I think an interesting one (that is still controversial) is that megakaryocytes(MKs) in the lung actually produce a significant amount of the platelets in your body. Rather than platelets all coming from bone marrow MKs. It is interesting because these two different platelet origins have different responses to infection.

Continental drift was a theory formed in 1912 by a German meteorologist, Alfred Wegener. Geologists balked at the idea of enormous landmasses moving and said the idea of an Urkonintent was ridiculous. And besides, he was a weatherman, German weatherman, so outside of his field and untrustworthy as a German was considered at the outbreak of WW1.

Then, 50 or so years later his theory was rediscovered when different fields were trying to understand polar magnetic drift evident in iron ore formation. The only explanation that made sense from the evidence is that mountains were not permanent and oceans didn't exist in some areas - a lot like the land masses moved.

Wegener was eventually vindicated in almost all areas except drift speed. There was an Urkonintent, which has been named Pangaea. The continents do move but because they sit upon plates. He had taught the world about the world but died before anyone thought he was right.

The Dead Internet conspiracy theory was written with total crackpot paranoid thinking about ruling elites, likely antisemitic undertones, and general tinfoil hat reasoning about AI. Plus generative language models were nowhere near advanced or skilled enough at the time the conspiracy was purported to be happening.

But it was accidentally prophetic in at least two ways by 2024:

1. Corporations have completely strangled online social spaces to the point that most people only visit about 1 to 3 of them, and
2. Online discourse in those social spaces has been absolutely captured and manipulated by multiple governments trying to manipulate other countries and stir them into pointless ragebait frenzies.

It wasn't due to the illuminati, the Jews, or anything weird and bigoted conspiracies of old have traditionally blamed. It was thanks to billionaires, corporate and government espionage, AI grifters, and unregulated scammer networks (digital currency counts too) jumping onto the same technology at the same time and ruining everything on the Internet in similar ways.

Many scientific hypotheses started out as what seemed like crazy ideas at the time. When Galileo and Newton challenged the ideas of Aristotle, this was seen as fringe and radical. When Einstein challenged the accepted Newtonian dogma it was seen as scientific heresy at first. These ideas only seem mainstream to us with hindsight.

Bacteria being the cause of ulcers.

https://en.wikipedia.org/wiki/Timeline_of_peptic_ulcer_disease_and_Helicobacter_pylori

A lot of science around trees and forest management has gone this way. Forest used to be seen as competitive areas that needed to be thoroughly managed to be healthy. Now we know that’s not true at all, and overall would be better off if we just let them be (in most, though not all cases). Same with the idea that trees communicate with each other and share resources. This was dismissed and ridiculed for a long time, but has now been pretty resoundingly proven true. Peter Wohlleben’s The Secret Life of Trees talks a lot about this.

Epigenetics vindicates a small portion of the theory behind Lamarckism, though there’s still a lot of research to be done to understand the actual mechanisms underlying it

I'll go with... Probably not a good idea to ingest radium.

You've led me to quite a Christian Scientist rabbit hole, but I cannot for the life of me find the requirement to start smoking. Rereading, is that maybe a typo that should've said they required people to stop smoking? I can't find that either, but it seems to make more sense to me.

Kind of a reverse Uno on your question, but I thought it was interesting while Nazism came to prominence, some scientists were like hey I'm just as racist and anti-semitic as you, but this race stuff you're doing isn't very scientific. They were dismissed as quacks. Later after doing horrible experiments, nazi scientists were frustrated that their findings weren't adding up to their ideology.

Quantum Mechanics: The early concepts of quantum mechanics, such as quantized energy levels and wave-particle duality, were initially met with resistance, even by scientists like Albert Einstein, who helped develop them.

Reason for Rejection: The ideas were counterintuitive and challenged classical physics' deterministic view, introducing probabilistic interpretations of nature.

Adoption: The overwhelming experimental evidence, such as the photoelectric effect, blackbody radiation, and the behavior of atoms and subatomic particles, eventually led to the acceptance of quantum mechanics as a fundamental framework in physics.

Off the top of my head - handwashing before surgery/delivering a baby reducing patient deaths (though you mention germ theory), plate tectonics, the evolution of species, heliocentricism.