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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)

#111

Post by salawat »

lordnacho wrote: post #108
grandchild wrote: post #107

Earlier quoted context omitted.

> according to the kid who told me Come on, you can do better than this and actually invest the minute to type this into your search engine of choice and verify: https://www.swissinfo.ch/eng/society/swiss-salaries-teachers... So according to this, Swiss teachers make between CHF 95,590 and CHF 110,590 annually. Cost of living is also higher in Switzerland, so it's a bit less than "120k" would suggest, but still a sol…

It's in the ballpark, and will certainly get to 120K once you have some seniority. The point was more that a person thinking about what to do could admit to saying he wanted to be a teacher in Switzerland, whereas in the US it seems like making Walter White a teacher was the perfect way to say he'd somehow failed.

Admittedly, if the choice is being a "successful" chemist, and bringing into existence VX gas, TNT, Phosgene, Thalidomide, Teflon, various industrial chemical wastes that tend to end up creating Superfund sites, and being a chemistry teacher... I may be getting pretty lame as I get older, but I think the Teacher strictly speaking has the quantifiably lesser destructive footprint of the two outcomes. Then again, the argument there is likely one against mixing business majors, industrial chemists, and more lawyers than you can shake a stick at. So... Yeah. Take it with a grain of salt and call me in the morning.

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

#113

Post by heikkilevanto »

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.

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

#114

Post by bollu »

pfdietz wrote: post #72
ThenAsNow wrote: post #62

Earlier quoted context omitted.

I can't make sense of your claim. Compression could be done adiabatically, or not, but that doesn't mean it's isothermal or somehow inherently adiabatic. In fact, for it to be isothermal would require the transport away of compression heat, which would be decidedly non-adiabatic. The parent is correct.

I didn't say the compression was isothermal. The parent is not correct. Compression occurs at a shock, but this is not heating due (solely) to adiabatic compression. This is clearly seen by considering the case where mach number goes to infinity: in that limit, the fraction of heating due to compression goes to zero (as the gas density remains below some finite limiting value.) What is causing heating is a dissipativ…

This is very interesting, is there a textbook for this?

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

#115

Post by gaustin »

yetihehe wrote: post #95
_fi0w wrote: post #88

Earlier quoted context omitted.

If only teachers were as intelligent and wise as HN’s anonymous commenters.

If only all people were as intelligent and wise as HN’s anonymous commenters (I wish I would too). When you think about this, it's almost like instagram but for knowledge.

I love this veiled (but true) insult. That is the core of my love-hate relationship with this site.

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

#116

Post by pfdietz »

ThenAsNow wrote: post #89
pfdietz wrote: post #82

Earlier quoted context omitted.

(you have to wait a short time before you can reply to a message; it's not a depth limit) Practitioners may say that, but it's sloppy and makes no sense when examined closely, as I've argued here. Compression (as the word is properly defined) is finite even as mach number and heating increase without limit.

The basis of the disagreement hinges on your original claim that "compression is a process that is adiabatic, generating no entropy" which doesn't have any valid basis. Nothing about even the definition of compression that you provided above implies that compression is or isn't by definition isentropic (also, adiabatic and isentropic are not the same thing). Are you trying to argue that flow passing through a shock i…

Of course it has a valid basis. The alternative is to say that in any process that reduces the volume of the material, all the heating is due to compression (even though the amount of heating can vary widely in different processes with the same reduction in volume.)

The logical error you are committing is saying "if a process includes compression, then the heating is due to compression".

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

#117

Post by nemo44x »

_fi0w wrote: post #92
nemo44x wrote: post #61

Earlier quoted context omitted.

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.

My parents, both with master’s degrees, worked at least eight hours every day teaching, grading assignments, and then preparing for the following day. I would guess about ten hours on average, seeing as I was mostly left alone as a child while my parents worked over the kitchen table. Yes, they don’t teach during the summer. Their pay reflects that. I won’t even touch on personal expenditures for supplies. Grifters?!…

> ...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 the top. I don’t think individual teachers are. However, their unions are pretty close.

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

#118

Post by nemo44x »

Digit-Al wrote: post #99
nemo44x wrote: post #78

Earlier quoted context omitted.

Did you go to public schools? I did. The student body is mainly uninterested, incapable, or irredeemable. Some great diamonds in the ruff to be sure. But certainly these people would excel regardless of a 1-off actual good teacher seeing as most of them are just mailing it in, like their student body. Why go to the trouble of getting a masters to waste it like this? FWIW I don’t believe teachers should need a bachelo…

It's "diamonds in the rough" not "ruff". Sorry to assume you spoke English as a first language ;-)

Touché.

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

#119

Post by nemo44x »

dragonwriter wrote: post #87
nemo44x wrote: post #85

Earlier quoted context omitted.

They get paid for that extra time if they choose to work it. Otherwise a teacher works 30 hours a week when normalized to a 48 hour work year. This is part-time work. But they get golden health care, pension, and early retirement. Good for them. This is why teachers aren’t suckers as the OP suggested. They’re in on a great scam. Good for them. The sucker working retail could only dream.

> Otherwise a teacher works 30 hours a week when normalized to a 48 hour work year. This is part-time work. No, it's full-time seasonal work. > The sucker working retail could only dream. Retail generally doesn't require a four-year degree, plus a post-graduate credential as a basic qualification. Compared to professions that do, schoolteachers pay and benefits are between unremarkable and substandard.

Let’s just forget about their sweet pensions and lifelong benefits package.

They have public sector unions that negotiate their compensation. I don’t think it’s teachers that are being bullied here.

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

#120

Post by lm28469 »

nemo44x wrote: post #59
flatline wrote: post #55

Earlier quoted context omitted.

I mean, the HS teacher that told me this had a masters in Mech E. Or so he claimed, hmm...

It’s amazing a man would work for a masters degree and end up teaching mainly below average people at a public institution. What’s a masters degree worth?

My (public) high school physics/chemistry teacher had two PHDs and is responsible for me getting interested in science in general.

He probably had more impact on the world than some CERN researchers spending their entire lives working on theoretical physics with 0 application in the real world whatsoever

Who should teach below average people ? Below average teachers with no education ?

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