Raygun Gothic: The other major influence on the Empire’s aesthetics (albeit adapted to much newer technologies and materials than would be usual), along with Crystal Spires and Togas and – to a lesser extent – Everything Is An iPod In The Future. This one is notably major because for a variety of reasons – some of which involve obvious worldbuilding features and others of which would, if described, sound like a The Reason You Suck speech – its host culture never lost the optimism and essential idea that there’s a big bright beautiful Tomorrow just around the corner, courtesy of Science! (Capital and exclamation point definitely included.) Particularly since they actually did keep arriving.
(This is also why the second movement of their national anthem is just like Make Way For Tomorrow, Today, sung without a single trace of irony.)