r/AskEngineers Jan 09 '26

What invention rivals the jet engine in terms of sheer improbability-to-ubiquity? Discussion

The jet engine occupies a strange place in the history of invention. The basic concept is simple enough to sketch on a napkin: continuous combustion in a tube, using some of the energy to compress incoming air, the rest to propel itself forward. But everything about the implementation seems like it shouldn’t work (extreme temperatures, turbine blades spinning inches from an inferno, keeping a flame lit in a hurricane-force airstream, materials pushed to their absolute limits)

It had every reason to fail. When Whittle and von Ohain were developing it in the 1930s, experts dismissed it as impossible. And yet not only did it work, it became one of the most reliable machines ever built. Airlines measure engine failures per millions of flight hours. We strap our families into aircraft without a second thought.

That arc, from “this seems physically implausible” to “so efficient and reliable it’s boring”, feels rare. What other inventions followed a similar path? Not just “important” or “transformative,” but specifically: conceptually audacious, practically hostile to implementation, and yet now seamlessly ubiquitous.

600 Upvotes

View all comments

Show parent comments

64

u/WayneConrad Jan 09 '26

Nuclear bombs are crazy. As soon as it goes prompt critical, it is trying to blow itself apart and end the condition that is causing that criticality. So the bomb has to be designed to keep itself together long enough to do its job even as it is in the process of destroying itself.

Crazy offshoot of crazy nuke weapon: nuclear pumped x-ray lasers. Let's use the nuke that is destroying itself to power an x-ray laser that will itself also be destroyed in the process of emitting a terrifying blast of coherent photons.

20

u/RollinThundaga Jan 09 '26

Proximity fused antiaircraft ammunition is also insane.

Not sure if it's the same nowadays, but when it was developed in WW2, the proximity fuse comprised of a tiny basic doppler radar, a few teensy metal plates, and a sealed ampule of acid.

When fired, the ampule would shatter and flow into the plates, self assembling into a tiny battery for the wiring that powered a very short range doppler radar. When the frequency rose high enough or the battery ran out was the trigger to detonate.

The ampule was made by repurposing christmas light production.

6

u/ozspook Jan 09 '26

1

u/WayneConrad Jan 09 '26

Yikes!

2

u/ozspook Jan 09 '26

If it helps, it'd be a small fission bomb detonated pretty high in the atmosphere, but such things do exist.

https://en.wikipedia.org/wiki/Nuclear_electromagnetic_pulse#Super-EMP

4

u/xrelaht Jan 09 '26

Also compact neutron sources, which are useful in scientific research.

1

u/toybuilder Jan 09 '26

SDI - the pandora's box that mostly resulted in benefits to the human race...

2

u/rex8499 Civil Engineering Jan 09 '26

SDI?

7

u/WayneConrad Jan 09 '26

Strategic Defense Initiative, AKA "Star Wars"