I learnt about the synthesis of nano-iron.
What's nano-iron good for? Cleaning Arsenic out of water, reducing it to a few parts per billion, 1 gram is good for 2000 litres (or so).
Why the nano? It's in nano-particle form. As in nano-technology. As in a science that has only really been known about for two decades.
Don't you need an expensive laboratory to do that sort of thing? No - it takes oleic acid (prepared from soap), petroleum fuel, and rust. A couple of magnets help for separating it out afterward, but...
This is why learning new things is essential. This is why an interest in science is worth the hassle. If we can find out about these sorts of things, we can move beyond mere survivalism, into something more....