Physics
drorzel | March 12, 2009There's a really good article from Martin Rees in the latest issue of Seed, on the scientific challenges that won't be affected by the LHC:
The LHC hasn't yet provided its first results, the much-anticipated answers to questions we've been asking for so long. But they should surely come in 2009, bringing us closer to understanding the bedrock nature of particles, space, and timeâ--âtoward a unified theory of the basic forces. This would push forward a program that started with Newton (who showed that the force that made the apple fall was same one holding the planets in orbit), and continued…
drorzel | March 11, 2009Most people's first exposure to the ideas of modern atomic physics comes through the Bohr model of hydrogen, which treats the atom as something like a little solar system, with the positively charged nucleus as the sun, and negatively charged electrons orbiting in well-defined circular orbits. It's a very compelling picture, and works well for hydrogen (provided you make a couple of really odd assumptions), but it's completely wrong on the details. Electrons do not move in well-defined orbits, but rather exists as fuzzy wavefunctions spread over the space near the nucleus.
It turns out,…
drorzel | March 10, 2009The Gordon Research Conferences are a great program, if you're in a field that offers them. These are mostly in New England in the summer, and involve a lot more down time than most professional conferences, to allow for more informal interaction between attendees. At past Gordon conferences, I've played soccer with a Nobel laureate, and basketball with a number of Ivy League faculty.
I got an email announcement of the 2009 Atomic Physics Gordon Conference, to be held at the Tilton School in Tilton, NH June 28-July 3. This year's meeting is chaired by Tiku Majumder at Williams, and he's put…
rallain | March 6, 2009Temperature is a pretty weird thing if you think about it. How do you best define temperature? Let me go ahead and give you my favorite definition:
Temperature is the thing that two objects have in common when they have been in contact for a long time.
Yes, that is a good definition. Maybe now you can see why temperature is weird. Doesn't it have something to do with energy? Well, something - yes. Let me take an example. Suppose pour some hot coffee into a paper cup (I use paper because styrofoam(TM) is trademarked). Further suppose that this is super hot coffee from McDonald's. Can…
drorzel | March 6, 2009Over at Unqualified Offerings, Thoreau is bemused by his students' reaction to unusual numbers:
[I]t is fascinating how we condition people to be used to numbers in a certain range, and as soon as a number is either very big or very small it becomes disconcerting. On one level, I'm glad that they are able to do the conversion and that they at least realize that numbers need to be checked. I've had people happily measure the dimensions of an object in millimeters, get their conversion to meters wrong, and cheerfully tell me that their tiny metal cylinder has a volume of 27 cubic meters. At…
drorzel | March 5, 2009I'm looking travel arrangements for this year's DAMOP meeting in Charlottesville, VA in May, and, boy, do the options suck.
Flying into Charlottesville itself involves at least one stop, and undoubtedly one of those ridiculous little prop planes that require me to spend the whole flight in something close to a fetal position. Driving would take better than eight hours, according to Google, which isn't something I'm fired up to do (it's better than a prop plane, though, and wouldn't take all that much longer once you figure in time sitting in airports).
Probably the best option is to fly into…
drorzel | March 5, 2009EurekAlert had a press release yesterday titled Quantum paradox directly observed -- a milestone in quantum mechanics, which sounds like it ought to be great. The actual release, though....
For one thing, the description of the actual experiment is so vague as to be completely useless. It's not easy to quote without copying the whole thing, but it's short, so go read it yourself. Do you have any idea what's going on?
Second, it doesn't provide a complete citation for the article-- it gives the title, authors, and journal, but not the relevant page and volume information, which you need in…
rallain | March 4, 2009Some time ago, I wrote about the awesome things the Greeks did in astronomy. Basically they calculated the size of the Earth, distance and size of the moon and distance and size of the sun. The value obtained for the distance to the sun was a bit off, but still a bang up job if you ask me. (where bang-up is meant as a good thing) If the greeks were in my introductory physics lab, they would need to include uncertainties with their measurements. What would the uncertainty in the final value look like?
In my introductory physics lab course, I have students measure things and estimate the…
drorzel | February 28, 2009One of last year's physics majors is spending the year in rural Uganda working at a clinic/ school there. He's keeping a blog, which is intermittently updated by western standards, but remarkably up-to-date given where he is.
This week, he blogged about putting his physics education to use:
I have been doing a lot of electrical work the last two days. I connected a laboratory and rewired the whole system so that some safety switches would be in place and so that I would be the sole person with the knowledge and ability to decide who will have light. Actually, it is to break it up so that we…
rallain | February 26, 2009First, I think we should all be using smaller lighter cars. They get better gas mileage, they are better for the environment and maybe even reduce traffic? (ok, not sure about that last one - but it is possible). In Buzz Out Loud 918, they were discussing Toyota working on new car bodies built from sea-weed based plastics (from a wired article). One point that was brought is the comparison between old plastic bodies (the pontiac fiero comes to my mind) and these new plastics that should be much stronger. Well, here is the problem. Light strong bodied cars can be dangerous. Really? Yes…
drorzel | February 26, 2009ScienceWoman offers a good discussion question:
You are in a room with a bunch of other female faculty/post-docs/grad students from your university. You know a few of them, but most of them are unfamiliar to you. The convener of the meeting asks each of you to introduce yourself by answering the following question: "What is one aspect of your professional life that you are good at?"
It's a good topic that doesn't necessarily have anything to do with gender or the academy, so I will shamelessly steal it re-pose it without that frame:
What is one thing in your professional life that you do…
rallain | February 25, 2009I overheard this high school student complaining about a teacher. Here is essentially what she said (about a class her friend is in):
"This teacher is crazy. He said we have a test the next day and he gave them a study guide. But he didn't give the answers to the study guide. My friend and her mom stayed up till midnight looking up the answers on google."
I am pretty sure this was regarding a math class. So, what is the problem? I think there are a couple, but it mainly has to do with the nature of assessment. What is the point of assessing if students know (memorize temporarily) stuff…
pontiff | February 25, 2009Zotero, a Firefox extension for managing research sources, has announced the release of Zotero 1.5 beta. I've heard good things from those who use Zotero. This major update adds some nifty synchronizing and automatic backup. The next step after this for Zotero, I believe, is adding sharing capabilities.
By the way does anyone know what happened to arXiv on you harddrive? It's not been updated in over a year, which is a shame. Personally I find the arXiv's lack of publicity accessible methods for obtaining the full text kind of a bummer. There is so much fun you could have given the…
drorzel | February 25, 2009Over at Dot Physics, Rhett is taking another whack at photons. If you recall, the last time he did this wasn't too successful, and this round fares no better:
So back to the photon. In my original post I made the claim that the photoelectric effect is not a great experiment to show photons. Maybe that is not how it came off, but that is what I meant. The photoelectric effect can be explained quite well with the classical electromagnetic waves model and a quantum nature of matter. Of course there is a quantum nature to light as well.
I think the biggest problem with the photon is that the…
drorzel | February 24, 2009The winners of the American Physical Society's Science Writing Awards for 2008 were announced today:
Ann Finkbeiner won in the Journalist category for The Jasons, her book about a secretive groups of scientists who work on classified problems for the US government.
Gino Segre won in the Scientist category, for Faust in Copenhagen, about the early days of quantum mechanics.
Julia Cort won in the Broadcast category for the NOVA ScienceNow episode Asteroid, about whether a giant asteroid will kill us all in 2036.
Alexandra Siy and Dennis Kunkel have won in the Children's category, for their…
rallain | February 24, 2009Basically, the title says it all. Here is a short tutorial on projectile motion calculations with a spreadsheet.
Record your screencast online
I left out a lot of details, so maybe these links will help:
Spreadsheet tutorial for numerical calculations (video)
More details on numerical calculations
Projectile motion
rallain | February 24, 2009Quantum mechanics is not my area of expertise. Really, I have no area of expertise. However, I think it is time to bring the whole photon thing back up. Yes, I know I was a little harsh before. Maybe I should start over.
First, models. Yes models. I think science is all about models. Scientists build models that attempt to agree with observations. These models could be mathematical, physical, conceptual or numerical (like a computer program). For example, take Newton's Law of gravity (which isn't really a law). It says that the gravitational force between two objects has the…
drorzel | February 24, 2009the results from yesterday's poll on reporting exam scores were pretty strongly divided. 47% favored giving histograms, or some very detailed breakdown, while 33% were in favor of statistical measures only (mean, standard deviation, extrema, that sort of thing). 19% were in favor of giving no collective information at all.
My own usual practice is to give the high score, low score, and class mean, and that's it. This has as much to do with student psychology as anything else.
I provide the high score to prevent students with low scores from thinking "Oh, this was just impossible, so nobody…
drorzel | February 24, 2009Tallying up the results of yesterday's poll about formula sheets (as of 8:00 Tuesday morning, 39 total comments), people were overwhelmingly in favor of formula sheets. 72% of respondents reported being allowed to use formula sheets as students, and 69% were in favor of allowing formula sheets as faculty. A substantial number of the "no" responses were in favor of providing important formulae on the test paper.
This is more or less in accord with my own preferences. My general practice is to allow students to make up their own formula sheets in intermediate classes. In the introductory…
drorzel | February 23, 2009No, this isn't a mistake-- I'm doing two quasi-polls on academic issues today, because I care what you think...
I'm handing back last Thursday's exams today. The scores on the test were about what I expect, given the material. As I'm looking at the scores, trying to assess the class as a whole, I'm curious about the issue of score reporting, so I'll throw this out to the general readership:
What information do you think students should be given about exam scores?
You can answer this from either a faculty or a student perspective (please indicate which).
My general practice is to hand back…