Physics
rallain | January 27, 2009We have all seen the Kobe Bryant video of him jumping over an Aston Martin - this keeps coming up on the Internet. There has been vast discussions of whether this is real or fake. I will do my best to examine the evidence. In short (in case you don't want to read the whole thing) Kobe can most likely really jump that high, it is possible that there was some perspective trickery involved. Here is the video in case you are brand new to the WWW:
Oh - don't forget I already analyzed Kobe Bryant jumping over a pool of snakes. I voted that was real.
First, let me give a personal note to Kobe and…
drorzel | January 26, 2009Much of LiveJournal has been sunk in a sea of suck for the last couple of weeks, but there's a really interesting discussion of science education over at "Faraday's Cage is where you put Schroedinger's Cat." The first post has to do with the idea of "gatekeeping":
In my class today, a very brief discussion occurred between the teacher and another student about a topic which has bothered me for a long, long time: gatekeeping.
This particular student is a grad student in mechanical engineering, and she was talking about her personal teaching philosophy. She said it bothered her that in the…
ksharpe | January 25, 2009Review by Chad Orzel, from Uncertain Principles
Originally posted on: January 25, 2009, 4:18 PM
Michael Brooks's 13 Things That Don't Make Sense turned up on a lot of "Best science books of 2008" lists, and the concept of a book about scientific anomalies seemed interesting, so I ordered it from Amazon. It's a quick read (a mere 210 pages, and breezily written), but ultimately a frustrating book.
It took me several chapters to pin down what bugged me about the book, but it all became clear when I looked at the back cover flap, and saw that the author is a former editor of New Scientist. The…
rallain | January 25, 2009When you pour a beer, there is this foamy top called the head. The size of the head decreases over time. What is this process dependent on? Clearly, little bubbles of beer are popping. Does each bubble have an equal probability of popping? Do only the bubbles on the top (or bottom) pop? I became aware of this idea from a colleague. Maybe he was going to do an analysis, but I haven't seen it yet. If you do (Gerard), I am sorry for doing this before you. This may have been investigated before, but in the spirit of re-doing everything I have not searched for previous beer head studies.…
drorzel | January 23, 2009The last course report covered the first six classes of the relativity unit. This week, we had the final two relativity lectures, and today was the start of quantum mechanics.
Class 7: This lecture was about how you can use special relativity to show that a magnetic field in a stationary frame is an electric field in a moving frame. The basic idea is that when you move to a frame that is moving in the same direction as the (canonical) current, you see the spacing between the negative charges decrease due to length contraction, meaning that the wire no longer appears neutral. This leads to an…
drorzel | January 23, 2009The Physics and Astronomy colloquium this week was by Jill Linz from Skidmore, talking about a couple of physics outreach programs she's worked on. This being right up my alley, I made it a point to get in early enough to see the colloquium (I spent the morning at home with the sick SteelyKid, and Kate was good enough to come home for the afternoon), before giving an exam in the afternoon.
Linz took a somewhat different approach to physics outreach than a lot of other projects, which tend to focus on high-school students taking physics. She pointed out that if you look at the full student…
drorzel | January 22, 2009My graduate alma mater made some news this week, with a new quantum teleportation experiment in which they "teleport" the state of one ytterbium ion to another ytterbium ion about a meter away. That may not sound like much, but it's the first time anybody has done this with ions in two completely separate traps, in different vacuum systems. It's also written up in Physics World, though they spell Chris Monroe's name wrong throughout.
The paper is coming out in Science, and I may try to write it up for a ResearchBlogging post over the weekend. I may also need to add it to the quantum…
rallain | January 20, 2009So, you are taking a college science course. Maybe it is physics, maybe it is chemistry, maybe its a lab. Either way, you always end up with these problems that involve unit conversions. You think you have the hang of it, but sometimes you make some mistakes. Here is my explanation for converting units.
Convert units? Me? Why? I have google. Yes, that is true, google (for the most part) does an excellent job at unit conversions. But....I doubt your instructor will let you use google on your test. Don't you think you should have a good idea of how to do it? Don't worry. Unit conversion only…
drorzel | January 20, 2009This is flagged as a ResearchBlogging post, but it's a different sort of research than I usually write up here, as this is a paper from Physical Review Special Topics-- Physics Education Research. This is, however, a legitimate and growing area of research in physics departments, and some of the findings from the PER field are really interesting.
This particular paper, though, is mostly kind of depressing. The authors, including Nobel laureate Carl Wieman, gave students in three introductory physics classes a survey about their attitudes toward physics. They asked the students to indicate…
drorzel | January 19, 2009Back in the "Uncomfortable Questions" thread, Thony C suggested that I should do running updates on the course I'm teaching now. I meant to get to this sooner, but last weekend's bout with norovirus kind of got in the way...
I like the idea, though, so below the fold are a bunch of comments on the classes I've had thus far this term:
Class 1: Introduction to Relativity. I do a quick recap of the two classical physics classes that are pre-requisites for my class, showing the various conservation laws, and Maxwell's equations. I then set up a version of the problem that led to relativity,…
drorzel | January 19, 2009I think I missed this the first time around, but this weekend, I watched the bloggingheads conversation about quantum mechanics between Sean Carroll and David Albert. In it, David makes an extended argument against the Many-Worlds Interpretation of quantum mechanics (starting about 40:00 into the conversation).
The problem is, I can't quite figure out what the problem is supposed to be.
The argument has something to do with a thought experiment in which you take a million particles, prepared in a state such that a measurement of their spin will give an equal probability of measuring "up" or…
rallain | January 19, 2009I just can't pass this up. One of the chemistry majors had a complaint with the power company. After an unusually high previous power bill, they checked the electric meter half way through the month. The meter said they had used 90,000 kilowatt-hrs of electricity. That is a lot of energy. It is also a lot of money. If I estimate 10 cents per kilowatt hour (the prices varies in space and time), this would be a $9,000 bill.
So, what is the deal? Is it a broken electric meter? Could be. If it is not, maybe it is a short. Shorts usually blow a fuse, but if it were an older house, could…
drorzel | January 19, 2009Over at Biocurious, Philip is thinking about digital notebooks, and has found a system that works for him:
My computer algebra system of choice is Mathematica, and because of Mathematica's notebook system, it became extremely straightforward to include sufficient commentary among the analysis and calculations. The important "working" details of my day are recorded on paper that is heavy on scribbles, numbers, and comments on the minutiae of a particular instrument or measurement, followed by references to specific data files collected that day. The Mathematica notebooks where I visualize and…
purepedantry | January 16, 2009Scientists by have found evidence for the holographic principle in the search for gravity waves:
According to Hogan, the holographic principle radically changes our
picture of space-time. Theoretical physicists have long believed that
quantum effects will cause space-time to convulse wildly on the tiniest
scales. At this magnification, the fabric of space-time becomes grainy
and is ultimately made of tiny units rather like pixels, but a hundred
billion billion times smaller than a proton. This distance is known as
the Planck length, a mere 10-35 metres. The Planck length is
far beyond the…
rallain | January 16, 2009It has been windy here lately. Sometimes I think that is an ok thing. You see, when I ride my bike to work I am probably going to have the wind at my back for one of directions. It is great feeling like Lance Armstrong because of the boost you get from the wind. With a good wind at my back, I can almost keep up with the traffic (I would keep up if they went the 25 mph speed limit).
Of course, with a great boost comes a great drag. When I ride into the wind, I feel weak. I pedal as fast as I can and cars just whiz right by like I am standing still. When you are in a car, you don't…
pontiff | January 16, 2009The Perimeter Scholars Institute is a Masters level course designed to prepare students for cutting-edge research in theoretical physics. It looks pretty cool with some outstanding lecturers. The application deadline is February 1. All accepted students will be fully supported. Details below the fold.
Perimeter Institute for Theoretical Physics (PI) is a leading international research centre whose goal is to catalyze breakthroughs in our understanding of the physical world. PI strives to create a lively and dynamic research atmosphere where many approaches to fundamental questions, both…
terrasig | January 16, 2009The best coverage of the science behind the apparent "bird-strike" cause of yesterday's USAirways miracle on the Hudson can be found at Scientific American online:
It basically comes down to the physics equation for kinetic energy: Energy is proportional to mass times velocity squared. The velocity of the aircraft allows for the impact of this feathered bird to generate enough force to cause an engine to malfunction. [A 12-lb Canada goose struck by a 150-mph aircraft at lift-off generates the force of a 1,000-lb weight dropped from a height of 10 feet, according to birdstrike.org.]
Yes, this…
drorzel | January 16, 2009A number of people have commented on the big New York Times article about the new intro physics classes at MIT:
At M.I.T., two introductory courses are still required -- classical mechanics and electromagnetism -- but today they meet in high-tech classrooms, where about 80 students sit at 13 round tables equipped with networked computers.
Instead of blackboards, the walls are covered with white boards and huge display screens. Circulating with a team of teaching assistants, the professor makes brief presentations of general principles and engages the students as they work out related…
drorzel | January 15, 2009Over at Cosmic Variance, Sean writes:
You know what the world really needs? A good book about time. Google tells me there are only about one and a half million such books right now, but I think you'll agree that one more really good one is called for.
So I'm writing one. From Eternity to Here: The Origin of the Universe and the Arrow of Time is a popular-level book on time, entropy, and their connections to cosmology, to be published by Dutton. Hopefully before the end of this year!
Dammit! Now it's a race to see whose pop-physics book will be out first. The approximately final draft of my…
ksharpe | January 13, 2009Review by Chad Orzel from Uncertain Principles
Originally posted on: Tue, Jan 13, 2009 9:26 AM
Or, Brian Greene Writes a Kid's Book...
This is a very odd book. It's printed on boards, like a book for very small children, but the story is a bit beyond what I would imagine reading to a normal kid of the age to want books of that format. It's too short and simple, though, to have much appeal to significantly older children, aside from the fact that the story is written over the top of 15 absolutely gorgeous reproductions of pictures of astronomical objects.
This is probably one of those objects…