The double irony would be for the author to have persevered in physics and now hold several patents over solid state batteries that are going to revolutionize society and fix climate change, while their CS major friends just got fired by some GAFAM for not getting enough minimum-pay workers to click on funny cat memes.
Having taught low-temperature condensed matter labs, a big part of the grade is figuring out what went wrong, and either correcting for it, or at least acknowledging that it went wrong. The student needed to give more information about the experimental setup (what instruments did they use? four point or two point resistance? resistivity vs resistance? what is R_0?) and why they think the experiment didn't work. It looks to me like they had something miswired, so they only measured noise.
Indeed, a scientist should have some exposure to experimentation. Experiments don't always work on the first try, and often require some knowledge and skill.
The ones who can't solder go into electrical engineering and sit at a computer terminal all day. (joking of course)
You sure it isn’t Schottky diodes formed by the metallic contacts that are interfering with the measurement of the bulk germanium properties?
I’d sputter deposit metallic contact regions and solder to those, then maybe compare two different thickness samples and look at the difference in resistivity vs. temperature, essentially de-embedding your fixture.
Came here to say this. You can’t solder leads on to semiconductors willy-nilly. The work functions are too different. So instead of an ohmic contact, you get a diode.
Possibly, but the OP is probably measuring the equivalent of back-to-back series diodes, which would be very symmetrical (if built on the same process). With soldering though, I’m sure they are not equivalent. As the other poster said, they need Ohmic contacts.
Exactly my experience back in the days doing the mandatory "advanced experimental physics laboratory semester" where you had to do like 14 vastly different experiment of the caliber described in that post in the course of one semester on old equipment that would break during the experiment, with less than motivated PhD students or post grads as teachers. Of the 14 experiments only two worked and we got the expected results.
This experience drove me right into theoretical physics and writing computer simulations of electron dynamics and light-matter interactions in confined semiconductors (quantum dots, graphene and the like). That was fun.
Now I am working on medical device software development, as the other stuff does not pay the bills.
Yeah I don't quite understand how the physics curriculum is set. There is more and more physics discovered over time and yet the time you get to study remains the same. 4 years is not enough time to learn the math and physics you need to do anything real, not counting the other important stuff you need to do (like English comp and partying and getting your heart broken).
Heh this strikes me as funny. I remember studying hierarchical image classifiers... If you think physics changes fast you should check out CS sometime.
At my uni (and probably and most others) undergrad physics just ends around 1930s. Then for master's you get some of the mid-20 century (phase transitions and intro to qft). Then you specialize and learn the remaining 50 years
(1) 'to teach you to think like a physicist' as my professor was fond of saying to us. No one is going to be able to learn all of the subjects knowledge in 4 years, let alone a complex and rigorous field like physics.
(2) to give you a core foundation of understanding on which all other physics is built upon.
By teaching the core subjects and lessons of physics, you can get a pretty good understanding of the world, how it works, and how to derive equations to explain it.
As for it not being able to learn enough to do anything real. I beg to differ, like all fields you tend to learn the most in 'the field'. Most physicists learn by doing just like any other field. Take for instance engineering, there are some exceptions but most of the engineers I have known in my life have really only become fully viewed as engineers once they had some years of experience under their belts... Same thing goes for comp sci, and same goes for physics.
It's hard to explain because the field is viewed as an abstraction to those outside of it. The goal of understanding something new, discovering some new phenomenon, or better understanding an old one. But what that looks like in practice is years of working in a lab failing, trying things, taking results, tilting your head and going 'thats weird', and charting to colleagues about how to get something to work. Those who have done experimental physics, this is just experimentation and it makes sense, those who haven't, this probably sound simplistic and it is. Like your own fields, it's hard to really capture the depth of what experimentation looks like because even in physics it varies from sub field to sub field.
So it goes, sorry for the rambling from an experimental physicist
Thanks for the thoughtful response. I think maybe my objection to MY curriculum was being handed a lot of mathematical tools which I didn't need, and so it was impossible for me to "slot them in" to my toolbox. Most named solutions to differential equations were just like...why? (e.g. Bessel functions, or Green's function or...). I think it's a failure of pedagogy - I personally think you should give students the problem before giving them the solution. But the physics curriculum seems to want to give you solutions first and then tell you how you can use them. My brain doesn't work that way; tools fulfill a need. It would be like teaching a carpenter all the ins and outs of every tool in the shop, without ever building anything. How is the student supposed to organize that knowledge? Alphabetically?
I suspect that, just like how algorithms rarely pop up in software practice, so too do these kinds of tools pop up in physics practice, and when they do you probably get that same happy jolt of "Hey I finally get to apply this knowledge!" And that happens about once every 2 years.
Astronomy tends to be a way to get "newer" physics involved (at least in terms of discoveries), but it's also worth noting that formulations used usually evolve from what was originally published (Maxwell's equations are a well-known example), so you're getting more of a cleaned-up version, with insights based on newer discoveries.
> on old equipment that would break during the experiment
Isn’t that closer to the real conditions in a research lab?
I met some NASA scientists doing atmospheric sampling on a plane, and they had to accompany their equipment to manage any equipment glitches during the expensive sampling process (a custom modified 747 flying from Hawaii to New Zealand IIRC)
Can confirm, work in a top physics university in the lab. It is not a rare sight to see equipment from 10, 20, 30 years ago still in operation. Though it really depends on the equipment. Optics? They don't really go bad if you treat them right. Electronics? You'd be surprised as the quality of design and fab went into that plastic box that looks older than you.
Really physics discovery is partially limited by equipment, but in my time in the lab I have seen great physicists get remarkable results with equipment or setups that I personally thought was not up to the task.
As to college level experimental physics lab: the goal is not to get you to reproduce the nobel winning results, but to learn how to think like an experimental physicist. To hunt down issues, to calculate sources of error, to find out that some guy keeps running the microwave while you are taking sensitive measurements and that it actually impacted them and how.
It is the unimaginative or poorly taught that think the experimental physics lab in undergrad isn't important.
Yeah I've bought some old test equipment and it's a wonder than you just plug it in and it is still within specs. They knew how to build them back when HP was called HP and not agilent/keysight/whatever they rename themselves in next decade.
It's not that bad of a course, it's just a struggle because it's different than all other physics courses you take.
In that class you aren't being graded on getting to the right answer. You are getting graded on how you approach getting the right answer, and no one expects you to get the right answer - in the ball park is generally the average for the course.
> one semester on old equipment that would break during the experiment
I saw that as a learning opportunity, teaches you which glues are cryo-proof, how to switch fuses on amplifiers (and other, more complicated electronics quick-fixes), and how important knowing people to borrow equipment from is.
Unless your lab is swimming in money, those are valuable skills for an experimentalist. And even if you swim in money, buying fancy new stuff has a minimum 8 week lead time while walking down the hall to the correct shelf to pilfer takes 5 minutes and gets you results before lunch.
> with less than motivated PhD students or post grads as teachers
This is an unfortunate truth everywhere I taught. Unfortunately, teaching the same thing 14 times a semester is no fun, and every single person who enjoys teaching (and is good at it) knows it, and instead teaches any available lecture, seminar, tutorial or exercise - anything, where you get to teach something new every week and that allows you to stay with the same students for longer.
Wow! I'm less than a year from applying to grad programs and all of my undergrad research experience is in very similar things. Theoretical is my jam. Did you do a PhD? If so do you now believe it was worth it?
In total, yes it was. Working for some years in a field, having the time afforded to emerse yourself into a subject and deeply think about it, calculating yourself into frustrating dead ends and also
into successes, writing papers, going to conferences presenting your results, have scientific exchanges with peers, write applications for research grants, sit in committees, work as a referee for scientific journals, teaching students, then writing a coherent and compelling thesis and finally defending it against & having a scientific discussion on eye-to-eye level with your supervisors will shape your character... a lot.
You might wanna skip that postdoc thing though if you know you don't wanna stay in academia (and trust me, you don't).
This was one of the funniest things going around the Physics department when I was in school. I can assure you it is older than 2007. 1998 or ‘99 iirc.
As an odd coincidence, I did the same experiment on a shoestring budget with substandard equipment also. I too used a fancy computer algorithm to get a best fit. Except that I managed to get four significant decimal places in the result — an improvement over the (also outdated) textbook.
The author of the angry rant had a life-defining experience of overwhelming frustration.
The same scenario resulted in a positive life-defining experience for me
It’s funny how unpredictably things pan out even in identical circumstances…
But in some way we all end up in the same place :) (HN)
I really enjoyed the labs and it was seeing the predictions pan out in front of my eyes that actually got me interested in the first place. But you have to know what your getting into. The labs are extremely time consuming and required preparation.
Talking of a shoestring budget, sometimes it's a good thing. I actually learned more useful things about EE by fixing broken test gear than doing an undergraduate course. The course was so heavily theoretical that when it came to actually building prototypes, nothing worked and no one knew why, not even the lab techs. So I spent most of the time going round helping fixing people's limping final year projects.
Agree with this. I had to make my own equipment everywhere I went. The people I met later in my career who went to nice schools, with illustrious research experience had no idea what they were doing. Okay that's an exaggeration. But, when they entered industry they trusted every black box and rationalized every bizarre thing they saw as if their results depended entirely on their domain of interest.
Negative concentrations no problem! That must mean the machine is tracking the previous known value and this is the difference! Oh my oh my... The things I've seen the highly/expensively educated get paid lots of money to do, present, and be rewarded for in regulated industries....
This was my experience when doing some of measurements back while getting higher ed.
Sometimes you just get random results that has no relation to what you expected to get based on theory (and not just theory, but common sense). They're not zero and not over the top, they're just useless.
Welcome to experimental science. In this case they actually knew what they were looking for. Once you actually start doing real science, the first difficulty is to understand if what you are observing is actually what to expect or not (and that is not always straight forward).
Not really related of the article, but a question I just realized I don’t know the answer to: where does the temperature of an atom “live”? Is it entirely in the electrons? Does the nucleus have any temperature?
The "temperature of an atom" is something very different from the temperature of a material with billions of atoms. For the material, what matters most is usually vibrations of atoms, where the nucleus contributes the most to kinetic energy, because it is heavy, and the electronic configuration contributes to potential energy.
For an atom, you basically have to do quantum physics and talk about von Neuman entropy of it's quantum state. This kind of temperature is very removed from the everyday concepts of "heat" and "heat transfer".
Temperature is the motion of the whole atom. Individual atoms don't really have temperature, temperature is a bulk property, the average of motion of lots of atoms.
That's a good question. it depends how long you wait and how strongly coupled they are.
For electrons and nuclear motion they are often strongly coupled enough that they quickly reach equilibrium and thus are at the same temperature (e.g. in liquids or solids). But on short timescales they can absolutely be at distinct temperatures. In dilute gases they can also become somewhat decoupled (there can be a well defined electronic temperature and nuclear temperature).
One case whether this can take a much longer period of time is when dealing with nuclear spin -- this is much more weakly coupled to the electrons and so can take much longer to equilibriate.
Not a physicist, but I think temperature lives in motion of particles, let it be electrons, the nucleus, whole atoms, or otherwise. Because electrons shroud the nucleus and have much less mass, they are more prone with external interactions where they can change momentum by absorbing and releasing energy. The nucleus is not exempt from this, but takes a not more energy to change their momentum. That being said, "temperature" as we are accustomed to, is more like a statistical average of the total motion of all particles in the system.
> 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.
It's not just the pay; the pressure as a graduate student and not-yet-tenured professor is immense. The darkly humorous "A (de)motivational letter", purportedly by one "Prof. Hardass Slavedriver", sums it up: https://lifesciencephdadventures.wordpress.com/2013/01/04/a-...
It's not just darkly humorous, it could almost be satire:
> It has to the the kind of chemistry that people read and then jizz in their pants, they’re so excited about it. That’s right: we only do jizz-worthy chemistry
I'll assume due to the nature of chemistry, the field doesn't suffer as much from non-reproducible data, but overall, this sentence alone might explain cases like the Francesca Gino fraud [0], or why the head of Stanford resigned over integrity issues [1]? Or the Schön scandal? [2]
I mean take the analogy seriously for a moment: What the author is asking for in the analogie's universe, is for one of his students to just invent Stable Diffusion so he can generate pornography for his colleagues to.. well?
But no word about integrity or honesty. Nothing. Just results.
Author took it as inspiration:
> The truth is that under all the profanities, and the slave-driver mentality of the professor I saw someone who truly wanted to develop their students.
PhD students of HN enlighten me, after reading this crap, how is this "slave-driver" not just incentivizing to cheat?
I think any system that rewards high performance also has the potential to reward (good enough) cheating. This letter can be motivational, and show the intense pressure to cheat in academia at the same time.
I'm not a PhD student, but I stopped after a masters exactly because I didn't want the pressure we're discussing.
Huh? Nothing matters but results anywhere. Why would it be different in academia, where funding is always tight and tenure-track jobs scarce and hotly contested?
Assuming this is real, it looks like he measured some high quality noise. No way the resistivity would jump 2x over 5 degrees and stay constant at constant temperature (the biggest suspect according to his own confessions).
I guess this must be from '99. Consequently the author went to get his Masters and PhD in CS.[0]
Having gone through a similar ordeal and frustration at the end of my uni career, in the end I went out with the highest admiration for the experimentalists and their tech staff.
Also, there are many a decent xysicists in tech. Physics skews to supernerds like good CS folks, so there's quite a bit of problem-solving and subject matter crossover beyond the closest neighbor, EE/CS.
The Goog has pockets of okayness here and there, so maybe they've found a comfortable home after 12 years. :)
What I'm taking away from the comment section is that if you have trouble replicating an experiment, you should take advantage of Cunningham's law: instead of having your pleads for help ignored by some highly demotivated PhD's posing as your thesis advisors, instead post a rant about your failure on HN and have those same advisors give you a snarky reply with how to do it correctly ( you even get references to correcting literature!)
I feel this pain. On a lower level, my A Level physics practical exam was a life-changing experience that reduced me to tears because I could not assemble the experimental paraphernalia into a stable structure that would not fall over when I touched it.
87 comments
[ 2.6 ms ] story [ 178 ms ] threadHaving taught low-temperature condensed matter labs, a big part of the grade is figuring out what went wrong, and either correcting for it, or at least acknowledging that it went wrong. The student needed to give more information about the experimental setup (what instruments did they use? four point or two point resistance? resistivity vs resistance? what is R_0?) and why they think the experiment didn't work. It looks to me like they had something miswired, so they only measured noise.
The ones who can't solder go into electrical engineering and sit at a computer terminal all day. (joking of course)
I’d sputter deposit metallic contact regions and solder to those, then maybe compare two different thickness samples and look at the difference in resistivity vs. temperature, essentially de-embedding your fixture.
It's not my sub field, but the description of the setup seemed soo haphazard
This experience drove me right into theoretical physics and writing computer simulations of electron dynamics and light-matter interactions in confined semiconductors (quantum dots, graphene and the like). That was fun.
Now I am working on medical device software development, as the other stuff does not pay the bills.
Because Mathematics is just applied philosophy. Which is just applied language... which is just applied sociology.
(1) 'to teach you to think like a physicist' as my professor was fond of saying to us. No one is going to be able to learn all of the subjects knowledge in 4 years, let alone a complex and rigorous field like physics.
(2) to give you a core foundation of understanding on which all other physics is built upon.
By teaching the core subjects and lessons of physics, you can get a pretty good understanding of the world, how it works, and how to derive equations to explain it.
As for it not being able to learn enough to do anything real. I beg to differ, like all fields you tend to learn the most in 'the field'. Most physicists learn by doing just like any other field. Take for instance engineering, there are some exceptions but most of the engineers I have known in my life have really only become fully viewed as engineers once they had some years of experience under their belts... Same thing goes for comp sci, and same goes for physics.
It's hard to explain because the field is viewed as an abstraction to those outside of it. The goal of understanding something new, discovering some new phenomenon, or better understanding an old one. But what that looks like in practice is years of working in a lab failing, trying things, taking results, tilting your head and going 'thats weird', and charting to colleagues about how to get something to work. Those who have done experimental physics, this is just experimentation and it makes sense, those who haven't, this probably sound simplistic and it is. Like your own fields, it's hard to really capture the depth of what experimentation looks like because even in physics it varies from sub field to sub field.
So it goes, sorry for the rambling from an experimental physicist
I suspect that, just like how algorithms rarely pop up in software practice, so too do these kinds of tools pop up in physics practice, and when they do you probably get that same happy jolt of "Hey I finally get to apply this knowledge!" And that happens about once every 2 years.
Isn’t that closer to the real conditions in a research lab?
I met some NASA scientists doing atmospheric sampling on a plane, and they had to accompany their equipment to manage any equipment glitches during the expensive sampling process (a custom modified 747 flying from Hawaii to New Zealand IIRC)
Really physics discovery is partially limited by equipment, but in my time in the lab I have seen great physicists get remarkable results with equipment or setups that I personally thought was not up to the task.
As to college level experimental physics lab: the goal is not to get you to reproduce the nobel winning results, but to learn how to think like an experimental physicist. To hunt down issues, to calculate sources of error, to find out that some guy keeps running the microwave while you are taking sensitive measurements and that it actually impacted them and how.
It is the unimaginative or poorly taught that think the experimental physics lab in undergrad isn't important.
My one remaining did-not-graduate nightmare is that I never completed that course. And I was an experimentalist.
> This experience drove me right into theoretical physics
Had a summer student work on my nearly-intractable dissertation experiment. He immediately switched to theory.
In that class you aren't being graded on getting to the right answer. You are getting graded on how you approach getting the right answer, and no one expects you to get the right answer - in the ball park is generally the average for the course.
I saw that as a learning opportunity, teaches you which glues are cryo-proof, how to switch fuses on amplifiers (and other, more complicated electronics quick-fixes), and how important knowing people to borrow equipment from is.
Unless your lab is swimming in money, those are valuable skills for an experimentalist. And even if you swim in money, buying fancy new stuff has a minimum 8 week lead time while walking down the hall to the correct shelf to pilfer takes 5 minutes and gets you results before lunch.
> with less than motivated PhD students or post grads as teachers
This is an unfortunate truth everywhere I taught. Unfortunately, teaching the same thing 14 times a semester is no fun, and every single person who enjoys teaching (and is good at it) knows it, and instead teaches any available lecture, seminar, tutorial or exercise - anything, where you get to teach something new every week and that allows you to stay with the same students for longer.
You might wanna skip that postdoc thing though if you know you don't wanna stay in academia (and trust me, you don't).
https://web.archive.org/web/20001031193257/http://www.cs.wis...
The author of the angry rant had a life-defining experience of overwhelming frustration.
The same scenario resulted in a positive life-defining experience for me
It’s funny how unpredictably things pan out even in identical circumstances…
I really enjoyed the labs and it was seeing the predictions pan out in front of my eyes that actually got me interested in the first place. But you have to know what your getting into. The labs are extremely time consuming and required preparation.
Life is what you take out of it :)
Negative concentrations no problem! That must mean the machine is tracking the previous known value and this is the difference! Oh my oh my... The things I've seen the highly/expensively educated get paid lots of money to do, present, and be rewarded for in regulated industries....
https://improbable.com/publications/classics/
Sometimes you just get random results that has no relation to what you expected to get based on theory (and not just theory, but common sense). They're not zero and not over the top, they're just useless.
For an atom, you basically have to do quantum physics and talk about von Neuman entropy of it's quantum state. This kind of temperature is very removed from the everyday concepts of "heat" and "heat transfer".
For electrons and nuclear motion they are often strongly coupled enough that they quickly reach equilibrium and thus are at the same temperature (e.g. in liquids or solids). But on short timescales they can absolutely be at distinct temperatures. In dilute gases they can also become somewhat decoupled (there can be a well defined electronic temperature and nuclear temperature).
One case whether this can take a much longer period of time is when dealing with nuclear spin -- this is much more weakly coupled to the electrons and so can take much longer to equilibriate.
> 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.
I wish academia pays better.
It's not just darkly humorous, it could almost be satire:
> It has to the the kind of chemistry that people read and then jizz in their pants, they’re so excited about it. That’s right: we only do jizz-worthy chemistry
I'll assume due to the nature of chemistry, the field doesn't suffer as much from non-reproducible data, but overall, this sentence alone might explain cases like the Francesca Gino fraud [0], or why the head of Stanford resigned over integrity issues [1]? Or the Schön scandal? [2]
I mean take the analogy seriously for a moment: What the author is asking for in the analogie's universe, is for one of his students to just invent Stable Diffusion so he can generate pornography for his colleagues to.. well?
But no word about integrity or honesty. Nothing. Just results.
Author took it as inspiration:
> The truth is that under all the profanities, and the slave-driver mentality of the professor I saw someone who truly wanted to develop their students.
PhD students of HN enlighten me, after reading this crap, how is this "slave-driver" not just incentivizing to cheat?
[0]https://www.theatlantic.com/science/archive/2023/08/gino-ari... [1]https://www.theguardian.com/us-news/2023/jul/19/stanford-pre... [2]https://en.wikipedia.org/wiki/Sch%C3%B6n_scandal
I'm not a PhD student, but I stopped after a masters exactly because I didn't want the pressure we're discussing.
When you do it right you get this sort of picture. https://pdfs.semanticscholar.org/3753/2b8a21825d66633f33684a...
Having gone through a similar ordeal and frustration at the end of my uni career, in the end I went out with the highest admiration for the experimentalists and their tech staff.
[0]https://pages.cs.wisc.edu/~kovar/cv.html
did he quit and go into CS, is he on HN?
Did he make any other discoveries regarding the assiness of other fields of human endeavor as the years went by?
Also, there are many a decent xysicists in tech. Physics skews to supernerds like good CS folks, so there's quite a bit of problem-solving and subject matter crossover beyond the closest neighbor, EE/CS.
The Goog has pockets of okayness here and there, so maybe they've found a comfortable home after 12 years. :)
Electron Band Structure in Germanium, My Ass - https://news.ycombinator.com/item?id=30690075 - March 2022 (1 comment)
Electron Band Structure in Germanium, My Ass (2001) - https://news.ycombinator.com/item?id=16360479 - Feb 2018 (38 comments)
Electron Band Structure In Germanium, My Ass - https://news.ycombinator.com/item?id=2513293 - May 2011 (97 comments)
True dat.