@grey @Titanbreakerkun @dickflatteningenthusiast My background is in physics, so what I'm saying here might not be universal, but I think it could be... anyway most of the text books you use, even up to graduate school, were written sometime in the 60's or earlier, and have very minor edition changes. Classical Electrodynamics, the standard text on E&M topics, was written in 62, and has only three editions, the last in 99. Maybe we'll get to a point where even these texts are impossible to find, but I doubt it. I think it would take something really big to erase everything we've learned. Now if we are still smart enough to understand it in the future is a more realistic question. Knowing how a specifically radio telescope built in the 60's works if you have no instructions or people with experience? Even more likely.