Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

A requiem for amateur chemistry

lcamtuf.substack.com

Post reply on HN
Print view View original

151–156 of 156 posts

Re: A requiem for amateur chemistry

#151

Post by wrp »

watwut wrote: post #122
wrp wrote: post #106

Earlier quoted context omitted.

> ...it is not even the case that kids today were less educated either. This claim could be supported or contradicted by evidence. Do you have any? My experience is not K-12 education, but at the college level, standardized measures such as the GRE show declining levels of ability over the decades. A given score today doesn't mean the same as 40 years ago, because the test has needed to be recalibrated for a lower av…

High school drop out rates were 27.2% in 1960. This is one third of students not even finishing high school. Meanwhile college enrolment rates were miniscule compared to today. Yet also, getting into top university requires way more effort then it used to in 1950-1960. > standardized measures such as the GRE show declining levels of ability over the decades. A given score today doesn't mean the same as 40 years ago,…

I agree with your points about high school completion and college enrollment, however I think the reason for the increased difficulty of getting into a school is due to increased competition rather than an increase in absolute standards. A way to test this would be to look at the history of schools that use admissions tests. (I'm thinking of elaborate tests such as at Cal-Tech.)

> The data dont show consistend decline in years where it did not changes, but there are massive drops in scores when the test was recalibrated.

I'm a bit confused about what you are referring to, but I think that by "recalibrated" you are referring to 2011 when they introduced the revised scale. I think I can clear this up by explaining about standardized testing.

The purpose of the GRE, SAT, and some other tests created by the Educational Testing Service is not to measure absolute performance of individuals but relative performance of populations. The goal of test design is to adjust the difficulty of the test to provide maximal discrimination in the tails. So when the average performance of a population changes, they have to adjust the difficulty of the test to keep the results curve in a nice shape. This is what I meant by "recalibration". If they achieve their goals in this, average scores shouldn't change much over the years.

Re: A requiem for amateur chemistry

#152

Post by postultimate »

cft wrote: post #33
mncharity wrote: post #16

I wonder if some other country might be different? Brasil? IIRC, countries with major resource extraction industries, internationally outsourced for lack of domestic expertise, with associated lost value capture, are more highly incentivized to increase STEM graduates. Unlike the US, where the research I recall, said there's no shortage outside of programming (and PhD flexibility). And indeed without programming, the…

A country where you can order the chemicals for amateur chemistry by mail would be a developed AND a free country at the same time. I'm very interested in such an example

This one ?

https://archive.ph/0iu7V

Re: A requiem for amateur chemistry

#153

Post by wrewrtet »

akiselev wrote: post #75
WalterBright wrote: post #51

Earlier quoted context omitted.

Mechanical engineering (I'm an ME) turned out to be very very hard to do as a hobby. Even with a complete machine shop, it takes a loooong time to make something simple, such as a steam engine. My engine finally worked, but the hours expended on it were extensive. With software I can build amazing programs in short amounts of time.

Engines usually push (their contemporary) materials to their limits so it's not really a surprise that they're harder to make from scratch. The infrastructure to make ICEs is one of the largest in the world and they are only so cheap because of their scale and production steadily getting automated since the post war consumer boom. Making that automation, however, has been easier than ever! DIY CNC designs are a dime…

The typical "model engineering" steam engine doesn't push materials to the limits. Cylinders are typically cast iron or bored out of brass rod. Tolerances aren't too tight.

It is a slow process because metal is kind of recalcitrant, and making one-off parts is a lot more time consuming than manufacturing in series. To be a model engineer you have to love the process and love spending time alone in the workshop. Another tedious/fascinating aspect is the jigs and fixtures that are often necessary to make even one example of a particular part. Model engineers have to devise ways of performing machining operations (often conceptually very simple operations) and it really has to be something you love. If you see the manufacturing process purely as a barrier to realizing what you designed on paper, it can be a real drag.

So, rather than a high-tech thing, pushing limits, I think the task here (making a small steam engine) is an example of craftsmanship (with lathe, file etc.) and of doing something that is intellectually/conceptually/materially very simple and undemanding, but doing by hand using inherently slow traditional processes. It's an aesthetic choice (and CNC, aluminum extrusions etc. would be ruled out for aesthetic reasons).

Re: A requiem for amateur chemistry

#154

Post by Symbiote »

kragen wrote: post #147
refurb wrote: post #146

Earlier quoted context omitted.

https://www.americanelements.com/strontium-metal-7440-24-6

you said 'The other option is to just procure chemicals through other products. Naphtha is basically a mixture of hexanes. You can buy a lot of nitrate salts used for food or gardening. It’s not hard to procure metals.' but this americanelements link doesn't seem to be a case of 'procure chemicals through other products' but rather 'buy from a place that lists things by cas number and probably only sells to corporati…

Try eBay.

https://www.ebay.com/itm/125395009075 etc

Re: A requiem for amateur chemistry

#155

Post by kragen »

Symbiote wrote: post #154
kragen wrote: post #147

Earlier quoted context omitted.

you said 'The other option is to just procure chemicals through other products. Naphtha is basically a mixture of hexanes. You can buy a lot of nitrate salts used for food or gardening. It’s not hard to procure metals.' but this americanelements link doesn't seem to be a case of 'procure chemicals through other products' but rather 'buy from a place that lists things by cas number and probably only sells to corporati…

Try eBay. https://www.ebay.com/itm/125395009075 etc

that also doesn't look like 'procure chemicals through other products', that's a listing for 10 grams of, supposedly, pure strontium

Re: A requiem for amateur chemistry

#156

Post by agumonkey »

wrp wrote: post #65

Another aspect of this issue is the apparent difference in intellectual preparedness of kids today. I think this is partly due to educational environment and partly a result of selection bias (in that accounts of the past focus on the "smart" kids). When I was a teenager, rummaging around the attic at grandma's house I stumbled upon my dad's old scientific stuff. I was shocked at the sophistication of what a high sch…

I'm very sad (physically so) when I run into these things.

Another anecdata:

- found an old junior high school math book: they had lessons on finances, taxes, maybe compounding interests. All in simple terms, no mathematical proofs or analysis. Still very useful long term knowledge.

- someone on reddit posted pictures of his grand father's notebook. Biology lecture notes about plants. It was utterly beautiful, drawings and writing, superb regularity, density .. Saying it looked like a product wouldn't be exaggerating a lot.

And now your comment got me to think that this seem to be a worldwide trend, not even a nation-wide education system degradation. That's super odd.

Post reply on HN