Physics
drorzel | March 31, 2008My post-tenure sabbatical, alas, is officially over today, as I begin teaching the honors section of the introductory E&M class. This will keep me busy for most of the morning, which makes it the perfect opportunity for a Dorky Poll:
Electricity or magnetism?
Yes, I know they're unified, and thus merely different manifestations of a single electromagnetic force. That's not the question-- you have to pick one or the other. Which one do you take?
Electricity would seem the obvious choice, given that the Internet isn't much good without it. Magnetism has that cool and counter-intuitive…
pontiff | March 29, 2008Lawsuit brought against CERN and the LHC for the possibility that it might produce black holes which will eat the earth. I look forward to seeing string theory on trial. Maybe something like an inverse "Inherit the Wind" play to follow.
Oh, and this made me laugh:
Mr. Sancho, who describes himself as an author and researcher on time theory, lives in Spain, probably in Barcelona, Mr. Wagner said.
Probably in Barcelona?
drorzel | March 29, 2008Over at Evolving Thoughts, John Wilkins pokes string theorists:
Ernst Rutherford, the "father" of nuclear physics, once airily declared "In science there is only physics. All the rest is stamp collecting". By this he meant that the theory of physics is the only significant thing in science. Such mundane activities as taxonomy in biology were just sampling contingent examples of physics.
So it is with some amusement that I note that in order to make sense of string theory, a group of physicists have been trying to do taxonomy over string theories.
I'm never sure who reads what blogs, but I…
pontiff | March 28, 2008Linear optics quantum computing, where one combines linear optics with the nonlinear processes of single photon creation and single photon detection, is a relative newcomer onto the scene of possible routes toward quantum computing. Whenever I think about these schemes, what jumps into my head is a crazily filled optical bench, like the one below from the Zeilinger group:
Now, I'm but a mere theorist, but I think even theorists like me understand that trying to build a large scale version of this scheme, which has considerable overhead behind it in terms of the number of modes needed, is a…
drorzel | March 28, 2008Back in the comments of one of the "Uncomfortable Question" threads, Matthew Jarpe asked (as background research for a new novel):
If someone were to hand you the keys to your own particle accelerator and you could do any experiment you wanted, what would it be?
Well, if somebody just gave me the keys to CERN, and left for the weekend, I'd be sorely tempted to steal some vacuum pumps and digital electronics. Because, dude, they've got some awfully nice stuff, and they'd hardly miss it...
I assume that the question is really intended to be what sort of particle physics experiment would I do…
drorzel | March 25, 2008Here's a picture of the gas-handling line leading to the discharge region seen in the plasma post:
How many valves can you count in that picture? If you said "seven," give yourself a pat on the back. Here's the same picture with the valves numbered for your convenience:
("Seven! Seven valves! Ha ha ha ha ha ha ha!!! thunder, lightning)
So why all the hardware?
Well, the gas bottle contains krypton gas at a pressure of several atmospheres. The discharge tube feeds into a vacuum system at 10-7 torr, thanks to some honkin' big pumps. We'd like both of them to stay that way, so some valves are…
drorzel | March 24, 2008A couple more pretty pictures of the apparatus, to pass the time:
This is the plasma discharge source that we use to make metastable atoms. We excite the gas using a RF coil (under the tinfoil) with a couple of watts of power at 145 MHz (local ham radio people must love me...), which creates a discharge in the glass tube. Some small fraction of the atoms are excited to the state that we want in the chaos of the plasma, and we work with those downstream.
When it's working right, there's a pretty steep pressure drop across the discharge region:
The pressure is much lower on the left (there's…
drorzel | March 24, 2008Behold, the end of the world is at hand!
They said I was mad-- mad!-- but now they'll pay...
Well, ok, it's not actually a doomsday weapon. It's a shot of the main experiment chamber in my lab, taken in very low light in an attempt to capture the orange glow of the ion gauge inside the chamber. It only looks like an instrument of apocalypse.
Here's a better lit picture:
And here's one showing a bit of the atomic beam line behind the chamber:
The large copper coils in the foreground are for the magneto-optical trap, while the longer coil stretching off to the right is the Zeeman slower. The…
jstemwedel | March 20, 2008Since March is Women's History Month, I thought it might be appropriate to recognize some women who were a part of my history -- namely, the women who taught me chemistry and physics. (This shouldn't be interpreted as a slight against the women who taught me biology -- I simply don't remember them as well -- nor against the men who taught me science. They made an impact on me, but this post isn't about them.)
I didn't realize it until just now, but none of my science teachers in junior high or high school were women. That strikes me as kind of weird. In contrast, during my undergraduate…
pontiff | March 20, 2008In high school, we had software which would simulate dynamics of different shaped objects. I used to set up part of the screen as a "hoop" and then try to design the crazies way for a ball to bounce off all sorts of shapes set with different initial velocities and into the hoop. It was kind of cool how Rube Goldburg you could get with this physics simulation, and it was, I'll admit, both quite fun, and absolutely geeky. Now, via Slate, I find that someone has made this into a game:
pontiff | March 20, 2008Dear Digg, no, this article and press release do not mean that Scientists Invent Room Temperature Superconducting Material. It means that scientists have put molecular silane under hundreds of giga-Pascals presures (for comparison, atmospheric pressure is 100 kilo-Pascals) at a temperature of around 20 Kelvin, and gotten it to superconduct. While this is certainly cool, it is not "room temperature" as far as I can tell.
One day I was driving down the road and listening to AM radio when Paul Harvey came on and did his schtick ("and now you know, the rest of the story.") At one point in the…
drorzel | March 20, 2008Johan Larson asks:
How would you change the requirements and coursework for the undergraduate Physics major?
This is a good one, but it's a little tough to answer. I have ideas about things I'd like to change locally, but I'm not sure I really have the perspective I would need to be able to say how much of what I see is a problem with physics education in general, and how much is due to local quirks (our trimester calendar being the biggest such issue) that don't generalize well.
That said, my feeling is that most of the problems we have are with the introductory classes. I went to an…
drorzel | March 19, 2008"A" asks:
Given the chance, would you take a job at a major research-university, or do you enjoy teaching a lot and doing some research at your small liberal arts college?
My first answer is "no," though I guess it would depend on the terms of the offer. In general terms, though, I'm very happy with my job.
I went to a small liberal arts college, and really enjoyed the experience, so I actually went to grad school with the idea of getting a Ph.D. and then teaching at a small college. I've ended up pretty much exactly where I wanted to be-- well, OK, I'd probably be even happier at a certain…
drorzel | March 18, 2008Via Steinn, a "meme" asking people to name women in science:
Rules:
1. You can't choose people from your own institution or company.
2. You can't google or use the internet to aid in your search. (But if you know someone is a scientist, but not sure what disciple, you can look that up).
3. You can consult textbooks, journals, and class notes.
4. You can ask others to help you brainstorm, but they can't use the internet just to get 5 names fast (see #2).
5. Living and deceased scientists are acceptable.
6. Links to or references about the named scientists are greatly appreciated. Let's share…
drorzel | March 17, 2008In one of his March Meeting posts, Doug Natelson writes about laser cooling experiments that explore condensed matter phenomena:
While the ultracold gases provide an exquisitely clean, tunable environment for studying some physics problems, it's increasingly clear to me that they also have some significant restrictions; for example, while optical lattices enable simulations of some model potentials from solid state physics, there doesn't seem to be any nice way to model phonons or the rich variety of real-life crystal structures that can provide so much rich phenomenology.
I would dissent…
drorzel | March 17, 2008Over at Physics and Physicists, ZapperZ is thinking about the intro curriculum, and offers a suggestion:
I believe that we should have a more open-ended experiment to be given to the students. So I'll give an example. Note that while thing is something that I've thought about for a while, I'm still writing this off the top of my head. So there may be other problems with it that I haven't carefully considered.
Give them a problem to solve such as something like this:
Construct a pendulum clock. To make this clock useful, it would be helpful if the pendulum can swing back and forth once as…
drorzel | March 15, 2008Paul Krugman is now a famour economist, but many years ago, he was "an oppressed assistant professor, caught up in the academic rat race." So, he did what any good academic would do in that situation: he wrote a silly paper to cheer himself up. In this case, a paper discussing the issues that arise in interstellar trade because of realtivistic effects.
It's a brilliant bit of silliness. It's hard to pick a favorite bit, but this is pretty good:
To conclude this section, we should say something about the assumption that the trading planets lie in the same inertial frame. This will turn out to…
pontiff | March 14, 2008Happy Talk like a physicist day, Happy Pi day, and Happy birthday dear uncle Albert.
So how does one talk like a physicist? I mean its hard for me to say, because I'm a physicist (or was, or am, or was molded into who I am by physicists.) But one can certainly sing like a physicist! Here is a song from grad school:
Schrödinger's cat, is getting rather fat
He wants to play, must way for radon decay
Why is he trapped in that box (clap, clap, clap)
He would rather be alive than dead
Schrödinger's kitten, stuck their sittin'
Stuck in a superposition, a quantum mechanical prison
Why is she…
drorzel | March 14, 2008The next lab visit experiments I want to talk about are really the epitome of what I called the "NIST Paradigm" in an earlier post. These are experiments on "four-wave mixing" done by Colin McCormick (who I TA'd in freshman physics, back in the day), a post-doc in Paul Lett's lab at NIST. As Paul said when I visited, if they had had a better idea of the field they were dabbling in, they would've thought that what they were trying was impossible; thanks to their relative ignorance, though, they just plowed ahead, and accomplished something pretty impressive.
The basic scheme is laid out in…
drorzel | March 14, 2008Today has been dubbed "Talk Like a Physicist Day". Why? Because we're at least as cool as pirates, that's why.
Over at Swans on Tea, Tom offers some vocabulary tips:
Use "canonical" when you mean "usual" or "standard." As in, "the canonical example of talking like a physicist is to use the word 'canonical.'"
Use "orthogonal" to refer to things that are mutually-exclusive or can't coincide. "We keep playing phone tag -- I think our schedules must be orthogonal"
"About" becomes "to a first-order approximation"
Things are not difficult, they are "non-trivial"
Large discrepancies are "orders of…