Archives August 2013

"Getting information off the Internet is like taking a drink from a fire hydrant" Mitchell Kapor, software designer In 1963, the Advanced Research Project Agency (ARPA) unit, set up by the U.S. Defense Department, began to build a computer network. Driven by fear of the Soviet nuclear threat, it aimed to link computers at different locations, so researchers could share data electronically without having fixed routes between them, making the system less vulnerable to attacks—even nuclear ones. Data was converted into telephone signals using a modem (modulator-demodulator), developed at AT&T in the late 1950s. In the 1.960s, key advances were made, including "packet switching"—the system of packaging, labeling, and routing data that enables it to be delivered across the network between machines. Paul Baran (b. 1926) proposed this system, which broke each message down into tiny chunks. These would be fired into the network, which would then route ("switch") the more...

Michael Faraday (1791-1867), one of Britain's foremost physicists, is most famous for discovering principles relating to magnetic induction and the relationship between magnetism and electricity. But Faraday was also an inventive lecturer and actually initiated the tradition of the Christmas lectures at the Royal Institution (the lectures still go on to this day and are televised in the United Kingdom). Faraday even has the honor of having a unit of measurement named after him; the farad is a unit of electrical capacitance. However, an achievement of this scientist that much less often finds its way into the history books is that he also invented the toy balloon. Faraday's career began not in physics but in chemistry. He was appointed as a chemicals assistant at the Royal Institution and performed experiments in this capacity, investigating chlorine and the nature of gases. It was while researching the properties of hydrogen that Faraday more...

"Demeter, goddess of agriculture, ate Pelop's shoulder, but [made him] a prosthetic ivory shoulder." Ampuloves, History of prosthetic The earliest written reference to an artificial limb occurs in an epic Indian poem, the "Rig-Veda," which was compiled between 3500 and 1800 B.C.E. Written in Sanskrit, the poem includes a description of the amputation of the warrior Queen Vishpla's leg during battle. Later fitted with an iron prosthesis by the Ashvins (celestial physicians), she returned to combat. Most authorities doubt the story of Queen Vishpla, and turn to the Histories of Herodotus for the first plausible reference to a prosthetic limb. Herodotus describes how, in the mid sixth century B.C.E., Hegesistratus of Elis, a Persian soldier and seer imprisoned by the Spartans, was sentenced to death, and cut off part of his foot to escape from the stocks. Hegesistratus fashioned a wooden prosthesis to help walk the 30 miles (48 km) more...

“... embracing the fracture with a pair of hot tongs and closing so tight till the weld leans out..." Vannoccio Biringuccio, sixteenth-century writer Welding is the process of joining pieces of metal with heat, pressure, or a combination of both, so that they completely fuse together. The first instance of welding is thought to have been in the smelting of iron ore to create wrought iron, some of the earliest evidence of which was discovered in a Hattic tomb in northern Anatolia, dated to around 2500 B.C.E. Lumps of the iron ore were heated in furnaces until the impurities melted into a slag, trapped in pores in the still solid iron. The hot piece was then hammered to expel the liquid slag and weld together the particles of surrounding iron. Similar methods of heating and hammering were used to join separate pieces of iron, and examples of this were discovered in more...

By the time Isaac Fenn was granted a patent, in 1765, for his distance-measuring hodometer, the device had existed, in various forms and with various names, for centuries. In Roman times it was called an odometer and comprised little more than a wheel that could be pushed along, coupled to a mechanical system for counting the number of revolutions the wheel made, and thus the distance it had traveled. The eighteenth and nineteenth century saw the mapping of India and the division of vast tracts of land into farms in regions such as the United States and Australia. Reasonably accurate surveying and distance measurement became important. The surveyor's perambulator wheel (the "waywiser" or trundle wheel) was in everyday use. The accuracy of this device was good on a smooth surface such as a pavement or macadamed road. On rough terrain, such as farmland, wheel bounce and slippage became a problem more...

Superconductors are materials that have no electrical resistance, so electricity can flow through them with out any loss. The superconductivity phenomenon was first discovered in 1911 by researchers in Germany who used solid mercury as their conducting material. Superconductivity was at first seen only in certain substances when supercooled to temperatures close to absolute zero, or -459°F (-273°C)—the coldest temperature theoretically possible. In 1986 Georg Bednorz (b. 1950) and Alex Muller (b. 1927), both researchers at IBM, discovered a new type of superconducting material, copper oxide perovskites, that could superconduct at -396°F (-238°C). Paul Chu, at the University of Houston, improved on this by bringing the superconducting temperature up to a relatively balmy -296°F (-182°C). For the first time, superconductivity could be made to occur at temperatures in the range of liquid nitrogen. The discovery quickly led to a huge meeting of physicists in New York, a meeting that became more...

Superconductors are materials that have no electrical resistance, so electricity can flow through them with out any loss. The superconductivity phenomenon was first discovered in 1911 by researchers in Germany who used solid mercury as their conducting material. Superconductivity was at first seen only in certain substances when supercooled to temperatures close to absolute zero, or -459°F (-273°C)—the coldest temperature theoretically possible. In 1986 Georg Bednorz (b. 1950) and Alex Muller (b. 1927), both researchers at IBM, discovered a new type of superconducting material, copper oxide perovskites, that could superconduct at -396°F (-238°C). Paul Chu, at the University of Houston, improved on this by bringing the superconducting temperature up to a relatively balmy -296°F (-182°C). For the first time, superconductivity could be made to occur at temperatures in the range of liquid nitrogen. The discovery quickly led to a huge meeting of physicists in New York, a meeting that became more...

A precious child was born in 1469 in khatri family at Talwandi, near Lahore. The village is called Nankana Sahib which is now in Pakistan. The name of the boy was Nanak, known to the world as Guru Nanak Dev. At the age of seven he joined the village school.   He was very intelligent, and learned the alphabet in one day. Once he composed a beautiful hymn which is now in Guru Granth Sahib.   He used to think about God for hours together. When his father gave him twenty rupees to do some profitable business, he spent the money on feeding the hungry men. His father became worried about his work and approach towards life. So Nanak was married at the age of fourteen. But even marriage could not stop him from thinking about God. His father sent him to Sutanpur and was made a Government store-keeper by more...

In 1821 the Estonian physicist Thomas J. Seebeck made an accidental discovery: Not only does a potential (that is, voltage) difference exist between the two ends of an electrical conductor if these ends are at different temperatures, but also the voltage is a direct function of the temperature difference. If a circuit is made of a uniform material, the net loop voltage is zero. If, however, two different metallic conductors, such as platinum and palladium, are connected, a positive voltage is produced. The thermocouple, after being calibrated using the melting points of certain pure substances such as lead (621.68°F/327.6°C), silver (1,762°F/961°C), and nickel (2,647°F/1,453°C), can measure temperatures nearly up to the melting points of its two components. The Italian physicist Leopoldo Nobili (1784-1845) was slightly less ambitious and used a series of antimony bismuth bars to construct a thermopile in 1829. This was used to investigate infrared radiation and was more...

The Holi Festival is one of the most important and interesting festivals of Hindus. It comes in the Hindi month of Fagun. All persons young and old, men and women, boys and girls look forward to this  a day with great joy. There is a story.about the origin of this festival. Prahlad was a devotee of Vishnu. His father Hirnakashyap, hated Vishnu. He wanted to punish his son for chanting the name of Vishnu. He tried many ways to kill him but all failed. Hirnakashyap was determined to kill him. In the end he asked his sister, Holika to enter the fire with Prahlad. Her body was fire proof. Fortunately, Prahlad came out of the fire safe but his paternal aunt (Holika) was burnt to death. So this festival is celebrated in honour of this event. It is also said that the Holi is the beginning of the harvest season. more...