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Electron band structure in germanium, my ass (2001)

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Re: Electron band structure in germanium, my ass (2001)

#161

Post by don-code »

Natsu wrote: post #141
don-code wrote: post #87

Earlier quoted context omitted.

This is, more or less, exactly what happened when I took Electronics I in college. The course was structured in such a way that you could not move on to the next lab assignment until you completed the one before it. You could complete the lab assignments at your own pace. If you failed the lab, you failed the class, regardless of your grade. The second or third lab had us characterize the response of a transistor in…

It's funny, because while that's a terrible educational experience, you actually learned some important lessons despite them. I remember the first time I found out that the software documentation I had been relying upon was simply and utterly wrong. It was so freeing to start looking at how things actually behaved instead of believing the utterly false documentation because the world finally made sense again.

Sometimes it's not even rare that documentation is wrong. The documentation for a vendor who I won't name - but might be at Series J and worth north or $50 billion - seems to be wrong more often than it's right.

We frequently say, don't blame the tools, it's you. That pushes "blame the tools" outside of the Overton window, and when we need to blame a tool, we're looked at like we have five heads.

Ten years ago, I was dealing with a bizarre problem in RHEL where we'd stand up an EC2 instance with 4GB of memory, have 4.4GB of memory reported to the system, and be able to use 3.6GB of it. I spent _a long_ time trying to figure out what was going on. (This was around the time we started using Node.js at that company, and needed 4GB of RAM just for Jenkins to run Webpack, and we couldn't justify the expensive of 8GB nodes.)

I did a deep dive into how the BIOS advertises memory to the system, how Linux maps it, and so forth, before finally filing a bug with Red Hat. 36 hours later, they identified a commit in the upstream kernel, which they forgot to cherry-pick into the RHEL kernel.

That's a very human mistake, and not one I dreamed the humans at Red Hat - the ones far smarter than me, making far more money than me - could ever make! Yet here we were, and I'd wasted a bunch of time convinced that a support ticket was not the right way to go.

Re: Electron band structure in germanium, my ass (2001)

#162

Post by MarkusQ »

morgoths_bane wrote: post #132
MarkusQ wrote: post #98

Earlier quoted context omitted.

So wait, so you've decided a film by the director of An Inconvenient Truth, that was praised by everybody from Bill Gates to Oprah, has won awards and gotten a 90% on Rotten Tomatoes is "right wing propaganda"? You may want to recalibrate you sense of where the center is.

Bill Gates and Oprah are both billionaires. Billionaires in general want solutions that defend capital. Privately run schools that receive government funding, in addition to tuition, while also being able to set their own curriculum free from the state is certainly within their collective class interest. Many seem to make the mistake of assuming that one’s allegiance to the US Democratic Party means that the individu…

If you think _all_ of the Overton Window is "right of center" than you are surely miscallibrated (there's even a meme floating around that describes this exact conceptual error).

Re: Electron band structure in germanium, my ass (2001)

#163

Post by fluoridation »

shadowgovt wrote: post #122
oddmiral wrote: post #106

Earlier quoted context omitted.

100 + 28 degrees are not harder to mark than 64, and then aim 0 and 100 properly. :-/

What would be the process to do that? To aim 0 and 100 properly, you'd need a tool to calculate a 100:28 (25:7) ratio on an arbitrary distance, wouldn't you? One can build such a tool, but it's not a doubled-over piece of string.

Surely you can simply use a ruler and rotate it away from the parallel to achieve any arbitrary scale, right?

Re: Electron band structure in germanium, my ass (2001)

#164

Post by dragonwriter »

BeetleB wrote: post #85

Oh, BTW, the whole "Friction is directly proportional to the normal force": My Ass! I could never reproduce it well in the lab, because it's really not true. Take a heavy cube the shape of a book. Orient it so that the spine is on the floor. It's a lot more friction to move it in one direction than in the transverse direction. Yet the normal force is the same. Any kid knows this, and I feel dumb it never occurred to…

Friction is proportional to the normal force, more specifically, it is the normal force times the coefficient of friction.

What you are describing (if the normal force is actually the same) is a contact situation where the coefficient of friction is different in different directions (anisotropic friction.)

Re: Electron band structure in germanium, my ass (2001)

#166

Post by ryandrake »

npongratz wrote: post #129
sio8ohPi wrote: post #91

Earlier quoted context omitted.

Having been on the other side of the table... there's a tactic students will sometimes use, where they don't understand the question but will simply attempt to regurgitate everything written on their notecard that is related in hopes that they'll accidentally say the right words. Sounds like you did understand it, but the volume perhaps made it look like you were just dumping. It is indeed annoying to grade. Grading…

Sure, we could speculate about his true unstated reasons for marking wrong my answer. I highly doubt the science teacher marked me wrong for "dumping", though. He had every opportunity to explain that to me after I got my exam graded and I asked him about it. Then he had the opportunity to explain that face-to-face with my parents. He did not do so. He said that while I got the answer right, he was "mad", thus the ma…

Good experience to prepare you for the rest of your academic and working life where your performance rating will often be strongly influenced the evaluator's current mood or biases. Or the police officer's mood when you get pulled over. Or most other authority figures' feelings when they're making decisions that affect you. It's unfairness all the way until we die.

Re: Electron band structure in germanium, my ass (2001)

#167

Post by joshstrange »

jerf wrote: post #27

One of my Core Memories when it comes to science, science education, and education in general was in my high school physics class, where we had to do an experiment to determine the gravitational acceleration of Earth. This was done via the following mechanism: Roll a ball off of a standard classroom table. Use a 1990s wristwatch's stopwatch mechanism to start the clock when the ball rolls of the table. Stop the stopw…

> you are never graded on whether you did your best and honestly report what you observe. From grade school on, you are graded on whether or not the grading authority likes the results you got. You might hope that there comes some point in your career where that stops being the case, but as near as I can tell, it literally never does. Right on up to professorships, this is how science really works.

This, so much this. I disliked any lab work in my science classes (in HS/College) for this exact reason. I can't tell you how many numbers I fudged because I wasn't getting the "right" results and there was no time/appetite/interest in figuring out why it was wrong, my options were lie and get a good grade or report what I saw and get a bad grade.

And yes, in college specifically, the equipment we were working was rough. There was so much of "let's ask the other 2 groups near us and we will all shave our numbers a bit to match/make sense".

Re: Electron band structure in germanium, my ass (2001)

#168

Post by a_shoeboy »

sio8ohPi wrote: post #91
npongratz wrote: post #50

Earlier quoted context omitted.

> From grade school on, you are graded on whether or not the grading authority likes the results you got. I took an exam in a high school science class where I answered a question with the textbook's definition exactly as presented in the textbook, complete with the page number the definition was found on. I knew a bit about the topic, so I then cited outside scientific sources that explained why the definition was i…

Having been on the other side of the table... there's a tactic students will sometimes use, where they don't understand the question but will simply attempt to regurgitate everything written on their notecard that is related in hopes that they'll accidentally say the right words. Sounds like you did understand it, but the volume perhaps made it look like you were just dumping. It is indeed annoying to grade. Grading…

I used to write my undergrad history essays in rhymed couplets because I figured the grad assistant doing the grading would be grateful for a break in the monotony and it was faster and easier than writing an actual good essay. Probably wouldn't work in the LLM era, but it was very effective in the 90's.

Re: Electron band structure in germanium, my ass (2001)

#169

Post by __MatrixMan__ »

don-code wrote: post #87
jerf wrote: post #27

One of my Core Memories when it comes to science, science education, and education in general was in my high school physics class, where we had to do an experiment to determine the gravitational acceleration of Earth. This was done via the following mechanism: Roll a ball off of a standard classroom table. Use a 1990s wristwatch's stopwatch mechanism to start the clock when the ball rolls of the table. Stop the stopw…

This is, more or less, exactly what happened when I took Electronics I in college. The course was structured in such a way that you could not move on to the next lab assignment until you completed the one before it. You could complete the lab assignments at your own pace. If you failed the lab, you failed the class, regardless of your grade. The second or third lab had us characterize the response of a transistor in…

I only took two electronics classes, but in the later one I was the class hero for just buying a bunch of potentiometers on amazon so that we didn't have to waste all of that expensive time sitting around waiting for our turn with the only good one left. It cost me like $10

Re: Electron band structure in germanium, my ass (2001)

#170

Post by dkarl »

jerf wrote: post #27

One of my Core Memories when it comes to science, science education, and education in general was in my high school physics class, where we had to do an experiment to determine the gravitational acceleration of Earth. This was done via the following mechanism: Roll a ball off of a standard classroom table. Use a 1990s wristwatch's stopwatch mechanism to start the clock when the ball rolls of the table. Stop the stopw…

At my high school, somehow physics was the dumb jock science course. I think it was because the head football coach taught physics for decades before retiring my sophomore year. Anyway, as a kid who was doing well in school and was headed for college, it was a natural decision for me to not bother taking physics and study for the AP test on my own. But one day a kid showed up in one of my classes with a hall pass for me to go to the physics classroom. The new teacher needed my help.

She had planned on teaching a lab on gravity and acceleration that day, but she was having trouble getting the right experimental results. Now, this story is not going to reflect well on her, so I want to say up front that she was already taking physics education at my high school to unprecedented heights by 1) trying out the lab on her own before trying to teach it, and 2) actually giving a shit about the results. I doubt the coach who had previously taught physics ever bothered to do any of the experiments himself, and I'm guessing everyone who ever turned in a lab report to him got an A regardless of the contents.

So there I am, a future physics major walking into a physics classroom for the first time in my academic career. I'm nervous because I have a reputation as a smart kid, and specifically as a smart science and math kid, but I was better with math and theory than with machines and measurements. I'm excited about getting to look smart in front of the other kids, but I'm also sweating bullets that there might be something about the equipment that I might not be able to figure out. So I ask her to show me what the experiment is and how she's doing it.

The experimental setup is a small but heavy piece of metal attached to a long, thin strip of the kind of paper used for carbon copies. (Or carbonless copies maybe. You know the paper where you write on one sheet, and there's a pressure-sensitive sheet underneath that creates a copy? It was a long strip of that pressure-sensitive paper.) The final piece of the experimental setup was a loud clacking thing that the strip of paper fed through. When it was turned on, a little hammer inside it slammed down every 1/4 of a second. The idea was, as the paper traveled through, the hammer left a mark every 1/4 of a second, and you could measure how far the paper traveled in each interval between the hammer strikes. Much more precise than a stopwatch!

You have already figured out how the experiment works. You hold the clacker at a fixed height against the wall or some other high fixed point, thread the weight end of the paper through it, turn the clacker on, drop the weight, and the clacker leaves marks on the paper that let you calculate g.

The teacher understood this, to an extent. But she decided that it would be less of a logistical hassle if the students did the experiment at their lab tables, by holding the clacker on the table and pulling the weight horizontally across the table with their hand. She tried this quite a few times herself, plotted the numbers, and could not get the plot to look like a parabola like in the textbook. I explained to her, "We're measuring gravity, so gravity has to do the work. If we move it with our hands, we're just measuring our hands. If gravity moves it, we'll measure gravity." We tried it, it worked, and she sent me back to whatever class I had been in when she sent for me.

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