Strings, Rings, and Other Things

Backstory: In my classes, I put my email address on the syllabus and tell students that I'll write back as soon as I can (sometimes even at crazy hours, if I happen to be up). Kim is even nicer: she even gives her students her home phone number (with strict instructions not to call past bedtime).

Fast forward to last night: Just as we were starting to clean up from dinner, the phone rang. Kim answered, and then said, "So you're having trouble with quantum mechanics? Sure, I'll get him." She handed the phone to me, and in response to my inquiring look she explained, "It's A---."

It turns out that A--- has the dubious fortune of taking classes from both Kim and me this semester, so when her study group got stuck on stuff for my class, she knew how to reach me. After a couple minutes of attempting to help over the phone, one of the folks in their group said, "We've got lots of questions on this stuff: can we just come talk to you in person?"

I paused for a moment as several thoughts flashed through my head: "Are you kidding? We've got to clean up and start moving toward bedtime." "This would be delightfully random." "Studies show high retention rates for students who make strong connections with faculty in their first semester of college." So I responded, "Sure! Here's our address." And a few minutes later, three students showed up at our door.

They stuck around for half and hour or so, maybe a bit more, and it went really well: with some extra hints and nudging from me, I think all three of them really solidified their understanding of the topic.[1] They also looked like they were having fun, and none of them could quite believe that it was real. (After ten or fifteen minutes, one of them randomly exclaimed, "Hey, remember that time in freshman year when we went to a professor's house at night for help on our homework?") It was fun, and I like to think that it had a positive impact, too.


[1]Namely, how to calculate probabilities when measuring the spin of an electron in a specified superposition state. Maybe I should have looked for some visually simpler way to represent superposition states than Dirac's ket notation, but I don't really know of a better alternative.

Quite a while ago, I mentioned the "#WowGood2Know" facts that I'd started including with the homework assignments in my intro physics classes; folks seem to like them. Well, this semester I mostly ran out of my existing list of those, and I decided to do something a little different: I shared a slightly longer discussion inspired by a (linked) blog post. That went over pretty well: according to my anonymous midterm course feedback survey, most people were at least a little interested and read what I'd written (even if they didn't usually follow the links), so I kept it up sporadically throughout the semester as I found more relevant links to share. I've now collected all of those discussions onto a web page: "Important Stuff Nobody Thought to Tell You (probably).

If you have a look at that list, you'll find that I wound up focusing on a specific theme: broadly on our social attitudes toward women, and more specifically on sexual violence. I might go further and say that the topic was fundamentally "rape culture", except that I made a point of not using that bit of jargon anywhere (though of course some of the articles I linked to do). I think that every single week that I included one of these discussions on the homework, I had at least one student stop by either after class or at some other time to thank me for drawing attention to these issues and for sharing such thought provoking reading. (A few became downright enthusiastic about what I was doing.) That made me feel awfully glad that I was doing it... and kinda cruddy that the bar was so low.

Not surprisingly (but disappointingly), every single person who gave me that sort of feedback was a woman.

Just before finals last year, I put up some workplace safety posters around our building:(I thought about making my own, but it was hard to find good raptor art so I just went with the best existing version I could find online.) I added post-it notes denoting "21" days, then "22", then "23", and a fair number of students seemed to be amused by the whole thing. (I even admitted responsibility to a few of them.)

Flash forward to this past Monday, when I walked into the building and found these: I have no idea who might have done it, but I was so, so proud. I can only assume it was a student (or more than one).

(Sadly, I realized today that these two posters had disappeared. My first assumption was that a housekeeping person saw the "vandalized" posters and took them down without thinking, but it struck me that it's also possible that they were taken by people who found them as funny as I do.)

My summer research student had a mysterious minor disaster at the end of the day: his backpack (and the textbook inside it) was quite thoroughly damp. The backpack had been fine when he set it down beside his desk early this morning; he only noticed the water damage when he started packing up for home.

We have no idea where the water came from. Apart from the wet spot on the floor where the backpack had been, every surface (and ceiling) in his office seemed completely dry (and no papers or dust showed signs of water). The backpack was damp all over, and the textbook had water damage along all three exposed edges of the pages as if water had flowed over the top and around down to the bottom. There weren't any water bottles that could have leaked, and he was in his office most of the day without noticing a thing.

Because of what we've been studying the past day or two, we both initially concluded that water must have quantum tunneled into his backpack from a nearby pipe. :) My more serious guess is that one of the facilities maintenance people (who've been cleaning the area) came by at a time when we were working elsewhere and spilled a fair bit of water onto (and into) his backpack. My charitable assumption is that they didn't notice the spill at all, or else they surely would have said something or at least made some effort to rescue the book. But even that seems surprising: what are the odds that they'd dump a bunch of water into his backpack and nowhere else?

Whatever the cause, we stayed an hour late at work interleaving paper towels between the pages to draw the water out. If that's helped by morning, we'll proceed to stacking heavy weights on top to flatten the pages. I hope it works! (And if it doesn't, hey, I got a free copy of that book from the publisher last year that I'm not particularly using. Merry Christmas to him, or something.)

[Despite first appearances, I promise that the humor here is reasonably accessible to non-physicists.]

The last homework assignment in my statistical mechanics class asked the students to write a computer program to simulate the simple Ising model of a ferromagnet. You model the magnetic material as an array of sites that are "spin up" and "spin down", and the simulation produces images showing how the up (black) and down (white) sites are distributed for various temperatures. Below a certain "critical temperature" the system is mostly magnetized; above that temperature, it becomes increasingly random. Especially interesting things happen right at (or very near) the critical temperature.

A couple of my students found some particularly unexpected results as the temperature approached this special value. Things went pretty much as expected as T decreased closer and closer to the critical temperature (the cluster size gets larger and larger, for example):



But when they made that last temperature change as described at the end of the page scanned above, it led to a result that I didn't expect at all:
( At the 'critical temperature' T=Mr )
I've gotta say, my students can be pretty cool.