I was reading about the First Opium War recently...

I was reading about the First Opium War recently, and I have to ask: how did China and the rest of the world fall so far behind Europe? In 1800 China had a GDP six times that of Russia's and the world's largest population and area. But it literally didn't matter when their military was so out of date that 2/3 of men used polearms and bows, average redcoat could engage even the best Chinese troops from three times their effective range with four times their effective firepower, British artillery could destroy their Chinese counterparts with counter-battery fire well beyond their ability to engage, and a single ship of the line carried more (and better) guns than an entire Chinese junk fleet. What exactly happened that set the Asian militaries 200 years behind their European counterparts after thousands of years of being equal or superior? And why was Japan and no one else able to quickly overcome this difference?

Hong Xiuquan was right, the Manchus were a poison in China. They actively weakened their own nation to stay in control, and even then the Qing were under a constant state of rebellion

They weren't exposed to the technological revolution happening around the Mediterranean and Europe.

That doesn't explain the rest of the world though. I only used China as an example because they were by far the most populous country in the world and the most powerful non-European country.

Many rebellions took place in Qing. Taiping rebellion cost about ~20-30 million casualties. Dungan revolt cost about 20 million. Plus few famines and other minor revolts. Plus Opium epidemic that destabalized most of the officials.

Epiricalism, industrialization, and the Scientific method are all esoteric and complicated subjects developed by Western Powers. Now, how are you gonna access and transfer that knowledge when only 200 or so people even speak just one of the languages of these technologically superior foreigners. It wasn't so much what did the Asians do that set them back it's what they didn't do to catch up. The japs got so for ahead due to the meiji restoration, in which the emperor was part of a reform movement overthrew a conservative out of date shogunate. One of the specific goals of the meiji restoration was to modernize Japan to the level of the Europeans because they were forced to open their country to international trade due to a European show of might. This started around the late 1860's. China, on the other hand only began reform in 1901 under Emperess Cixi after Qing got BTFO by Japs with western technology. Before hand they thought they were hot shit and didn't need to reform. Eventually this was too late as Qing collapsed in 1912, and ushered in the republican era. One important thing to note was that in Japan, instability preceded reform, with the reformers winning out in unifying the country. In China, it was the opposite an old unresponsive government was relatively more stable before trying to implement reforms to catch up to western powers.

tl;dr western philosophy, technology, and intellectual practices take time to be understood by foreign countries, and Japanese got a head start

Mughals did the same to India, no other country in Asia had an even remote chance of catching them, the Americas were playing catch up without any sort of connection, and Africa is Africa.

Probaby gommunizm

There are a few key factors that play into what pushed Europe so far ahead, one thing to note is that for most of history, Europe wasn't ahead of places like China and Japan by much and this is why those two countries went mostly untouched until the 1800s when industrialization arose.

One huge factor was the "great game" that was played by the monarchs of Europe against each other, mostly for control of prestigious duchies and principalities in Germany or Italy. By fighting each other and manipulating other countries against each other Britain and France gained experience in dominating entire regions without having to fight the wars entirely yourself, this is actually still seen today in proxy wars like Syria.

Second was a common enemy and a need, the Ottoman Empire and Its vassals across Northern Africa blocked European trade through the silk road and Europe badly needed the spices from India. So after the Iberian nations beat back the Moroccans they pushed around Africa for a route to India (and then discovered America.) Those two nations built a new silk road out of a series of ports built in poor islands and regions and kept the local rulers loyal and fighting each other. Once Spain had done this, it was easy for the Dutch, French and British to take it from their over stretched empires. Once they did that, the test of the world was not in a position to industrialize, while the aforementioned European nations were in desperate need of a way to get ahead of one another, namely Britain and France. The wars of the 1700s against France lead to proto industrial societies growing in the populated Netherlands and France, all it took was the Brits sparking up oil in Scotland for the Agrarian and then Industrial Revolution to take. Meanwhile China was so big it didn't need to industrialize and Japan wasnt trading with anyone at that time. The rest of the world was dominated by Europeans who had been putting them against their neighbors for 300 years.

what about Ottomans?
Sure BTFO Anglos during Gallipoli