Physics
drorzel | February 23, 2009In the basement, across the hall from my lab, there are three plastic-covered collages made up of formula sheets from long-ago exams. One of my colleagues let the students in a Physics for Pre-Meds class write whatever they wanted on one sheet of paper to bring into the final, and made art from the collected pages after the test.
I was thinking about this last night as I graded last Thursday's exams, looking at the formula sheets I collected from the students. The range of things that people decide to immortalize on paper is pretty impressive.
Of course, such sheets are not universally loved…
rallain | February 21, 2009This is one of my favorite demos. Easy to do and doesn't really require any equipment. The basic idea is that you support a meter stick horizontally with two fingers. Slide your fingers in and they will both meet at the center of mass. Here is a video.
Meterstick friction demo from Rhett Allain on Vimeo
So, how does it work? To explain this, you need to understand friction and equilibrium. Well, nobody really understands friction - but anyway..
First, what is equilibrium? Equilibrium means that an object's motion does not change. For this case that means that both it's velocity and it…
pontiff | February 20, 2009Okay, so keeping running notes on friendfeed isn't going to work for me. Just too hard to do this and make a readable record. Really we should just be taping the talks.
Summary of day one below the fold (this may be a bit off as this is being written a day later.)
Jack Harris, Optomechanical systems
Papers: arXiv:0811.1343, arXiv:0707.1724.
Jack talked about his cool work coupling optical systems to mechanical systems. Take a cavity and stick a mechanical system (a dielectric membrane of thickness 50nm and quality factor of about a million) into it. Jack showed how you could cool the…
drorzel | February 20, 2009I left off last time with a brief introduction to uncertainty, followed by two classes worth of background, both mathematical and Mathematica.
Class 15 picked up the physics again, starting with an explanation of the connection between the Fourier theorem and uncertainty, namely that any attempt to construct a wavefunction that has both particle and wave propertied will necessarily involve some uncertainty in both position and momentum. This is basically Chapter 2 of the book-in-progress, with a bit more math.
After that, I start laying out quantum mechanics in a more formal way, stating…
drorzel | February 19, 2009A few days ago, Bee put up a post titled Do We Need Science Journalists?, linking back to Bora's enormous manifesto from the first bit of the Horgan-Johnson bloggingheads kerfuffle. My first reaction was "Oh, God, not again..." but her post did make me think of one thing, which is illustrated by Peter Woit's latest (no doubt a kerfuffle-in-the-making).
Bee quotes Bora urging bloggers to keep twirling, twirling, twirling toward the better day when scientists communicate to the general public, without all the hype and exaggeration:
Perhaps if we remove those middle-men and have scientists and…
drorzel | February 18, 2009I've already mentioned two of the program items I was on at Boskone (global warming and quantum physics for dogs). I should at least comment on the other two, "Physics: What We Don't Understand" and "Is Science Addicted to Randomness?" They both featured me and Geoff Landis, but other than that were very different.
"Physics: What We Don't Understand" took off from a column by John Cramer from ten years ago, laying out seven big problems in (astro)physics that hadn't been solved. We talked about how some of Cramer's items have been more or less solved (gamma-ray bursts, solar neutrinos, and…
rallain | February 17, 2009The first thing from AAPT that I would like to mention is SAM Animation that Brian Gravel demonstrated. SAM is free software that allows for the easy creation of stop motion animations. Basically, you use a web camera to take successive pictures and put them together as a movie. The software includes features (I think they call it an onion view) to see your previous frame while you are making the next frame. I think the software also lets you do time-lapse videos (which I think are awesome but they take lots of patience).
Fine, it is cool, but what do you do with it? Besides make movies…
drorzel | February 17, 2009I no longer remember the context, but the Gravity Probe B experiment came up in discussion around the department last week, and nobody could really remember what the status of it was. It came up again during the "Physics: What We Don't Understand" panel Saturday morning, where Geoff Landis was able to supply a few details from inside NASA. It came up again during a later panel on the year in physics and astronomy, and again, Geoff was able to supply some details.
I'm not sure what the deal is, but there's evidently something in the air at the moment making people think about Gravity Probe B,…
drorzel | February 16, 2009On Saturday at Boskone, I gave a talk on the Many-Worlds Interpretation of QM. This was held up a bit by waiting for the projector to arrive (I was busy enough with other stuff that I didn't notice that I hadn't received confirmation of my request for a projector until late Thursday night, so this was entirely my fault). They were able to come up with a projector, sparing people the need to squint at my tiny tablet PC screen, but it took some time off the beginning of the talk.
The talk consisted of me reading the dog dialogue from Chapter 4 (not to different from the original post), then…
rallain | February 15, 2009Someone complained about a teacher using this question and the answer was disputed. After some time, the teacher claimed that the answer was that lightning is static electricity because she looked it up on the internet. So, I decided to look also, here is what I found searching for "what kind of electricity is lightning?" in google:
Electricity Facts - Dialogue for Kids (Idaho Public Television)
A couple of complaints about this site:
First, I am not fond of the term "Science Facts". What is a science fact? Something that is proven true? This really is not how science works.
Second, I am…
pontiff | February 14, 2009In addition to the distinguished Dr. Hawking, the Perimeter institute lands nine very impressive distinguished research chairs, including some familiar quantum names.
The presser:
Nine Leading Researchers Join Stephen Hawking as Distinguished Research Chairs at Perimeter Institute in Ontario, Canada
WATERLOO, Ontario, Canada, February 9, 2009 - Dr. Neil Turok, Director of Canada's Perimeter Institute for Theoretical Physics (PI), is pleased to announce the appointment of nine more outstanding international scientists to the positions of PI Distinguished Research Chairs.
The new Chairs…
rallain | February 13, 2009The local Society of Physics Students invited me to watch the movie Sunshine and then participate in a post movie discussion. There was one thing in the movie that really got me. Of course the movie made many of the common space mistakes. But this one didn't seem necessary. Let me outline this part of the movie (I guess I should say spoiler alert - although this isn't central to the main plot). Here are three frames of a comic I drew to reproduce the scene.
After watching Sunshine, the astronauts try to go from one ship to another without space suits (well, one of them had a suit).…
drorzel | February 13, 2009I've been a Grumpy Blogger this week, what with one thing and another (some of my general malaise has finally resolved into a cold, which I suspect explains a lot). I'm headed to Boskone for the weekend, though, so let's end the week on a positive note. I'm declaring this a Happy News Open Thread: if you've got something positive to report, leave it in the comments.
some happy thoughts to get things started:
Two of Union's librarians (one of whom is a regular in our lunchtime basketball games) have won an award from the American Library Association. Congratulations, Bruce and Gail!
One of…
pontiff | February 12, 2009Over at the fact builders blog, the fact master discusses The Physics of....Pink Floyd. Being two areas I greatly enjoy, I was reminded by the fact builders picture of the cover of "The Dark Side of the Moon" of a little known piece of Pink Floyd strangeness. Anyone notice something peculiar about the back and cover of DSOTM:
Update: Ian provides a picture of the inside of the DSOTM, where, we find, all hell breaks loose:
rallain | February 12, 2009Since this could be current events, I am reposting my analysis of space debris in the movie Wall-E.
Here is a shot from the scene where the space craft is leaving Earth:
In this scene, the spacecraft has to break through all the Earth-based space debris. The first problem is that the unused satellites are just sitting there. If they were to stay in orbit, they must move. Maybe the WALL-E creators are sticking with the no air means no gravity idea. At least they are consistent.
The other problem with that scene is the sheer amount of junk in orbit. Suppose that was 300 km above the surface of…
drorzel | February 11, 2009I didn't expect the post griping about the Best American Science Writing anthology to generate as much discussion as it did. Shows what I know.
In comments, "bsci" made a good suggestion:
Instead of complaining about this volume, I'd love it if you and your readers made a list of the best physics writing in the past year. I assure you that I would be one of many readers of the pieces on the list.
That's a good suggestion, so let's put it out there: What were the best articles about physical sciences published last year? These could be in general magazines (The New Yorker, etc.), in science…
rallain | February 10, 2009Last friday I volunteered as a science fair judge. It took half a day, but I did get free food and tons of things to blog about. There are so many things to say about science fairs that I don't really know where to begin. I actually might not even address all the issues. Here is what I would like to talk about (in no particular order):
What is the purpose of a science fair?
How do you win a science fair? Tips.
What about judging? Are the normal methods reliable?
Data Analysis tips for middle schoolers
Creativity vs. the Internet vs. parents.
Social Science Fair posters? Er?
Why…
drorzel | February 10, 2009I'm running a little behind this week, but I wouldn't want this week's Science Saturday bloggingheads to slip by without a mention. It's a conversation between George Johnson and Louisa Gilder about The Age of Entanglement, which I liked quite a bit:
The conversation is primarily about her book, the story it tells, and how she came to write it. There's also some discussion of publishing in general, and a bit about the recent teleportation results from Maryland, toward the end.
drorzel | February 10, 2009Like a lot of physics departments, we offer an upper-level lab class, aimed at juniors and seniors. There are a lot of ways to approach this sort of course, but one sensible way to think about it is in terms of giving students essential skills and experiences. That is, i's a course in which they learn to do the things that no physics major should graduate without doing.
I'm sure that other disciplines do something similar, so I thought I might throw this out there as a general question:
What are the essential skills and experiences a student ought to have before graduating with a degree in…
drorzel | February 9, 2009Kind of a belated gripe, but something I was reminded of today that I forgot to blog when I first noticed it. I griped last year about the fomulaic nature of the "Best Science Writing" anthology, but I had no idea that the 2008 version would be worse.
OK, I haven't read it, but I leafed through it in the store, and there's not a chance that I would squander beer money on it: there isn't a single piece about physics in it. Not one of the 19 articles highlighted by special guest editor Sylvia Nasar is about physics. Or astronomy. Or geology. Or, really, anything that wasn't essentially…