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Graphene, a hexagonal one atom thick graphite crystal film, was theorised for decades but never characterised.
Fusion!
The combine is among the greatest feats of automation in history, with one of the biggest effects on society. It freed entire towns & villages from the backbreaking toil of harvest and, with other innovations, took America from 90% of it's population in agriculture to 2% today. 
We'll start small: Subtraction.
I'll do a proper deep-dive thread soon, but this is a taster:
There are a dizzying array of fighter aircraft in the skies now, but the more astute of you will have noticed recurring themes, and even entire countries with coherent design philosophies.
Aluminium is by far the most common metal in the Earth's crust, at over 8% by mass. Yet it's only been industrially exploited in it's pure form for a century and a half, and for a while it was a precious metal.
Consider a simple question: Where does all the sound go?
Heat Exchangers (HX) are absolutely crucial to our hot-blooded world: On them we rely to generate our power, regulate our engines, cool our houses & thinking machines, create the chemistries for entire food chains.
The sharpest object in the universe…
Most reactors in operation today are light water reactors, and there are good reasons for that: Water is both moderator & coolant, they have safe negative reactivity coefficients and decently high power density.
What we're building right now are Generation III pressurised water or boiling water reactors. They're sturdy and mature, if a tad expensive.
Be warned: By the end of this thread you will need to stand in judgement of a man and decide for yourself whether he was a saint or a monster.
Something new…
Earlier this year, the SwRI in San Antonio generated electricity from a closed cycle supercritical CO2 powerplant. Why is this important?
We're not talking about photovoltaics, the creation of current in semiconductor layers. No, concentrated solar is more dramatic, and has unique abilities.
On the 26th September, 2022, NASA gave it a try: The 500kg DART spacecraft did a 6.6km/s head on collision with the asteroid Dimorphos, a 170m long, 5 million-ton loosely aggregated asteroid, orbiting a much larger twin.
Here are the motorway maps of several European countries. What do you notice in each?
First, the cheap seats for comparison:
The RBMK-1000 is a huge cylindrical channel reactor, with an 11.8m diameter, 7m high core. 1,700 tons of graphite is arranged in packed blocks with channels for fuel & control rods. There are 1,661 fuel channels, 211 control channels, and 192 tons of Uranium fuel.
It wasn't always so. The venerable 707, doyenne of the 60s jet set, was more than twice as wasteful: Its fuel consumption per hour was 50% greater than a modern 787-8, even though the 787 is 50% heavier, flies 50% further and carries a hundred more passengers. 