If you ask me? Mobile/WiFi internet… The way and amount of time we use our phones had changed A LOT since their diffusion. I guess the release of the iPhone changed our idea of what a phone is too
Edit: when I say modern world I’m referring to the last 50 years. So stuff like “the electricity” or “the telephone” doesn’t count.
Something worth repeating is that transistors are a direct application of quantum mechanics. Quantum physics isn’t a metaphysical thing about half dead cats and working only on a few ultra cold atoms. If you want to explain how a piece of silicium can be conductive or insulating depending on it’s polarisation you need… Quantum physics.
its* polarization (or polarisation, in your part of the world.)
Holes and dots.