose at hand. Man has been constantly developing newer and better weapons ever since he picked up the first rock.
Some of the oldest remains that we have of ancient people are weapons made of stone. Ancient people also used spears. Bows and arrows were in use by about 20,000 BC. During the Bronze age people learned to make things of metal, many people used swords. People also built huge machines which could throw rocks to destroy the defensive walls of enemy cities. Some of these machines were called catapults or siege engines. Later, gunpowder was invented in China and the Europeans began using it to make guns and cannons. These weapons were much better than the older weapons, and helped the Europeans to conquer people in many parts of the world. People in many parts of the world used guns such as rifles and shotguns for hunting animals, and handguns for shooting other people.
People continued to invent new weapons. In 1884 the machine gun was invented, which could shoot many bullets very fast. Soldiers began to use land mines, a bomb hidden in the ground, which explodes when someone walks on it. Small submarines were able to use torpedos to attack bigger ships and hide under the ocean. When airplanes were invented, people began to use them to shoot enemies and to drop bombs on them. They built tanks which had big guns and strong armor. Poison gas was used in World War I but was outlawed and rarely used afterwards.
In World War II, cities were heavily bombed from the air and Nazi Germany used V-2 missiles to carry bombs to England. Both sides used many firebombs. At the end of World War II, the United States used atomic bombs (nuclear bombs) to destroy the Japanese cities of Hiroshima and Nagasaki.
After World War II, people continued to develop new weapons, including intercontinental ballistic missiles. People became concerned about weapons of mass destruction, weapons that can kill many people very fast, and are usually cheap and easy to make and use. One kind of weapon of mass destruction is poison gas. New kinds of poison gas, such as nerve gas, are much more powerful than the old kinds. Another kind of weapon of mass destruction is disease germs, which could be used to make many people sick and maybe kill them.
Old-fashioned weapons still kill many people in wars and fighting. In wars in Africa in the 1990s and early 21st century, many people were killed with machetes (big knives). People sometimes try to make laws, treaties, and international agreements to try to control weapons because they are worried about all the killing done with them. Laws vary from country to country, for example, in the United States, the "right to keep and bear arms" is guaranteed to all citizens by the Constitution. A country may say that people in that country cannot keep or use guns, or only when the government allows it. The laws of war forbid certain weapons, and countries may agree with each other that they should not use certain weapons against each other, or should not have more than a certain number of particular kinds of weapons.
Things specifically made as weapons that most ordinary people can carry, include non lethal:
Weapons that soldiers or police personnel carry, include:
Weapons that the defense people of a national government have, include:
Other types of weapons include:
Christmas cake
A Christmas cake is a heavy cake containing much dried fruit and usually having a covering of icing. It is made to be eaten at Christmas. It can also be called a fruitcake.
A common favorite of many is the traditional Scottish Christmas cake, the "Whisky Dundee." It was named this because the cake came from Dundee and is made with Scotch whisky. It is a light and crumbly cake, and light on fruit and candied peel—only currants, raisins, sultanas and cherries. This Christmas cake is mostly good for people who do not like very sweet and moist cakes. As with all fruitcakes, almonds (or other nuts) can be removed by people who do not like them or those with bad nut allergies.
At the other end of the Christmas cake tradition, the apple cream Christmas cake is a sweet mix of sliced apples, raisins and other fruit, with eggs, cream cheese, and heavy whipping cream.
In the middle of the other two listed above is the mincemeat Christmas cake. It is simply any traditional or vegetarian mincemeat mixed with flour, eggs, and other pastry ingredients, to transform it into a cake batter; or it can also be steamed as a Christmas pudding.
A premade fruitcake mix can be bought at a grocery store.
Christmas cracker
A Christmas cracker is a tube of brightly coloured paper. When pulled apart, it makes a pop sound. It usually contains a small gift, a paper hat and a joke. It is generally used at Christmas parties or Christmas dinner. It is a British tradition which started back in the 1840s.
Fingerplate
A fingerplate is a plate that is fixed to a door near the handle or keyhole. It is for stopping dirt getting on the door. It is made of metal or glass.
Floodlight
A floodlight is a large electric light. It makes a very strong and bright beam of light. It is used for lighting the outside of buildings, football grounds, etc. at night.
Headrest
A headrest is something which supports the head. It is usually a suitably shaped part of the back of a chair or of a front seat in a car.
It is designed to support passenger's shoulder part and neck to prevent whiplash in cases of crash at the rear.
Inkpad
An inkpad is a small box that contains a pad of cloth or other material. It is impregnated with ink (the pad is inky). A marker is pressed onto the pad, then onto paper. Any raised marks on the pad leave an impression in ink on the paper.
Ink pads are used with rubber stamps. On the stamp is the symbol of an organisation, for example. After a form has been passed by an official, it is stamped to show it is authentic. Another variation is a date stamp, placed on all letters which arrive in the building. Another version is a stamp with a facsimile (copy) of an official's signature. Using this, staff can send out letters when the official is not present. Rubber stamps and ink pads have been used for at least a hundred years by civil servants and businesses. They are still in use in many countries, but are gradually being replaced with other systems.
Jack-in-the-box
A jack-in-the-box is a children's toy which is a box from which a figure on a spring jumps when the top is opened. You twist the knob until the spring shoots out the toy, which you put back in the box and do it all over again. Many kids have fun when they see the jack jumping out from the box.