Principle of physics according to which the energy of interacting bodies or particles in a closed system remains constant, though it may take different forms (e.g., kinetic energy, potential energy, thermal energy, energy in an electric current, or energy stored in an electric field, in a magnetic field, or in chemical bonds [see bonding]). With the advent of relativity physics in 1905, mass was recognized as equivalent to energy. When accounting for a system of high-speed particles whose mass increases as a consequence of their speed, the laws of conservation of energy and conservation of mass become one conservation law. Seealso Hermann von Helmholtz.
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In physics, the principle that certain quantities within an isolated system do not change over time. When a substance in an isolated system changes phase, the total amount of mass does not change. When energy is changed from one form to another in an isolated system, there is no change in the total amount of energy. When a transfer of momentum occurs in an isolated system, the total amount of momentum is conserved. The same is true for electric charge in a system: charge lost by one particle is gained by another. Conservation laws make it possible to predict the macroscopic behaviour of a system without having to consider the microscopic details of a physical process or chemical reaction.
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Planned management of a natural resource or of a particular ecosystem to prevent exploitation, pollution, destruction, or neglect and to ensure the future usability of the resource. Living resources are renewable, minerals and fossil fuels are nonrenewable. In the West, conservation efforts date to 17th-century efforts to protect European forests in the face of increasing demands for fuel and building materials. National parks, first established in the 19th century, were dedicated to the preservation of uncultivated land not only to provide a safe haven to wildlife but to protect watershed areas and help ensure a clean water supply. National legislation and international treaties and regulations aim to strike a balance between the need for development and the need to conserve the environment for the future.
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Maintenance and preservation of works of art, their protection from future damage, deterioration, or neglect, and the repair or renovation of works that have deteriorated or been damaged. Research in art history has relied heavily on 20th- and 21st-century technical and scientific advances in art restoration. Modern conservation practice adheres to the principle of reversibility, which dictates that treatments should not cause permanent alteration to the object.
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(1933–42) U.S. unemployment program. One of the earliest New Deal programs, it was established to relieve unemployment during the Great Depression by providing national conservation work primarily for young unmarried men. Recruits lived in semimilitary work camps and received $30 a month as well as food and medical care. Projects included planting trees, building flood barriers, fighting forest fires, and maintaining forest roads and trails. It employed a total of 3 million men during its existence.
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The NRDC lobbies Congress and other public officials for a public policy that promotes conservation of the natural and built environment. The NRDC works against urban sprawl, pollution, and habitat destruction, and promotes actions to mitigate global warming and increase the use of renewable energy. It also sometimes files suit in federal court against corporations and government agencies for violations of the Clean Air Act, and the Clean Water Act. Other operations carried out by the NRDC include public education and sponsorship of scientific studies.
In 2001, NRDC launched the BioGems Initiative to mobilize concerned individuals in defense of exceptional and imperiled ecosystems. The initiative matches NRDC's legal and institutional expertise with the work of citizen activists.
It has issued a report on the health effects arising from the September 11, 2001 attacks.
In December 2006, Green Day and NRDC jointly launched a website to raise awareness on the U.S.'s petroleum dependence.. The NRDC takes the position that new nuclear power plants are not a solution for America's energy needs, or for addressing global warming.
NRDC runs a number of programs pushing for environmental stewardship:
The NRDC has been involved in some of the most important Supreme Court cases interpreting United States administrative law. Ironically, most of these decisions came out against the NRDC. See, for example: