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Electron Band Structure in Germanium, My Ass (2001) (wisc.edu)
163 points by lyk 8 months ago | hide | past | web | favorite | 38 comments



Oh man. In the junior year of my Physics degree we had a special lab section called "Modern Physics Lab". It was 2 credits (a lab is normally 1 credit in the Florida university system and denotes how much time you're in the classroom during a week), and basically a self-study course on how to properly conduct experiments in the modern physics domain. Replicating results from early modern physics like Milliken oil drop, identifying lattice structures using X-ray spectroscopy, etc.

Everything in the lab was broken, and the faculty knew it. They told us on syllabus day that about 50% of our lab time was going to be spent repairing the old shitty equipment. Why? Because unless you're working at MIT or CERN that's how labs in the real world work. Everything's broken and you don't have any funding but you still have to publish.

And truth be told I learned more about both basic circuits and how to foster a "get shit done" attitude from that class than any other lab class I had to take. The modules were on a rotation and I remember one of the groups that ended up on a particular experiment spent almost the entire semester fixing one module that nobody got to do that semester. It was an old out-of-production expansion card that plugged in to some old DOS box and interfaced with some piece of tech I can't remember. Literally everything about the setup was out of production. The amount of investigation and creativity they had to come up with in order to try and fix that experiment was impressive. I don't remember if they succeeded.

That lab was an experience.


I remember my 2 unit physics Lab Class, barely. We did the Millikan Oil Drop as one of three of the horrendous experiments we had to preform. Jesus.

The experiment, in brief, is to irradiate tiny oil drops and then tune a pair of charged plates until you can get one oil drop to levitate. Since electrons are unitary in charge, you can then back calculate the charge of the electron based on the charge you put on the plates.

The set up is that you have a microscope, an oil atomizer to make the drops, the charged plates, and a small radioactive source to put electrons on the oil drops. Spritz, open the lead chamber, irradiate, look at the drops in the microscope, tune the charge, repeat.

Numerous problems emerged:

Myself and my partner were pretty blind without our glasses, which you have to take off to use the microscope. So we could see nothing. (found this out on the first day, fuuuuun)

The oil drops, when imaged, are about the same size as your retina cells, in the given microscope. This means you can never be sure that you have an oil drop or your eyes are just too noisy to see it. (found this out by the end of the first week)

The room must be perfectly dark to see the oil drops in dim light, also you must take data on a computer or by writing somehow. (found this out on the first day too)

The small bit of radioactive material was made radioactive in 1961. Given the halflife of the sample, my banana was more radioactive (found this out in 2 weeks)

The plates weren't connected to anything. (2 weeks wasted)

The oil atomizer was meant for baby oil, not vegetable oil, as was given to us and wasn't actually atomizing anything. (another weeks wasted)

The end result was, well, nothing.

We got nothing. Not for lack of trying. I think I slept about 2 hours a night that whole quarter, the rest of the time was spent in the lab and on HW for other classes. My partner and I discovered that if you put your thumb over the co-ax of a high voltage, low current powersource it would zap you something fierce and keep you awake through the early morning hours. I also discovered that taking 2 ibuprofen per Rockstar will lessen the jitters of the caffeine enough so that you can read your own writing later on. So that's nice, I guess.

Stay in CS kids. Physics is for idiots.


> Myself and my partner were pretty blind without our glasses, which you have to take off to use the microscope. So we could see nothing.

Intuitively, this doesn't make sense to me. Microscopes have a focus. You should be able to adjust that focus such that the microscope is also correcting your vision, just like I (very nearsighted) have no trouble using binoculars without wearing my glasses.

What am I missing?


Honestly, you are right, but it was nearly a decade ago now. We should have seen something.

We should have done a lot of things better, actually.

Maybe we really didn't have a microscope? The apparatus was built in ~1961 and had been used yearly for the next 50 years. Any semblance of a manual had long since disappeared. Perhaps a lens or two had been raided in the 1980's ans we couldn't figure that out in the soup of other problems. I've really no idea, a decade on, which of the problems we were having that was our 'show-stopper'.

All I know is that Advanced Physics Lab (2 units) continued the time honored tradition of the Physics major breaking you, and then kicking you while you were down and laughing at your idiocy, for 4 years straight.

Somehow, I miss those times...


> Why? Because unless you're working at MIT or CERN that's how labs in the real world work. Everything's broken and you don't have any funding but you still have to publish.

That's close, but not quite the real issue.

The lesson is to document everything. Repeatability IS an issue even if no one is going to repeat the experiment--because YOU need that information to make any progress. It allows you to isolate to one thing, change one thing, and see what the result is. And THAT is the core of debugging.

I wish I could send every programmer through a physics lab class. The number of times I have had the following conversation with software people is staggering:

"Well, I did X and it didn't work."

"Oh? So, what was it supposed to do before you did X and what was it supposed to do afterword?"

"I dunno."

"THEN WHY THE HELL DID YOU DO X AT ALL?" <bangs head on table>


Virtually everything, and I mean everything in your post was wrong, but I still enjoyed the hell out of it.

Laser scientists know that if you use (a well anti-reflection coated) Ge window or lens to transmit a high power CO2 laser beam, slight absorption heats it a little. Heating it a little makes it more absorptive. So it heats a little more. And so forth, until the motherf——r cracks: “thermal runaway.”

Guess why? You are going to be a good experimental physicist eventually. Eventually. I spent two years blowing up homemade nitrogen lasers at Berkeley. Keep posting!


> You are going to be a good experimental physicist eventually.

He switched to CS and now gets paid to work on A-list videogames all day: http://pages.cs.wisc.edu/~kovar/cv.html

Edit: Oops, LinkedIn says he's now at Google.


Conclusion: 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.


The last line from his CV is a gem:

"Two years experience in swing dancing (east coast swing and lindy hop)."


Swing dancing is wonderful, and is very compatible with the analytical nerd brain as far as building up something beautiful from components, expressing yourself within a structure, getting physical exercise, etc etc.


"...by waving your hands and chanting "to first order"."

I've found that to be very successful in all walks of life.


Another classic in the same vein as the linked article is http://people.cs.uchicago.edu/~dinoj/scilies.html, which contains this nugget:

"Correct to within an order of magnitude."

Wrong.


Used to be ok in some branches of astrophysics. Now they know the age of the universe more accurately than any test you’ll get in a hospital. Stay the f—— out of hospitals (and courtrooms).


It is a joke, but not completely without any connection to reality: Sometimes, in astrophysics, you are happy if you get the order of magnitude correct to an order of magnitude.


Haha, I found that particularly hilarious XD. We did this all throughout my physics degree.


Why the experimental points don't have error bars?

Is it not possible to use four terminal sensing? https://en.wikipedia.org/wiki/Four-terminal_sensing Perhaps the sample is too irregular, but for very low resistance samples using only two terminals never work.

Can they use a lock-in amplifier? https://en.wikipedia.org/wiki/Lock-in_amplifier When it works, it's like magic. I'm not sure that it is useful here

> I attached them as appropriate to the second-rate equipment I scavenged from the back of the lab, none of which worked properly.

Yep, that's usual.

In next life, remember to be a mathematician.


Lock-in amplifiers are indeed great. They essentially shift your signal up in frequency, where you have less background. Here, it might be hard to apply because you would need to modulate the heating. Not impossible, but the maximum frequency is certainly limited.

Part of being a physicist is having a high pain tolerance to non-working hardware. This includes cables.


I think this is a good deal older than 2007, but my memory could be playing tricks on me. I could swear I had read this when I was studying semiconductors in school, in the early 2000s.

Edit: could be I'm thinking of Britney Spears' Guide to Semiconductor Physics, and I read this article later.


Considering he graduated from Stanford in '99 I would say so.


From the previous discussion at https://news.ycombinator.com/item?id=2514041 looks like the Britney Spears tutorial in semiconductor physics is at http://britneyspears.ac/lasers.html


Possible, his homepage says it's published on July 2001 in Annals of Improbable Research.



There are actually more women in physics and other natural sciences than CS. So, don't despair, your chances are already better than most geeks!


I remember reading this when it was first published. I was a freshman student taking physics at the time, cranking out truly boring and awful "lab reports" once a week.

I think this got printed up and hung in the dorm common room as some cathartic exercise.

I dimly remember some other reports of a similar style on other subjects, but I don't recall what they were beyond that.



This is my experience as well. The readings never matched what the text books said. Whenever the graph didn't match everyone told me that equipment was old or not calibrated. But it happened in all the equipment and at different labs. Fortunately I never cared about physics and simply started doing computer science.


This post shows how the "weak" are weeded out from the sciences. If your frustration level is as low as shown in the article, you won't become happy doing science. If you instead like getting hit in the face repeatedly for years, welcome onboard until you fall off!


He ended up finishing his BSc and got a PhD at CS, works at Google now.


I remember reading about this post on Quora two years ago. A Raytheon Engineer who went by the name of Jacob Vanwagoner had posted this. Pretty impressive fella.


Oldie but goodie. Reminds me of another oldie, Andras Konya's "My C++ Experience/Disaster", which is sadly gone from the internet now.



That's just an excerpt from the whole essay. It seems all of his essays are gone from the internet.



I would guess the letter sent to Bjarne is just one part of the essay. As you can see from this snapshot: https://archive.fo/mMrs1, the essay starts with, "I strongly dislike the "wildly popular" computer language C++. My experience with it has been nothing but a disaster...".


Not what I was expecting but exactly what my day needed.


"Electron Band Structure in Germanium, My Ass (I Will Not See the Electron Band Structure in Germanium)"


Mods: The title is wrong; this was written in 2001.

Citation: http://pages.cs.wisc.edu/~kovar/cv.html


Thanks, updated!




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