Einstein laid the theoretical foundations for lasers in 1917, and it took over 40 years of "impractical" scientific work before the first functioning laser was built. It took decades more for them to become a cheap, ubiquitous technological building-block. The research is still continuing, and there's no reason to assume it will stop eventually bearing fruit (for the societies that haven't decimated their scientific workforce, anyways). Look at the insanity required to design and build the EUV lasers in ASML's machines, which were used to fabricate the CPU I'm using right now, over a century after Einstein first scribbled down those obscure equations!