I think that glass is under-appreciated. Without it we would not have telescopes and microscopes (and all the scientific (and later engineering) that came from them), and later movies and photography—the latter also led to photolithography.
Would also need laters: modern communications would be much different if we still had to use copper cable (esp. over long distances), or microwave relays.
* https://en.wikipedia.org/wiki/Glass
* https://en.wikipedia.org/wiki/Telescope
* https://en.wikipedia.org/wiki/Microscope
* https://en.wikipedia.org/wiki/Photolithography
Nevermind the day-to-day quality of life improvements of eye glasses. Also:
* https://en.wikipedia.org/wiki/Optical_fiber
Would also need laters: modern communications would be much different if we still had to use copper cable (esp. over long distances), or microwave relays.