The literary genre of science fiction is diverse, and its exact definition remains a contested question among both scholars and devotees. This lack of consensus is reflected in debates about the genre's history, particularly over determining its exact origins. There are two broad camps of thought, one that identifies the genre's roots in early fantastical works such as the Sumerian Epic of Gilgamesh (earliest Sumerian text versions c. 2150-2000 BCE). A second approach argues that science fiction only became possible sometime between the 17th and early 19th centuries, following the Scientific Revolution and major discoveries in astronomy, physics, and mathematics.
Question of deeper origins aside, science fiction developed and boomed in the 20th century, as the deep integration of science and inventions into daily life encouraged a greater interest in literature that explores the relationship between technology, society, and the individual. In recent decades, the genre has diversified and become firmly established as a major influence on global culture and thought.
Ancient Indian poetry such as the Hindu epic Ramayana (5th to 4th century BCE) includes Vimana flying machines able to travel into space, under water, and destroy entire cities using advanced weapons. In the first book of the Rigveda collection of Sanskrit hymns (1700–1100 BCE), there is a description of "mechanical birds" that are seen "jumping into space speedily with a craft using fire and water...containing twelve stamghas (pillars), one wheel, three machines, 300 pivots, and 60 instruments." The ancient Hindu mythological epic, the Mahabharatha (8th and 9th centuries BCE) includes the story of King Revaita, who travels to heaven to meet the creator Brahma and is shocked to learn that many ages have passed when he returns to Earth, anticipating the concept of time travel.