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189-722: In 2008, Congress denied funding for the program, and in 2009 the Obama administration called for work on the program to cease. During the Cold War , the United States, in an effort to achieve and maintain an advantage in the nuclear arms race with the Soviet Union , invested large amounts of money and technical resources into nuclear weapons design, testing, and maintenance. Many of the weapons designed required high upkeep costs, justified primarily by their Cold War context and

378-476: A Democrat from Illinois , took office following his victory over Republican nominee John McCain in the 2008 presidential election . Four years later, in the 2012 presidential election , he defeated Republican nominee Mitt Romney , to win re-election. Obama is the first African American president, the first multiracial president, the first non-white president, and the first president born in Hawaii. Obama

567-531: A new executive order that would have protected another four million illegal immigrants from deportation, but the order was blocked by the Supreme Court in a 4–4 tie vote that upheld a lower court's ruling. Despite executive actions to protect some individuals, deportations of illegal immigrants continued under Obama. A record high of 400,000 deportations occurred in 2012, though the number of deportations fell during Obama's second term. In continuation of

756-400: A nuclear chain reaction . This was accomplished by shooting one piece of the uranium onto the other by means of four cylindrical silk bags of cordite powder. This was a widely used smokeless propellant consisting of a mixture of 65 percent nitrocellulose , 30 percent nitroglycerine , 3 percent petroleum jelly , and 2 percent carbamite that was extruded into tubular granules. This gave it

945-598: A second bailout of US automakers, possibly saving General Motors and Chrysler from bankruptcy at the cost of $ 9.3 billion. For homeowners in danger of defaulting on their mortgage due to the subprime mortgage crisis , Obama launched several programs, including HARP and HAMP . Obama re-appointed Ben Bernanke as Chair of the Federal Reserve Board in 2009, and appointed Janet Yellen to succeed Bernanke in 2013. Short-term interest rates remained near zero for much of Obama's presidency, and

1134-541: A 5–4 majority upheld the constitutionality of the Affordable Care Act, even though it made state Medicaid expansion voluntary. In King v. Burwell , a 6–3 majority allowed the use of tax credits in state-operated exchanges. The October 2013 launch of HealthCare.gov , a health insurance exchange website created under the provisions of the ACA, was widely criticized, even though many of the problems were fixed by

1323-572: A Senate filibuster in a 55–41 vote in favor of the bill. In 2013, the Senate passed an immigration bill with a path to citizenship, but the House did not vote on the bill. In 2012, Obama implemented the DACA policy, which protected roughly 700,000 illegal immigrants from deportation; the policy applies only to those who were brought to the United States before their 16th birthday. In 2014, Obama announced

1512-732: A Task Force of the Secretary of Energy's Advisory Board (SEAB), the RRW program and weapon designs should have the following characteristics: However, the full SEAB disavowed the Task Force's recommendations regarding the RRW, because the Task Force did not consider the program's potentially adverse impacts on U.S. nonproliferation objectives, which were beyond its expertise. The RRW program has not to date publicly announced that it has developed any new nuclear weapon designs which are intended to be placed into production. Presumably, once that occurs,

1701-600: A ban on denying coverage based on pre-existing conditions . However, the House bill included a tax increase on families making more than $ 1 million per year and a public health insurance option , while the Senate plan included an excise tax on high-cost health plans . The 2010 Massachusetts Senate special election victory of Scott Brown seriously imperiled the prospects of a health care reform bill, as Democrats lost their 60-seat Senate super-majority . The White House and House Speaker Nancy Pelosi engaged in an extensive campaign to convince both centrists and liberals in

1890-620: A bipartisan basis by the National Governors Association , and the Council of Chief State School Officers . The criteria were not mandatory, they were incentives to improve opportunities to get a grant. Most states revised their laws accordingly, even though they realized it was unlikely they would when a highly competitive new grant. Race to the Top had strong bipartisan support, with centrist elements from both parties. It

2079-545: A budget. House Republicans passed a budget that would defund Obamacare , but Senate Democrats refused to pass any budget that defunded Obamacare. Meanwhile, the country faced another debt ceiling crisis . Ultimately the two sides agreed to a continuing resolution that re-opened the government and suspended the debt ceiling. Months after passing the continuing resolution, Congress passed the Bipartisan Budget Act of 2013 and an omnibus spending bill to fund

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2268-467: A common set of core design components to various use requirements, such as different sized missile warheads, different nuclear bomb types, etc. NNSA officials believe the program is needed to maintain nuclear weapons expertise in order to rapidly adapt, repair, or modify existing weapons or develop new weapons as requirements evolve. They see the ability to adapt to changing military needs rather than maintain additional forces for unexpected contingencies as

2457-457: A copy of the complete design. Unlike the implosion design, which required sophisticated coordination of shaped explosive charges, the gun-type design was considered almost certain to work so it was never tested before its first use at Hiroshima. After the war, numerous components for additional Little Boy bombs were built. By 1950, five complete weapons had been created, and these were retired by November 1950. There are two primary accounts of how

2646-419: A crash that could destroy or damage the military base from which the weapon was launched. The Little Boy was 120 inches (300 cm) in length, 28 inches (71 cm) in diameter and weighed approximately 9,700 pounds (4,400 kg). The design used the gun method to explosively force a hollow sub- critical mass of enriched uranium and a solid target cylinder together into a super-critical mass, initiating

2835-612: A cut in military spending , a scaling back of tax deductions for mortgages and employer-provided health insurance, a raise of the Social Security retirement age, and reduced spending on Medicare, Medicaid, and federal employees. The proposal never received a vote in Congress, but it served as a template for future plans to reduce the national debt. After taking control of the House in the 2010 elections , Congressional Republicans demanded spending cuts in return for raising

3024-477: A design which was test fired in the 1980s, but never entered service. LLNL staff have previously hinted in the press that LLNL was considering a design entry based on the tested but never deployed W89 design. This warhead had been proposed as a W88 warhead replacement as early as 1991. The W89 design was already equipped with all then-current safety features, including insensitive high explosives, fire-resistant pits, and advanced detonator safety systems. The W89

3213-435: A fuel. All the design, development, and technical work at Los Alamos was consolidated under Lieutenant Commander Francis Birch 's group. In contrast to the plutonium implosion-type nuclear weapon and the plutonium gun-type fission weapon, the uranium gun-type weapon was much simpler to design. As a high-velocity gun was no longer required, the overall length of the gun barrel could be dramatically decreased, and this allowed

3402-498: A full-scale test in the implosion-type design made it much more difficult to establish whether the necessary simultaneity of compression had been achieved. While there was at least one prominent scientist ( Ernest O. Lawrence ) who advocated for a full-scale test, by early 1945 Little Boy was regarded as nearly a sure thing and was expected to have a higher yield than the first-generation implosion bombs. Though Little Boy incorporated various safety mechanisms, an accidental detonation of

3591-463: A fully-assembled weapon was very possible. Should the bomber carrying the device crash, the hollow "bullet" could be driven into the "target" cylinder, possibly detonating the bomb from gravity alone (though tests suggested this was unlikely), but easily creating a critical mass that would release dangerous amounts of radiation. A crash of the B-29 and subsequent fire could trigger the explosives, causing

3780-510: A high surface area and a rapid burning area, and could attain pressures of up to 40,000 pounds per square inch (280,000 kPa). Cordite for the wartime Little Boy was sourced from Canada; propellant for post-war Little Boys was obtained from the Picatinny Arsenal . The bomb contained 64 kilograms (141 lb) of enriched uranium. Most was enriched to 89% but some was only 50% uranium-235, for an average enrichment of 80%. Less than

3969-504: A key program driver. However, Congress has rejected the notion that the RRW is needed to meet new military requirements. In providing funds for 2006, the Appropriations Committee specified, "any weapons design under the RRW program must stay within the military requirements of the existing deployed stockpile and any new weapon design must stay within the design parameters validated by past nuclear tests". According to

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4158-448: A kilogram of uranium underwent nuclear fission , and of this mass only 0.7 grams (0.025 oz) was transformed into several forms of energy, mostly kinetic energy , but also heat and radiation. Inside the weapon, the uranium-235 material was divided into two parts, following the gun principle: the "projectile" and the "target". The projectile was a hollow cylinder with 60% of the total mass (38.5 kilograms [85 lb]). It consisted of

4347-487: A major bill addressing the issue, in part because many Republicans and some Democrats questioned whether global warming is occurring and whether human activity contributes to it. Following his inauguration, Obama asked that Congress pass a bill to put a cap on domestic carbon emissions. After the House passed the American Clean Energy and Security Act in 2009, Obama sought to convince the Senate to pass

4536-400: A modern new arsenal composed of such untested designs that would be more reliable, safe and effective than the current U.S. arsenal based on more than 1,000 tests since 1945". Critics maintain that this innocuous-sounding program could significantly damage US national security. Critics believe an expansive RRW program would anger US allies as well as hostile nations. They worry it would disrupt

4725-577: A one-year reduction in the FICA payroll tax , and other measures. Obama ultimately persuaded many wary Democrats to support the bill, though many liberals such as Bernie Sanders continued to oppose it. The $ 858 billion Tax Relief, Unemployment Insurance Reauthorization, and Job Creation Act of 2010 passed with bipartisan majorities in both houses of Congress and was signed into law by Obama on December 17, 2010. Shortly after Obama's 2012 re-election, Congressional Republicans and Obama again faced off over

4914-451: A peak of 12.2 million in 2007. The nation's immigrant population hit a record 42.2 million in 2014. In November 2015, Obama announced a plan to resettle at least 10,000 Syrian refugees in the United States. Energy production boomed during the Obama administration. An increase in oil production was driven largely by a fracking boom spurred by private investment on private land, and

5103-601: A portion of a bill to be unconstitutional, and he subsequently issued several signing statements. Obama also signed the Omnibus Public Land Management Act of 2009 , which added 2 million acres (8,100 km ) of land to the National Wilderness Preservation System , as well as a law raising the cigarette pack tax by 62 cents (equivalent to $ 0.88 in 2023). On February 17, 2009, Obama signed

5292-474: A propellent, or creating a "double gun" with two projectiles) were pursued in the early years of the project, while the facilities to manufacture fissile material were being constructed. The belief that the gun design would be an easy engineering task once fuel was available led to a sense of optimism at Los Alamos, although Oppenheimer established a small research group to study implosion as a fallback in early 1943. A full ordnance program for gun-design development

5481-508: A second one sometime in December", assuming the second weapon would be a gun type; designing an implosion bomb for enriched uranium was considered, and this would increase the production rate. The enriched uranium projectile was completed on 15 June, and the target was completed on 24 July. The target and bomb pre-assemblies (partly assembled bombs without the fissile components) left Hunters Point Naval Shipyard , California, on 16 July aboard

5670-574: A single firestorm, and the fire-damaged area was only one-quarter as great as at Hiroshima, due in part to a southwest wind that pushed the fires away from the city. As the map shows, the Hiroshima firestorm jumped natural firebreaks (river channels), as well as prepared firebreaks. The spread of fire stopped only when it reached the edge of the blast-damaged area, encountering less available fuel. The Manhattan Project report on Hiroshima estimated that 60% of immediate deaths were caused by fire, but with

5859-401: A stack of nine uranium rings, each 6.25 inches (159 mm) in diameter with a 4-inch (100 mm) bore in the center, and a total length of 7 inches (180 mm), pressed together into the front end of a thin-walled projectile 16.25 inches (413 mm) long. Filling in the remainder of the space behind these rings in the projectile was a tungsten carbide disc with a steel back. At ignition,

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6048-580: A strategy of letting Congress drive the process, with the House and Senate writing their own bills. In the Senate, a bipartisan group of senators on the Finance Committee known as the Gang of Six began meeting with the hope of creating a bipartisan healthcare reform bill, even though the Republican senators involved with the crafting of the bill ultimately came to oppose it. In November 2009,

6237-451: A tamper and neutron reflector of tungsten carbide and steel, both materials having a combined mass of 2,300 kilograms (5,100 lb). Neutron initiators inside the assembly were activated by the impact of the projectile into the target. The material was split almost in half, with at one end a group of rings of highly enriched uranium with 40% of the supercritical mass, and at the other end another group of slightly larger rings with 60% of

6426-450: A transition away from coal as an energy source, but the falling price of wind, solar, and natural gas energy sources also contributed to coal's decline. Obama encouraged this successful transition away from coal in large part due to the fact that coal emits more carbon than other sources of power, including natural gas. Obama's campaign to fight global warming found more success at the international level than in Congress. Obama attended

6615-465: A trend that began with the passage of the Immigration and Nationality Act of 1965 , the percentage of foreign-born people living in the United States reached 13.7% in 2015, higher than at any point since the early 20th century. After having risen since 1990, the number of illegal immigrants living in the United States stabilized at around 11.5 million individuals during Obama's presidency, down from

6804-537: A truck driver and model maker from Illinois who had studied every photograph and document on the Hiroshima bomb to make an accurate model, corrected earlier published accounts. The fuzing system was designed to trigger at the most destructive altitude, which calculations suggested was 1,900 feet (580 m). It employed a three-stage interlock system: The Little Boy pre-assemblies were designated L-1, L-2, L-3, L-4, L-5, L-6, L-7, and L-11. Of these, L-1, L-2, L-5, and L-6 were expended in test drops. The first drop test

6993-643: A universal accounting system for emissions, required each country to monitor its emissions, and required each country to create a plan to reduce its emissions. Several climate negotiators noted that the US-China climate deal and the EPA's emission limits helped make the deal possible. In 2016, the international community agreed to the Kigali accord, an amendment to the Montreal Protocol which sought to reduce

7182-544: Is also a concern. (See Nuclear weapons design and Teller-Ulam design for technical context.) The question of whether the plutonium-gallium alloy used in the cores of the weapons suffered from aging has been a major topic of research at the weapons laboratories in recent decades. Though many at the labs still insist on scientific uncertainty on the question, a study commissioned by the National Nuclear Security Administration to

7371-600: Is merely an excuse for designing new weapons and maintaining jobs at the weapons laboratories. They note that the Secretaries of Defense and Energy have certified that the existing nuclear weapons stockpile is safe and reliable in each of the last nine years. The existing stockpile was extensively tested before the US entered the moratorium on nuclear weapons tests. According to Sidney Drell and Ambassador James Goodby , "It takes an extraordinary flight of imagination to postulate

7560-533: The 2008 Democratic National Convention , Chief of Staff Rahm Emanuel , and Defense Secretary Robert Gates , whom Obama chose to retain from the previous administration. An early list of suggestions came from Michael Froman , then an executive at Citigroup . Obama described his Cabinet choices as a " team of rivals ", and Obama chose several prominent public officials for Cabinet positions, including defeated rival Hillary Clinton as Secretary of State. Obama nominated several former Clinton administration officials to

7749-522: The 2009 United Nations Climate Change Conference , which drafted the non-binding Copenhagen Accord as a successor to the Kyoto Protocol . The deal provided for the monitoring of carbon emissions among developing countries , but it did not include Obama's proposal to commit to cutting greenhouse gas emissions in half by 2050. In 2014, Obama reached an agreement with China in which China pledged to reach peak carbon emission levels by 2030, while

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7938-657: The Affordable Care Act , sometimes referred to as "the ACA" or "Obamacare", the Dodd–Frank Wall Street Reform and Consumer Protection Act , and the Don't Ask, Don't Tell Repeal Act of 2010 . The American Recovery and Reinvestment Act and Tax Relief, Unemployment Insurance Reauthorization, and Job Creation Act served as economic stimuli amidst the Great Recession . After a lengthy debate over

8127-472: The American Recovery and Reinvestment Act (ARRA) to address the Great Recession . The ARRA had been passed, after much debate, by both the House and Senate four days earlier. While it was originally intended to be a bipartisan bill, Congressional passage of the bill relied largely on Democratic votes, though three Republican senators voted for it. The lack of Republican support for the bill, and

8316-518: The B-29s to carry the two atomic bomb shapes as part of Project Silverplate in late 1943. Another explanation of the names, from a classified United States Air Force history of Project Silverplate from the 1950s, implies a possible reconciliation of the two versions: that the terms "Thin Man" and "Fat Man" were first developed by someone at or from Los Alamos (i.e., Serber), but were consciously adopted by

8505-495: The Consumer Financial Protection Bureau , which was charged with protecting consumers against abusive financial practices. On signing the bill, Obama stated that the bill would "empower consumers and investors," "bring the shadowy deals that caused the crisis to the light of day," and "put a stop to taxpayer bailouts once and for all." Some liberals were disappointed that the law did not break up

8694-402: The D.C. Circuit to fill Scalia's seat. However, Senate Majority Leader Mitch McConnell , Judiciary Committee Chair Chuck Grassley , and other Senate Republicans argued that Supreme Court nominations should not be made during a presidential election year, and that the winner of the 2016 presidential election should instead appoint Scalia's replacement. Garland's nomination remained before

8883-679: The Gulf of Mexico . Because the pipeline crossed international boundaries, its construction required the approval of the US federal government, and the US State Department engaged in a lengthy review process. President Obama vetoed a bill to construct the Keystone Pipeline in February 2015, arguing that the decision of approval should rest with the executive branch. It was the first major veto of his presidency, and Congress

9072-477: The Hanford Site was designed to produce around 20 kilograms of plutonium per month, and each Fat Man bomb used around 6 kilograms of material.) Because of the simplicity of the gun-type design, laboratory testing could establish that its parts worked correctly on their own: for example, dummy projectiles could be shot down the gun barrel to make sure they were "seated" correctly onto a dummy target. Absence of

9261-639: The House of Representatives and the Senate , and Speaker of the House Nancy Pelosi and Senate Majority Leader Harry Reid both remained in their posts. Republicans John Boehner and Mitch McConnell continued to serve as House Minority Leader and Senate Minority Leader, respectively. The presidential transition period began following Obama's victory in the 2008 U.S. presidential election , though Obama had chosen Chris Lu to begin planning for

9450-829: The Naval Gun Factory in Washington, D.C.; the target case and some other components by the Naval Ordnance Plant in Center Line, Michigan ; and the tail fairing and mounting brackets by the Expert Tool and Die Company in Detroit, Michigan . The bomb, except for the uranium payload, was ready at the beginning of May 1945. Manhattan District Engineer Kenneth Nichols expected on 1 May 1945 to have enriched uranium "for one weapon before August 1 and

9639-701: The New Deal . The act increased regulation and reporting requirements on derivatives (particularly credit default swaps ), and took steps to limit systemic risks to the US economy with policies such as higher capital requirements , the creation of the Orderly Liquidation Authority to help wind down large, failing financial institutions, and the creation of the Financial Stability Oversight Council to monitor systemic risks. Dodd-Frank also established

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9828-551: The Supreme Court of the United States during Obama's tenure, but Obama made only two successful appointments. During the 111th Congress , when Democrats held a majority in the Senate, Obama successfully nominated two Supreme Court Justices: Justice Antonin Scalia died in February 2016, during the 114th Congress , which had a Republican majority in the Senate. In March 2016, Obama nominated Chief Judge Merrick Garland of

10017-516: The Trinity nuclear test . Since that had been estimated at 18 kilotons of TNT (75 TJ), speech writers rounded up to 20 kilotons. Further discussion was then suppressed, for fear of lessening the impact of the bomb on the Japanese. Data had been collected by Luis Alvarez , Harold Agnew , and Lawrence H. Johnston on the instrument plane, The Great Artiste , but this was not used to calculate

10206-498: The Trinity nuclear test . There were several reasons for not testing a Little Boy type of device. Primarily, there was the issue of fissile material availability. K-25 at Clinton Engineer Works was designed to produce around 30 kilograms of enriched uranium per month, and the Little Boy design used over 60 kilograms per bomb. So testing the weapon would incur a considerable delay in use of the weapon. (By comparison, B Reactor at

10395-584: The UN declaration on sexual orientation and gender identity ; and lifting the 7½-year ban on federal funding for embryonic stem cell research . Obama also ordered the closure of the Guantanamo Bay detention camp , in Cuba , though it remains open. He lifted some travel and money restrictions to the island. Obama signed many landmark bills into law during his first two years in office. The main reforms include:

10584-690: The United States debt ceiling , the statutory limit on the total amount of debt that the Treasury Department can issue. The 2011 debt-ceiling crisis developed as Obama and Congressional Democrats demanded a "clean" debt-ceiling increase that did not include spending cuts. Though some Democrats argued that Obama could unilaterally raise the debt ceiling under the terms of the Fourteenth Amendment , Obama chose to negotiate with Congressional Republicans. Obama and Speaker of

10773-407: The electricity grid , repair public housing, and weatherize modest-income homes. Obama also promoted the use of plug-in electric vehicles , and 400,000 electric cars had been sold by the end of 2015. According to a report by The American Lung Association, there was a "major improvement" in air quality under Obama. Upon entering office, Obama focused on handling the global financial crisis and

10962-559: The expanded Children's Health Insurance Program (S-CHIP); winning approval of a congressional budget resolution that put Congress on record as dedicated to dealing with major health care reform legislation in 2009; implementing new ethics guidelines designed to significantly curtail the influence of lobbyists on the executive branch; breaking from the Bush administration on a number of policy fronts, except for Iraq, in which he followed through on Bush's Iraq withdrawal of US troops; supporting

11151-455: The heavy cruiser USS  Indianapolis , arriving on 26 July. The target inserts followed by air on 30 July. Although all of its components had been individually tested, no full test of a gun-type nuclear weapon occurred before the Little Boy was dropped over Hiroshima . The only test explosion of a nuclear weapon concept had been of an implosion-type device employing plutonium as its fissile material, which took place on 16 July 1945 at

11340-503: The nuclear fission of uranium-235 , whereas Thin Man was based on fission of plutonium-239 . Fission was accomplished by shooting a hollow cylinder (the "bullet") onto a solid cylinder of the same material (the "target") by means of a charge of nitrocellulose propellant powder. Little Boy contained 64 kilograms (141 lb) of highly enriched uranium , although less than a kilogram underwent nuclear fission. Its components were fabricated at three different plants so that no one would have

11529-424: The stratosphere , where they dissipate and become part of the global environment. Because Little Boy was an air burst 580 meters (1,900 ft) above the ground, there was no bomb crater and no local radioactive fallout. However, a burst of intense neutron and gamma radiation came directly from the fission of the uranium. Its lethal radius was approximately 1.3 kilometers (0.8 mi), covering about half of

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11718-592: The "Fat Man." In September 1945, another Project Alberta physicist, Norman F. Ramsey , stated in his brief "History of Project A," that the early bomb ballistic test shapes designs were referred to as "Thin Man" and "Fat Man" by (unspecified) " Air Force representatives" for "security reasons," so that their communications over telephones sounded "as if they were modifying a plane to carry Roosevelt (the Thin Man) and Churchill (the Fat Man)," as opposed to modifying

11907-809: The 2010 Deepwater Horizon oil spill , which was the worst oil spill in US history. In December 2016, President Obama invoked the Outer Continental Shelf Lands Act to ban offshore oil and gas exploration in large parts of the Arctic and Atlantic Oceans. During Obama's tenure, the battle over the Keystone XL Pipeline became a major issue, with advocates arguing that it would contribute to economic growth and environmentalists arguing that its approval would contribute to global warming. The proposed 1,000-mile (1,600 km) pipeline would have connected Canada's oil sands with

12096-579: The 2011 withdrawal from Iraq, promoted discussions that led to the 2015 Paris Agreement on global climate change, drew down US troops in Afghanistan in 2016, initiated sanctions against Russia following its annexation of Crimea and again after interference in the 2016 US elections , brokered the Joint Comprehensive Plan of Action nuclear deal with Iran, and normalized US relations with Cuba . Obama nominated three justices to

12285-457: The 5 psi overpressure threshold. Ordinary urban buildings experiencing it were crushed, toppled, or gutted by the force of air pressure. The picture at right shows the effects of a nuclear bomb-generated 5 psi pressure wave on a test structure in Nevada in 1953. A major effect of this kind of structural damage was that it created fuel for fires that were started simultaneously throughout

12474-684: The Cabinet and to other positions. On April 28, 2009, the Senate confirmed former Kansas governor Kathleen Sebelius as Secretary of Health and Human Services, completing Obama's initial Cabinet. During Obama's presidency, four Republicans served in Obama's Cabinet: Ray LaHood as Secretary of Transportation, Robert McDonald as Secretary of Veterans Affairs, and Gates and Chuck Hagel as Secretaries of Defense. Security and international affairs Economic affairs †Appointed by President Bush ‡Originally appointed by President Bush, reappointed by President Obama There were three vacancies on

12663-550: The Democratic primary. Several other candidates, including Senator Joe Biden of Delaware and former senator John Edwards of North Carolina , also ran for the nomination, but these candidates dropped out after the initial primaries. In June, on the day of the final primaries, Obama clinched the nomination by winning a majority of the delegates, including both pledged delegates and superdelegates . Obama selected Biden as his running mate, and they were officially nominated as

12852-519: The Democratic ticket at the 2008 Democratic National Convention . With Republican president George W. Bush term-limited, the Republicans nominated Senator John McCain of Arizona for president and Governor Sarah Palin of Alaska for vice president. Obama won the presidential election with 365 of the total 538 electoral votes and 52.9% of the popular vote. In the concurrent congressional elections , Democrats added to their majorities in both

13041-616: The Director of the Manhattan Project, Major General Leslie R. Groves , ordered that some Little Boys be prepared as an interim measure until a solution could be found. No Little Boy assemblies were available, and no comprehensive set of diagrams of the Little Boy could be found, although there were drawings of the various components, and stocks of spare parts. At Sandia Base , three Army officers, Captains Albert Bethel, Richard Meyer, and Bobbie Griffin attempted to re-create

13230-561: The Federal Reserve did not raise interest rates during Obama's presidency until December 2015. There was a sustained increase of the US unemployment rate during the early months of the administration, as multi-year economic stimulus efforts continued. The unemployment rate reached a peak in October 2009 at 10.0%. However, the economy added non-farm jobs for a record 75 straight months between October 2010 and December 2016, and

13419-558: The House John Boehner attempted to negotiate a "grand bargain" to cut the deficit, reform entitlement programs , and re-write the tax code, but the negotiations eventually collapsed due to ideological differences between the Democratic and Republican leaders. Congress instead passed the Budget Control Act of 2011 , which raised the debt ceiling, provided for domestic and military spending cuts, and established

13608-581: The House passed the Affordable Health Care for America Act on a 220–215 vote, with only one Republican voting for the bill. In December 2009, the Senate passed its own health care reform bill, the Patient Protection and Affordable Care Act (PPACA or ACA), on a party-line, 60–39 vote. Both bills expanded Medicaid and provided health care subsidies; they also established an individual mandate , health insurance exchanges , and

13797-529: The House to pass the Senate's health care bill, the Patient Protection and Affordable Care Act. In March 2010, after Obama announced an executive order reinforcing the current law against spending federal funds for elective abortion services, the House passed the Patient Protection and Affordable Care Act. The bill, which had passed the Senate in December 2009, did not receive a single Republican vote in either house. On March 23, 2010, Obama signed

13986-632: The Japanese city of Hiroshima on 6 August 1945 during World War II , making it the first nuclear weapon used in warfare. The bomb was dropped from the Boeing B-29 Superfortress Enola Gay piloted by Colonel Paul W. Tibbets Jr. , commander of the 509th Composite Group , and Captain Robert A. Lewis . It exploded with an energy of approximately 15 kilotons of TNT (63  TJ ) and had an explosion radius of approximately 1.3 kilometers which caused widespread death across

14175-581: The Little Boy. They were supervised by Harlow W. Russ, an expert on Little Boy who served with Project Alberta on Tinian, and was now leader of the Z-11 Group of the Los Alamos Laboratory's Z Division at Sandia. Gradually, they managed to locate the correct drawings and parts, and figured out how they went together. Eventually, they built six Little Boy assemblies. Although the casings, barrels, and components were tested, no enriched uranium

14364-621: The Naval Ordnance Plants in Pocatello, Idaho , and Louisville, Kentucky . Enough fissionable material was available by 1948 to build ten projectiles and targets, although there were only enough initiators for six. However, no actual fissionable components were produced by the end of 1948, and only two outer casings were available. By the end of 1950, only five complete Little Boy assemblies had been built. All were retired by November 1950. The Smithsonian Institution displayed

14553-404: The Obama administration highlighted as a major problem. The federal minimum wage increased during Obama's presidency to $ 7.25 per hour; in his second term, Obama advocated for another increase to $ 12 per hour. GDP growth returned in the third quarter of 2009, expanding at a 1.6% pace, followed by a 5.0% increase in the fourth quarter. Growth continued in 2010, posting an increase of 3.7% in

14742-408: The Obama administration played only a small role in this development. The Obama administration promoted the growth of renewable energy , and solar power generation tripled during Obama's presidency. Obama also issued numerous energy efficiency standards, contributing to a flattening of growth of the total US energy demand. In May 2010, Obama extended a moratorium on offshore drilling permits after

14931-537: The PPACA into law. The New York Times described the PPACA as "the most expansive social legislation enacted in decades," while the Washington Post noted that it was the biggest expansion of health insurance coverage since the creation of Medicare and Medicaid in 1965. Both houses of Congress also passed a reconciliation measure to make significant changes and corrections to the PPACA; this second bill

15120-714: The RNEP program does proceed. On March 2, 2007, the NNSA announced that the Lawrence Livermore National Laboratory RRW design had been selected for the initial RRW production version. One of the selection reasons given was that the LLNL proposed design was more closely tied to historical underground tested warhead designs. It was described by Thomas P. D'Agostino, acting head of the National Nuclear Security Administration , as having been based on

15309-450: The RRW designs has been selected. Historically, the weapon's nuclear series identification is assigned at the entrance to phase 3, and if the design proceeds forwards to complete phase 2 and enter phase 3 this can be expected in 1–2 years. The design is intended for first production unit (FPU) delivery by the end of 2012. On March 2, 2007, the NNSA announced that the Lawrence Livermore National Laboratory RRW design had been selected for

15498-414: The RRW program is described as: And (pp 94) Funding is listed as $ 25 million for FY 2006, $ 28 million for FY 2007, and $ 89 million for FY 2008. As defined in an earlier UC report, nuclear weapons engineering phases are: The FY08 RRW budget therefore indicates that one of the RRW designs has been approved and is entering the design definition and cost study phase. The document does not state which of

15687-461: The RRW should be assigned a numerical weapon designation when the design selection is made. On December 1, 2006, the NNSA announced that it had decided to move forwards with the RRW program after analyzing the initial LLNL and LANL RRW proposals. At that time, NNSA's Nuclear Weapons Council had not selected which of the two designs to proceed forwards with. According to the FY 2008 NNSA budget (pp 88),

15876-578: The Reliable Replacement Warhead were being finalized by Lawrence Livermore National Laboratory and Los Alamos National Laboratory , and that a selection of one of those designs would be made by November 2006, to allow the RRW development program to be included in the Fiscal 2008 US government budget. The article confirmed prior descriptions of the RRW, describing the weapons in the following terms: Based on prior weapons programs,

16065-626: The Senate for longer than any other Supreme Court nomination in history, and the nomination expired with the end of the 114th Congress. President Donald Trump later nominated Neil Gorsuch to Scalia's former seat on the Supreme Court, and Gorsuch was confirmed by the Senate in April 2017. Obama's presidency saw the continuation of battles between both parties over the confirmation of judicial nominees. Democrats continually accused Republicans of stalling nominees throughout Obama's tenure. After several nomination battles, Senate Democrats in 2013 reformed

16254-647: The Supreme Court : Sonia Sotomayor and Elena Kagan were confirmed as justices, while Merrick Garland was denied hearings or a vote from the Republican-majority Senate . Economic policy actions Other domestic policy actions Foreign policy actions Supreme Court nominations Barack Obama announced his candidacy for the Democratic nomination in the 2008 presidential election on February 10, 2007. Obama faced senator and former first lady Hillary Clinton in

16443-578: The Supreme Court ruled that the Constitution guarantees same-sex couples the right to marry in the case of Obergefell v. Hodges . The Obama Administration filed an amicus brief in support of gay marriage and Obama personally congratulated the plaintiff. Obama also issued dozens of executive orders intended to help LGBT Americans, including a 2010 order that extended full benefits to same-sex partners of federal employees. A 2014 order prohibited discrimination against employees of federal contractors on

16632-510: The U.S. had historically become extremely compact, low weight, highly integrated, and low-margin designs which used exotic materials. In many cases the components were toxic and/or unstable. A number of older US designs used high explosive types which degraded over time, some of which became dangerously unstable in short lifetimes ( PBX 9404 and LX-09 ). Some of these explosives have cracked in warheads in storage, resulting in dangerous storage and disassembly conditions. Most experts believe that

16821-524: The US pledged to cut its emissions by 26–28 percent compared to its 2005 levels. The deal provided momentum for a potential multilateral global warming agreement among the world's largest carbon emitters. Many Republicans criticized Obama's climate goals as a potential drain on the economy. At the 2015 United Nations Climate Change Conference , nearly every country in the world agreed to a landmark climate deal in which each nation committed lowering their greenhouse gas emissions. The Paris Agreement created

17010-979: The White House, and rescinded the Mexico City Policy , which banned federal grants to international groups that provide abortion services or counseling. On January 29, Obama signed a bill for the first time in his presidency; the Lilly Ledbetter Fair Pay Act of 2009 revised the statute of limitations for filing pay discrimination lawsuits. On February 3, he signed the Children's Health Insurance Program Reauthorization Act (CHIP), expanding CHIP's health care coverage from 7 million children to 11 million children. On March 9, 2009, Obama lifted restrictions on federal funding of embryonic stem cell research . Obama stated that, like Bush, he would employ signing statements if he deems

17199-489: The atomic bomb would not be difficult to design and that the difficulty would lie only in the production of fuel. Calculations in mid-1942 by theoretical physicists working on the project reinforced the idea that an ordinary artillery gun barrel would be able to impart sufficient velocity to the fissile material projectile. Several different weapon designs, including autocatalytic assembly, a nascent version of implosion, and alternative gun designs (e.g., using high explosives as

17388-479: The basis of sexual orientation or gender identity. In 2015, Secretary of Defense Ash Carter ended the ban on women in combat roles, and in 2016, he ended the ban on transgender individuals openly serving in the military. On the international stage, Obama advocated for gay rights, particularly in Africa. The Great Recession of 2008–09 caused a sharp decline in tax revenues in all cities and states. The response

17577-482: The beginning of his presidency, Obama supported comprehensive immigration reform, including a pathway to citizenship for many immigrants illegally residing in the United States. However, Congress did not pass a comprehensive immigration bill during Obama's tenure, and Obama turned to executive actions. In the 2010 lame-duck session, Obama supported passage of the DREAM Act , which passed the House but failed to overcome

17766-685: The bill as well. The legislation would have required the US to cut greenhouse gas emissions by 17 percent by 2020 and by 83 percent by the middle of the 21st century. However, the bill was strongly opposed by Republicans and neither it nor a separate proposed bipartisan compromise ever came up for a vote in the Senate. In 2013, Obama announced that he would bypass Congress by ordering the EPA to implement new carbon emissions limits. The Clean Power Plan , unveiled in 2015, seeks to reduce US greenhouse gas emissions by 26 to 28 percent by 2025. Obama also imposed regulations on soot, sulfur, and mercury that encouraged

17955-474: The bipartisan Joint Select Committee on Deficit Reduction to propose further spending cuts. As the Joint Select Committee on Deficit Reduction failed to reach an agreement on further cuts, domestic and military spending cuts known as the "sequester" took effect starting in 2013. In October 2013, the government shut down for two weeks as Republicans and Democrats were unable to agree on

18144-436: The bomb bay along the narrow catwalk on the port side. Jeppson held a flashlight while Parsons disconnected the primer wires, removed the breech plug, inserted the powder bags, replaced the breech plug, and reconnected the wires. Before climbing to altitude on approach to the target, Jeppson switched the three safety plugs between the electrical connectors of the internal battery and the firing mechanism from green to red. The bomb

18333-560: The bomb was test dropped near Tinian. L-11 was the assembly used for the Hiroshima bomb, and was fully assembled with its nuclear fuel by 31 July. Parsons, the Enola Gay ' s weaponeer, was concerned about the possibility of an accidental detonation if the plane crashed on takeoff, so he decided not to load the four cordite powder bags into the gun breech until the aircraft was in flight. After takeoff, Parsons and his assistant, Second Lieutenant Morris R. Jeppson , made their way into

18522-417: The bomber used was the one subsequently known as Jabit . L-6 was used as a dress rehearsal on 29 July. The B-29 Next Objective , piloted by Major Charles W. Sweeney , flew to Iwo Jima , where emergency procedures for loading the bomb onto a standby aircraft were practiced. This rehearsal was repeated on 31 July, but this time L-6 was reloaded onto a different B-29, Enola Gay , piloted by Tibbets, and

18711-415: The caveat that "many persons near the center of explosion suffered fatal injuries from more than one of the bomb effects." Local fallout is dust and ash from a bomb crater, contaminated with radioactive fission products. It falls to earth downwind of the crater and can produce, with radiation alone, a lethal area much larger than that from blast and fire. With an air burst , the fission products rise into

18900-471: The city. The Hiroshima bombing was the second nuclear explosion in history, after the Trinity nuclear test . Little Boy was developed by Lieutenant Commander Francis Birch 's group at the Manhattan Project 's Los Alamos Laboratory during World War II, a reworking of their abandoned Thin Man nuclear bomb. Like Thin Man, it was a gun-type fission weapon . It derived its explosive power from

19089-527: The conditions for a large-scale explosion. As a consequence of the discovery of the Pu-240 contamination problem, in July 1944 almost all research at Los Alamos was redirected to the implosion-type plutonium weapon, and the laboratory was entirely reorganized around the implosion problem. Work on the gun-type weapon continued under Person's Ordnance (O) Division, for use exclusively with highly enriched uranium as

19278-510: The country's largest banks or reinstate the Glass-Steagall Act , while many conservatives criticized the bill as a government overreach that could make the country less competitive. Under the bill, the Federal Reserve and other regulatory agencies were required to propose and implement several new regulatory rules , and battles over these rules continued throughout Obama's presidency. Obama called for further Wall Street reform after

19467-496: The damage and the number of victims at Hiroshima were much higher, as Hiroshima was on flat terrain, while the hypocenter of Nagasaki lay in a small valley. According to figures published in 1945, 66,000 people were killed as a direct result of the Hiroshima blast, and 69,000 were injured to varying degrees. Later estimates put the deaths as high as 140,000 people. The United States Strategic Bombing Survey estimated that out of 24,158 Imperial Japanese Army soldiers in Hiroshima at

19656-530: The deal, the bill passed the Republican House in large part due to the fact that the failure to pass any bill would have resulted in the total expiration of the Bush tax cuts. US government debt grew substantially during the Great Recession , as government revenues fell. Obama largely rejected the austerity policies followed by many European countries. US government debt grew from 52% of GDP when Obama took office in 2009 to 74% in 2014, with most of

19845-675: The design, possibly including more fissile material in the pit and a thicker radiation case or hohlraum (see Teller-Ulam design: Basic principle ). In an April 15, 2006, article by Walter Pincus in the Washington Post, Linton F. Brooks, administrator of the US National Nuclear Safety Administration, the US nuclear weapon design agency within the United States Department of Energy , announced that two competing designs for

20034-425: The difference in uncertainty owing to having better data on the latter. To put these numerical differences into context, it is necessary to know that the acute effects of nuclear detonations, especially the blast and thermal effects, do not scale linearly, but generally as a cubic root . Specifically, the distance of these effects scale as a function of the yield raised to an exponential power of 1 ⁄ 3 . So

20223-453: The end of the year. The number of uninsured Americans dropped from 20.2% of the population in 2010 to 13.3% of the population in 2015, though Republicans continued to oppose Obamacare as an unwelcome expansion of government. Many liberals continued to push for a single-payer healthcare system or a public option, and Obama endorsed the latter proposal, as well as an expansion of health insurance tax credits, in 2016. Risky practices among

20412-460: The energy yield of the untested Little Boy design could be determined only at the moment of detonation, using instruments dropped by parachute from a plane flying in formation with the one that dropped the bomb. Radio-transmitted data from these instruments indicated a yield of about 15 kilotons. Comparing this yield to the observed damage produced a rule of thumb called the 5 pounds per square inch (34  kPa ) lethal area rule. Approximately all

20601-514: The final fate of the Bush tax cuts. Republicans sought to make all tax cuts permanent, while Obama sought to extend the tax cuts only for those making under $ 250,000. Obama and Congressional Republicans came to an agreement on the American Taxpayer Relief Act of 2012 , which made permanent the tax cuts for individuals making less than $ 400,000 a year (or less than $ 450,000 for couples). For earnings greater than that amount,

20790-504: The firestorm area. An estimated 30% of immediate fatalities were people who received lethal doses of this direct radiation, but died in the firestorm before their radiation injuries would have become apparent. Over 6,000 people survived the blast and fire, but died of radiation injuries. Among injured survivors, 30% had radiation injuries from which they recovered, but with a lifelong increase in cancer risk. To date, no radiation-related evidence of heritable diseases has been observed among

20979-730: The first actions of Obama's presidency focused on reversing measures taken by the Bush administration following the September 11 attacks . In his first week in office, Obama signed Executive Order 13492 suspending all ongoing proceedings of the Guantanamo military commissions and ordering the Guantanamo detention facility to be shut down within the year. Another order, Executive Order 13491 , banned torture and other coercive techniques, such as waterboarding . Obama also issued an executive order placing tighter restrictions on lobbying in

21168-502: The first atomic bombs got their names. Los Alamos Laboratory and Project Alberta physicist Robert Serber stated, many decades after the fact, that he had named the first two atomic bomb designs during World War II based on their shapes: Thin Man and Fat Man . The "Thin Man" was a long, thin device, and its name came from the Dashiell Hammett detective novel and series of movies about The Thin Man . The "Fat Man"

21357-459: The first fifty years after 1945, every published description and drawing of the Little Boy mechanism assumed that a small, solid projectile was fired into the center of a larger, stationary target. However, critical mass considerations dictated that in Little Boy the more extensive, hollow piece would be the projectile. Hollow cylinders have higher critical masses than solid pieces of fissile material, because any neutrons encountered by or generated by

21546-427: The first quarter, with lesser gains throughout the rest of the year. The country's real GDP grew by about 2% in 2011, 2012, 2013, and 2014, peaking at 2.9% in 2015. In the aftermath of the recession, median household income (adjusted for inflation) declined during Obama's first term, before recovering to a new record high in his final year. The poverty rate peaked at 15.1% in 2010 but declined to 12.7% in 2016, which

21735-410: The global cooperation in nonproliferation that is vital to diplomacy with emerging nuclear powers such as Iran and North Korea and to controlling clandestine trafficking in nuclear materials and equipment. Obama administration Barack Obama 's tenure as the 44th president of the United States began with his first inauguration on January 20, 2009, and ended on January 20, 2017. Obama,

21924-582: The government through 2014. In 2015, after John Boehner announced that he would resign as Speaker of the House, Congress passed a bill that set government spending targets and suspended the debt limit until after Obama left office. During his presidency, Obama, Congress, and the Supreme Court all contributed to a major expansion of LGBT rights. In 2009, Obama signed the Matthew Shepard and James Byrd Jr. Hate Crimes Prevention Act , which expanded hate crime laws to cover crimes committed because of

22113-470: The growth in debt coming between 2009 and 2012. In 2010, Obama ordered the creation of the National Commission on Fiscal Responsibility and Reform (also known as the "Simpson-Bowles Commission") in order to find ways to reduce the country's debt. The commission ultimately released a report that called for a mix of spending cuts and tax increases. Notable recommendations of the report include

22302-478: The hypocenter, left a permanent shadow , having absorbed the fireball heat that permanently bleached the surrounding stone. Simultaneous fires were started throughout the blast-damaged area by fireball heat and by overturned stoves and furnaces, electrical shorts, etc. Twenty minutes after the detonation, these fires had merged into a firestorm , pulling in surface air from all directions to feed an inferno which consumed everything flammable. The Hiroshima firestorm

22491-591: The inability of Democrats to win that support, foreshadowed the gridlock and partisanship that continued throughout Obama's presidency. The $ 787 billion bill combined tax breaks with spending on infrastructure projects, extension of welfare benefits, and education. Following his inauguration, Obama and the Senate worked to confirm his nominees to the United States Cabinet . Three Cabinet-level officers did not require confirmation: Vice President Joe Biden , whom Obama had chosen as his running mate at

22680-451: The income tax increased from 35% to 39.6%, which was the top rate before the passage of the Bush tax cuts. The deal also permanently indexed the alternative minimum tax for inflation, limited deductions for individuals making more than $ 250,000 ($ 300,000 for couples), permanently set the estate tax exemption at $ 5.12 million (indexed to inflation), and increased the top estate tax rate from 35% to 40%. Though many Republicans did not like

22869-507: The independent JASON group concluded in November 2006 that "most plutonium pits have a credible lifetime of at least 100 years". The oldest pits currently in the US arsenal are still less than 50 years old. The concept underlying the RRW program is that the US weapons laboratories can design new nuclear weapons that are highly reliable and easy and safe to manufacture, monitor, and test. If that proves to be possible, designers could adapt

23058-438: The initial RRW production version. The National Defense Authorization Act for Fiscal Year 2008 , H.R. 4986, Section 3111, forbids the expenditure of funds for the RRW program beyond Phase 2A; in effect, this prevents the RRW program from going forward without explicit Congressional authorization. Section 3121 Subsection 1 requires the study of the reuse of previously manufactured plutonium cores in any RRW warheads, so as to avoid

23247-404: The insensitive explosives ( PBX 9502 , LX-17 ) currently in use are highly stable and may even become more stable over time. The use of beryllium and highly toxic beryllium oxide material as neutron reflector layers was a major health hazard to bomb manufacturer and maintenance staff. The long term stability of plutonium metal, which may lose strength, crack, or otherwise degrade over time

23436-463: The issues. In 1982, Los Alamos created a replica Little Boy from the original drawings and specifications. This was then tested with enriched uranium but in a safe configuration that would not cause a nuclear explosion. A hydraulic lift was used to move the projectile, and experiments were run to assess neutron emission. After hostilities ended, a survey team from the Manhattan Project that included William Penney , Robert Serber, and George T. Reynolds

23625-405: The law, including a $ 116 billion income tax cut, temporarily reduced taxes for 98% of taxpayers, bringing tax rates to their lowest levels in 60 years. The Obama administration would later argue that the stimulus saved the United States from a "double-dip" recession. Obama asked for a second major stimulus package in December 2009, but no major second stimulus bill passed. Obama also launched

23814-400: The major financial institutions on Wall Street were widely seen as contributing to the subprime mortgage crisis , the financial crisis of 2007–08 , and the subsequent Great Recession , so Obama made Wall Street reform a priority in his first term. On July 21, 2010, Obama signed the Dodd–Frank Wall Street Reform and Consumer Protection Act , the largest financial regulatory overhaul since

24003-613: The manufacture of additional plutonium cores. Section 3124 reaffirms the commitment of the U.S. to the Treaty on the Non-Proliferation of Nuclear Weapons and encourages the mutual reduction in armament of the U.S. and Russia through negotiation. President Obama's 2009 Department of Energy budget calls for development work on the Reliable Replacement Warhead project to cease. Opponents of the RRW program believe it has nothing to do with making US weapons safer or more reliable, but

24192-412: The material are more likely to get scattered in the air than to continue a chain reaction. The larger piece would also avoid the effects of neutron reflection from the tungsten carbide tamper until it was fully joined with the rest of the fuel. Once joined and with its neutrons reflected, the assembled fissile core would comprise more than two critical masses of uranium-235. In 2004, John Coster-Mullen ,

24381-646: The move, as the plan raised national emission standards but provided the single national efficiency standard that auto industry officials group had long desired. In 2012, Obama set even higher standards, mandating an average fuel efficiency of 54.5 miles per US gallon (4.32 L/100 km). Obama also signed the "cash-for-clunkers" bill, which provided incentives to consumers to trade in older, less fuel-efficient cars for more efficient cars. The American Recovery and Reinvestment Act of 2009 provided $ 54 billion in funds to encourage domestic renewable energy production, make federal buildings more energy-efficient, improve

24570-659: The national debt limit , he signed the Budget Control Act of 2011 and the American Taxpayer Relief Act of 2012 . In foreign policy, he increased US troop levels in Afghanistan , reduced nuclear weapons with the United States–Russia New START treaty, and ended military involvement in the Iraq War . He gained widespread praise for ordering Operation Neptune Spear , the raid that killed Osama bin Laden , who

24759-481: The officers in Silverplate when they were adopting their own codenames for their own project (including "Silverplate"). As Silverplate involved modifying B-29s for a secret purpose, deliberately using codenames that would align with modifying vehicles for Roosevelt and Churchill would serve their needs well. Because of its perceived simplicity, the gun-type nuclear weapon design was the first approach pursued by

24948-479: The passage of Dodd-Frank, saying that banks should have a smaller role in the economy and less incentive to make risky trades. Obama also signed the Credit CARD Act of 2009 , which created new rules for credit card companies. During his presidency, Obama described global warming as the greatest long-term threat facing the world. Obama took several steps to combat global warming, but was unable to pass

25137-420: The people inside the area where the shock wave carried such an overpressure or greater would be killed. At Hiroshima, that area was 2.2 miles (3.5 km) in diameter. The damage came from three main effects: blast, fire, and radiation. The blast from a nuclear bomb is the result of X-ray -heated air (the fireball) sending a shock wave or pressure wave in all directions, initially at a velocity greater than

25326-469: The permanent extension of most of the Bush tax cuts , which had been enacted between 2001 and 2003. Those tax cuts were set to expire during Obama's presidency since they were originally passed using a Congressional maneuver known as reconciliation , and had to fulfill the long-term deficit requirements of the "Byrd rule". During the lame duck session of the 111th Congress , Obama and Republicans wrangled over

25515-514: The point directly under the explosion was completely destroyed, except for about 50 heavily reinforced, earthquake-resistant concrete buildings, only the shells of which remained standing. Most were completely gutted, with their windows, doors, sashes, and frames ripped out. The perimeter of severe blast damage approximately followed the 5 pounds per square inch (34 kPa) contour at 1.1 miles (1.8 km). Later test explosions of nuclear weapons with houses and other test structures nearby confirmed

25704-510: The practical differences in effects at these yield ranges are smaller than may at first appear, if one assumes that there is a linear relationship between yield and damage. Although Little Boy exploded with the energy equivalent of around 15 kilotons of TNT, in 1946 the Strategic Bombing Survey estimated that the same blast and fire effect could have been caused by 2.1 kilotons of conventional bombs distributed evenly over

25893-425: The presence of the isotope plutonium-240 (Pu-240) raised the rate of spontaneous fission of the plutonium to an unacceptable amount. Previous analyses of plutonium had been made from samples created by cyclotrons and did not have as much of the contaminating isotope. If reactor-bred plutonium was used in a gun-type design, they concluded, it would predetonate , causing the weapon to destroy itself before achieving

26082-750: The presidency at 12:00 pm, EST , and completed the oath of office at 12:05 pm, EST. He delivered his inaugural address immediately following his oath. Obama's transition team was highly complimentary of the Bush administration's outgoing transition team, particularly with regards to national security, and some elements of the Bush-Obama transition were later codified into law. [REDACTED] The full text of Barack Obama's First Inaugural Address at Wikisource. Within minutes of Obama's taking office, his chief of staff, Rahm Emanuel , issued an order suspending last-minute regulations and executive orders signed by his predecessor George W. Bush . Some of

26271-547: The primary as the "SKUA9" design which he said had been tested a number of times. The W89 warhead design was a 13.3-inch-diameter (340 mm) by 40.8-inch-long (1,040 mm) weapon, with a weight of 324 pounds (147 kg) and yield of 200 kilotonnes of TNT (840  TJ ). As noted above, major safety features inherent in the tested W89 design include: Modifications for the RRW design would probably have included replacing beryllium neutron reflector layers with another material, and increased performance margins throughout

26460-463: The projectile rings that were slid over a 1-inch rod. This rod then extended forward through the tungsten carbide plug, impact-absorbing anvil, and nose plug backstop, eventually protruding out of the front of the bomb casing. This entire target assembly was secured at both ends with locknuts. When the hollow-front projectile reached the target and slid over the target insert, the assembled super-critical mass of uranium would be completely surrounded by

26649-405: The projectile slug was pushed 42 inches (1,100 mm) along the 72-inch-long (1,800 mm), 6.5-inch-wide (170 mm) smooth-bore gun barrel. The slug "insert" was a 4-inch cylinder, 7 inches in length with a 1-inch (25 mm) axial hole. The slug comprised 40% of the total fissile mass (25.6 kilograms or 56 pounds). The insert was a stack of six washer-like uranium discs somewhat thicker than

26838-532: The proposals of advanced educational reformers. In the competition points were awarded for allowing charter schools to multiply, for compensating teachers on a merit basis including student test scores, and for adopting higher educational standards. There were incentives for states to establish college and career-ready standards, which in practice meant adopting the Common Core State Standards Initiative that had been developed on

27027-491: The range of the 5 pounds per square inch (34 kPa) overpressure damage expected from a detonated 12 kiloton weapon with a height of burst at 1,968 feet (600 m) would be expected to be 0.98 miles (1.58 km), whereas a 20 kiloton weapon would have the same range extend to 1.12 miles (1.80 km), a difference of only 0.14 miles (0.23 km). The areas affected for each would be 3.02 square miles (7.8 km ) and 3.91 square miles (10.1 km ), respectively. As such,

27216-427: The role of private banks in lending out federally insured student loans , created a new income-based loan repayment plan known as Pay as You Earn , and increased the amount of Pell Grant awards given each year. He also instituted new regulations on for-profit colleges , including a "gainful employment" rule that restricted federal funding from colleges that failed to adequately prepare graduates for careers. From

27405-410: The same target area: "220 B-29s carrying 1.2 kilotons of incendiary bombs , 400 tons of high-explosive bombs, and 500 tons of anti-personnel fragmentation bombs ." Since the target was spread across a two-dimensional plane, the vertical component of a single spherical nuclear explosion was largely wasted. A cluster bomb pattern of smaller explosions would have been a more energy-efficient match to

27594-554: The scientists working on bomb design during the Manhattan Project . In 1942, it was not yet known which of the two fissile materials pathways being simultaneously pursued— uranium-235 or plutonium-239 —would be successful, or if there were significant differences between the two fuels that would impact the design work. Coordination with British scientists in May 1942 convinced the American scientists, led by J. Robert Oppenheimer , that

27783-464: The severe destruction region. The first effect of the explosion was blinding light, accompanied by radiant heat from the fireball. The Hiroshima fireball was 1,200 feet (370 m) in diameter, with a surface temperature of 10,000 °F (6,000 °C), about the same temperature as at the surface of the sun. Near ground zero, everything flammable burst into flame. One famous, anonymous Hiroshima victim, sitting on stone steps 850 feet (260 m) from

27972-551: The similar but more comprehensive Equality Act . Neither bill passed Congress. In May 2012, Obama became the first sitting president to support same-sex marriage , shortly after Vice President Joe Biden had also expressed support for the institution. The following year, Obama appointed Todd M. Hughes to the Court of Appeals for the Federal Circuit , making Hughes the first openly gay federal judge in US history. In 2015,

28161-498: The specific and technically sophisticated applications they were created for. With the end of the Cold War, however, nuclear testing has ceased in the United States, and new warhead development has been significantly reduced. As a result, the need for high technical performance of warheads has decreased considerably, and the need for a longer-lasting and reliable stockpile has taken a high priority. Prior nuclear weapons produced by

28350-484: The speed of sound, analogous to thunder generated by lightning. Knowledge about urban blast destruction is based largely on studies of Little Boy at Hiroshima. Nagasaki buildings suffered similar damage at similar distances, but the Nagasaki bomb detonated 2.0 miles (3.2 km) from the city center over hilly terrain that was partially bare of buildings. In Hiroshima, almost everything within 1.0 mile (1.6 km) of

28539-520: The stimulus bill was enacted in February 2009, health care reform became Obama's top domestic priority, and the 111th Congress passed a major bill that eventually became widely known as " Obamacare ". Health care reform had long been a top priority of the Democratic Party, and Democrats were eager to implement a new plan that would lower costs and increase coverage. In contrast to Bill Clinton 's 1993 plan to reform health care, Obama adopted

28728-480: The subsequent Great Recession that had begun before his election, which was generally regarded as the worst economic downturn since the Great Depression . On February 17, 2009, Obama signed into law a $ 787 billion economic stimulus bill that included spending for health care, infrastructure, education, various tax breaks and incentives , and direct assistance to individuals. The tax provisions of

28917-400: The supercritical mass, which was fired onto the smaller group, with four polonium-beryllium neutron initiators to make the supercritical mass explode. A hole in the center of the larger piece dispersed the mass and increased the surface area, allowing more fission neutrons to escape, thus preventing a premature chain reaction. But, for this larger, hollow piece to have minimal contact with

29106-518: The survivors' children. After the surrender of Japan was finalized, Manhattan Project scientists began to immediately survey the city of Hiroshima to better understand the damage, and to communicate with Japanese physicians about radiation effects in particular. The collaboration became the Atomic Bomb Casualty Commission in 1946, a joint U.S.–Japanese project to track radiation injuries among survivors. In 1975 its work

29295-521: The target. When the war ended, it was not expected that the inefficient Little Boy design would ever again be required, and many plans and diagrams were destroyed. However, by mid-1946 the Hanford Site reactors were suffering badly from the Wigner effect . Faced with the prospect of no more plutonium for new cores and no more polonium for the initiators for the cores that had already been produced,

29484-399: The time of the bombing, 6,789 were killed or missing as a result of the bombing. The exact measurement of the explosive yield of the bomb was problematic since the weapon had never been tested. President Harry S. Truman officially announced that the yield was 20 kilotons of TNT (84 TJ). This was based on Parsons's visual assessment that the blast was greater than what he had seen at

29673-523: The transition in May 2008. John Podesta , Valerie Jarrett , and Pete Rouse co-chaired the Obama-Biden Transition Project. During the transition period, Obama announced nominations for his cabinet and administration . In November 2008, Congressman Rahm Emanuel accepted Obama's offer to serve as White House Chief of Staff . Obama was inaugurated on January 20, 2009, succeeding George W. Bush . Obama officially assumed

29862-413: The tungsten carbide tamper , it must be the projectile, since only the projectile's back end was in contact with the tamper prior to detonation. The rest of the tungsten carbide tamper surrounded the sub-critical mass target cylinder (called the "insert" by the designers) with air space between it and the insert. This arrangement packs the maximum amount of fissile material into a gun-assembly design. For

30051-516: The ultimate fate of the cuts. Obama wanted to extend the tax cuts for taxpayers making less than $ 250,000 a year, while Congressional Republicans wanted a total extension of the tax cuts, and refused to support any bill that did not extend tax cuts for top earners. Obama and the Republican Congressional leadership reached a deal that included a two-year extension of all the tax cuts, a 13-month extension of unemployment insurance ,

30240-480: The unemployment rate fell to 4.7% in December 2016. The recovery from the Great Recession was marked by a lower labor force participation rate, some economists attributing the lower participation rate partially to an aging population and people staying in school longer, as well as long-term structural demographic changes. The recovery also laid bare the growing income inequality in the United States , which

30429-523: The use of HFCs , organic compounds that contribute to global warming. From the beginning of his presidency, Obama took several actions to raise vehicle fuel efficiency in the United States. In 2009, Obama announced a plan to increase the Corporate Average Fuel Economy to 35 miles per US gallon (6.7 L/100 km)], a 40 percent increase from 2009 levels. Both environmentalists and auto industry officials largely welcomed

30618-592: The use of the filibuster so that it could no longer be used on executive or judicial nominations (excluding the Supreme Court). Republicans took over the Senate after the 2014 elections , giving them the power to block any judicial nominee, and the 114th Congress confirmed just 20 judicial nominees, the lowest number of confirmations since the 82nd Congress . Obama's judicial nominees were significantly more diverse than those of previous administrations, with more appointments going to women and minorities. Once

30807-515: The victim's sexual orientation. In December 2010, Obama signed the Don't Ask, Don't Tell Repeal Act of 2010 , which ended the military's policy of disallowing openly gay and lesbian people from openly serving in the United States Armed Forces . Obama also supported the passage of ENDA , which would ban discrimination against employees on the basis of gender or sexual identity for all companies with 15 or more employees, and

30996-405: The weapon to detonate. If immersed in water, the uranium components were subject to a neutron moderator effect, which would not cause an explosion but would release radioactive contamination . For this reason, pilots were advised to crash on land rather than at sea. Ultimately, Parsons opted to keep the explosives out of the Little Boy bomb until after the B-29 had taken off, to avoid the risk of

31185-415: The weapon to fit into a B-29 bomb bay without difficulty. Though not an optimal use of fissile material compared to the implosion design, it was seen as a nearly guaranteed weapon. The design specifications were completed in February 1945, and contracts were let to build the components. Three different plants were used so that no one would have a copy of the complete design. The gun and breech were made by

31374-515: The weapons will receive numbers in the US warhead designation sequence, which currently runs from the Mark 1 nuclear bomb (aka Little Boy ) to the W91 nuclear warhead, which was cancelled in the 1990s. RRW designs would presumably receive designations after that number, though new RNEP nuclear bunker buster weapons could conceivably be type-standardized and numbered prior to any RRW reaching that point, if

31563-490: The work to Naval Captain William Sterling Parsons , who, along with Ed McMillan , Charles Critchfield , and Joseph Hirschfelder would be responsible for rendering the theory into practice. Concern that impurities in reactor-bred plutonium would make predetonation more likely meant that much of the gun-design work was focused on the plutonium gun. To achieve high projectile velocities, the plutonium gun

31752-479: The yield at the time. More rigorous estimates of the bomb yield and conventional bomb equivalent were made when more data was acquired following the end of the war. A 1985 study estimated the bomb's yield was around 15 kilotons of TNT (63 TJ). After being selected in April 1945, Hiroshima was spared conventional bombing to serve as a pristine target, where the effects of a nuclear bomb on an undamaged city could be observed. While damage could be studied later,

31941-481: The yield was estimated in the 1960s at 16.6 ± 0.3 kilotons. A review conducted by a scientist at Los Alamos in 1985 concluded, on the basis of existing blast, thermal, and radiological data, and then-current models of weapons effects, that the best estimate of the yield was 15 kilotons of TNT (63 TJ) with an uncertainty of 20% (±3 kt). By comparison, the best value for the Nagasaki bomb was evaluated as 21 kilotons of TNT (88 TJ) with an uncertainty of 10% (±2 kt),

32130-665: Was legalized nationwide in 2015 after the Court ruled so in Obergefell . He advocated for gun control in response to the Sandy Hook Elementary School shooting , indicating support for a ban on assault weapons , and issued wide-ranging executive actions concerning global warming and immigration. In foreign policy, he ordered military interventions in Iraq and Syria in response to gains made by ISIL after

32319-555: Was sworn in for a second term on January 20, 2013. During this term, he condemned the 2013 Snowden leaks as unpatriotic, but called for more restrictions on the National Security Agency (NSA) to address privacy issues. Obama also promoted inclusion for LGBT Americans . His administration filed briefs that urged the Supreme Court to strike down same-sex marriage bans as unconstitutional ( United States v. Windsor and Obergefell v. Hodges ); same-sex marriage

32508-606: Was 17 feet (5.2 m) long with a narrow diameter (suggesting its codename as the Thin Man) which created considerable difficulty in its ballistics dropping from aircraft and fitting it into the bomb bay of a B-29. In early 1944, Emilio G. Segrè and his P-5 Group at Los Alamos received the first samples of plutonium produced from a nuclear reactor, the X-10 Graphite Reactor at Clinton Engineer Works in Oak Ridge, Tennessee . Analyzing it, they discovered that

32697-491: Was also reportedly designed using recycled pits from the earlier W68 nuclear weapon program, recoated in vanadium to provide the temperature resistance. The W89 warhead was test fired in the 1980s. It had entered Phase 2A technical definition and cost study in November, 1986, and Phase 3 development engineering and was assigned the numerical designation W89 in January 1988. The lead designer, Bruce Goodwin, referred to

32886-471: Was conducted with L-1 on 23 July 1945. It was dropped over the sea near Tinian in order to test the radar altimeter by the B-29 later known as Big Stink , piloted by Colonel Paul W. Tibbets , the commander of the 509th Composite Group . Two more drop tests over the sea were made on 24 and 25 July, using the L-2 and L-5 units in order to test all components. Tibbets was the pilot for both missions, but this time

33075-449: Was established by March 1943, with expertise provided by E.L. Rose , an experienced gun designer and engineer. Work was begun to study the properties of barrels, internal and external ballistics , and tampers of gun weapons. Oppenheimer led aspects of the effort, telling Rose that "at the present time [May 1945] our estimates are so ill founded that I think it better for me to take responsibility for putting them forward." He soon delegated

33264-713: Was opposed by the left wing of the Democratic Party, and by the right wing of the Republican Party, and criticized for centralizing too much power in Washington. Complaints also came from middle-class families, who were annoyed at the increasing emphasis on teaching to the test, rather than encouraging teachers to show creativity and stimulating students' imagination. Obama also advocated for universal pre-kindergarten programs, and two free years of community college for everyone. Through her Let's Move program and advocacy of healthier school lunches, First Lady Michelle Obama focused attention on childhood obesity , which

33453-516: Was responsible for the September 11 attacks . In 2011, Obama ordered the drone-strike killing in Yemen of al-Qaeda operative Anwar al-Awlaki , who was an American citizen. He ordered military involvement in Libya in order to implement UN Security Council Resolution 1973 , contributing to the overthrow of Muammar Gaddafi . After winning re-election by defeating Republican opponent Mitt Romney, Obama

33642-479: Was roughly 2.0 miles (3.2 km) in diameter, corresponding closely to the severe blast-damage zone. (See the USSBS map, right.) Blast-damaged buildings provided fuel for the fire. Structural lumber and furniture were splintered and scattered about. Debris-choked roads obstructed firefighters. Broken gas pipes fueled the fire, and broken water pipes rendered hydrants useless. At Nagasaki, the fires failed to merge into

33831-470: Was round and fat so it was named after Kasper Gutman, a rotund character in Hammett's 1930 novel The Maltese Falcon , played by Sydney Greenstreet in the 1941 film version . Little Boy was named by others as an allusion to Thin Man since it was based on its design. It was also sometimes referred to as the "Mark I" nuclear bomb design, with "Mark II" referring to the abandoned Thin Man, and "Mark III" to

34020-486: Was sent to Hiroshima to evaluate the effects of the blast. From evaluating the effects on objects and structures, Penney concluded that the yield was 12 ± 1 kilotons. Later calculations based on charring pointed to a yield of 13 to 14 kilotons. In 1953, Frederick Reines calculated the yield as 15 kilotons of TNT (63 TJ). Based on the Project Ichiban data, and the pressure-wave data from The Great Artiste ,

34209-443: Was signed into law on March 30, 2010. The Patient Protection and Affordable Care Act became widely known as the Affordable Care Act (ACA) or "Obamacare". The Affordable Care Act faced considerable challenges and opposition after its passage, and Republicans continually attempted to repeal the law. The law also survived two major challenges that went to the Supreme Court. In National Federation of Independent Business v. Sebelius ,

34398-408: Was still higher than the 12.5% pre-recession figure of 2007. The relatively small GDP growth rates in the United States and other developed countries following the Great Recession left economists and others wondering whether US growth rates would ever return to the levels seen in the second half of the twentieth century. Obama's presidency saw an extended battle over taxes that ultimately led to

34587-412: Was succeeded by Republican Donald Trump , who won the 2016 presidential election . Historians and political scientists rank him among the upper tier in historical rankings of American presidents . Obama's accomplishments during the first 100 days of his presidency included signing the Lilly Ledbetter Fair Pay Act of 2009 relaxing the statute of limitations for equal-pay lawsuits; signing into law

34776-514: Was superseded by the Radiation Effects Research Foundation . In 1962, scientists at Los Alamos created a mockup of Little Boy known as "Project Ichiban" in order to answer some of the unanswered questions about the exact radiation output of the bomb, which would be useful for setting benchmarks for interpreting the relationship between radiation exposure and later health outcomes. But it failed to clear up all

34965-558: Was supplied for the bombs. By early 1947, the problem caused by the Wigner effect was on its way to solution, and the three officers were reassigned. The Navy Bureau of Ordnance began in 1947 to produce 25 "revised" Little Boy mechanical assemblies for use by the nuclear-capable Lockheed P2V Neptune aircraft carrier aircraft (which could be launched from, but not land on, the Midway -class aircraft carriers ). Components were produced by

35154-455: Was then fully armed. Jeppson monitored the bomb's circuits. The bomb was dropped at approximately 08:15 (JST) on 6 August 1945. After falling for 44.4 seconds, the time and barometric triggers started the firing mechanism. The detonation happened at an altitude of 1,968 ± 50 feet (600 ± 15 m). It was less powerful than the Fat Man , which was dropped on Nagasaki , but

35343-675: Was three times higher in 2008 than it had been in 1974. In December 2015, Obama signed the Every Student Succeeds Act , a bipartisan bill that reauthorized federally mandated testing but shrank the federal government's role in education, especially with regard to troubled schools. The law also ended the use of waivers by the Education Secretary. In post-secondary education, Obama signed the Health Care and Education Reconciliation Act of 2010 , which ended

35532-439: Was to cut education budgets. Obama's $ 800 billion stimulus package included $ 100 billion for public schools, which every state used to protect its educational budget. However, in terms of sponsoring innovation, Obama and his Education Secretary Arne Duncan pursued K-12 education reform through the Race to the Top grant program. With over $ 15 billion of grants at stake, 34 states quickly revised their education laws according to

35721-413: Was unable to override it. In November 2015, Obama announced that he would not approve of the construction of the pipeline. On vetoing the bill, he stated that the pipeline played an "overinflated role" in US political discourse and would have had relatively little impact on job creation or climate change. Little Boy Little Boy is the name of the type of atomic bomb used in the bombing of

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