>>64012106Probably never left the drawing board.
We 'have the technology' to make Project Orion or Brilliant Pebbles in the sense that guys like the OP worked out all the principles and a basic design and agreed it was pretty epic.
We 'have the technology' to yeet spacecraft into a nearly orbital trajectory out of a giant centrifuge in the sense that investors have been tricked into funding a prototype demonstrator and don't even know what a real payload would look like.
We have railguns in the sense that we keep developing nearly working railguns, never completely solve the barrel wear problems or find a brilliant enough use case for them, and then defund them.
New tech takes massive investment and a lot of time, and if you spend enough time and money you can probably make any sci-fi idea into something functional, but will it solve your problems cheaper and better than what anyone invented by 1980 that's spent the last 45 years since 1980 being incrementally improved, probably not.