There have been instances of technological stagnation in history, generally for reasons of conservatism and isolation. Most notable among them is the matter of late Imperial China, which progressed little from the 15th to the 19th century technologically and actively shunned foreign ideas and methods as barbaric. Natually, those civilizations that did stagnate were superseeded by those that did not.
Stagnation in Star Wars
Technology in the Star Wars galaxy seems to have progressed little over the course of millenia. Technology seen in the early days of the Galactic Republic differs little, if any, from technology available during the time of the Galactic Empire and later. Given the scope of the Star Wars society and the number of corporations competing in various fields, it is likely that there are few additional scientific discoveries and technological breakthroughs for them to make. Even innovations like the Death Star are actually just unprecedented up-scalings of established technologies.
Stagnation in Star Trek
While the changes in the technology used by the Federation over the course of a few centuries suggest relatively rapid technological progress in the Star Trek universe, Star Trek: Enterprise reveals that all of the advanced technologies used by the Federation in the 24th century were actually well-established technologies for other Star Trek civilizations by the 22nd century. For the Federation, developing new technology is largely a matter of acquiring it from neighbors who already have it.
Stagnation in Warhammer 40,000
Technological development is in a state of stagnation throughout most of the galaxy in Warhammer 40,000. The reasons vary from one faction to another:
- Humanity underwent a drastic technological backslide when warp storms isolated most human colonies from each other. In the Imperium that arose later, technology is regarded with superstitious awe by most and understood by a pitiful handful. Most research efforts are aimed at recovering lost technologies.
- Eldar numbers were drastically reduced in the Fall of their civilization, and much of their old technology base became unreachable in the Eye of Terror.
- Ork technological ability derives from information genetically stored in their gene pool, resulting in little or no actual research and development. Ork Mekboyz often invent new and exotic implementations of technology, but nearly all of these are one shot devices that never become common Orkish tools, and they never expand the Orkish technology base.
- The Tyranids have no technology base, relying upon recombination of DNA inherent to their family tree or acquired from life forms they have consumed in order to produce new Tyranid forms for various tasks.
- The Tau are actually progressing, but they are a relatively new power in the galaxy and have not caught up to other civilizations in all technological fields.