Science fictional space warfare is main theme and central sub-genre of science fiction that can trace its roots back to classical times, and to the "future war" novels of the 19th century. With the Modern Age, directly with franchises as Star Wars and Star Trek, it is considered one of the most popular general sub-genres and themes of science fiction. An interplanetary, or more often an interstellar or intergalactic war, has become a staple plot device. Space warfare, represented in science fiction, has a predominant role, it is a central theme and at the same time it is considered parent, overlapping genre of space opera, military science fiction and Space Western.
Usually, lasers are used rather than bullets. Willy Ley claimed in 1939 that bullets would be a more effective weapon in a real space battle.
List of fictional doomsday devices
Destruction of planets and stars has been a frequently used aspect of interstellar warfare since the Lensman series. It has been calculated that a force on the order of 1032 joules of energy, or roughly the total output of the sun in a week, would be required to overcome the gravity that holds together an Earth-sized planet. The destruction of Alderaan in Star Wars: Episode IV – A New Hope is estimated to require 1.0 × 1038 joules of energy, millions of times more than would be necessary to break the planet apart at a slower rate.
Fictional space warfare tends to borrow elements from naval warfare, often calling space forces as space navies or simply navies. David Weber's Honorverse series of novels portrays several of such space navies such as the Royal Manticoran Navy, which imitate themes from Napoleonic-era naval warfare.
The Federation Starfleet (Star Trek), Imperial Navy (Star Wars), Systems Alliance Navy (Mass Effect), UNSC ("Halo") and Earthforce (Babylon 5) also use a naval-style rank-structure and hierarchy. The former is based on the United States Navy and the Royal Navy. The United Nations Space Command in Halo fully echoes all ranks of the United States Armed Forces, even the pay-grade system.