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A residential smoke detector is the most familiar piece of nuclear technology for some people

Nuclear technology is technology that involves the reactions of atomic nuclei. Among the notable nuclear technologies are nuclear power, nuclear medicine, and nuclear weapons. It has found applications from smoke detectors to nuclear reactors, and from gun sights to nuclear weapons.

History and scientific background[link]

Discovery[link]

The vast majority of common, natural phenomena on Earth only involve gravity and electromagnetism, and not nuclear reactions. This is because atomic nuclei are generally kept apart because they contain positive electrical charges and therefore repel each other.

In 1896, Henri Becquerel was investigating phosphorescence in uranium salts when he discovered a new phenomenon which came to be called radioactivity.^[1] He, Pierre Curie and Marie Curie began investigating the phenomenon. In the process, they isolated the element radium, which is highly radioactive. They discovered that radioactive materials produce intense, penetrating rays of three distinct sorts, which they labeled alpha, beta, and gamma after the Greek letters. Some of these kinds of radiation could pass through ordinary matter, and all of them could be harmful in large amounts. All the early researchers received various radiation burns, much like sunburn, and thought little of it.

The new phenomenon of radioactivity was seized upon by the manufacturers of quack medicine (as had the discoveries of electricity and magnetism, earlier), and a number of patent medicines and treatments involving radioactivity were put forward. Gradually it was realized that the radiation produced by radioactive decay was ionizing radiation, and that even quantities too small to burn posed a severe long-term hazard. Many of the scientists working on radioactivity died of cancer as a result of their exposure. Radioactive patent medicines mostly disappeared, but other applications of radioactive materials persisted, such as the use of radium salts to produce glowing dials on meters.

As the atom came to be better understood, the nature of radioactivity became clearer. Some larger atomic nuclei are unstable, and so decay (release matter or energy) after a random interval. The three forms of radiation that Becquerel and the Curies discovered are also more fully understood. Alpha decay is when a nucleus releases an alpha particle, which is two protons and two neutrons, equivalent to a helium nucleus. Beta decay is the release of a beta particle, a high-energy electron. Gamma decay releases gamma rays, which unlike alpha and beta radiation are not matter but electromagnetic radiation of very high frequency, and therefore energy. This type of radiation is the most dangerous, and most difficult to block. All three types of radiation occur naturally in certain elements.

It has also become clear that the ultimate source of most terrestrial energy is nuclear, either through radiation from the Sun caused by stellar thermonuclear reactions or by radioactive decay of uranium within the Earth, the principal source of geothermal energy.

Fission[link]

In natural nuclear radiation, the byproducts are very small compared to the nuclei from which they originate. Nuclear fission is the process of splitting a nucleus into roughly equal parts, and releasing energy and neutrons in the process. If these neutrons are captured by another unstable nucleus, they can fission as well, leading to a chain reaction. The average number of neutrons released per nucleus that go on to fission another nucleus is referred to as k. Values of k larger than 1 mean that the fission reaction is releasing more neutrons than it absorbs, and therefore is referred to as a self-sustaining chain reaction. A mass of fissile material large enough (and in a suitable configuration) to induce a self-sustaining chain reaction is called a critical mass.

When a neutron is captured by a suitable nucleus, fission may occur immediately, or the nucleus may persist in an unstable state for a short time. If there are enough immediate decays to carry on the chain reaction, the mass is said to be prompt critical, and the energy release will grow rapidly and uncontrollably, usually leading to an explosion.

When discovered on the eve of World War II, this insight led multiple countries to begin programs investigating the possibility of constructing an atomic bomb — a weapon which utilized fission reactions to generate far more energy than could be created with chemical explosives. The Manhattan Project, run by the United States with the help of the United Kingdom and Canada, developed multiple fission weapons which were used against Japan in 1945. During the project, the first fission reactors were developed as well, though they were primarily for weapons manufacture and did not generate electricity.

However, if the mass is critical only when the delayed neutrons are included, then the reaction can be controlled, for example by the introduction or removal of neutron absorbers. This is what allows nuclear reactors to be built. Fast neutrons are not easily captured by nuclei; they must be slowed (slow neutrons), generally by collision with the nuclei of a neutron moderator, before they can be easily captured. Today, this type of fission is commonly used to generate electricity.

Fusion[link]

If nuclei are forced to collide, they can undergo nuclear fusion. This process may release or absorb energy. When the resulting nucleus is lighter than that of iron, energy is normally released; when the nucleus is heavier than that of iron, energy is generally absorbed. This process of fusion occurs in stars, which derive their energy from hydrogen and helium. They form, through stellar nucleosynthesis, the light elements (lithium to calcium) as well as some of the heavy elements (beyond iron and nickel, via the S-process). The remaining abundance of heavy elements, from nickel to uranium and beyond, is due to supernova nucleosynthesis, the R-process.

Of course, these natural processes of astrophysics are not examples of nuclear "technology". Because of the very strong repulsion of nuclei, fusion is difficult to achieve in a controlled fashion. Hydrogen bombs obtain their enormous destructive power from fusion, but their energy cannot be controlled. Controlled fusion is achieved in particle accelerators; this is how many synthetic elements are produced. A fusor can also produce controlled fusion and is a useful neutron source. However, both of these devices operate at a net energy loss. Controlled, viable fusion power has proven elusive, despite the occasional hoax. Technical and theoretical difficulties have hindered the development of working civilian fusion technology, though research continues to this day around the world.

Nuclear fusion was initially pursued only in theoretical stages during World War II, when scientists on the Manhattan Project (led by Edward Teller) investigated it as a method to build a bomb. The project abandoned fusion after concluding that it would require a fission reaction to detonate. It took until 1952 for the first full hydrogen bomb to be detonated, so-called because it used reactions between deuterium and tritium. Fusion reactions are much more energetic per unit mass of fuel than fission reactions, but starting the fusion chain reaction is much more difficult.

Nuclear weapons[link]

A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission or a combination of fission and fusion. Both reactions release vast quantities of energy from relatively small amounts of matter. Even small nuclear devices can devastate a city by blast, fire and radiation. Nuclear weapons are considered weapons of mass destruction, and their use and control has been a major aspect of international policy since their debut.

The design of a nuclear weapon is more complicated than it might seem. Such a weapon must hold one or more subcritical fissile masses stable for deployment, then induce criticality (create a critical mass) for detonation. It also is quite difficult to ensure that such a chain reaction consumes a significant fraction of the fuel before the device flies apart. The procurement of a nuclear fuel is also more difficult than it might seem, as no naturally occurring substance is sufficiently unstable for this process to occur.

One isotope of uranium, namely uranium-235, is naturally occurring and sufficiently unstable, but it is always found mixed with the more stable isotope uranium-238. The latter accounts for more than 99% of the weight of natural uranium. Therefore some method of isotope separation based on the weight of three neutrons must be performed to enrich (isolate) uranium-235.

Alternatively, the element plutonium possesses an isotope that is sufficiently unstable for this process to be usable. Plutonium does not occur naturally, so it must be manufactured in a nuclear reactor.

Ultimately, the Manhattan Project manufactured nuclear weapons based on each of these elements. They detonated the first nuclear weapon in a test code-named "Trinity", near Alamogordo, New Mexico, on July 16, 1945. The test was conducted to ensure that the implosion method of detonation would work, which it did. A uranium bomb, Little Boy, was dropped on the Japanese city Hiroshima on August 6, 1945, followed three days later by the plutonium-based Fat Man on Nagasaki. In the wake of unprecedented devastation and casualties from a single weapon, the Japanese government soon surrendered, ending World War II.

Since these bombings, no nuclear weapons have been deployed offensively. Nevertheless, they prompted an arms race to develop increasingly destructive bombs to provide a nuclear deterrent. Just over four years later, on August 29, 1949, the Soviet Union detonated its first fission weapon. The United Kingdom followed on October 2, 1952; France, on February 13, 1960; and China component to a nuclear weapon. Approximately half of the deaths from Hiroshima and Nagasaki died two to five years afterward from radiation exposure.^[2][3] A radiological weapons is a type of nuclear weapon designed to distribute hazardous nuclear material in enemy areas. Such a weapon would not have the explosive capability of a fission or fusion bomb, but would kill many people and contaminate a large area. A radiological weapon has never been deployed. While considered useless by a conventional military, such a weapon raises concerns over nuclear terrorism.

There have been over 2,000 nuclear tests conducted since 1945. In 1963, all nuclear and many non-nuclear states signed the Limited Test Ban Treaty, pledging to refrain from testing nuclear weapons in the atmosphere, underwater, or in outer space. The treaty permitted underground nuclear testing. France continued atmospheric testing until 1974, while China continued up until 1980. The last underground test by the United States was in 1992, the Soviet Union in 1990, the United Kingdom in 1991, and both France and China continued testing until 1996. After signing the Comprehensive Test Ban Treaty in 1996 (which had as of 2011 not entered into force), all of these states have pledged to discontinue all nuclear testing. Non-signatories India and Pakistan last tested nuclear weapons in 1998.

Nuclear weapons are the most destructive weapons known - the archetypal weapons of mass destruction. Throughout the Cold War, the opposing powers had huge nuclear arsenals, sufficient to kill hundreds of millions of people. Generations of people grew up under the shadow of nuclear devastation, portrayed in films such as Dr. Strangelove and The Atomic Cafe.

However, the tremendous energy release in the detonation of a nuclear weapon also suggested the possibility of a new energy source.

Civilian uses[link]

Nuclear power[link]

Nuclear power is a type of nuclear technology involving the controlled use of nuclear fission to release energy for work including propulsion, heat, and the generation of electricity. Nuclear energy is produced by a controlled nuclear chain reaction which creates heat—and which is used to boil water, produce steam, and drive a steam turbine. The turbine is used to generate electricity and/or to do mechanical work.

Currently nuclear power provides approximately 15.7% of the world's electricity (in 2004) and is used to propel aircraft carriers, icebreakers and submarines (so far economics and fears in some ports have prevented the use of nuclear power in transport ships).^[4] All nuclear power plants use fission. Despite years of effort and the occasional hoax (i.e. cold fusion), no man-made fusion reaction has produced more energy than it consumed and been a viable source of electricity.

Medical applications[link]

The medical applications of nuclear technology are divided into diagnostics and radiation treatment.

Imaging - medical and dental x-ray imagers use of Cobalt-60 or other x-ray sources. Technetium-99m is used, attached to organic molecules, as radioactive tracer in the human body, before being excreted by the kidneys. Positron emitting nucleotides are used for high resolution, short time span imaging in applications known as Positron emission tomography.

Radiation therapy is an effective treatment for cancer.

Industrial applications[link]

Oil and Gas Exploration- Nuclear well logging is used to help predict the commercial viability of new or existing wells. The technology involves the use of a neutron or gamma-ray source and a radiation detector which are lowered into boreholes to determine the properties of the surrounding rock such as porosity and lithography.[1]

Road Construction - Nuclear moisture/density gauges are used to determine the density of soils, asphalt, and concrete. Typically a Cesium-137 source is used.

Commercial applications[link]

An ionization smoke detector includes a tiny mass of radioactive americium-241, which is a source of alpha radiation. Tritium is used with phosphor in rifle sights to increase nighttime firing accuracy. Luminescent exit signs use the same technology.^[5]

Food processing and agriculture[link]

The Radura logo, used to show a food has been treated with ionizing radiation.

Food irradiation^[6] is the process of exposing food to ionizing radiation in order to destroy microorganisms, bacteria, viruses, or insects that might be present in the food. The radiation sources used include radioisotope gamma ray sources, X-ray generators and electron accelerators. Further applications include sprout inhibition, delay of ripening, increase of juice yield, and improvement of re-hydration. Irradiation is a more general term of deliberate exposure of materials to radiation to achieve a technical goal (in this context 'ionizing radiation' is implied). As such it is also used on non-food items, such as medical hardware, plastics, tubes for gas-pipelines, hoses for floor-heating, shrink-foils for food packaging, automobile parts, wires and cables (isolation), tires, and even gemstones. Compared to the amount of food irradiated, the volume of those every-day applications is huge but not noticed by the consumer.

The genuine effect of processing food by ionizing radiation relates to damages to the DNA, the basic genetic information for life. Microorganisms can no longer proliferate and continue their malignant or pathogen activities. Spoilage causing micro-organisms cannot continue their activities. Insects do not survive or become incapable of procreation. Plants cannot continue the natural ripening or aging process. All these effects are beneficial to the consumer and the food industry, likewise.^[6]

The amount of energy imparted for effective food irradiation is low compared to cooking the same; even at a typical dose of 10 kGy most food, which is (with regard to warming) physically equivalent to water, would warm by only about 2.5 °C (4.5 °F).

The specialty of processing food by ionizing radiation is the fact, that the energy density per atomic transition is very high, it can cleave molecules and induce ionization (hence the name) which cannot be achieved by mere heating. This is the reason for new beneficial effects, however at the same time, for new concerns. The treatment of solid food by ionizing radiation can provide an effect similar to heat pasteurization of liquids, such as milk. However, the use of the term, cold pasteurization, to describe irradiated foods is controversial, because pasteurization and irradiation are fundamentally different processes, although the intended end results can in some cases be similar.

Food irradiation is currently permitted by over 40 countries and volumes are estimated to exceed 500,000 metric tons (490,000 long tons; 550,000 short tons) annually world wide.^[7][8][9]

Food irradiation is essentially a non-nuclear technology; it relies on the use of ionizing radiation which may be generated by accelerators for electrons and conversion into bremsstrahlung, but which may use also gamma-rays from nuclear decay. There is a worldwide industry for processing by ionizing radiation, the majority by number and by processing power using accelerators. Food irradiation is only a niche application compared to medical supplies, plastic materials, raw materials, gemstones, cables and wires, etc.

Accidents[link]

Nuclear accidents, because of the powerful forces involved, are often very dangerous. Historically, the first incidents involved fatal radiation exposure. Marie Curie died from aplastic anemia which resulted from her high levels of exposure. Two scientists, an American and Canadian respectively, Harry Daghlian and Louis Slotin, died after mishandling the same plutonium mass. Unlike convention weapons, the intense light, heat, and explosive force is not the only deadly component to a nuclear weapon. Approximately half of the deaths from Hiroshima and Nagasaki died two to five years afterward from radiation exposure.^[2][3]

Civilian nuclear and radiological accidents primarily involve nuclear power plants. Most common are nuclear leaks that expose workers to hazardous material. A nuclear meltdown refers to the more serious hazard of releasing nuclear material into the surrounding environment. The most significant meltdowns occurred at Three Mile Island in Pennsylvania and Chernobyl in the Soviet Ukraine. The earthquake and tsunami on March 11, 2011 caused serious damage to three nuclear reactors and a spent fuel storage pond at the Fukushima Daiichi nuclear power plant in Japan. Military reactors that experienced similar accidents were Windscale in the United Kingdom and SL-1 in the United States.

Military accidents usually involve the loss or unexpected detonation of nuclear weapons. The Castle Bravo test in 1954 produced a larger yield than expected, which contaminated nearby islands, a Japanese fishing boat (with one fatality), and raised concerns about contaminated fish in Japan. In the 1950s through 1970s, several nuclear bombs were lost from submarines and aircraft, some of which have never been recovered. The last twenty years^[when?] have seen a marked decline in such accidents.

See also[link]

• Atomic age
• Lists of nuclear disasters and radioactive incidents
• Nuclear power debate
• Outline of nuclear technology

References[link]

External links[link]

• Nuclear Energy Institute – Beneficial Uses of Radiation
• Nuclear Technology
• National Isotope Development Center – U.S. Government source of isotopes for basic and applied nuclear science and nuclear technology - production, research, development, distribution, and information

Bill Gates
Gates at the World Economic Forum in 2007
Born	William Henry Gates III (1955-10-28) October 28, 1955 (age 56) Seattle, Washington, United States
Residence	Medina, Washington, United States
Nationality	American
Alma mater	Harvard University (dropped out)
Occupation	Chairman of Microsoft Co-Chair of the Bill & Melinda Gates Foundation CEO of Cascade Investment Chairman of Corbis
Years active	1975–present
Net worth	US$ 61 billion (2012)[1]
Board member of	Berkshire Hathaway
Religion	None (Agnostic[2][3])
Spouse	Melinda Gates (m. 1994) «start: (1994)»"Marriage: Melinda Gates to Bill Gates" Location: (linkback:http://en-wiki.pop.wn.com/index.php/Bill_Gates)
Children	3
Parents	William H. Gates, Sr. Mary Maxwell Gates
Signature
Website
Bill Gates

William Henry "Bill" Gates III (born October 28, 1955 in Seattle, Washington)^[4] is an American business magnate, computer programmer and philanthropist. Gates is the former chief executive officer (CEO) and current chairman of Microsoft, the world’s largest personal-computer software company he co-founded with Paul Allen. He is consistently ranked among the world's wealthiest people^[5] and was the wealthiest overall from 1995 to 2009, excluding 2008, when he was ranked third;^[6] in 2011 he was the wealthiest American and the second wealthiest person.^[7][8] During his career at Microsoft, Gates held the positions of CEO and chief software architect, and remains the largest individual shareholder, with 6.4 percent of the common stock.^[9] He has also authored or co-authored several books.

Gates is one of the best-known entrepreneurs of the personal computer revolution. Gates has been criticized for his business tactics, which have been considered anti-competitive, an opinion which has in some cases been upheld by the courts.^[10][11] In the later stages of his career, Gates has pursued a number of philanthropic endeavors, donating large amounts of money to various charitable organizations and scientific research programs through the Bill & Melinda Gates Foundation, established in 2000.^[12]

Gates stepped down as chief executive officer of Microsoft in January 2000. He remained as chairman and created the position of chief software architect. In June 2006, Gates announced that he would be transitioning from full-time work at Microsoft to part-time work, and full-time work at the Bill & Melinda Gates Foundation. He gradually transferred his duties to Ray Ozzie, chief software architect, and Craig Mundie, chief research and strategy officer. Gates's last full-time day at Microsoft was June 27, 2008. He remains at Microsoft as non-executive chairman.

Early life[link]

Bill Gates was photographed by the Albuquerque, New Mexico police in 1977 after a traffic violation (details of which have been lost over time).

Gates was born in Seattle, Washington, to William H. Gates, Sr. and Mary Maxwell Gates. His parents are of English, German, and Scots-Irish descent.^[13][14] His father was a prominent lawyer, and his mother served on the board of directors for First Interstate BancSystem and the United Way. Gates's maternal grandfather was J. W. Maxwell, a national bank president. Gates has one elder sister, Kristi (Kristianne), and one younger sister, Libby. He was the fourth of his name in his family, but was known as William Gates III or "Trey" because his father had the "II" suffix.^[15] Early on in his life, Gates's parents had a law career in mind for him.^[16] When Gates was young, his family regularly attended a Congregational church.^[17][18][19]

At 13 he enrolled in the Lakeside School, an exclusive preparatory school.^[20] When he was in the eighth grade, the Mothers Club at the school used proceeds from Lakeside School's rummage sale to buy a Teletype Model 33 ASR terminal and a block of computer time on a General Electric (GE) computer for the school's students.^[21] Gates took an interest in programming the GE system in BASIC, and was excused from math classes to pursue his interest. He wrote his first computer program on this machine: an implementation of tic-tac-toe that allowed users to play games against the computer. Gates was fascinated by the machine and how it would always execute software code perfectly. When he reflected back on that moment, he said, "There was just something neat about the machine."^[22] After the Mothers Club donation was exhausted, he and other students sought time on systems including DEC PDP minicomputers. One of these systems was a PDP-10 belonging to Computer Center Corporation (CCC), which banned four Lakeside students—Gates, Paul Allen, Ric Weiland, and Kent Evans—for the summer after it caught them exploiting bugs in the operating system to obtain free computer time.^[23]

At the end of the ban, the four students offered to find bugs in CCC's software in exchange for computer time. Rather than use the system via Teletype, Gates went to CCC's offices and studied source code for various programs that ran on the system, including programs in FORTRAN, LISP, and machine language. The arrangement with CCC continued until 1970, when the company went out of business. The following year, Information Sciences, Inc. hired the four Lakeside students to write a payroll program in COBOL, providing them computer time and royalties. After his administrators became aware of his programming abilities, Gates wrote the school's computer program to schedule students in classes. He modified the code so that he was placed in classes with mostly female students. He later stated that "it was hard to tear myself away from a machine at which I could so unambiguously demonstrate success."^[22] At age 17, Gates formed a venture with Allen, called Traf-O-Data, to make traffic counters based on the Intel 8008 processor.^[24] In early 1973, Bill Gates served as a congressional page in the U.S. House of Representatives.^[25]

Gates graduated from Lakeside School in 1973. He scored 1590 out of 1600 on the SAT^[26] and enrolled at Harvard College in the autumn of 1973.^[27] While at Harvard, he met Steve Ballmer, who later succeeded Gates as CEO of Microsoft.

The Poker Room in Currier House at Harvard University, in which Bill Gates and Steve Ballmer formed Microsoft

In his sophomore year, Gates devised an algorithm for pancake sorting as a solution to one of a series of unsolved problems^[28] presented in a combinatorics class by Harry Lewis, one of his professors. Gates's solution held the record as the fastest version for over thirty years;^[28][29] its successor is faster by only one percent.^[28] His solution was later formalized in a published paper in collaboration with Harvard computer scientist Christos Papadimitriou.^[30]

Gates did not have a definite study plan while a student at Harvard^[31] and spent a lot of time using the school's computers. Gates remained in contact with Paul Allen, and he joined him at Honeywell during the summer of 1974.^[32] The following year saw the release of the MITS Altair 8800 based on the Intel 8080 CPU, and Gates and Allen saw this as the opportunity to start their own computer software company.^[33] He had talked this decision over with his parents, who were supportive of him after seeing how much Gates wanted to start a company.^[31]

Microsoft[link]

BASIC[link]

MITS Altair 8800 Computer with 8-inch (200 mm) floppy disk system

After reading the January 1975 issue of Popular Electronics that demonstrated the Altair 8800, Gates contacted Micro Instrumentation and Telemetry Systems (MITS), the creators of the new microcomputer, to inform them that he and others were working on a BASIC interpreter for the platform.^[34] In reality, Gates and Allen did not have an Altair and had not written code for it; they merely wanted to gauge MITS's interest. MITS president Ed Roberts agreed to meet them for a demo, and over the course of a few weeks they developed an Altair emulator that ran on a minicomputer, and then the BASIC interpreter. The demonstration, held at MITS's offices in Albuquerque was a success and resulted in a deal with MITS to distribute the interpreter as Altair BASIC. Paul Allen was hired into MITS,^[35] and Gates took a leave of absence from Harvard to work with Allen at MITS in Albuquerque in November 1975. They named their partnership "Micro-Soft" and had their first office located in Albuquerque.^[35] Within a year, the hyphen was dropped, and on November 26, 1976, the trade name "Microsoft" was registered with the Office of the Secretary of the State of New Mexico.^[35] Gates never returned to Harvard to complete his studies.

Microsoft's BASIC was popular with computer hobbyists, but Gates discovered that a pre-market copy had leaked into the community and was being widely copied and distributed. In February 1976, Gates wrote an Open Letter to Hobbyists in the MITS newsletter saying that MITS could not continue to produce, distribute, and maintain high-quality software without payment.^[36] This letter was unpopular with many computer hobbyists, but Gates persisted in his belief that software developers should be able to demand payment. Microsoft became independent of MITS in late 1976, and it continued to develop programming language software for various systems.^[35] The company moved from Albuquerque to its new home in Bellevue, Washington on January 1, 1979, after the former rejected his loan application.^[34]

During Microsoft's early years, all employees had broad responsibility for the company's business. Gates oversaw the business details, but continued to write code as well. In the first five years, Gates personally reviewed every line of code the company shipped, and often rewrote parts of it as he saw fit.^[37]

IBM partnership[link]

IBM approached Microsoft in July 1980 regarding its upcoming personal computer, the IBM PC.^[38] The computer company first proposed that Microsoft write the BASIC interpreter. When IBM's representatives mentioned that they needed an operating system, Gates referred them to Digital Research (DRI), makers of the widely used CP/M operating system.^[39] IBM's discussions with Digital Research went poorly, and they did not reach a licensing agreement. IBM representative Jack Sams mentioned the licensing difficulties during a subsequent meeting with Gates and told him to get an acceptable operating system. A few weeks later Gates proposed using 86-DOS (QDOS), an operating system similar to CP/M that Tim Paterson of Seattle Computer Products (SCP) had made for hardware similar to the PC. Microsoft made a deal with SCP to become the exclusive licensing agent, and later the full owner, of 86-DOS. After adapting the operating system for the PC, Microsoft delivered it to IBM as PC-DOS in exchange for a one-time fee of $50,000.^[40]

Gates did not offer to transfer the copyright on the operating system, because he believed that other hardware vendors would clone IBM's system.^[40] They did, and the sales of MS-DOS made Microsoft a major player in the industry.^[41] Despite IBM's name on the operating system the press quickly identified Microsoft as being very influential on the new computer, with PC Magazine asking if Gates were "The Man Behind The Machine?"^[38] He oversaw Microsoft's company restructuring on June 25, 1981, which re-incorporated the company in Washington state and made Gates President of Microsoft and the Chairman of the Board.^[34]

Windows[link]

Microsoft launched its first retail version of Microsoft Windows on November 20, 1985, and in August, the company struck a deal with IBM to develop a separate operating system called OS/2. Although the two companies successfully developed the first version of the new system, mounting creative differences caused the partnership to deteriorate. It ended in 1991, when Gates led Microsoft to develop a version of OS/2 independently from IBM.^[42]

Management style[link]

From Microsoft's founding in 1975 until 2006, Gates had primary responsibility for the company's product strategy. He aggressively broadened the company's range of products, and wherever Microsoft achieved a dominant position he vigorously defended it. He gained a reputation for being distant to others; as early as 1981 an industry executive complained in public that "Gates is notorious for not being reachable by phone and for not returning phone calls."^[43]

As an executive, Gates met regularly with Microsoft's senior managers and program managers. Firsthand accounts of these meetings describe him as verbally combative, berating managers for perceived holes in their business strategies or proposals that placed the company's long-term interests at risk.^[44][45] He often interrupted presentations with such comments as, "That's the stupidest thing I've ever heard!"^[46] and, "Why don't you just give up your options and join the Peace Corps?"^[47] The target of his outburst then had to defend the proposal in detail until, hopefully, Gates was fully convinced.^[46] When subordinates appeared to be procrastinating, he was known to remark sarcastically, "I'll do it over the weekend."^[48][49][50]

Gates's role at Microsoft for most of its history was primarily a management and executive role. However, he was an active software developer in the early years, particularly on the company's programming language products. He has not officially been on a development team since working on the TRS-80 Model 100,^[51] but wrote code as late as 1989 that shipped in the company's products.^[49] On June 15, 2006, Gates announced that he would transition out of his day-to-day role over the next two years to dedicate more time to philanthropy. He divided his responsibilities between two successors, placing Ray Ozzie in charge of day-to-day management and Craig Mundie in charge of long-term product strategy.^[52]

Antitrust litigation[link]

Bill Gates giving his deposition at Microsoft on August 27, 1998

Many decisions that led to antitrust litigation over Microsoft's business practices have had Gates's approval. In the 1998 United States v. Microsoft case, Gates gave deposition testimony that several journalists characterized as evasive. He argued with examiner David Boies over the contextual meaning of words such as, "compete", "concerned", and "we".^[53] BusinessWeek reported:

Early rounds of his deposition show him offering obfuscatory answers and saying 'I don't recall,' so many times that even the presiding judge had to chuckle. Worse, many of the technology chief's denials and pleas of ignorance were directly refuted by prosecutors with snippets of e-mail that Gates both sent and received.^[54]

Gates later said he had simply resisted attempts by Boies to mischaracterize his words and actions. As to his demeanor during the deposition, he said, "Did I fence with Boies? ... I plead guilty. Whatever that penalty is should be levied against me: rudeness to Boies in the first degree."^[55] Despite Gates's denials, the judge ruled that Microsoft had committed monopolization and tying, and blocking competition, both in violation of the Sherman Antitrust Act.^[55]

Appearance in ads[link]

Gates appeared in a series of ads to promote Microsoft in 2008. The first commercial, co-starring Jerry Seinfeld, is a 90-second talk between strangers as Seinfeld walks up on a discount shoe store (Shoe Circus) in a mall and notices Gates buying shoes inside. The salesman is trying to sell Mr. Gates shoes that are a size too big. As Gates is buying the shoes, he holds up his discount card, which uses a slightly altered version of his own mugshot of his arrest in New Mexico in 1977 for a traffic violation.^[56] As they are walking out of the mall, Seinfeld asks Gates if he has melded his mind to other developers, after getting a yes, he then asks if they are working on a way to make computers edible, again getting a yes. Some say that this is an homage to Seinfeld's own show about "nothing" (Seinfeld).^[57] In a second commercial in the series, Gates and Seinfeld are at the home of an average family trying to fit in with normal people.

Post-Microsoft[link]

Since leaving day-to-day operations at Microsoft (where he remains Chairman^[58]), Gates continues his philanthropy and, among other projects, purchased the video rights to the Messenger Lectures series called The Character of Physical Law, given at Cornell University by Richard Feynman in 1964 and recorded by the BBC. The videos are available online to the public at Microsoft's Project Tuva.^[59][60]

In April 2010, Gates was invited to visit and speak at the Massachusetts Institute of Technology where he asked the students to take on the hard problems of the world in their futures.^[61][62]

Personal life[link]

Bill and Melinda Gates, June 2009

Gates married Melinda French on January 1, 1994. They have two daughters, Jennifer Katharine Gates (1996) and Phoebe Adele (2002), and one son, Rory John (1999).

The Gates's home is an earth-sheltered house in the side of a hill overlooking Lake Washington in Medina. According to King County public records, as of 2006 the total assessed value of the property (land and house) is $125 million, and the annual property tax is $991,000.

His 66,000 sq ft (6,100 m²) estate has a 60-foot (18 m) swimming pool with an underwater music system, as well as a 2,500 sq ft (230 m²) gym and a 1,000 sq ft (93 m²) dining room.^[63]

Also among Gates's private acquisitions is the Codex Leicester, a collection of writings by Leonardo da Vinci, which Gates bought for $30.8 million at an auction in 1994.^[64] Gates is also known as an avid reader, and the ceiling of his large home library is engraved with a quotation from The Great Gatsby.^[65] He also enjoys playing bridge, tennis, and golf.^[66][67]

Gates was number one on the Forbes 400 list from 1993 through to 2007 and number one on Forbes list of The World's Richest People from 1995 to 2007 and 2009. In 1999, Gates's wealth briefly surpassed $101 billion, causing the media to call him a "centibillionaire".^[68] Since 2000, the nominal value of his Microsoft holdings has declined due to a fall in Microsoft's stock price after the dot-com bubble burst and the multi-billion dollar donations he has made to his charitable foundations. In a May 2006 interview, Gates commented that he wished that he were not the richest man in the world because he disliked the attention it brought.^[69] Gates has several investments outside Microsoft, which in 2006 paid him a salary of $616,667 and $350,000 bonus totalling $966,667.^[70] He founded Corbis, a digital imaging company, in 1989. In 2004 he became a director of Berkshire Hathaway, the investment company headed by long-time friend Warren Buffett.^[71] In March 2010 Bill Gates was bumped down to the second wealthiest man behind Carlos Slim.

Philanthropy[link]

Gates (second from right) with Bono, Queen Rania of Jordan, Former British Prime Minister Gordon Brown, President Umaru Yar'Adua of Nigeria and other participants in a 'Call to Action on the Millennium Development Goals' during the Annual Meeting 2008 of the World Economic Forum in Davos, Switzerland

Gates began to appreciate the expectations others had of him when public opinion mounted suggesting that he could give more of his wealth to charity. Gates studied the work of Andrew Carnegie and John D. Rockefeller, and in 1994 sold some of his Microsoft stock to create the William H. Gates Foundation. In 2000, Gates and his wife combined three family foundations into one to create the charitable Bill & Melinda Gates Foundation, which is the largest transparently operated charitable foundation in the world.^[72] The foundation allows benefactors access to information regarding how its money is being spent, unlike other major charitable organizations such as the Wellcome Trust.^[73][74] The generosity and extensive philanthropy of David Rockefeller has been credited as a major influence. Gates and his father met with Rockefeller several times, and modeled their giving in part on the Rockefeller family's philanthropic focus, namely those global problems that are ignored by governments and other organizations.^[75] As of 2007, Bill and Melinda Gates were the second-most generous philanthropists in America, having given over $28 billion to charity.^[76] They plan to eventually give 95% of their wealth to charity.^[77]

The foundation was at the same time criticized because it invests assets that it has not yet distributed with the exclusive goal of maximizing return on investment. As a result, its investments include companies that have been charged with worsening poverty in the same developing countries where the Foundation is attempting to relieve poverty. These include companies that pollute heavily, and pharmaceutical companies that do not sell into the developing world.^[78] In response to press criticism, the foundation announced in 2007 a review of its investments, to assess social responsibility.^[79] It subsequently canceled the review and stood by its policy of investing for maximum return, while using voting rights to influence company practices.^[80] The Gates Millennium Scholars program has been criticized for its exclusion of Caucasian students.^[81][82]

Gates's wife urged people to learn a lesson from the philanthropic efforts of the Salwen family, which had sold its home and given away half of its value, as detailed in The Power of Half.^[83] Gates and his wife invited Joan Salwen to Seattle to speak about what the family had done, and on December 9, 2010, Gates, investor Warren Buffett, and Mark Zuckerberg (Facebook's CEO) signed a promise they called the "Gates-Buffet Giving Pledge", in which they promised to donate to charity at least half of their wealth over the course of time.^[84][85][86]

Recognition[link]

In 1987, Gates was officially declared a billionaire in the pages of Forbes' 400 Richest People in America issue, just days before his 32nd birthday. As the world's youngest self-made billionaire, he was worth $1.25 billion, over $900 million more than he'd been worth the year before, when he'd debuted on the list.^[87]

Bill Gates and Steve Jobs at the fifth D: All Things Digital conference (D5) in 2007

Time magazine named Gates one of the 100 people who most influenced the 20th century, as well as one of the 100 most influential people of 2004, 2005, and 2006. Time also collectively named Gates, his wife Melinda and U2's lead singer Bono as the 2005 Persons of the Year for their humanitarian efforts.^[88] In 2006, he was voted eighth in the list of "Heroes of our time".^[89] Gates was listed in the Sunday Times power list in 1999, named CEO of the year by Chief Executive Officers magazine in 1994, ranked number one in the "Top 50 Cyber Elite" by Time in 1998, ranked number two in the Upside Elite 100 in 1999 and was included in The Guardian as one of the "Top 100 influential people in media" in 2001.^[90]

In 1994, he was honoured as the twentieth Distinguished Fellow of the British Computer Society. Gates has received honorary doctorates from Nyenrode Business Universiteit, Breukelen, The Netherlands, in 2000;^[91] the Royal Institute of Technology, Stockholm, Sweden, in 2002; invited in 2003 to deliver the keynote address^[92] of the Golden Jubilee of the Indian Institute of Technology,held in San Jose, California;^[93] Waseda University, Tokyo, Japan, in 2005; Tsinghua University, Beijing, China, in April 2007;^[94] Harvard University in June 2007;^[95] the Karolinska Institutet, Stockholm, in January 2008,^[96] and Cambridge University in June 2009.^[97] He was also made an honorary trustee of Peking University in 2007.^[98] Gates was also made an honorary Knight Commander of the Order of the British Empire (KBE) by Queen Elizabeth II in 2005,^[99] in addition to having entomologists name the Bill Gates flower fly, Eristalis gatesi, in his honor.^[100]

In November 2006, he and his wife were awarded the Order of the Aztec Eagle for their philanthropic work around the world in the areas of health and education, particularly in Mexico, and specifically in the program "Un país de lectores".^[101] In October 2009, it was announced that Gates will be awarded the 2010 Bower Award for Business Leadership of The Franklin Institute for his achievements in business and for his philanthropic work. In 2010 he was honored with the Silver Buffalo Award by the Boy Scouts of America, its highest award for adults, for his service to youth.^[102]

In 2011, Bill Gates was ranked as the fifth most powerful person in the world, according to rankings by Forbes magazine.^[103]

Investments[link]

• Cascade Investments LLC, a private investment and holding company, incorporated in United States, is controlled by Bill Gates, and is headquartered in the city of Kirkland, Washington.
• bgC3, a new think-tank company founded by Bill Gates.
• Corbis, a digital image licensing and rights services company.
• TerraPower, a nuclear reactor design company.

Books and films[link]

To date, Bill Gates has authored two books. The Road Ahead, written with Microsoft executive Nathan Myhrvold and journalist Peter Rinearson, was published in November 1995, and it summarized the implications of the personal computing revolution and described a future profoundly changed by the arrival of a global information superhighway. Business @ the Speed of Thought was published in 1999, and discusses how business and technology are integrated, and shows how digital infrastructures and information networks can help getting an edge on the competition.

Gates has appeared in a number of documentaries, including the 2010 documentary film Waiting for "Superman",^[104] and the BBC documentary series The Virtual Revolution.

Gates was prominently featured in Pirates of Silicon Valley, a 1999 film which chronicles the rise of Apple and Microsoft from the early 1970s to 1997. He was portrayed by Anthony Michael Hall.

See also[link]

	Biography portal
	Microsoft portal

• List of billionaires (also see List of college dropout billionaires and List of wealthiest non-inflated historical figures)
• Paul Allen – Microsoft's co-founder, friend, and fellow billionaire
• Gary Kildall (October 25, 2004). "The Man Who Could Have Been Bill Gates". Bloomberg BusinessWeek. http://www.businessweek.com/magazine/content/04_43/b3905109_mz063.htm. Retrieved June 9, 2010. 

Books[link]

• Fridson, Martin (2001). How to Be a Billionaire: Proven Strategies from the Titans of Wealth. John Wiley & Sons. ISBN 0-471-41617-7. 
• Gates, Bill (1996). The Road Ahead. Penguin Books. ISBN 0-14-026040-4. 
• Lesinski, Jeanne M. (2006). Bill Gates (Biography (a & E)). A&E Television Networks. ISBN 0-8225-7027-0. 
• Manes, Stephen (1994). Gates: How Microsoft's Mogul Reinvented an Industry and Made Himself The Richest Man in America. Touchstone Pictures. ISBN 0-671-88074-8. 
• Wallace, James (1993). Hard Drive: Bill Gates and the Making of the Microsoft Empire. New York: HarperCollins Publishers. ISBN 0-471-56886-4. 

References[link]