[dylan604]

Which is interesting in how I grew up "knowing" the asteroid/meteor killed the dinosaurs, but TFA suggests it was just a theory at the time of my learning. Or how I grew up with images of the planets, not knowing that they were only taken when I was a small kid. It is just a weird thing to think about how some knowledge we accept as known might not have been known by our grandparents or even our parents. It just seems like we would have known things for a lot longer.

[tshaddox]

My memory is the opposite: I recall learning that an asteroid impact was the most likely explanation, and the K-T boundary was the biggest piece of evidence, and the only problem was that they hadn’t discovered a candidate impact crater. And it wasn’t until the first decade of the 2000s that consensus started to emerge that the big crater in the Yucatán is the likely cause.

[zdragnar]

The pictures of the planets bit makes sense, as even with a telescope (through which we've seen the plants for a very long time) there's not really enough light for early film techniques to capture well.

I do identify a bit with the dinosaur example, and to use another: plate tectonics wasn't a formalized and accepted theory until late in the 1960's. It spread to schools quickly, but by that point my parents had already graduated, and it was new for my parents when my older brother went to school.

[WorldMaker]

I had a teacher get in trouble for discussing plate tectonics in the 1990s, in a public school. Turns out it still upsets a lot of religious groups and also was tied to some peculiar schools of climate change denialists in the 90s. I still don't entirely know how denying plate tectonics was useful for climate change denial that decade, I just remember how weird it was for the teacher to suggest to forget a whole science lecture because people didn't want us to know it. Come to think of it, that probably also was around the time we watched Jurassic Park in class.

[dylan604]

Did the Streisand Effect kick in making you (and/or other students) unable to forget it? "Whoa, teacher says to forget it, so I'm really going to remember it now!"

Come to think of it, if a teacher said to remember something because it will be on a test versus forget something because religious types are upset, I know I'd remember the thing I was just told to forget knowing it now would not be on a test. Then again, as a teen, I was really starting to question the religious part of my upbringing in light of science.

[WorldMaker]

That effect certainly kicked in for me. Led me down several science rabbit holes at a precocious age that I don't think I would have if it was test required.

[Apocryphon]

That is wild, did they believe in this

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

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

[WorldMaker]

On the religious side, I know several megachurches in my city got directly infected by Ken Ham [1] himself. (A person to which I have negative respect, including his massive wastes of state tax incentives that affect my own tax dollars.) One of his schticks was the the "Earth is only 6000 years old because the bible says so". I spent a lot of time in High School (private, years after the public school incident above) rolling my eyes through arguments using another of his schticks used to "combat" things like tectonic theory, the simplistic argument fallacy "Were you there?" I still have so much hate for that anti-science tactic.

[1] https://en.wikipedia.org/wiki/Ken_Ham

[dylan604]

> "Were you there?"

Was he there when the Red Sea parted, or is he only using one source for evidence? Noah's Ark? Sodom and Gomorrah and Lot's salt pillar wife? No, then it's not proven. Even back then, that was my equally lame retort, but it tended to make someone take a pause when they (if) they realized the limb they were standing one wasn't very strong

[WorldMaker]

The programmed response back was "No, but God was there and he wrote the bible through his prophets." If I tried to get into the arguments that the bible was fallible they'd weasel out of it. Biblical literalism is the hill they all want to die on, for better and much worse for society.

[dylan604]

plate tectonics is a good one. I definitely remember my mom telling me as a kid how South America and Africa look like they fit together, and my dad talking about Pangea being the name when the pieces were fit together. it wasn't until much later that I realized that my parents were not taught this in school, but my dad just kept up with current events much more. It is weird to think that something is so new that even your parents were not taught it.

[tzs]

Is the coastlines of South America and Africa looking like they fit together actually because of plate tectonics, or is it just a coincidence?

The shape we see for the coastlines of South America and Africa is affected by sea level. Depending on when you happened to look over the last say 140 million years sea level would have varied from around 135 meters below current sea level to around 75 meters above current sea level. That is a range of 210 meters.

Surely over that range both costs would change quite a bit, and I can't think of any mechanism that would make those changes complimentary in a way to keep the two coasts looking like they fit together.

[dylan604]

are you playing devil's advocate? perhaps you're just not familiar with Pangea? here's a video to show plate movement:

https://www.youtube.com/watch?v=OGdPqpzYD4o

[tzs]

I'm familiar with that. We see that shortly after a split the edges of the two sides of the split match, as we would expect. As they separate water fills the gap so those matching edges and now also matching coastlines.

Those two edges will continue to match as they get farther and farther apart. The coastlines will always match if the coastline stays at the elevation of the edge.

But as sea level changes the elevation of the coastline should change. For example, suppose sea level rose 300 meters. I don't think there is enough water available for that currently. 200 meters looks like it might be the maximum. But suppose that when Earth was receiving a lot of water from comet bombardment long ago that had been a bit heavier and so we did have enough for 300 meters.

Looking at topographic maps of the east side of South America and the west side of Africa it looks like 300 meters of sea level rise would reshape those coasts in vastly different ways and they would no longer be anywhere the edges of the split and would not match each other.

I couldn't find a good topographic map of the ocean floor to see how much of a sea level drop would be needed to make the coasts no longer match.

What I'm wondering then is if there is something that makes it so the topography of each continent and the limits of possible sea level variation make it so the coastlines long after a split when the two parts are far apart will still be close enough to where the original edges are that the coastlines will keep matching? Or is it just an accident that it has worked out that way on Earth?

[dylan604]

I really do not know what you are getting with all of those words. Put simply, if the continents were puzzle pieces, would you not attempt to put South America and Africa together? QED

[bruce511]

Obviously it will vary by location and age. But I was in high school in the early 80s, and plate tectonics & Pangea were already in our text books. (And in my country it takes forever for stuff to make it into textbooks.)

I don't recall there being any controversy about it - it was used as the basis for a number of topics in geography (Indian Subcontinent forming Himalayas, bio-diversity and gene relations in Biology etc.)

I suspect the real lesson here us that education is far from consistent both regionally, nationally and historically.

[blibble]

it's still "just" a theory, in the same way gravitation is "just" a theory

and always will be until it's dis-proven, or someone invents a time machine and we can go and see it for ourselves

[dylan604]

until it's dis-proven, or until it is proven.

we have plenty of evidence of the movement of plates. we know where subduction zones are. what does it take to prove a theory if not repeatable tests/observations?

[blibble]

the large body of corroborating evidence (and ability to be dis-proven) is what makes it a theory

but we can't "prove" plate tectonics, because we can't directly observe what's going on the earth's crust over a period of millions of years

in scientific nomenclature, a theory is a very robust thing indeed

vs. the vernacular, where it isn't, e.g. "I have a theory that my cat vomits behind the couch after I give him ice-cream"

[mr_toad]

> we can't directly observe what's going on the earth's crust over a period of millions of years

Depends what you mean by “observe”. The parallel lines of reversing magnetic polarity that are embedded in the sea floor on either side of the great rifts are observations that demand explanation.

[blibble]

well that's easy to explain

the devil went over the seabed with a big magnet, to trick you

just like he concocted the entire fossil record, planet-wide rock strata, carbon 14...

(sarcasm, for the USians)