10 ms·
Electron Band Structure In Germanium, My Ass
- wbhart 16y agoOh, lovely story. I had precisely this happen in Physics at Uni. I wrote down every piece of data, wrote out my computations in full. When I submitted it, I got a D. I challenged my prof to check any one of the data points or computations and exhibit a single error (I knew he wouldn't because I had checked myself). He refused to check even a single one. Every single person for 20 years had fudged the results!!
- jabo 16y agoI don't understand a wee bit of that, so Go Computer Science! :)
- lloeki 16y agoHe's unit-testing Germanium.resistivity(intensity, temperature) like so: fixed_i = lambda t: Germanium.resistivity(42, t) for t in range(100, 350, step=10): assertEqual(fixed_I(t), k*math.expr(t/tref)) Unfortunately fixed_i returns results akin to /dev/urandom because of broken hardware.
- jrockway 16y agoYeah, I remember a number of labs where I didn't get the data that was expected and had to do the experiment again. Knowing the expected result, producing excellent data was easy; instead of a painstaking data-collection process, I outsourced that to a "function" with "noise". Hey look, r=0.999! I understand this is the same process by which the top quark was discovered.
- starwed 16y agoHey look, r=0.999! I had to grade physics labs one semester -- this was always an instant tell that students were making shit up. :)
- linker3000 16y agoI see the test results for germanium but where are the results for his ass?
- mikecane 16y agoThis pops up every few years. I always forget it and laugh out loud brand new when re-reading it.
- joss82 16y ago"Going into physics was the biggest mistake of my life. I should've declared CS. I still wouldn't have any women, but at least I'd be rolling in cash." This advice should be told to all high schoolers. Well, at least male ones.
- pbsurf 16y agoThere really is no reason to earn an undergraduate degree in physics (as I learned the hard way). It is just as easy to get into a physics graduate program with an ECE or EECS degree plus a couple semesters of upper division quantum mechanics and maybe a semester of stat mech - and you have the option of getting a decent job instead.
- 2muchcoffeeman 16y agoOr do both! I always cringe when I meet good programmers that have no understanding of what is going on at the hardware level.
- stdbrouw 16y agoBecause knowing the hardware is, of course, essential to make a well-functioning CRUD app.
- JonnieCache 16y agoHah, this exactly mirrors my experience in chemistry lessons aged 15. Failing to reproduce experimental results with broken equipment then faking the data with an excel function to get the teachers off my back so I could go back to doing something useful like staring out of the window, or using the magnesium ribbon to heat-seal peoples pencil cases shut. Good to know that it carries on up to the undergraduate level. And I even managed to associate with women during my eventual CS degree! Feeling pretty smug right now.
- yummyfajitas 16y agoFailing to reproduce experimental results with broken equipment then faking the data with an excel function to get the teachers off my back... I had the exact opposite experience. I once failed to get an experiment working, but kept trying until I was the last person in the lab. Eventually the professor asked why I hadn't finished, and together we discovered the spectrometer was utterly broken. He gave a a grade of 0-25% to everyone who got the "right" answer, depending on how realistically they faked it (some people didn't bother to add noise or quantize their answers).
- alex_c 16y agoYour own example suggests you're in the (vast) minority.
- starwed 16y agoEh, in my experience, despite the fact that points were not deducted for getting the "wrong" result, and they were frequently told so, students still preferred to falsify data. I think it is because if they get the "correct" result they can also just copy an analysis from elsewhere, whereas with the "wrong" result they would have to actually do it themselves.
- schmittz 16y agoThat's so funny because I always loved getting the answer wrong. I could get full credit for explaining possible sources of error, versus having to develop a well-established analysis independently. You'd think more students would think this way.
- ldite 16y agoFunny as hell when I was a physics undergraduate 10 years ago, and still funny now. I still routinely use the phrase "to first order" when justifying horrific approximations.
- nhebb 16y agoThis is why the only lab I enjoyed was in Materials Science. The goal of the labs was never to try to get the data to match some pre-defined equation. Instead, the goal was to test materials and interpret the results. Plus, we got to break stuff. :)
- schmittz 16y agoAs a materials science major, this comment made me smile. All my labs at Carnegie Mellon were like that, it was(is) great. We just take a bunch of materials and then argue which one would be the best choice. The only time I had to produce results was when we synthesized a known superconducting structure and just had to show that it superconducted (how strongly wasn't important). Good times that sound much better than people's experiences in physics and chemistry. Vindication!
- JoeAltmaier 16y agoI had this insight in Junior High - testing friction by putting blocks on top of other blocks, or in a block train, and using a 'force meter' to see how hard I had to pull. The 'force meter' was a piece of spring steel stuck into another block, with a hook on the end. It was totally non-linear on every surface I tested. The book said it was supposed to be linear. The students were all furtively fudging it, and eventually the teacher said something like "well, its supposed to be linear so do the best you can". Insight: this was all a bunch of crap. Turns out that friction is totally non-linear anyway, for most materials, but I didn't read that until 20 years later.
- Zaak 16y agoThat reminds me of a story about Richard Feynman visiting a physics class outside the US. The diplomat types were very upset with him for pointing out that their books and classes were terrible, teaching things like the energy of a ball going down an incline without taking rotational kinetic energy into account.
- perlgeek 16y agoHe's so totally right about the hand waving approximations used in solid state physics. All fields of physics need to use some approximations, but those in the solid state were usually the ones with the worst reasons, just things like "it works if we do that" or even "it doesn't if we don't do this". It went on like that in three courses (two on solid state physics, one on electronics). Only after that did I happen to come across a decent book which explained some of the approximations in a way that didn't make me cringe, and some of the stuff started to make sense in retrospect. Others are still a mystery to me, and probably always will be.
- schmittz 16y agoIt's often poorly explained, I completely agree, but people forget that even Planck introduced his constant just because it made the data fit. It turned out to be arguably the most fundamentally important constant (along with its reduced form) in all of physics.
- arethuza 16y agoAren't all fundamental physical constants like that - they are essentially meaningless values plugged into theories to make them align with observations?
- drhodes 16y agoyeahbut, some are interrelated. Like the speed of light and the permittivity of freespace (1/c^2 * mu). If you measure that constant and solve back for c, then you better get ~3 * 10^8 m/s.
- lscharen 16y agoMostly because we (humans) made up physical units (i.e. meters) while we were inventing physics. There's nothing keeping you from re-deriving physics equations without the messy constants. http://en.wikipedia.org/wiki/Natural_units http://en.wikipedia.org/wiki/Natural_units
- sliverstorm 16y agoThe way I have always approached labs is a thorough report on my procedure, complete results (totally wrong or not) and an analysis of Whether I got good results, Why I got the wrong results, How might one improve the experiment to get better result... That has always served me well. I don't usually get A+'s on lab reports, but I think that's my fault and for an unrelated reason. It certainly seems to me reflection on what was done and thoughtful analysis on why it was good/how it could be fixed (with specific statements or suggestions, not general ones)/what went wrong demonstrates understanding of the material that simple results do not. I guess if you are being trained primarily to be a lab worker who's job is to produce accurate numbers, that's important, but if the labs are for learning...
- cubicle67 16y agoI read an essay, I think by Isaac Asimov, where he described a graph like this as a "shotgun curve"
- elwin 16y agoI sympathize with the horrible equipment. While getting a physics degree, I had a lab where we measured resistivity. My team was the last to succeed in getting numerical data from the 20-year-old oscilloscope via floppy disk. The students scheduled after us had to take a digital photograph of the oscilloscope screen and reconstruct the data from that. Broken equipment is not confined to undergraduate classes. A few terms later, I had to use the digital photograph method to get data from a spectrometer in a research lab. If my analysis had succeeded, we would likely have published, and the professor would have had a chance at tenure, all on the strength of data obtained by counting pixels.
- laeus 16y agoThis "lab report" always brings back good memories because it indirectly launched my career in the game industry. I was finishing up my CS degree at UW Madison and working in Mike Gleicher's computer graphics lab in Spring '02. I had previously met Lucas through a fellow CS student (Alex Mohr, now at Pixar). At some point, Lucas was contacted by the AI programmer at Ensemble Studios (Mike Kidd). Mike, a UW alum, had seen the Germanium treatise and wanted Lucas to apply at ES. A month later, knowing how eager I was to join the game industry, Lucas mentioned Mike's email to me and forwarded him my info. Long story short, I got an interview at ES and was hired straight out of college into a dream job. I look forward to seeing this link pop up again in a few years. :)
- beefman 16y agoAll scientific results should be reported this bluntly.
- BrotherSand 16y agoHilarious! First time I've seen this and I laughed so hard I had tears running down my face. I think it was figure 1 "check this shit out" that made me really lose it. Got some odd looks on the train.
- Groxx 16y agoAn oldie, but a goodie. Easily my favorite scientific report paper of all time. >Banking on my hopes that whoever grades this will just look at the pictures, I drew an exponential through my noise. I believe the apparent legitimacy is enhanced by the fact that I used a complicated computer program to make the fit. I understand this is the same process by which the top quark was discovered. Absolutely brilliant.
- tinyrock 16y agoThe crap results were probably due to the soldering messing around with the crystal properties. Using a pressure-contacts approach instead seemed to do the trick: http://tinyrock.com/resources/4000918/Bandgap-Measurements-In-Ge http://tinyrock.com/resources/4000918/Bandgap-Measurements-I... Has it really been 10 years!
- bluesmoon 16y agoDuring my physics practicals for my high school final exam, I had to measure the voltage of a Daniel Cell using a Dry Cell (1.5V), a 2metre length of wire and a bunch of other stuff. The only problem... the dry cell was dead, so only carried 0.8V or something. So, my results consistently showed that the Daniel Cell had a PD of 1.7V (it's supposed to be ~1.1V). The examiner came up with a brilliant solution to "fix" my data. Switch the labels on the data columns.
- Niksko 16y agoAh, physics, the slower cousin of mathematics. How I weep for you.