Until computers get a lot smarter in understanding research papers, you'll always have the problem of unknown unknowns. How do you discover things in other fields if you don't even know the terminology? For example a medical researcher reinvented (or at least claims to have reinvented) some calculus: https://academia.stackexchange.com/questions/9602/rediscover...
If you never heard of calculus, googling for solutions can be difficult.
I think that Paul Otlet may be your man for that sort of thing. He was obsessed with how to organize and catalog not only things, but knowledge and information.
Interesting guy, and ahead of his time. It's too bad that his work (along with the rest of the world) was mostly dropped on the floor in the chaos of WWI and II. There's a book about him called, "Cataloging the World: Paul Otlet and the Birth of the Information Age."
This is a paper from 1994, before the Internet etc we're popular.
But let's try:
1. Google to find what the relevant fields are - you get math. Search a forum about math -> discover math.stackexchange.com -> ask for help or even just terminology regarding "area under my graph/curve"? Once you get that , you could follow on it(say ask for a library of the most accurate integration method we know of today).
2. Google that, find relevant results and dig for terminology, and follow on it.
And sure , this isn't a bulletproof method, and you won't get 100% coverage. But it help find connections .
Its still people answering the stack overflow questions, and its still people writing the posts Google finds.
Not to mention knowing what to search for and how to find it is itself a very broad skill that requires ploymath type knowledge to really get the most out of it.
Same reason librarians seem to know a bit of everything.
If you never heard of calculus, googling for solutions can be difficult.