system
Given the following post, respond as if you're commenting on Reddit:
human
[Avatar: The Last Airbender/Legend of Korra] How did technology advance so quickly?

When Aang was alive, the Four Nations were roughly at a Medieval level of technology with swords, horse drawn carriages, archers, plate armor, some primitive gliders. The Fire Nation was by far the most technologically advanced, but they at most had early industrial era inventions.

Then less than 100 years later in Korra's day we have high rise architecture, radio, black and white movies, commercial automobiles.

How did everything advance so fast?
gpt
In the last century we went from inventing flight to launching someone into space in 58 years.  

Look at the technology in Korra.  It basically approximated the 1930s.  Look 70 years before that.  The 1860s.  Civil War era technology.  Not too dissimilar.  Yeah, they lacked guns, but they had bending.  Necessity is the mother of invention, and they didn't need them.  

It would make sense that technology would develop faster.  For the first time, the 3 nations were working together.  A Fire Nation development could be improved on by an Earth Kingdom engineer.