SDI programs from the era that did not produce anything include the nuclear pumped X-Ray laser, which never worked at all. The shocking amount spent on that bullshit would have been enough to fund a huge amount of useful work in science, defense, or whatever.

The thing that's frustrating about that (aside from the fact that people are ignorant of such things, but still feel qualified to comment on the topic) is that plenty of people knew it was bullshit three decades ago. The sheer hypocrisy of the politics of SDI is almost unique in human history, considering how much money was wasted by people who claimed to be concerned about excessive government spending.

The "nuclear pumped X-ray laser" may or may not have been feasible - tests were inconclusive. That type of research is similar to the Google "moonshot" projects, many of which have been busts, eh?

Regardless, other SDI technologies such as Brilliant Pebbles and Brilliant Eyes are direct predecessors to current, successful, military technologies. There have also been many spinoffs benefiting civilians.

> The "nuclear pumped X-ray laser" may or may not have been feasible - tests were inconclusive. That type of research is similar to the Google "moonshot" projects, many of which have been busts, eh?

In the analogy Larry Page or Sergey Brin of Google would be Edward Teller, capable of forcing pursuit of an absurd project well past the point where it's obviously ridiculous to continue, simply because he can fire anyone he wants. But those guys aren't blatantly ideological, demented old men, and I'm not aware of Google ever burning money in a manner quite as cosmically absurd as Project Excalibur. The business wouldn't survive much of that.