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    Electron band structure in germanium, my ass (2001)

    (pages.cs.wisc.edu)
    896 points tux3 | 11 comments | 01 Apr 25 12:25 UTC | HN request time: 1.998s | source | bottom
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    jerf ◴[01 Apr 25 13:57 UTC] No.43546861[source]▶
    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 stopwatch when the ball hits the floor.

    Anyone who has ever had a wristwatch of similar tech should know how hard it is to get anything like precision out of those things. It's a millimeter sized button with a millimeter depth of press and could easily need half a second of jabbing at it to get it to trigger. It's for measuring your mile times in minutes, not fractions of a second fall times.

    Naturally, our data was total, utter crap. Any sensible analysis would have error bars that, if you treat the problem linearly, would have put 0 and negative numbers within our error bars. I dutifully crunched the numbers and determined that the gravitational constant was something like 6.8m/s^2 and turned it in.

    Naturally, I got a failing grade, because that's not particularly close, and no matter how many times you are solemnly assured otherwise, 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.

    The lesson is taught early and often. It often sort of baffles me when other people are baffled at how often this happens in science, because it more-or-less always happens. Science proceeds despite this, not because of it.

    (But jerf, my teacher... Yes, you had a wonderful teacher who didn't only give you an A for the equivalent but called you out in class for your honesty and I dunno, flunked everyone who claimed they got the supposed "correct" answer to three significant digits because that was impossible. There are a few shining lights in the field and I would never dream of denying that. Now tell me how that idealism worked for you going forward the next several years.)

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    don-code ◴[01 Apr 25 15:53 UTC] No.43548274[source]▶
    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 a DIP-8 package, which was provided to us. If you blew it up, you got a slap on the wrist. That DIP-8 was otherwise yours for the class.

    I could _never_ get anything resembling linear output out of my transistor. The lab tech was unhelpful, insisting that it must be something with how I had it wired, encouraging me to re-draw my schematic, check my wires, and so on. It could _never_ be the equipment's fault.

    Eight (!) weeks into that ten week class, I found the problem: the DIP was not, in fact, just a transistor. It was a 555 timer that had somehow been mixed in with the transistors.

    I went and showed the lab technician. He gave me another one. At this point, I had two weeks to complete eight weeks of lab work, which was borderline impossible. So I made an appointment to see the professor, and his suggestion to me was to drop the class and take it again. Which, of course, would've affected my graduation date.

    I chose to take a horrible but passing grade in the lab, finished the class with a C- (which was unusual for me), and went on to pretend that the whole thing never happened.

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    1. michaelsbradley ◴[01 Apr 25 17:56 UTC] No.43549683[source]▶
    I was in honors freshman chemistry at university. Tough class, all homework (lots of it) graded rigorously, but only the midterm and final counted toward the course grade. So if you wanted an A you had to get an A on both exams.

    After midterm, during every other lecture at least, the professor would sound a refrain: “An orbital is not a house! An electron does not live in a house!”

    Final exam had a small number of complex problems to work out with pen and paper, tough stuff, lots of calculus. But the last question ended with “where does the electron live?”

    That final problem, if you ignored the end wording, was super easy, something almost trivial to do with Helium iirc. The class had about 25 students in it; about 5 of us independently had the same thought: “this is a trick question, ‘the orbital is not a house in which the electron lives!’” And, independently, that’s how we five answered.

    And we got marked wrong, all our course grades dropped to B+/- because of that one damn question.

    Over a lunch or whatever, we discovered our shared experience and approached the professor as a group. He listened patiently and said: “Ah, right, I did insist on that idea, it’s understandable why you would think it’s a trick question and answer that way. But I still consider your answers wrong, grades stay as they are.” Some in the group even went to the dean and, to my understanding, he said it’s best to consider it a life lesson and move on.

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    2. don-code ◴[01 Apr 25 20:32 UTC] No.43551027[source]▶
    I agree this seems overly principled to me.

    I recall a DSP class where there was an exam with a question like (not exactly this):

    > What does the following code print?

    > `printf("Hello, world!");`

    If you responded with:

    > Hello, world!

    ...which - of course - the whole class did, you got the question wrong.

    If you responded with:

    > "Hello, world!"

    ...which is actually not what that would print, you got the question right.

    A small band of us went to the professor and noted that, in fact, `printf("Hello, world!")` does not print the quotes. But he wanted us to show that it printed a string, and we denote strings by quotes.

    This was something that we learned to do just for him - all strings had to be enclosed by quotes, to denote that they were strings. As far as I'm concerned, it served no practical purpose; we never had to differentiate strings like "Hello" from ['H', 'e', 'l', 'l', 'o', 0] or other representations.

    A better example of how this could go - and not one that had anywhere near the same stakes - was a question on the entrance exam for my college radio station:

    > What is the airspeed velocity of an unladen swallow?

    I got this question right by answering, "Ni!"

    (edit: formatting)

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    3. AnimalMuppet ◴[01 Apr 25 20:33 UTC] No.43551031[source]▶
    Yeah? What "life lesson" does the dean think you're going to learn from that? That authority figures cannot be trusted because they will hurt you with bureaucratic stupidity. Does the dean, as an authority figure, really want that to be the lesson you learn?
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    4. lr4444lr ◴[01 Apr 25 20:44 UTC] No.43551130[source]▶
    Having gone both to a liberal arts institution and a large public university, it is not clear to me what the professors in the latter were actually doing vis a vis their teaching responsibilities that actually provided value.

    Lectures that came straight from the book I could have read, recitations and problem reviews done by grad students, and tests that were little more than variations on homework problems of varying difficulty.

    Maybe they were getting paid for research, but I dunno. At the liberal arts college, I actually received an education instead of bootstrapping it myself from a syllabus.

    5. microtherion ◴[01 Apr 25 21:25 UTC] No.43551509[source]▶
    Depending on your environment, the above printf might print nothing at all, because there is no trailing newline.
    6. vkou ◴[01 Apr 25 22:27 UTC] No.43551964[source]▶
    That sometimes you can do everything right and still lose.
    7. dudinax ◴[01 Apr 25 22:43 UTC] No.43552048[source]▶
    The kind of prof who never coded a useful program in his life.
    8. devnullbrain ◴[02 Apr 25 00:27 UTC] No.43552643[source]▶
    I have my own, similar stories but, as a mediocre student, they were lost in the noise of my own mistakes. Nonetheless it's injustice, so I still remember it. Some people on this site were really excellent students, where these deductions really mattered. I don't know how they cope.
    9. dkarl ◴[02 Apr 25 01:02 UTC] No.43552805[source]▶
    A kid might see it in terms of "authority figures," but live long enough and you'll understand it's everyone. Not just your professors and bosses, but your subordinates, your friends, your lovers, even your children will judge you unjustly from time to time. But that doesn't mean the world is poison and existence is a curse. It just means you have to learn to get by despite other people's imperfections the same way they get by despite yours.
    10. somat ◴[02 Apr 25 02:19 UTC] No.43553131[source]▶
    Yeah that sucks, the hard life lesson where you have to swallow your pride and go "fine, I will put quotes on the infernal thing"

    But... it does not print a string, a string goes into it but what comes out of the function is not that programmatic feature we call a string in any way shape or form, what comes out depends on the output device specified, it may be ink on paper, lit phosphors, or a stream of bytes. none of which can you use in your program as a string.

    sprintf being a notable exception of course. there you do get a string out of it.

    Update: language is weird and the more I read my statement the weirder it gets, all I can do is add this cryptic note. "When you print a string it does not produce a string", this usually means I am wrong about something.

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    11. jodrellblank ◴[02 Apr 25 14:59 UTC] No.43557437{3}[source]▶
    "string" is a type that only makes sense inside the context of a specific programming language, because programming languages differ on what a string is and how it behaves (is it guaranteed to be valid UTF8, does it carry its own length around with it, is it runes/graphemes and can't be split on byte boundaries easily, is it mutable, etc).

    Double quotes are a syntax sugar for string literals in source code, in a particular language, to avoid writing `string.from_byte_array([97, 98, 99])` or `new String({97, 98, 99});` or whatever. Strings are single quoted not double quoted in Dyalog APL, there's several different strings in SWI Prolog depending on using double quotes or backticks and how the flags are set.

    stdout is an untyped byte stream which could go to a printer or Braille terminal or anything as you say, but could be terminal control codes, image data, or whatever. The OS doesn't tend to have a 'string type' ... but in PowerShell `write-output "a"` will write a .NET System.String to the output stream, but it won't use "printf()".