Hard science fiction

Hard science fiction is a subset of science fiction which, while set in the future, obeys the laws and principles of science, or at the very least does not routinely and blatantly violate them. For various thematic purposes (such as being able to cross even short interstellar distances in a timespan shorter than decades via FTL drives) most science fiction is not completly "hard", although certain pieces of science fiction are harder than others in making less errors, such as having spacecraft move and manuever using Newtonian physics instead of behaving as they would inside an atmosphere.