to be replaced by similar weapons with names that better reflected the destructive capabilities of the device. These names ranged from the generic "pulse rifle" to series-specific weapons, such as the phasers from Star Trek. In the Warhammer 40,000 franchise, a human faction known as the Imperial Guard has a "lasgun", which is described as being a handheld laser weapon, as their main weapon, and larger cannon versions being mounted onto tanks and being carried around by Space Marines. The elf-like Aeldari, meanwhile, have a special unit called the Swooping Hawks equipped with a "lasblaster". In the Command & Conquer video game series, various factions make extensive use of laser and particle-beam technology. The most notable are Allied units Prism Tank from Red Alert 2 and Athena Cannon from Red Alert 3, the Nod's Avatar and Obelisk of Light from Tiberium Wars, as well as various units from Generals constructed by USA faction, including their "superweapon" particle cannon. Plasma weaponry Weapons using plasma (high-energy ionized gas) have been featured in a number of fictional universes. Weapons of mass destruction Nuclear weapons are a staple element in science-fiction novels. The phrase "atomic bomb" predates their existence, and dates back to H. G. Wells' The World Set Free (1914), when scientists had discovered that radioactive decay implied potentially limitless energy locked inside of atomic particles (Wells' atomic bombs were only as powerful as conventional explosives, but would continue exploding for days on end). Cleve Cartmill predicted a chain reaction-type nuclear bomb in his 1944 science-fiction story "Deadline", which led to the FBI investigating him, due to concern over a potential breach of security on the Manhattan Project. The use of radiological, biological, and chemical weapons is another common theme in science fiction. In the aftermath of World War I, the use of chemical weapons, particularly poison gas, was a major worry, and was often employed in the science fiction of this period, for example Neil Bell's The Gas War of 1940 (1931). Robert A. Heinlein's 1940 story "Solution Unsatisfactory" posits radioactive dust as a weapon that the US develops in a crash program to end World War II; the dust's existence forces drastic changes in the postwar world. In The Dalek Invasion of Earth, set in the 22nd century, Daleks are claimed to have invaded Earth after it was bombarded with meteorites and a plague wiped out entire continents. A subgenre of