Portal:Technology/Selected articles
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[edit] Selected articles
The selected are what we believe to be the best articles in Wikipedia related to technology.
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[edit] Selected articles list
[edit] 35 mm film
35 mm film is the basic gauge most commonly used for both still photography and motion pictures, and remains relatively unchanged since its introduction in 1892 by William Dickson and Thomas Edison, using film stock supplied by George Eastman. The photographic film is cut into strips 35 mm (about 1 3/8 inches) wide — hence the name. The standard negative pulldown is four perforations per frame along both edges, which makes for exactly 16 frames per foot.
A wide variety of largely proprietary gauges were used by the numerous different camera and projection systems independently invented around the late 19th century and early 20th century, ranging from 13 mm to 75 mm (0.51–2.95 in). Its longevity is largely because its size allows for a relatively good tradeoff between the cost of the film stock and the quality of the images captured. Additionally, the ubiquity of 35 mm movie projectors in commercial movie theaters makes it the only motion picture format, film or video, which can be played in almost any cinema in the world.
[edit] Nuclear weapon
A nuclear weapon is a tool employed to injure, defeat, or destroy an adversary. It derives its destructive force from nuclear reactions of fission or fusion. As a result, even a nuclear weapon with a small yield is significantly more powerful than the largest conventional explosives, and a single weapon is capable of destroying an entire city.
In the history of warfare, nuclear weapons have been used only twice, both during the closing days of World War II. The first event occurred on the morning of August 6, 1945, when the United States dropped a uranium gun-type device code-named "Little Boy" on the Japanese city of Hiroshima. The 2nd event occurred 3 days later when the United States dropped a plutonium implosion-type device code-named "Fat Man" on the city of Nagasaki. The use of these weapons, which resulted in the immediate deaths of around 100,000 to 200,000 people and even more over time, was and remains controversial.
Since the Hiroshima and Nagasaki bombings, nuclear weapons have been detonated on over 2,000 occasions for testing and demonstration purposes. The only countries known to have detonated such weapons are (chronologically) the United States, Soviet Union, United Kingdom, France, People's Republic of China, India, Pakistan, and North Korea.
[edit] Rocket
A rocket or rocket vehicle is a missile, aircraft or other vehicle which obtains thrust by the reaction of the rocket to the ejection of fast moving fluid from a rocket engine. Chemical rockets work by the action of hot gas produced by the combustible forces that accelerate the gas to extremely high speed and exert a large thrust on the rocket (since every action has an equal and opposite reaction).The history of rockets goes back to at least the 13th century.[1] By the 20th century, they have enabled human spaceflight to the Moon. In the 21st century, they have made commercial space tourism possible.
Rockets are used for fireworks and weaponry, as launch vehicles for artificial satellites, human spaceflight and exploration of other planets. While inefficient for low speed use, they are, compared to other propulsion systems, very lightweight and powerful, capable of attaining extremely high speeds with reasonable efficiency and accuracy
[edit] Laser
A laser is a device that emits light (electromagnetic radiation) through a process called stimulated emission. The term laser is an acronym for light amplification by stimulated emission of radiation. Laser light is usually spatially coherent, which means that the light either is emitted in a narrow, low-divergence beam, or can be converted into one with the help of optical components such as lenses. Typically, lasers are thought of as emitting light with a narrow wavelength spectrum ("monochromatic" light). This is not true of all lasers, however: some emit light with a broad spectrum, while others emit light at multiple distinct wavelengths simultaneously. The coherence of typical laser emission is distinctive. Most other light sources emit incoherent light, which has a phase that varies randomly with time and position.
[edit] Interstellar travel
Interstellar space travel is unmanned or manned travel between stars. The concept of interstellar travel in starships is a staple in science fiction. Interstellar travel is tremendously more difficult than interplanetary travel. Intergalactic travel, the travel between different galaxies, is even more difficult.
Many scientific papers have been published about related concepts. Given sufficient travel time and engineering work, both unmanned and generational interstellar travel seem possible, though representing a very considerable technological and economic challenge unlikely to be met for some time, particularly for crewed probes. NASA has been engaging in research into these topics for several years, and has accumulated a number of theoretical approaches.
The main difficulty of interstellar travel is the vast distances that have to be covered and therefore the time it takes with most realistic propulsion methods - from decades to millennia. Hence an interstellar ship would be much more severely exposed to the hazards found in interplanetary travel, including hard vacuum, radiation, weightlessness, and micrometeoroids. The long travel times make it difficult to design manned missions, and make economic justification of any interstellar mission nearly impossible, since benefits that do not become available for decades or longer have a present value close to zero.
[edit] Global Positioning System
The Global Positioning System (GPS) is the only fully functional Global Navigation Satellite System (GNSS). The GPS uses a constellation of between 24 and 32 Medium Earth Orbit satellites that transmit precise microwave signals, that enable GPS receivers to determine their location, speed, direction, and time. GPS was developed by the United States Department of Defense. Its official name is NAVSTAR-GPS. Although NAVSTAR-GPS is not an acronym[2], a few backronyms have been created for it[3]. The GPS satellite constellation is managed by the United States Air Force 50th Space Wing.
Similar satellite navigation systems include the Russian GLONASS (incomplete as of 2008[update]), the upcoming European Galileo positioning system, the proposed COMPASS navigation system of China, and IRNSS of India.
Following the shooting down of Korean Air Lines Flight 007 in 1983, President Ronald Reagan issued a directive making the system available free for civilian use as a common good.[4] Since then, GPS has become a widely used aid to navigation worldwide, and a useful tool for map-making, land surveying, commerce, scientific uses, and hobbies such as geocaching. GPS also provides a precise time reference used in many applications including scientific study of earthquakes, and synchronization of telecommunications networks.
[edit] Fusion power
Fusion power is power generated by nuclear fusion reactions. In this kind of reaction, two light atomic nuclei fuse together to form a heavier nucleus and in doing so, release energy. In a more general sense, the term can also refer to the production of net usable power from a fusion source, similar to the usage of the term "steam power." Most design studies for fusion power plants involve using the fusion reactions to create heat, which is then used to operate a steam turbine, similar to most coal-fired power stations as well as fission-driven nuclear power stations.
The largest current experiment is the Joint European Torus [JET]. In 1997, JET produced a peak of 16.1 MW of fusion power (65% of input power), with fusion power of over 10 MW sustained for over 0.5 sec. In June 2005, the construction of the experimental reactor ITER, designed to produce several times more fusion power than the power put into the plasma over many minutes, was announced. The production of net electrical power from fusion is planned for DEMO, the next generation experiment after ITER.
[edit] Solar cell
A solar cell or photovoltaic cell is a device that converts solar energy into electricity by the photovoltaic effect. Photovoltaics is the field of technology and research related to the application of solar cells as solar energy.
Sometimes the term devices intended specifically to capture energy from sunlight, while the term photovoltaic cell is used when the source is unspecified.
Assemblies of cells are used to make solar modules, which may in turn be linked in photovoltaic arrays.
Solar applications. Individual small devices as electronic calculators. Photovoltaic arrays generate a form of renewable electricity, particularly useful in situations where from the grid as in remote area power systems, Earth-orbiting satellites and space probes, remote radiotelephones and water pumping applications. Photovoltaic electricity is also increasingly deployed in grid-tied electrical systems.
Similar devices intended to capture from other sources include thermophotovoltaic cells, betavoltaics cells, and optoelectric nuclear battery.
[edit] Nanotechnology
Nanotechnology, sometimes shortened to "Nanotech", refers to a field whose theme is the control of matter on an atomic and molecular scale. Generally nanotechnology deals with structures 100 nanometers or smaller, and involves developing materials or devices within that size.
Nanotechnology is extremely diverse, ranging from novel extensions of conventional device physics, to completely new approaches based upon molecular self-assembly, to developing new materials with dimensions on the nanoscale, or the scale of nothing, even to speculation on whether we can directly control matter on the atomic scale.
There has been much debate on the future of implications of nanotechnology. Nanotechnology has the potential to create many new materials and devices with wide-ranging applications, such as in medicine, electronics, and energy production. On the other hand, nanotechnology raises many of the same issues as with any introduction of new technology, including concerns about the toxicity and environmental impact of nanomaterials, and their potential effects on global economics, as well as speculation about various doomsday scenarios. These concerns have led to a debate among advocacy groups and governments on whether special regulation of nanotechnology is warranted.
[edit] Black hole information paradox
The black hole information paradox results from the combination of quantum mechanics and general relativity. It suggests that physical information could "disappear" in a black hole. It is a contentious subject since it violates a commonly assumed tenet of science—that information cannot be destroyed.
In 1975, Stephen Hawking and Jacob Bekenstein showed that black holes should slowly radiate away energy, which poses a problem. From the no hair theorem one would expect the Hawking radiation to be completely independent of the material entering the black hole. Nevertheless, if the material entering the black hole were a pure quantum state, the transformation of that state into the mixed state of Hawking radiation would destroy information about the original quantum state. This violates Liouville's theorem and presents a physical paradox.
[edit] Superstring theory
Superstring theory is an attempt to explain all of the particles and fundamental forces of nature in one theory by modelling them as vibrations of tiny supersymmetric strings. It is considered one of the most promising candidate theories of quantum gravity. Superstring theory is a shorthand for supersymmetric string theory because unlike bosonic string theory, it is the version of string theory that incorporates fermions and supersymmetry.
The deepest problem in theoretical physics is harmonizing the theory of general relativity, which describes gravitation and applies to large-scale structures (stars, galaxies, super clusters), with quantum mechanics, which describes the other three fundamental forces acting on the atomic scale.
The development of a quantum field theory of a force invariably results in infinite (and therefore useless) probabilities. Physicists have developed mathematical techniques (renormalization) to eliminate these infinities which work for three of the four fundamental forces – electromagnetic, strong nuclear and weak nuclear forces - but not for gravity. The development of a quantum theory of gravity must therefore come about by different means than those used for the other forces.
[edit] Israel Aerospace Industries
Israel Aerospace Industries (Hebrew: התעשייה האווירית לישראל ha-ta'asiya ha-avirit le-yisra'el) or IAI (תע"א ta`a') is Israel's prime aerospace and aviation manufacturer, producing aerial systems for both military and civilian usage. It has 16,000 employees as of 2007.
In addition to local construction of fighter aircraft, IAI also builds civil aircraft (for Gulfstream, on the G100/G150 and G200) and performs local maintenance of foreign-built military and civilian aircraft. In addition, the company works on a number of missile and avionics systems. In 2003, Israel Aircraft Industries attempted to enter the VLJ (Very Light Jet) Market, by launching the Avocet ProJet, a 6-8 seat, high utilization air taxi, with a list price almost half the cost of the least expensive business jet available at that time.
In early 2006, the ProJet stalled after a major undisclosed US OEM pulled out of the program due to unspecified reasons.
Although the IAI main focus is aviation and high-tech electronics, it also manufactures military systems for ground and naval forces. Many of these products are specially suited for Israel Defence Forces needs, while others are also marketed to foreign militaries.
[edit] Lockheed Martin F-16 Fighting Falcon
The Lockheed Martin F-16 Fighting Falcon is a multirole jet fighter aircraft originally developed by General Dynamics for the United States Air Force. Designed as a lightweight fighter, it evolved into a successful multirole aircraft. The Falcon's versatility is a paramount reason it has proven a success on the export market, having been selected to serve in the air forces of 25 nations. The F-16 is the largest Western jet fighter program with over 4,400 aircraft built since production was approved in 1976. Though no longer being bought by the U.S. Air Force, advanced versions are still being built for export customers. In 1993, General Dynamics sold its aircraft manufacturing business to the Lockheed Corporation, which in turn became part of Lockheed Martin after a 1995 merger with Martin Marietta.
The Fighting Falcon is a dogfighter with numerous innovations including a frameless, bubble canopy for better visibility, side-mounted control stick to ease control while under high g-forces, and reclined seat to reduce the effect of g-forces on the pilot. Weapons include a M61 Vulcan cannon and various missiles mounted on up to 11 hardpoints. It was also the first fighter aircraft deliberately built to sustain 9-g turns. It has a thrust-to-weight ratio greater than one, providing enough power to climb and accelerate vertically – if necessary. Although the F-16's official name is "Fighting Falcon", it is known to its pilots as the "Viper", due it resembling a cobra snake and after the Battlestar Galactica starfighter. It is used by the Thunderbirds air demonstration team.
[edit] Space toilet
A space toilet, or zero gravity toilet, is a toilet that can be used in a low gravity environment. In the absence of gravity the collection and retention of liquid and solid waste is directed by use of air flow. Since the air used to direct the waste is returned to the cabin, it is filtered beforehand to control odor and cleanse bacteria. In older systems, waste water is vented into space and any solids are compressed and stored for removal upon landing. More modern systems expose solid waste to vacuum to kill bacteria, which prevents odor problems and kills pathogens.
The toilet used on the Space Shuttle is called the Waste Collection System (WCS). In addition to air flow, it also uses rotating fans to distribute solid waste for in-flight storage. Solid waste is distributed in a cylindrical container which is then exposed to vacuum to dry the waste. Liquid waste is vented to space. During STS-46, one of the fans malfunctioned, and crew member Claude Nicollier was required to perform in-flight maintenance (IFM). An earlier, complete failure, on the eight-day STS-3 test flight, forced its two-man crew (Jack Lousma and Gordon Fullerton) to use the much-hated "Apollo Bag" for waste elimination and disposal.
[edit] Virtual globe
A virtual globe is a 3D software model or representation of the Earth or another world. A virtual globe provides the user with the ability to freely move around in the virtual environment by changing the viewing angle and position. Compared to a conventional globe, virtual globes have the additional capability of representing many different views on the surface of the Earth. These views may be of geographical features, man-made features such as roads and buildings, or abstract representations of demographic quantities such as population.
In 1998, Microsoft released a popular offline virtual globe in the form of Encarta Virtual Globe 98. The first widely publicized online virtual globe was Google Earth.
Virtual globes may be used for study or navigation (by connecting to a GPS device) and their design varies considerably according to their purpose. Those wishing to portray a visually accurate representation of the Earth often use satellite image servers and are capable not only of rotation but also zooming and sometimes horizon tilting. Very often such virtual globes aim to provide as true a representation of the world as is possible with worldwide coverage up to a very detailed level. When this is the case the interface often has the option of providing simplified graphical overlays to highlight man-made features since these are not necessarily obvious from a photographic aerial view. The other issue raised by such detail available is that of security with some governments having raised concerns about the ease of access to detailed views of sensitive locations such as airports and military base.
[edit] Area 51
Area 51 is a nickname for a military base located in the southern portion of Nevada in the western United States (north-northwest of Las Vegas). Situated at its center, on the southern shore of Groom Lake, is a large military airfield and one of the most secretive places in the world. The base's primary purpose is to support development and testing of experimental aircraft and weapons systems.
The base lies within the United States Air Force's vast Nevada Test and Training Range. Although the facilities at the range are managed by the 99th Air Base Wing at Nellis Air Force Base, the Groom facility appears to be run as an adjunct of the Air Force Flight Test Center (AFFTC) at Edwards Air Force Base in the Mojave Desert, around 160 miles (260 km) from Groom, and as such the base is known as Air Force Flight Test Center (Detachment 3). Area 51 researcher Glenn Campbell claims that AFFTC Detachment 3 is located at Groom, citing the title of a leaked security manual, the mailbox in Henderson, Nevada he believes formerly served Groom, and the NASA biography of astronaut Carl E. Walz who was formerly a manager at AFFTC detachment 3 (AFFTC-DET3.)
[edit] Colonization of Callisto
NASA performed a study called HOPE (Revolutionary Concepts for Human Outer Planet Exploration) regarding the future exploration of the solar system. The target chosen was Callisto, a moon of Jupiter. It could be possible to build a surface base that would produce fuel for further exploration of the solar system.
Because it is outside of Jupiter's radiation belt and also geologically very stable, it could prove to be a suitable place for a base. This base would also be a center for exploration of the Jovian system, for example remote exploration of Ganymede and Europa. It would also be the ideal location for a Jovian system way station that could service spacecraft headed farther into the outer Solar System, using a gravity assist from a close fly-by of Jupiter after departing Callisto.
[edit] Radioactive decay
Radioactive decay is the process in which an unstable atomic nucleus loses energy by emitting ionizing particles and radiation. This decay, or loss of energy, results in an atom of one type, called the parent nuclide transforming to an atom of a different type, called the daughter nuclide. For example: a carbon-14 atom (the "parent") emits radiation and transforms to a nitrogen-14 atom (the "daughter"). This is a random process on the atomic level, in that it is impossible to predict when a given atom will decay, but given a large number of similar atoms the decay rate, on average, is predictable.
The SI unit of radioactive decay is the becquerel (Bq). One Bq is defined as one transformation (or decay) per second. Since any reasonably-sized sample of radioactive material contains many atoms, a Bq is a tiny measure of activity; amounts on the order of TBq (terabecquerel) or GBq (gigabecquerel) are commonly used. Another unit of radioactivity is the curie, Ci, which was originally defined as the activity of one gram of pure radium, isotope Ra-226. At present it is equal, by definition, to the activity of any radionuclide decaying with a disintegration rate of 3.7 × 1010 Bq. The use of Ci is presently discouraged by the SI.
[edit] Transhumanism
Transhumanism is an international intellectual and cultural movement supporting the use of science and technology to improve human mental and physical characteristics and capacities. The movement regards aspects of the human condition, such as disability, suffering, disease, aging, and involuntary death as unnecessary and undesirable. Transhumanists look to biotechnologies and other emerging technologies for these purposes. Dangers, as well as benefits, are also of concern to the transhumanist movement. It is often symbolized by H+ or h+.
Although the first known use of the term "transhumanism" dates from 1957, the contemporary meaning is a product of the 1980s when futurists in the United States began to organize what has since grown into the transhumanist movement. Transhumanist thinkers predict that human beings may eventually be able to transform themselves into beings with such greatly expanded abilities as to merit the label "posthuman". Transhumanism is therefore sometimes referred to as "posthumanism" or a form of transformational activism influenced by posthumanist ideals.
Transhumanist foresight of a transformed future humanity has attracted many supporters and detractors from a wide range of perspectives. Transhumanism has been described by one critic, Francis Fukuyama, as the world's most dangerous idea, while one proponent, Ronald Bailey, counters that it is the "movement that epitomizes the most daring, courageous, imaginative, and idealistic aspirations of humanity".
[edit] Cryonics
Cryonics is the low-temperature preservation of humans and animals that can no longer be sustained by contemporary medicine until resuscitation may be possible in the future. Currently, human cryopreservation is not reversible, which means that it is not currently possible to bring people out of cryopreservation. The rationale for cryonics is that people who are dead by the current legal or medical definitions are not necessarily dead by the information-theoretic definition of death and that people could be brought out of cryopreservation in the future.
In the United States, cryonics can only be legally performed on humans after they have been pronounced legally dead.
The word cryonics is derived from the Greek word κρύος (kryos), meaning cold.
