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The '''Minnesota Department of Transportation''' ('''Mn/DOT''', pronounced "min-dot") oversees transportation by [[land]], [[water]], and [[air]] in the [[U.S. state]] of [[Minnesota]]. The [[cabinet]]-level agency is responsible for maintaining the state's [[trunk highway]] system (including [[List of Minnesota state highways|state highways]], [[U.S. highway]]s, and [[interstate highway]]s), funding municipal [[airport]]s and maintaining [[radio navigation aid]]s, and other activities. Minnesota's lieutenant governor, [[Carol Molnau]], is currently head of the department (Commissioner of Transportation).
[[Image:Nuclear fireball.jpg|right|250px|A nuclear fireball lights up the night in an American nuclear test.]]
The '''history of nuclear weapons''' chronicles the development of [[nuclear weapon]]s—devices of enormous destructive potential which derive their energy from [[nuclear fission]] or [[nuclear fusion]] reactions—starting with the scientific breakthroughs of the [[1930]]s which made their development possible, continuing through through the [[nuclear arms race]] and [[nuclear testing]] of the [[Cold War]], and finally with the questions of [[nuclear proliferation|proliferation]] and possible use for terrorism in the early [[21st century]].
==History==
The first fission weapons ("atomic bombs") were developed in the [[United States]] during [[World War II]] in what was called the [[Manhattan Project]], and they were used. The [[Soviet Union]] started development shortly thereafter with their own [[Soviet atomic bomb project|atomic bomb project]], and not long after that both countries developed even more powerful fusion weapons ("hydrogen bombs"). During the [[Cold War]], these two countries each acquired nuclear weapons arsenals numbering in the thousands, placing many of them onto [[rocket]]s which could hit targets anywhere in the world. Currently there are at least seven countries with functional nuclear weapons (see [[List of countries with nuclear weapons]]). A considerable amount of international negotiating has focused on the threat of [[nuclear warfare]] and the proliferation of nuclear weapons to new nations or groups.
The agency's history can be traced to the state's '''Railroad and Warehouse Commission''' which emerged slowly from [[1871]] to [[1905]], and the '''State Highway Commission''' created in 1905. However, the Highway Commission was abolished in [[1917]] and replaced by a '''Department of Highways'''. For air transport, the '''Minnesota Aeronautics Commission''' was created in [[1933]]. Much of the railroad oversight was transferred to the [[Minnesota Department of Public Service]] in [[1967]]. Two years later in [[1969]], the [[Minnesota Department of Public Safety|Department of Public Safety]] was established and took over the [[Minnesota State Patrol|Highway Patrol]] and [[driver's license|Driver's License Bureau]]. Mn/DOT finally came into being in [[1976]] and took over the functions of the aeronautics and highway departments, plus transportation-related duties of the [[Minnesota State Planning Agency|State Planning Agency]] and Department of Public Service.
==Services and projects==
==Prelude: Physics and politics in the 1930s==
Mn/DOT operates networks of [[ramp meter]]s and [[traffic camera]]s in the [[Minneapolis-St. Paul]] [[metropolitan area]] in order to manage traffic flow. In [[2000]], the ramp meters were turned off for a study period mandated by the [[Minnesota Legislature]]. The bill was backed by [[Republican Party of Minnesota|Republican]] [[Minnesota State Senate|State Senator]] [[Dick Day]] of [[Owatonna, Minnesota]], who has often been critical of Mn/DOT policies and projects. The study showed that ramp meters reduce the number of crashes on highways, and marginally reduce travel time in many cases. However, the study also showed some places where the meters were more of a hindrance, and metering strategies have been altered since that time. There are about 430 ramp meters and more than 280 traffic cameras.
:''See the main articles at [[History of physics]], [[Nazi Germany]], and [[World War II]].''
[[Image:Atom diagram.png|250px|right|By the 1930s, the atom was seen as having most of its mass in the dense nucleus at its center.]]
In the first decades of the twentieth century, [[physics]] was revolutionized with developments in the understanding of the nature of [[atom]]s. In [[1898]], [[Madame Curie]] and her husband [[Pierre Curie|Pierre]] had discovered that present in [[pitchblende]], an ore of [[uranium]], was a substance which emitted large amount of [[radioactivity]], which they named [[radium]]. This raised the hopes of both scientists and lay people that the elements around us could contain tremendous amounts of unseen energy, waiting to be tapped.
The department has also put up informational [[variable message sign|electronic signage]] along highways to provide alert messages. Message boards have been in [[Rochester, Minnesota|Rochester]], [[Duluth, Minnesota|Duluth]] and the Twin Cities for some time. Part of the reason for the Rochester signs is occasional [[flood]]ing of [[U.S. Highway 52]]. The department expanded use of the signs after [[Amber Alert]] legislation allocated funding for larger networks. In the Twin Cities, Mn/DOT began using them to display freeway travel times in [[2003]] or [[2004]] to help drivers plan alternate routes to avoid heavy traffic if necessary (although a generic message like "buckle up for safety" is often encountered).
Experiments by [[Ernest Rutherford]] in [[1911]] indicated that the vast majority of an atom's [[atomic mass|mass]] was contained in a very small [[nucleus]] at its core, made up of [[proton]]s, surrounded by a web of whirring [[electron]]s. In [[1932]], [[James Chadwick]] discovered that the nucleus contained another fundamental particle, the [[neutron]], and in the same year [[John Cockcroft]] and [[Ernest Walton]] "split the atom" for the first time, the first occasion on which an atomic nucleus of one element had been successfully changed to a different nucleus by artificial means.
[[Twin Cities Public Television]] (TPT) station KTCI channel 17 has been used for many years to display [[weather]]-related information that is funded by Mn/DOT. The department also had a long-standing partnership with [[KBEM]] radio (88.5 FM) in [[Minneapolis, Minnesota|Minneapolis]] to relay area traffic information, although that relationship is coming to an end. After public outcry, the term was extended, but it is unclear how long the two organizations will continue the relationship. Mn/DOT paid KBEM [[United States dollar|US$]]400,000 per year to provide the information, about half of the station's annual budget. Video from traffic cameras is also shown on [[cable television]] systems in the metro area (at one time, this had also been shown on KVBM channel 45, today known as [[KSTC-TV|KSTC]]).
Great changes were also mounting on the political scene as well. [[Adolf Hitler]] was appointed chancellor of [[Germany]] in January [[1933]], and within only three months had asserted dictatorial control over the country. As part of the [[anti-semitic]] ideology of [[Nazism]], all [[Jewish]] civil servants were fired from their posts, including university professors, many of which fled to [[Great Britain]] and the [[United States]], if they could find jobs.
[[Image:Himmler Hitler.jpg|left|150px|thumb|[[Fascism]] began to take over Europe at the same time as discoveries were being made about the use of nuclear energy for war.]]
In [[1934]], French physicists [[Irène Joliot-Curie|Irène]] and [[Frédéric Joliot-Curie]] discovered that artificial [[radioactivity]] could be induced in stable elements by bombarding them with [[alpha particle]]s, and in the same year Italian physicist [[Enrico Fermi]] reported similar results when bombarding uranium with neutrons.
[[Snow plow]]s used on trunk highways are also operated by Mn/DOT.
In Germany, Hitler passed the first of the [[Nuremberg laws]] in [[1935]], officially stating that Jews were no longer citizens of the German state and preventing from marrying non-Jews. After a failed [[coup]] by [[Francisco Franco]]'s Nationalists in [[1936]], the [[Spanish Civil War]] broke out, backed by Hitler and Italian [[Fascist]] dictator [[Benito Mussolini]].
==See also==
In [[1938]], Germans [[Otto Hahn]] and [[Fritz Strassman]] released the results of their finding proving that what Fermi had witnessed in 1934 was no less than the bursting of the uranium nucleus: [[nuclear fission]]. Immediately afterwards, [[Lise Meitner]] and [[Otto Robert Frisch]] described the theoretical mechanisms of fission and revealed that large amounts of [[binding energy]] was released in the process. Hungarian [[Leo Szilard]] confirmed with his own experiments that along with energy, neutrons were given off in the reaction as well, creating the possibility of a [[nuclear chain reaction]], whereby each fission created two or more other fissions, exponentially releasing energy.
*[[Mn/ROAD]]
*[[MnPASS]]
==External links==
As the Nazi army marched into first [[Czechoslovakia]] in 1938, and then [[Poland]] in [[1939]], officially beginning [[World War II]], many of Europe's top physicists had already began to flee from the emminent conflict approaching. Scientists on both sides of the conflict were well aware of the possibility of utilizing nuclear fission as a weapon, but at the time no one was quite sure how it could be done. In the early years of the second world war, physicists abruptly stopped publishing on the topic of fission, an act of self-censorship to keep the opposing side from gaining any advantages.
*[http://www.dot.state.mn.us/ Minnesota Department of Transportation]
*[http://www.511mn.org/ 511mn.org] (state [[5-1-1]] webpage)
*[http://www.dot.state.mn.us/tmc/trafficinfo/map/refreshmap.html Twin Cities traffic map]
*[http://www.dot.state.mn.us/tmc/trafficinfo/metrocams/mapindex.html Twin Cities traffic cameras]
[[Category:Government of Minnesota|Department of Transportation]]
== From Los Alamos to Hiroshima==
[[Category:Transportation in Minnesota|Department of Transportation]]
:''See the main article at [[Manhattan Project]].''
[[Image:JROppenheimer-LosAlamos.jpg|right|200px|thumb|[[UC Berkeley|Berkeley]] physicist [[Robert Oppenheimer]] led the Allied scientific effort at [[Los Alamos National Laboratory|Los Alamos]].]]
By the beginning of [[World War II]], there was concern amongst scientists in the [[Allied]] nations that [[Nazi Germany]] might have [[German nuclear energy project|their own project to develop fission-based weapons]]. Organized research first began in Britain as part of the "[[TUBE ALLOYS]]" project, and in the United States a small amount of funding was given for research into uranium weapons starting in [[1939]]. At the urging of British scientists, though, who had made crucial calculations indicating that a fission weapon could be completed within only a few years, by [[1941]] the project had been wrested into better bureaucratic hands, and in [[1942]] came under the auspices of General [[Leslie Groves]] as the [[Manhattan Project]]. Scientifically led by the eccentric American physicist [[Robert Oppenheimer]], the project brought together the top scientific minds of the day (many exiles from Europe) with the production power of American industry for the goal of producing fission-based explosive devices before Germany could. Great Britain and the U.S. agreed to pool their resources and information for the project, but the other Allied power—the [[Soviet Union]] under [[Joseph Stalin]]—was not informed.
A massive industrial and scientific undertaking, the Manhattan Project involved many of the world's great physicists in the scientific and development aspects. The United States made an unprecedented investment into wartime research for the project, which was spread across over 30 sites in the U.S. and Canada. Scientific knowledge was centralized at a secret laboratory known as [[Los Alamos National Laboratory|Los Alamos]], previously a small ranch school near [[Santa Fe, New Mexico]].
Uranium appears in nature primarily in two isotopes: [[uranium-238]] and [[uranium-235]]. When the nucleus of uranium-235 absorbs a neutron, it undergoes nuclear fission, splitting into two "fission products" and releasing energy and 2.5 neutrons on average. Uranium-238, on the other hand, absorbs neutrons and does not fission, effectively putting a stop to any ongoing fission reaction. It was discovered that an atomic bomb based on uranium would need to be made of almost completely pure uranium-235 (at least 80% pure), or else the presence of uranium-238 would quickly derail the [[nuclear chain reaction]]. The team of scientists working on the Manhattan Project immediately realized that one of the largest problems they would have to solve was how to remove uranium-235 from natural uranium, which was composed of over 99% uranium-238. Two methods were developed during the wartime project, both of which took advantage of the fact that uranium-238 weighs a little more than uranium-235: [[Isotope_separation#Electromagnetic|electromagnetic separation]] and [[gaseous diffusion]]. Another secret site was erected at rural [[Oak Ridge National Laboratory|Oak Ridge]], [[Tennessee]], for the large-scale production and purification of the rare isotope. It was a massive investment: at the time, it was the largest factory under one roof, and employed thousands of employees at its peak, most of whom had no idea what they were working on.
[[Image:Fission bomb assembly methods.png|right|Fission bomb assembly methods.]]
Though uranium-238 cannot be used inside an atomic bomb, when it absorbs a neutron it transforms first into an unstable element, uranium-239, and then decays into [[neptunium]]-239 and finally the relatively stable [[plutonium]]-239, an element which does not exist in nature. Plutonium is also fissile and can be used to create a fission reaction, and after [[Enrico Fermi]] achieved the world's first sustained and controlled nuclear chain reaction in the creation of the first "atomic pile"—a primitive [[nuclear reactor]]—in a basement at the [[University of Chicago]], massive reactors were secretly created at what is now known as [[Hanford Site]] in the state of [[Washington]], using the [[Columbia River]] as cooling water, to transform uranium-238 into plutonium for a bomb.
For a fission weapon to operate, there must be a [[critical mass]]—the amount needed for a self-sustaining nuclear chain reaction—of fissile material bombarded with neutrons at any one time. The simplest form of nuclear weapon would be a "gun assembly" weapon, where a sub-critical mass of fissile material (such as uranium-235) would be shot at another sub-critical mass of fissile material. The result would be a critical or super-critical mass which, when bombarded with neutrons, would undergo fission at a rapid rate and create the desired explosion.
But it was soon discovered that plutonium cannot be used in a "gun assembly," as it has too high a level of background neutron radiation. If plutonium were used in a "gun assembly," the chain reaction would start in the split seconds before the critical mass was assembled, blowing the weapon apart before it would have any great effect (this is known as a [[fizzle]]). After some despair, Los Alamos scientists discovered another approach: using chemical explosives to [[implosion|implode]] a sub-critical sphere of plutonium, which would increase its density and make it into a critical mass. The difficulties with implosion were in the problem of making the chemical explosives deliver a perfectly uniform shock-wave upon the plutonium sphere—if it was off by only a little, the weapon would fizzle (which would be expensive, messy, and not a very effective military device).
After [[D-Day]], General Groves had ordered a team of scientists—Project [[ALSOS]]—to follow Eastward-moving victorious Allied troops into Europe in order to assess the status of the German nuclear program (and to prevent the Westward-moving Russians from gaining any materials or scientific manpower). It was concluded that while Nazi Germany had also had an atomic bomb program, headed by [[Werner Heisenberg]] the government had not made a significant investment in the project, and had been nowhere near success.
[[Image:Trinity explosion (color).jpg|left|thumb|200px|The atomic fireball at the "[[Trinity site|Trinity]]" nuclear test secretly rang in the atomic age.]]
By the unconditional surrender of Germany on [[May 8]], [[1945]], the Manhattan Project was still months away from a working weapon. That April, after the death of American president [[Franklin Delano Roosevelt|Roosevelt]], former vice-president [[Harry S. Truman]] was told about the secret wartime project for the first time.
Because of the difficulties in making a working plutonium bomb, it was decided that there should be a test of the weapon, and Truman wanted to know for sure if it would work before his meeting with Joseph Stalin at an upcoming conference on the future of postwar Europe. On [[July 16]], 1945, in the desert north of [[Alamogordo]], [[New Mexico]], the first [[nuclear test]] took place, code-named "[[Trinity Site|Trinity]]." The test released the equivalent of 19 thousand tons ([[kiloton]]s) of [[TNT]], far mightier than any weapon ever used before.
The news of the test's success was rushed to Truman, who used it as leverage at the upcoming [[Potsdam Conference]], held near Berlin.
[[Image:Hiroshima aftermath.jpg|right|thumb|200px|The [[atomic bombings of Hiroshima and Nagasaki]] killed hundreds of thousands of Japanese civilians.]]
After hearing arguments from scientists and military officers over the possible uses of the weapons against Japan (though some recommended using them as "demonstrations" in non-populated areas, most recommended using them against "built up" targets, a [[euphamism|euphamistic]] term for populated cities), Truman ordered the use of the weapons on Japanese cities, hoping it would send a strong message which would end in the capitulation of the Japanese leadership and avoid a lengthy invasion of the island. On [[August 6]], [[1945]], a uranium-based weapon, "[[Little Boy]]", was let loose on the Japanese city of [[Hiroshima]]. Three days later, a plutonium-based weapon, "[[Fat Man]]", was dropped onto the city of [[Nagasaki]]. [[Atomic bombings of Hiroshima and Nagasaki|The atomic bombs killed hundreds of thousands]] of Japanese outright, most of them civilians, with the heat, radiation, and blast effects. Many tens of thousands would die later of radiation sickness and related cancers. Truman promised a "rain of ruin" of Japan did not surrender immediately, threatening to eliminate Japanese cities, one by one; Japan surrendered on [[August 15]].
The weapons had been developed, and their power had been demonstrated to the world. The United States held a monopoly on nuclear weapons, but nobody thought this could last forever—the principles were based in fundamental research, which could be duplicated almost anywhere. The [[atomic age]] had begun.
==Red cloud on the horizon ==
:''See the main article at [[Soviet atomic bomb project]].''
[[Image:Kurchatov.jpg|right|200px|thumb|Soviet physicist [[Igor Kurchatov]] was in charge of analyzing the espionage coming in about the American nuclear project.]]
The Soviet Union were not invited to share in the new weapons developed by the United States and the other Allies, but they were not to be left out of the nuclear club for long. All during the war, information had been pouring in from a number of volunteer spies involved with the Manhattan Project (known in Soviet cables under the code-name of ''Enormoz''), and the Soviet nuclear physicist [[Igor Kurchatov]] was carefully watching the Allied weapons development. As such, it came as no surprise to Stalin when Truman had informed him at the Potsdam conference that he had a "powerful new weapon." Truman was shocked at Stalin's apparent disinterest.
Those in the U.S. project were all volunteers and none were Russians. One of the most valuable, [[Klaus Fuchs]], was a German émigré theoretical physicist who had been a part in the early British nuclear efforts and had been part of the UK mission to Los Alamos during the war. Fuchs had been intimately involved in the development of the implosion weapon, and passed on detailed cross-sections of the "Trinity" device to his Soviet contacts. Other Los Alamos spies—none of whom knew each other—included [[Theodore Hall]] and [[David Greenglass]]. The information was kept but not acted upon, as Russia was still too busy fighting the war in Europe to devote resources to this new project.
In the years immediately after World War II, the issue of who should control atomic weapons became a major international point of contention. Many of the Los Alamos scientists who had built the bomb began to call for "international control of atomic energy," often calling for either control by transnational organizations or the purposeful distribution of weapons information to all superpowers. But do to a deep distrust of the intentions of the Soviet Union, both in postwar Europe and in general, the policy-makers of the United States worked to attempt secure an American nuclear monopoly. A half-hearted plan for international control was proposed at the newly formed [[United Nations]] by [[Bernard Baruch]], but it was clear both to American commentators—and to the Soviets—that it was an attempt primarily to stymy Russian nuclear efforts. The Soviets vetoed the plan, effectively ending any immediate postwar negotiations on atomic energy, and made overtures towards banning the use of atomic weapons in general.
[[Image:Ac.beria3.jpg|left|200px|thumb|The iron hand of [[NKVD]] chief [[Lavrenty Beria]] was put in charge of the Russian project.]]
All the while, the Soviets had put their full industrial and manpower might into the development of their own atomic weapons. The initial problem for the Soviets was primarily one of resources—they had not scouted out uranium resources in the Soviet Union and the USA had made deals to seize monopolies over the largest known reserves in the [[Belgian Congo]]. The USSR used [[slave labor]] to mine the old deposits in [[Czechoslovakia]]—now an area under their control—and searched for other domestic deposits (which were eventually found).
Two days after the bombing of Nagasaki, the US government released an official technical history of the Manhattan Project, authored by Princeton physicist [[Henry DeWolf Smyth]], known colloquially as the [[Smyth Report]]. The santizied summary of the wartime effort focused primarily on the production facilities and scale of investment, written in part to justify the wartime expenditure to the American public. The Soviet program, under the suspicious watch of former [[NKVD]] chief [[Lavrenty Beria]] (a participant and victor in Stalin's [[Great Purge]] of the 1930s), would use the Report as a blueprint, seeking to duplicate as much as possible the American effort. The "secret cities" used for the Soviet equivalents of Hanford and Oak Ridge literally vanished from the maps for decades to come.
At the Soviet equivalent of Los Alamos, [[Sarov|Arzamas-16]], physicist [[Yuli Khariton]] led the scientific effort to develop the weapon. Beria distrusted his scientists, however, and he distrusted the carefully collected espionage information. As such, Beria assigned multiple teams of scientists to the same task without informing each team of the other's existence. If they arrived at different conclusions, Beria would bring them together for the first time and have them debate with their newfound counterparts. Beria used the espionage information as a way to double-check the progress of his scientists, and in his effort for duplication of the American project even rejected more efficient bomb designs in favor of ones which more closely mimicked the tried-and-true "[[Fat Man]]" bomb used by the U.S. against Nagasaki.
[[Image:Joe one.jpg|right|thumb|200px|The first Soviet bomb, "[[Joe-1]]," was tested on August 29, 1949.]]
Working under a stubborn and scientifically-ignorant administrator, the Soviet scientists struggled on with the knowledge that failure would certainly mean their deaths. On [[August 29]], [[1949]], the effort brought its results, when the USSR tested its first fission bomb, dubbed "[[Joe-1]]" in the USA, years ahead of American predictions. The news of the first Soviet bomb was announced to the world first by the United States, which had detected the [[nuclear fallout]] it generated from its test site in [[Semipalatinsk Test Site|Kazakhstan]].
The loss of the American monopoly on nuclear weapons marked the first tit-for-tat of the [[nuclear arms race]]. The response in the USA was one of apprehension, fear, and scapegoating, which would lead eventually into the Red-baiting tactics of [[McCarthyism]]. Before this, though, President Truman would announce his decision to begin a crash program to develop a far more powerful weapon than those which were used against Japan: the [[hydrogen bomb]].
== The hydrogen bomb ==
[[Image:EdwardTeller1958.jpg|right|thumb|250px|Hungarian physicist [[Edward Teller]] toiled for years trying to discover a way to make a fusion bomb.]]
The notion of using a fission weapon to ignite a process of [[nuclear fusion]] can be dated back to [[1942]]. At the first major theoretical conference on the development of an atomic bomb hosted by [[J. Robert Oppenheimer]] at the [[University of California, Berkeley]], participant [[Edward Teller]] directed the majority of the discussion towards [[Enrico Fermi]]'s idea of a "Super" bomb which would utilize the same reactions which powered the [[Sun]] itself. It was thought at the time that a fission weapon would be quite simple to develop and that perhaps work on a hydrogen bomb would be possible to complete before the end of the second World War. However in reality the problem of a "regular" atomic bomb was large enough to preoccupy the scientists for the next few years, much less the more speculative "Super." Only Teller continued working on the project—against the will of project leaders Oppenheimer and [[Hans Bethe]].
After the atomic bombings of Japan, many scientists at [[Los Alamos National Laboratory|Los Alamos]] rebelled against the notion of creating a weapon thousands of times more powerful than the first atomic bombs. For the scientists the question was in part technical— the weapon design was still quite uncertain and unworkable—and in part moral—such a weapon, they argued, could only be used against large civilian populations, and could thus only be used as a weapon of genocide. Many scientists, such as Bethe, urged that the United States should not develop such weapons and set an example towards the Soviet Union. Promoters of the weapon, including Teller, [[Ernest Lawrence]], and [[Luis Alvarez]], argued that such a development was inevitable, and to deny such protection to the people of the United States—especially when the Soviet Union was likely to create such a weapon themselves—was itself an immoral and unwise act.
Oppenheimer, who was now head of the General Advisory Committee of the successor to the Manhattan Project, the [[Atomic Energy Commission]], presided over an recommendation against the development of the weapon. The reasons were in part because the success of the technology seemed limited at the time (and not worth the investment of resources to confirm whether this was so), and because Oppenheimer believed that the atomic forces of the United States would be more effective if they consisted of many large fission weapons (of which multiple bombs could be dropped on the same targets) rather than the large and unwieldly predictions of massive super bombs, for which there were a relatively limited amounts of targets of the size to warrant such a development. Furthermore, were such weapons developed by both the USA and the USSR, they would be more effectively used against the USA than by it, as the USA had far more regions of dense industrial and civilian activity which would serve as ideal targets for the large weapons than the Soviet Union did.
[[Image:Ivy_Mike_H_Bomb.jpg|left|250px|thumb|The "[[Ivy Mike|Mike]]" shot in [[1952]] inaugurated the age of fusion weapons.]]
In the end, President Truman made the final decision, looking for a proper response to the first Soviet atomic bomb testing in [[1949]]. On [[January 31]], [[1950]], Truman announced a crash program to develop the hydrogen (fusion) bomb. At this point, however, the exact mechanism was still not known: the "classical" hydrogen bomb, whereby the ''heat'' of the fission bomb would be used to ignite the fusion material, seemed highly unworkable. However due to an insight by Los Alamos mathematician [[Stanislaw Ulam]], that the fission bomb and the fusion fuel could be in separate parts of the bomb, and the ''radiation'' of the fission bomb could first work in a way to ''compress'' the fusion material before igniting it. Teller pushed the notion further, and used the results of the boosted-fission "George" test (a boosted-fission device used a small amount of fusion fuel to boost the yield of a to confirm the fusion of heavy hydrogen elements before preparing for their first true multi-stage), Teller-Ulam hydrogen bomb test. Many scientists initially against the weapon, such as Oppenheimer and Bethe, changed their previous opinions, seeing the development as being unstoppable.
The first fusion bomb was tested by the United States in ''[[Operation Ivy]]'' on [[November 1]], [[1952]], on Elugelab Island in the Enewetak (or Eniwetok) Atoll of the [[Marshall Islands]], code-named "[[Ivy Mike|Mike]]". "Mike" used liquid [[deuterium]] as its fusion fuel and a large fission weapon as its trigger. The device was a prototype design and not a deliverable weapon: standing over 20 ft (6 m) high and weighing at least 140,000 lb (64 t) (its refrigeration equipment added an additional 24,000 lb as well), it could not have been dropped from even the largest planes. Its explosion yielded 10.4 [[megatons]] of energy—over 450 times the power of the bomb dropped onto [[Nagasaki]]— and obliterated Eluegelab, leaving an underwater crater 6240 ft (1.9 km) wide and 164 ft (50 m) deep where the island had once been. Truman had initially tried to create a media blackout about the test—hoping it would not become an issue in the upcoming presidential election—but on [[January 7]], [[1953]], Truman announced the development of the hydrogen bomb to the world as hints and speculations of it were already beginning to emerge in the press.
[[Image:Fireball comparison pic.jpg|right|300px|thumb|The smaller fireball in this composite photograph is of a 20 kiloton weapon (roughly the size of the weapon dropped on Nagasaki, Japan), while the larger fireball is of a 1 megaton weapon (a medium-sized hydrogen bomb), superimposed over the city of San Francisco for a sense of comparative size. The heat, blast, and radiation effects would spread over areas far larger than the fireballs would.]]
Not to be outdone, the Soviet Union exploded its first thermonuclear device, designed by the physicist [[Andrei Sakharov]], on [[August 12]], [[1953]], labeled "[[Joe-4]]" by the West. This created concern within the U.S. government and military, because, unlike "Mike," the Soviet device was a deliverable weapon, which the U.S. did not yet have. This first device though was arguably not a "true" hydrogen bomb, and could only reach explosive yields in the hundreds of kilotons (never reaching the megaton range of a "staged" weapon). Still, it was a powerful propaganda tool for the Soviet Union, and the technical differences were fairly oblique to the American public and politicians. Following the "Mike" blast by less than a year, "Joe-4" seemed to validate claims that the bombs were inevitable and vindicate those who had supported the development of the fusion program. Coming during the height of [[McCarthyism]], the effect was most pronounced by the security hearings in early [[1954]] which revoked former Los Alamos director Robert Oppenheimer of his security clearance, on the grounds that he was unreliable, had not supported the American hydrogen bomb program, and had made long standing left-wing ties in the 1930s. Edward Teller participated in the hearing as the only major scientist to testify against Oppenheimer, a role which resulted in his virtual expulsion from the physics community.
On [[February 28]], [[1954]], the U.S. detonated its first deliverable thermonuclear weapon (which used isotopes of [[lithium]] as its fusion fuel), known as the "Shrimp" device of the "[[Castle Bravo]]" test. The device yielded 15 megatons of energy, over twice its expected yield, and became the worst [[List of nuclear accidents|radiological disaster]] in U.S. history. The combination of the unexpectedly large blast and poor weather conditions caused a cloud of radioactive [[nuclear fallout]] to contaminate over 7,000 square miles, including Marshall Island natives and the crew of a Japanese fishing boat, as a snow-like mist. The contaminated islands were evacuated (and are still uninhabitable) but the natives received enough of a radioactive dose that they suffered far elevated levels of [[cancer]] and [[birth defect]]s in the years to come. The crew of the Japanese fishing boat, ''Fifth Lucky Dragon'', returned to port suffering from [[radiation sickness]] and skin burns. Their cargo, many tons of contaminated fish, managed to enter into the market before the cause of their illness was determined. When a crew member died from the sickness, and the full results of the contamination were made public by the USA, reignited Japanese concerns about the hazards of radiation and resulted in a boycott on eating fish (a main staple of the island country) for some weeks.
[[Image:Fallout map USA (FEMA).jpg|left|thumb|300px|[[Nuclear fallout|Fallout]] from a large nuclear exchange would potentially blanket a country—perhaps even the whole world—with radioactive fission products.]]
The age of hydrogen bombs had a profound effect on thoughts of [[nuclear war]] in the popular and military mind. With only fission bombs, nuclear war could be considered something which could easily be "limited." Dropped by planes and only able to destroy the most built up areas of major cities, it was possible to consider fission bombs simply a technological extension of previous wartime bombing (such as the extensive [[firebombing]] which took place against Japan and Germany during World War II), and claims that such weapons could lead to worldwide death or harm were easily brushed aside as grave exaggeration. Even the decades before the development of fission weapons there had been speculation about the possibility for human beings to end all life on the planet by either accident or purposeful maliciousness, but technology had never allowed for such a capacity. The far greater power of hydrogen bombs made this seem ever closer.
The "Castle Bravo" incident itself raised a number of questions about the survivability of a nuclear war. Government scientists in both the USA and the USSR had insisted that fusion weapons, unlike fission weapons, were "cleaner" as fusion reactions did not result in the dangerously radioactive by-products as did fission reactions. While technically true, this hid a more gruesome point: the last stage of a multi-staged hydrogen bomb often used the neutrons produced by the fusion reactions to induce fissioning in a jacket of natural uranium, and provided around half of the yield of the device itself. This fission stage made fusion weapons considerably more "dirty" than they were made out to be, a fact made bare by the towering cloud of deadly fallout which followed the "Bravo" test. When the Soviet Union tested its first megaton device in [[1955]], the possibility of a limited nuclear war seemed even more remote in the public and political mind: even if a city or country was not the direct target of a nuclear attack, the clouds of fallout and harmful fission products would disperse along with normal weather patterns and embed themselves in the soil and water of non-targeted areas of the planet as well. Speculation began to look towards what would happen as the fallout and dust created by a full-scale nuclear exchange would affect the world as a whole, rather than just the cities and countries which had been directly involved. In this way, the fate of the world was now tied to the fate of the bomb-wielding superpowers.
==Cold War==
During the Cold War, more countries joined the "nuclear club." On [[February 26]], [[1952]], Prime Minister [[Winston Churchill]] that the United Kingdom also had an atomic bomb—not a too surprising development, considering how many UK scientists worked at very high levels in the Manhattan Project. By the mid-1960s, both [[France]] and the [[People's Republic of China]] had also demonstrated nuclear capability, and these five countries were considered to be the 'Nuclear Powers' throughout the Cold War period.
After World War II, the [[balance of power]] between the Eastern and Western blocs, resulting in the fear of global destruction, prevented the further military use of atomic bombs. This fear was even a central part of [[Cold War]] strategy, referred to as the doctrine of [[Mutually Assured Destruction]] ("MAD" for short). So important was this balance to international political stability that a treaty, the [[Antiballistic Missile Treaty]] (or ABM treaty) was signed by the U.S. and the [[Soviet Union|USSR]] in 1972 to curtail the development of defenses against nuclear weapons and the [[ballistic missile]]s which carry them. This doctrine resulting in a large increase in the number of nuclear weapons, as each side sought to ensure it possessed the firepower to destroy the opposition in all possible scenarios and against all perceived threats.
[[Image:Minuteman3launch.jpg|right|thumb|200px|[[ICBM]]s, like the American [[Minuteman missile]], allowed nations to deliver nuclear weapons thousands of miles away with relative ease.]]
Early delivery systems for nuclear devices were primarily bombers like the American [[B-29 Superfortress]] and [[B-36 Peacemaker]], and later the [[B-52 Stratofortress]]. Ballistic missile systems, based on designs used by Germany under [[Wernher von Braun]] (specifically the [[V2 rocket]]), were developed by both American and Soviet teams (in the case of U.S., effort was directed by the captured German scientists and engineers). These systems, after testing, were used to launch satellites, such as [[Sputnik]], and to propel the [[Space Race]], but they were primarily developed to create the capability of Intercontinental Ballistic Missiles ([[ICBM]]s) with which nuclear powers could deliver that destructive force anywhere on the globe. These systems continued to be developed throughout the [[Cold War]], although plans and treaties, beginning with the Strategic Arms Limitation Treaty ([[SALT I]]), restricted deployment of these systems until, after the fall of the Soviet Union, system development essentially halted, and many weapons were disabled and destroyed (see [[nuclear disarmament]]).
[[Image:Nuclear weapon size chart.jpg|center|Relative sizes of a number of nuclear weapons.]]
There have been a number of potential nuclear disasters. Following air accidents U.S. nuclear weapons have been lost near [[Atlantic City, New Jersey]] (1957), [[Savannah, Georgia]] (1958) (see [[Tybee Bomb]]), [[Goldsboro, North Carolina]] (1961), off the coast of [[Okinawa]] (1965), in the sea near [[Palomares]], [[Spain]] (1966) and near [[Thule, Greenland|Thule]], [[Greenland]] (1968). Most of the lost weapons were recovered, the Spanish device after three months' effort by the [[DSV Alvin]] and [[DSV Aluminaut]]. The Soviet Union was less forthcoming about such incidents, but the environmental group [[Greenpeace]] believes that there are around forty non-U.S. nuclear devices that have been lost and not recovered, compared to eleven lost by America, mostly in submarine disasters. The U.S. have tried to recover Soviet devices, notably in the 1974 [[Operation Jennifer]] using the specialist salvage vessel ''[[Hughes Glomar Explorer]]''.
On [[January 27]], [[1967]], more than 60 nations signed the [[Outer Space Treaty]] banning nuclear weapons in space.
The end of the [[Cold War]] failed to bring an end to the threat of the use of nuclear weapons, although global fears of [[nuclear war]] reduced substantially.
In a major move of deescalation, [[Boris Yeltsin]] on [[January 26]], [[1992]] announced that [[Russia]] planned to stop targeting [[United States]] cities with nuclear weapons.
==Nuclear proliferation==
:''See the main article at [[Nuclear proliferation]].''
[[France]] made a point of conducting above-ground tests of nuclear weapons in the [[1990s]].
India's first test atomic explosion was in [[1974]] with [[Smiling Buddha]], which it initially described as a 'peaceful nuclear explosion'. [[India]] tested fission and perhaps fusion devices in [[1998]] and [[Pakistan]] successfully tested fission devices that same year, raising concerns that they would use nuclear weapons on each other. All of the former Soviet bloc countries with nuclear weapons ([[Belarus]], [[Ukraine]], and [[Kazakhstan]]) returned their warheads to [[Russia]] by [[1996]], though recent data has suggested that a clerical error may have left some warheads in the Ukraine.
In [[January]] [[2004]], Pakistani metallurgist and weapons scientist [[Abdul Qadeer Khan]] confessed to having been a part of an international [[nuclear proliferation|proliferation]] network of materials, knowledge, and machines from Pakistan to [[Libya]], [[Iran]], and [[North Korea]].
[[South Africa]] also had an active program to develop uranium based nuclear weapons, but dismantled its nuclear weapon program in the [[1990s]]. It is not believed that it actually tested such a weapon though it later claimed to have constructed several crude devices which it eventually dismantled. In the late [[1970s]] American spy satellites detected what appeared to be a flash of gamma rays which have been speculated to be a South African atomic test, but a later scientific review of the data suggested it may have been caused by natural events.
[[Israel]] is widely believed to possess an arsenal of potentially up to several hundred nuclear warheads, but this has never been officially confirmed or denied (though the existence of their [[Dimona]] nuclear facility was more or less confirmed by the leaks of dissident [[Mordechai Vanunu]] in 1986).
The [[United Kingdom]] has not run an independent development program since the failure of [[Blue Streak missile]] in the [[1960s]], buying American delivery systems and fitting British warheads instead ([[Polaris Sales Agreement]]).
The [[People's Republic of China]] possesses an arsenal of nuclear warheads estimated to be around 400 strong (in 2002). In 2003, [[North Korea]] announced it also had several nuclear explosives though it has not been confirmed and the validity of this has been a subject of scrutiny amongst weapons experts.
==Nuclear testing==
:''See the main article at [[Nuclear testing]].''
There have been around 2,000 nuclear explosions:
* [[United States]]: 1,030 tests (involving 1,125 devices), at Alamagordo, New Mexico, Nevada Test Site and different islands like the Bikini Atoll.
* [[Soviet Union]]: 715 tests, including tests at Semipalatinsk, Novaya Zemlya and Kapustin Yar Test Sites.
* [[France]]: 210 tests, at the Mururoa Atoll and in Algeria.
* [[United Kingdom]]: 45 tests (21 in [[Australia]]n territory, including 9 in mainland [[South Australia]] at Maralinga and Emu Field). Including tests at different islands and test cooperations with the United States.
* [[People's Republic of China]]: 45 tests (23 atmospheric and 22 underground, all conducted at [[Lop Nur]] Nuclear Weapons Test Base, in [[Malan]], [[Xinjiang]])
* [[India]]: 6 tests.
* [[Pakistan]]: 6 tests.
[[Image:Worldwide nuclear testing.png|center|Worldwide nuclear testing, by country.]]
== See also ==
*National weapons programs:
**[[Manhattan Project]] (USA)
***[[Los Alamos National Laboratory]]
**[[German nuclear energy project]]
**[[TUBE ALLOYS]] (UK)
**[[Japanese atomic program]]
**[[Soviet atomic bomb project]]
*More information about [[nuclear weapon]]s:
**[[Nuclear explosion]]
**[[Nuclear testing]]
**[[Nuclear weapon design]]
**[[Nuclear warfare]]
**[[Nuclear arms race]]
**[[Nuclear proliferation]]
**[[List of nuclear accidents]]
== References ==
The first nuclear programs:
*Gregg Herken, ''Brotherhood of the Bomb: The Tangled Lives and Loyalties of Robert Oppenheimer, Ernest Lawrence, and Edward Teller'' (New York: Henry Holt & Co., 2002). [http://www.brotherhoodofthebomb.com/]
*David Holloway, ''Stalin and the Bomb: The Soviet Union and Atomic Energy 1939-1956'' (New Haven: Yale University Press, 1995).
*Richard Rhodes, ''Dark Sun: The Making of the Hydrogen Bomb'' (New York: Simon and Schuster, 1995).
*Richard Rhodes, ''The Making of the Atomic Bomb'' (New York: Simon and Schuster, 1986).
*Henry DeWolf Smyth, ''Atomic Energy for Military Purposes'' (Princeton, NJ: Princeton University Press, 1945). ([[Smyth Report]]) [http://nuclearweaponarchive.org/Smyth/]
*Mark Walker, ''German National Socialism and the Quest for Nuclear Power, 1939-1949'' (London: Cambridge University Press, 1990).
Nuclear weapons and energy in culture:
*Spencer Weart, ''Nuclear Fear: A History of Images'' (Cambridge, MA: Harvard University Press, 1988).
Nuclear arsenals and capabilities:
*Chuck Hansen, ''U.S. Nuclear Weapons: The Secret History'', (Arlington, TX: Aerofax, 1988).
*Chuck Hansen, ''The Swords of Armageddon: U.S. nuclear weapons development since 1945'', (Sunnyvale, CA: Chukelea Publications, 1995). [http://www.uscoldwar.com/]
*Stephen Schwartz, ed., ''Atomic Audit: The Costs and Consequences of U. S. Nuclear Weapons Since 1940'' (Brookings Institution Press, 1998). [http://www.brook.edu/fp/projects/nucwcost/weapons.htm]
== External links ==
*[http://www.atomicarchive.com/ Timeline of atomic age events]
*[http://www.thebulletin.org/issues/2003/ma03/ma03stober_doc.html Nuclear History Documents from the National Security Archive]
*[http://www.fas.org/nuke/guide/ Federation of American Scientists - Worldwide Nuclear Forces Guide]
*[http://nuclearweaponarchive.org/ Nuclear Weapons Archive] - includes the nuclear weapon histories of many countries
[[Category:Nuclear weapons]]
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