Archives January 2013

"Experience is a dim lamp, which only lights the one who bears it." Louis-Ferdinand Celine, writer and physician During the latter half of the nineteenth century, there was considerable interest in the effects of electric currents being passed through gases at low pressures confined in glass tubes. Germans Julius Plucker and Heinrich Geissler noticed that if vaporized mercury was used as the gas, a bluish glow was emitted. An electrical engineer from the United States, Peter Cooper Hewitt (1861-1921), began to experiment with these mercury tubes and produced ones that emitted a great deal of an unflattering bluish-green light. Some of this light was in the ultraviolet and thus could not be seen. The fact that there is no emission in the red meant that the light made people appear like 'bloodless corpses." The dangerous effects of the ultraviolet emission could be alleviated by coating the tube with a fluorescent more...

Ever since Irving Langmuir's invention of the tungsten filament lamp in 1916, researchers at the General Electric Company (GEC) have been trying to produce more effective light bulbs. One of the problems with the tungsten filament (or incandescent) light bulb is that the tungsten evaporates during operation. This not only produces an absorbing coating on the inside wall of the bulb but it also weakens the filament, eventually leading to breakage. The manufacturers' dilemma is that the hotter filaments produce greater efficiency, but the greater evaporation shortens their lifetime. GEC research engineer Fredrick Moby made a breakthrough in 1960 when he placed an electrically heated, high temperature tungsten filament inside a compact fused quartz envelope filled with a halogen gas (usually iodine or bromine). His halogen lamp fitted into a standard light bulb socket. Not only did this bulb have a higher luminous efficiency, it also had about twice the more...

The introduction of the laptop computer presented a problem: namely, how to operate a computer's cursor without a mouse. The solution most widely adopted was created by American inventor Dr. George Gerpheide (b. 1952). His capacitive touchpad, invented in 1988, could detect a user's finger movement and transfer it to the on-screen cursor. Interestingly, Gerpheide developed this technology before point and click was the standard method of operating computer interfaces. This may explain why it was not until 1994 that Apple Computers bought the first license to use his technology (which first appeared on the Apple Powerbook 520). His touchpad works by employing several layers of material. At the top is a protective layer, about 3 inches (8 cm) square, that the user touches. Underneath are successive layers of electrodes arranged in horizontal and vertical rows, each separated by a thin layer of insulation. The electrodes are all connected to more...

Today's laptop computer has evolved over decades from different types of portable computers, but the Compaq was the most successful early model.   Alan Kay of the Xerox Corporation proposed the Dynabook concept in 1971. His idea was to create a portable, networked personal computer. However, at the time there was no market for it so the idea was shelved. In 1981 Alan Osborne of the Osborne Computer Corporation invented the Osborne 1, the first fully portable personal computer. The size of a small suitcase, it weighed about 24 pounds (11 kg). The first clamshell design was the GRiD Compass 1101, invented by Bill Moggride and released in 1982. Galivan Computer released what is considered to be the first true "laptop" computer in 1983; it was the smallest and lightest portable computer to date. However, it was Compaq Computer Corporation that stole the market from these rivals in 1983, with more...

There are no two opinions about the fact that morning walk is a boon for health. No diet or tonic is as effective as the morning walk. One has to pay nothing for it. I take a walk every morning with my friend Raju. Raju is my class mate and next door neighbour. We walk along the road. This lonely road leads out of the town. Yesterday we started at 5 a.m. As we went out a cool morning breeze welcomed us. We passed through some fields of wheat. The spreading fields presented a beautiful scene, the chirping of the birds created a lively sensation in our hearts. Some farmers were ploughing their fields at a distance. We passed through a small village where we saw village young women going to draw water. They were singing sweet folk songs; we enjoyed these songs very much. The golden ball  of sun more...

"[The optical trap] turned out to be a pretty important discovery. It led to Steve's [Chu] Nobel Prize..." Arthur Ashkin Radiation pressure is the force exerted by a beam of light when it is reflected from or absorbed by a body. Normal light beams are wide and brutal, but a focused laser beam can apply extremely delicate forces. If a small object has a mass less than about 1 gram and is dielectric, it can diffract a laser beam in such a way that the difference between the momentum of the radiation entering the object and that leaving it can be made to produce a force that traps the object in a specific position. A single laser beam can thus act like a pair of tweezers and individual atoms, molecules, and biological cells can be micro-manipulated using the beam. In 1970, Arthur Ashkin (b. 1922) of Bell Laboratories detected optical more...

During the rapid rise of the computer in the second half of the twentieth century, people were always searching for the next best way to interact with them. The early days of punched cards and paper tape became too cumbersome as computers advanced and keyboards became the input device of choice. In the 1960s, U.S. inventor Douglas Engelbart invented the computer mouse, which represented a milestone in computer interaction. The next big leap forward came in 1971 when Dr. Samuel C. Hurst invented the electronic touch screen interface. While teaching at the University of Kentucky, he was faced with the daunting task of reading a huge amount of data from a strip chart. Realizing that this work would normally take graduate students at least two months to complete, he decided to work on an easier method. What he came up with was the Elograph coordinate measuring system. It was an more...

"Smart phones differ from ordinary mobile phones in... how they are built and what they can do." David Wood, Symbian There is no standard definition for a smart phone, but in its basic sense it is a mobile phone with advanced functions. The first—called "Simon"—was developed by IBM in 1992 and released to the public in 1993. Simon's features included a calendar, an address book, a calculator, a notepad, e-mail, and fax capabilities. Instead of buttons for dialing, it had a touch screen for browsing and an on-screen keyboard for text input. In 1996 Nokia released its first smart phone, which combined their best-selling phone with the successful, but very expensive, palmtop computer developed by Hewlett-Packard. Later, several operating systems were developed specifically for smart phones, now a requirement for some smart phone definitions. The most widely used smart phone operating System is Symbian, which in 2005 accounted for 56 more...

"Science cannot solve the ultimate mystery of Nature... because... we ourselves are part of [it]." Max Planck, physicist At the heart of a SQUID (Superconducting Quantum Interface Device) are two Josephson junctions. These consist of two superconductors separated by an insulating barrier that is so thin that electrons can "tunnel" through. If a voltage is applied, the current across the barrier starts to oscillate at a high frequency, this being influenced by the ambient magnetic field. In the process, the electrical resistance of the SQUID changes. These changes can be used to measure very small and weak magnetic fields. The direct-current SQUID was invented by Robert Jaklevic, John Lambe, Arnold Silver, and James Mercereau in 1964, one year after the production of the first Josephson junction. The first models worked only at the temperature of liquid helium, -452°F (-269°C). The discovery of higher-temperature superconducting ceramics in 1987 meant that devices more...

"In recognition of the extraordinary services he has rendered by the discovery of the remarkable rays." The Royal Swedish Academy of Sciences, 1901  An X-ray is a form of electromagnetic radiation with a very short wavelength, in the range 10 to 0.01 nanometers. German physicist Wilhelm Rontgen (1845-1923) was experimenting with cathode rays in 1895 when he realized that these produced another form of radiation when they hit the glass of the cathode ray tube. He called them X-rays, as "X" stands for the unknown in mathematics. Rontgen discovered that X-rays passed through soft materials, such as paper, card, and fabric, and produced fluorescence and can be used to form images on a barium-coated photographic plate. His next experiments involved human tissue. He asked his wife to put her hand on the photographic plate and discovered that the X-rays passed through the flesh, but not through her bones, or her more...


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