Thermonuclear weaponMulti-stage fusion-fission nuclear weaponDiagram of the US W88 warhead, a standard thermonuclear design.
Nuclear weapons of the United StatesThe United States holds the second-largest arsenal of nuclear weapons (after the Russian Federation) among the nine nuclear-armed countries. Under the Manhattan Project, the United States became the first country to manufacture nuclear weapons and remains the only country to have used them in combat, with the bombings of Hiroshima and Nagasaki in World War II against Japan. In total it has conducted 1,054 known nuclear explosive tests, the most of any country.
Nuclear explosionA nuclear explosion is an explosion that occurs as a result of the rapid release of energy from a high-speed nuclear reaction. The driving reaction may be nuclear fission or nuclear fusion or a multi-stage cascading combination of the two, though to date all fusion-based weapons have used a fission device to initiate fusion, and a pure fusion weapon remains a hypothetical device. Nuclear explosions are used in nuclear weapons and nuclear testing.
List of states with nuclear weaponsMap of states with nuclear weapons by status in the Non-Proliferation Treaty (NPT) in 2025: Party to NPT and declared possession of nuclear weapons (China, France, Russia, United Kingdom, United States) Non-party to NPT and declared possession of nuclear weapons (India, North Korea, Pakistan) Non-party to NPT and non-declared possession of nuclear weapons (Israel) No state-developed nuclear weapons, but hosting nuclear weapons of Russia (Belarus) or of the United States (Belgium, Germany, Italy, Netherlands, Turkey) Former possession of nuclear weapons (Kazakhstan, South Africa, Ukraine)There are currently nine sovereign states that are generally understood to possess nuclear weapons, though only eight formally acknowledge possessing them.
Nuclear fissionReaction that splits an atomic nucleusInduced fission reaction. A neutron is absorbed by a uranium-235 nucleus, turning it briefly into an excited uranium-236 nucleus, with the excitation energy provided by the kinetic energy of the neutron plus the forces that bind the neutron.
Nuclear fusionReaction that combines atomic nucleiFusion plasma in China's Experimental Advanced Superconducting Tokamak.Nuclear fusion is a reaction in which two or more atomic nuclei combine to form a larger nucleus. The difference in mass between the reactants and products is manifested as either the release or the absorption of energy. This difference in mass arises as a result of the difference in nuclear binding energy between the atomic nuclei before and after the fusion reaction.
Nuclear reactionIn this symbolic representing of a nuclear reaction, lithium-6 (3Li) and deuterium (1H) react to form the highly excited intermediate nucleus 4Be which then decays immediately into two alpha particles of helium-4 (2He).Nuclear warfareMilitary conflict that deploys nuclear weaponryThe mushroom cloud over Hiroshima following the detonation of the Little Boy nuclear bomb on 6 August 1945. The atomic bombings of Hiroshima and Nagasaki remain the first and only wartime uses of nuclear weapons in history.Nuclear warfare, also known as atomic warfare, is a military conflict or prepared political strategy that deploys nuclear weaponry.
EnergyPhysical quantityEnergy (from Ancient Greek ἐνέργεια (enérgeia) 'activity') is the quantitativeproperty that is transferred to a body or to a physical system, recognizable in the capacity to do work and in the form of heat and light. Energy is a conserved quantity—the law of conservation of energy states that energy can be converted in form, but not created or destroyed. The unit of measurement for energy in the International System of Units (SI) is the joule (J).
Global catastrophic riskHypothetical global-scale disaster riskArtist's impression of a major asteroid impact. An asteroid caused the extinction of the non-avian dinosaurs.A global catastrophic risk or a doomsday scenario is a hypothetical event that could damage human well-being on a global scale, endangering or even destroying modern civilization.
MatterSomething that has mass and volumeHydrogen in its plasma state is the most abundant ordinary matter in the universe.In physical science, matter is anything that has mass and occupies space by having volume. All everyday objects that can be touched are ultimately composed of atoms, which are made up of interacting subatomic particles.
Explosive deviceAn explosive device typically refers to a bomb that is not used by a military. It contains an explosive with a detonator connected to a triggering mechanism to form a device used for a specific purpose.*As an Amazon Associate I earn from qualifying purchases.