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Glass viscosity calculations debunk the myth of flow in medieval windows (2017)

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Re: Glass viscosity calculations debunk the myth of flow in medieval windows (2017)

#131

Post by brixon »

ivalm wrote: post #63
smnrchrds wrote: post #58

Earlier quoted context omitted.

He must not have been the top of his class if he had ended up a HS teacher. Which is actually kinda sad. Pay and working conditions for teachers shouldn't be so that being a teacher is regarded as a failure.

You are the one regarding them as failures. I had a variety of teachers in school, some were very educated (PhDs), and simply found a calling in teaching. Not everything is about money, you shouldn’t look down on teachers.

Probably related to the old joke: Those who cannot do, teach and those that cannot teach, manage.

Re: Glass viscosity calculations debunk the myth of flow in medieval windows (2017)

#132

Post by elliekelly »

torben-friis wrote: post #3
nikisweeting wrote: post #2

Finally! I always knew my 7th grade science teacher was full of shit on that one, she was so adamant about some things that turned out to be wrong. This one was maybe more excusable because it was common to teach at the time. Maybe it ended up making us better students in the end because we learned to fact-check our teachers, and not to be adamant about things we only think are true (though I'm still guilty of that m…

What other unsubstantiated claims did she make?

"You won't always have a calculator in your pocket." - Every math teacher before 2005

Re: Glass viscosity calculations debunk the myth of flow in medieval windows (2017)

#133

Post by dunce2020 »

bloak wrote: post #104
parsecs wrote: post #19

Earlier quoted context omitted.

Or how reentry heating is apparently caused mostly by friction. (Compression of air is the main cause in actuality)

Technically it's not "friction" because "friction" has to be between two solids. But arguably that's just being pedantic. The air gets in the way of the object moving through it and slows it down, but energy is conserved, as always, so the energy ends up as heat. Knowing that the correct term is "air resistance" rather than "friction" doesn't seem to provide any insight into what's happening, so I don't understand th…

> so I don't understand the obsession with correcting people online who call it "friction".

It lets dumb people feel intelligent. The type of person that confuses trivia for insight.

Re: Glass viscosity calculations debunk the myth of flow in medieval windows (2017)

#134

Post by Pulcinella »

yters wrote: post #124

Well, glass is still a liquid, which was the most counter intuitive claim to me, whether or not the flow is humanly perceptible. In fact it is even more counter intuitive now, since glass is an even more solid liquid.

It makes more sense (to me at least) to think of glass as an amorphous solid and expand the concept of “states of matter.” It doesn’t have a repeating crystalline structure.

I think expand the concept of states of matter is key. It really helps make sense of a lot more things when you move beyond just solid, liquid, and gas (and plasma). A good example are liquid crystals, in LCDs yes but also cell membranes. What state of matter is the cell membrane? It makes more sense to create a new phase to categorize it. The lipid molecules are arranged in a certain orientation to each other (crystalline) but are also free to shuffle past each other (liquid). This is not just academic. Your body uses cholesterol to modify the fluidity vs. crystalinity of your cell membranes so they don’t “freeze) (stiffen too much) in the winter or melt in the summer.

Re: Glass viscosity calculations debunk the myth of flow in medieval windows (2017)

#135

Post by Traster »

heikkilevanto wrote: post #113

Yeah, I learned this "fact" in school as well. Later I found a simple refutation: If a church window pane would deform by a measurable amount in 1000 years (say 0.5mm), then a 100-year old telescope or camera lens would be totally useless, and yet they seem to function all right.

I mean... the obvious answer to that is that we don't use the same techniques to manufacture a telescope or camera lens that we used to manufacture church windows. In fact we don't use glass for large telescopes specifically because they'll deform under their own weight.

I'm not saying that original fact is correct, I'm just saying I don't think what you're saying disproves the idea that that glass could deform over time.

Re: Glass viscosity calculations debunk the myth of flow in medieval windows (2017)

#137

Post by rcxdude »

nemo44x wrote: post #61
smnrchrds wrote: post #58

Earlier quoted context omitted.

He must not have been the top of his class if he had ended up a HS teacher. Which is actually kinda sad. Pay and working conditions for teachers shouldn't be so that being a teacher is regarded as a failure.

Is it regarded as a failure? Teachers in public schools work part time for 25 years and get a scaling pension they “negotiated” with the politicians their union dues elected. I’d call them fantastic winners. Grifters? Sure. But certainly not losers.

"part-time" is not something I would ever describe teaching as. All the teachers I've seen take huge amounts of work home with them, even on vacation. There may be a slight lull in the summer but it's filled with training, learning changes in the curriculum, etc. It's not uncommon for teachers to pay for classroom materials out of pocket because the schools are unable or unwilling to pay for them (this would be utterly ridiculous in many other industries). Teaching is something you go into because you enjoy it or it satisfies you on some level and you can put up with ridiculous workloads, not because it pays well.

Re: Glass viscosity calculations debunk the myth of flow in medieval windows (2017)

#138

Post by rcxdude »

GuB-42 wrote: post #52
lozaning wrote: post #22

Earlier quoted context omitted.

For anyone thats interested in what the parent is talking about: http://www3.eng.cam.ac.uk/outreach/Project-resources/Wind-tu... I've had people get like legit upset at me when i correct this.

That's the now famous Bernouilli vs Newton debate. Personally, I am in camp Newton. Not that Bernouilli doesn't work, they both give the same results in the end, and they are both a simplification of the "truth" which is the Navier-Stokes equations. The reason I like the Newton explanation better is that if you start with the Bernouilli principle, it is much easier to come up with the wrong idea. The Newton is straig…

It's reasonable to phrase the working of a wing either in terms of momentum or in terms of a different in pressure between the top and bottom. What's incorrect is when trying to explain the action through bernouilli it's often asserted that the air above the wing must take the same time to transit the wing as the air on the bottom. Not only is this completely unjustified to assume when trying to solve the problem, it's also false in practice: in general air above and below will not pass the wing in the same time, even though the air over the top is travelling faster.

Re: Glass viscosity calculations debunk the myth of flow in medieval windows (2017)

#139

Post by nemo44x »

michaelt wrote: post #122
nemo44x wrote: post #117

Earlier quoted context omitted.

> ...shape society’s future while fighting its current failures. All while being inexplicably hated and ridiculed by students, parents, and I guess HN. I’m not sure how to interpret this. Are you saying they indoctrinate kids? Do they exist to teach kids __how__ to think or __what__ to think? Which current failures are they fighting? As to my previous comment about “grifters”, I’ll admit that was too cynical and over…

> Which current failures are they fighting? Depending on the teacher and school, everything from kids coming to school hungry or without supplies to obesity to discipline problems to cheating to bullying/cyberbullying to child abuse to uninvolved parents to mental health problems to anxiety to drugs to deficiencies in the curriculum to achievement gaps between genders, classes and races to lack of good role models to…

So it's the system that is failing, not the teachers...

Public schools are a part of the system and the system has only continued to grow larger and larger over the last 75+ years. So what is the solution, to make the system even larger? More of the same failed therapeutic?

More and more "solutions" have been added to an outdated school system and has continued to show worse and worse results. This is quantitatively proven. Yet, we continue to tinker and politicize public schooling. To your point, we've decided to inject more and more social issues into schools, expanding scope of all things except effective learning.

And the teachers unions are a huge part of this. They support unaccountable teachers, pay for time and not for merit, and combined with the progressive wing of the country they are allied with countless special interests which are all too eager to continue to have their interests blended into the curriculum. Because no time to make a customer for life then when they're young.

So yes, the system is failing and the solution has continued to be "Add more system". We spend more and more every year and get worse and worse results. We should dissolve the public school system (government should not be in this business at all) and grant each student a sum of money that parents can use to place kids in private schools of their choice that suit their child's abilities and the parents aspirations.

This is a good breakdown on how some teachers are in fact a big part of the problem with educating kids:

https://fee.org/articles/the-failure-of-american-public-educ...

Re: Glass viscosity calculations debunk the myth of flow in medieval windows (2017)

#140

Post by ivalm »

lordnacho wrote: post #103
ivalm wrote: post #63

Earlier quoted context omitted.

You are the one regarding them as failures. I had a variety of teachers in school, some were very educated (PhDs), and simply found a calling in teaching. Not everything is about money, you shouldn’t look down on teachers.

I think the public perception of teachers varies a lot between societies. In breaking bad it was clear that Americans don't think much of a guy who ends up teaching chemistry. If you go to other countries it's very different, eg in Switzerland it seemed totally legit to aspire to teaching. Salary was 120k according to the kid who told me.

My high school was in the US. I think good teachers anywhere are teachers because it is their calling. Breaking Bad is hardly the normative reference of how people should view teachers.
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