Physics
drorzel | November 3, 2009We're going to host the New York Section meeting of the American Physical Society next spring (joint with the New England Section, which will tax our resources), with the theme of the meeting being applications of nuclear physics. We've divided up the job of finding speakers for the meeting, and I'm supposed to be inviting people who can talk about nuclear energy, either fission or fusion.
This is not exactly in my wheelhouse, but I have a couple of ideas. It occurs to me, though, that I have access to a global audience which presumably includes some people who either could give a good talk…
pontiff | November 3, 2009Over the summer I started running a not so insignificant amount: 6 miles in the morning on the weekdays and 10 to 15 miles on the weekends (insert commenter telling me why this is wrong.) So, one or two or more hours out running around beautiful Seattle (My favorite route is Queen Anne to Fremont to Ballard Locks, around Magnolia and back up Queen Anne.) Which brings us to the subject of time. During my runs it seems that my watch, which runs using mechanical energy, decided that it had a new setting: relativistic mode. In other words I'd go out and run for two hours, and when I got back…
drorzel | November 3, 2009... until the release of How to Teach Physics to Your Dog. The official release is set for December 22nd, though the books are set to start printing in about three weeks. Exciting, isn't it?
Are you excited about the upcoming release of _How to Teach Physics to Your Dog_?(survey)
If you're still wondering what all the excitement is about, let me direct you to the book previews page at dogphysics.com, where you can download a PDF of Chapter 1, and watch a little video I made to go with a dramatic reading of Chapter 3's dog dialogue. There will probably be more previews in the next few weeks…
esiegel | November 2, 2009My heroes had the heart to lose their lives out on a limb,
And all I remember is thinking, "I want to be like them!" --Gnarls Barkley
And here's a new discovery (to me): the Violent Femmes version to help you through your post-Halloween Monday:
The Ares I-X rocket has been all over the news recently. I'm not sure that the news coverage sufficiently showcases how impressive this rocket actually is. Sure, you've all seen a picture of the rocket on the launchpad.
Yes, the rocket has a long history. Yes, it's nearly twice as high as the space shuttle (at a whopping 327 feet, or 99.7 meters).…
drorzel | November 2, 2009One of my pet peeves about physics as perceived by the public and presented in the media is the way that everyone assumes that all physicists are theoretical particle physicists. Matt Springer points out another example of this, in this New Scientist article about the opening panel at the Quantum to Cosmos Festival. The panel asks the question "What keeps you up at night?" and as Matt explains in detail most of the answers are pretty far removed from the concerns of the majority of physicists.
But it's a good question even for low-energy experimentalists like myself, as it highlights the…
rallain | November 2, 2009I am sad to say the following comes from a school that I attended. This was from an alumni newsletter regarding the activities of one of the physics faculty.
"Since the time of Archimedes, sciences advanced along two avenues, through new experiments and through theory...."
I have a problem with just that first part, but it goes on:
"For many centuries, theoretical physicists devised clever mathematical methods to describe many physical phenomena, yet some of the most important ones - like the properties of matter, of proteins and living things, or of weather patterns - are far too…
rallain | October 31, 2009Here is the deal. Why would you put a lot of effort into explaining something wrong? I just don't get it. Wouldn't it be easier and better to just not say anything? The particular show I am ranting about is the 2008 Punkin Chunkin on Discovery (I think). Fairly ok show, but they should have left the science out. The part that made me speak out was when they were talking about the different types of punkin chunkers. They have:
Compressed air
Catapult
Trebuchet
Centrifugal Force Machine
To explain these devices (the physics behind them), the show brought in the big guns. Let's bring…
esiegel | October 29, 2009The farther backwards you can look, the farther forwards you are likely to see. -- Winston Churchill
Sometimes, we point our most powerful telescopes at the sky, peering as deeply as we possibly can, hoping to shed some light on what the Universe was like oh-so-long ago, as close to the big bang as we can. The Hubble Space Telescope can get us distant galaxies as they were just a few billion years after the big bang.
But Hubble still has never seen one of the elusive, Holy Grails of astronomy: a metal-free star.
You see, immediately after the big bang, the Universe was filled with protons…
esiegel | October 28, 2009In 1908, a huge fireball streaked across the sky and exploded a few kilometers above the Earth's surface, downing trees for miles and miles around but leaving no impact crater on the ground. This mystery was known as the Tunguska event.
But how did this happen? The amount of energy released was estimated to be somewhere between 5 and 30 Megatons of TNT. (Comparably to a "typical" hydrogen bomb.) What could've caused this devastation?
My answer: a large meteor or small asteroid/comet could have done this easily. How? Let me explain.
When a meteor enters Earth's atmosphere, it's moving very,…
drorzel | October 28, 2009Here's an extremely dorky Dorky Poll topic. I can't believe I haven't used this one before:
What sort of particles do you prefer?(poll)
Choose only one.
rallain | October 27, 2009I know I saw this demo somewhere. Maybe it was at an AAPT conference a few years ago. I have always wanted to build this, but never got around to it. Until now. Here is the demo (it is easy, you should make one too)
So, how does this work? I think the simplest explanation is that the drinks do not spill because the string can only pull in the direction of the standing glasses. A slightly better explanation is that the string lets the tray rotate so that the sum of the acceleration and the gravitational field is in the direction of the open ending of the cup. I am still not happy with…
esiegel | October 26, 2009Perhaps you've been following my ongoing series on dark matter. Perhaps, like many, you're still skeptical. After all, it's not like we've gone and made it in a lab or discovered it in an experiment. 15 years after David Weinberg composed the Dark Matter Rap, we still don't know exactly what dark matter is.
But there's a whole lot that we do know about it just from looking out at the Universe.
You see, there are a whole bunch of scales we can see, from galaxies to clusters to superclusters and the large-scale structure of the Universe as a whole.
And-- since the big bang happened just under…
pontiff | October 26, 2009Michael Green's appointment to replace Stephen Hawking as the Lucasian chair, has, quite predictably, brought back into the spotlight the ever simmering STRING WARS!!!OMG!!!STRINGTHEORYRLZ!!. Okay, maybe not the spotlight, per se, but I did find the article about Green in the Guardian interesting (via the so wrong it hurts fellow):
But that was one of their arguments, that the academy is so biased towards string theory - hiring mostly string theorists, crowning mostly string theorists - that it has driven out all other ways of seeing (Smolin compared it to deciding that there was only one…
rallain | October 24, 2009Sometimes it is difficult to come up with new labs. Ideally, a lab should show use some of the basic physics principles as well as have something the students can measure. What to do with circular motion? I don't know how I forgot this, but here is a lab I used to do as an undergraduate student. I also like it because it doesn't really need fancy stuff like PASCO probes or anything. The basic idea is that a small mass is swung around in a circle with the tension in the string controlled by hanging a mass on the other end. Here, let me show you.
Circular Motion Lab from Rhett Allain on…
drorzel | October 22, 2009"Hey, SteelyKid, whatcha doin'?"
"Nothin'. You know, hangin' out."
"'S'cool."
Just 63 weeks old, and already she's got the exaggerated casual thing down...
Happily, she's not too cool to occasionally pose with her father:
She's a great big baby, but she's still small to me.
esiegel | October 22, 2009Yesterday, I showed you a video of an amazing incidence of magnetic levitation. There's another video, courtesy of Matthew Sullivan and his students, that demonstrates this equally as well:
What do you need to do to make this happen, and how does it work?
First off, you need to design a stable magnetic track. This is actually simpler than you might think; you just need three magnetic "lines", where the outer two go in one direction, and the inner one goes in the opposite direction:
Next, you need a high temperature superconductor, typically made of Yttrium, Barium, and Copper Oxide. This…
drorzel | October 22, 2009I've been buried in lab grading for a lot of this week, but I'm finally down to the last few stragglers. The experience has me thinking a bit about what we're doing here, and talking to people in other departments, and it seems like a good question for my wise and worldly readers.
At the moment, we run on 10-week terms, and in a ten-week term, we typically do seven labs (the other three are canceled to make time for exams, or to avoid doing labs in the first or last week of the term. Some fraction of those seven labs are full formal reports, with an abstract, introduction, procedure, results…
rallain | October 21, 2009My friend Konrad showed me this awesome toy he made.
I know it doesn't make sense yet, so let me explain. Basically, you take this marble and roll it down the tray through the pegs. The pegs sort of randomize where the marble rolls through the hidden section. Inside the hidden section, it looks like this:
The object of this toy is to find the cross-sectional area of the rings. Konrad said he built this based off of a toy he was given in middle school. He wasn't told how to do it, just to do it. Maybe I shouldn't say anymore about that toy except that it is awesome. No instructions,…
esiegel | October 21, 2009I don't understand French nearly well enough to understand the explanation in this video, but I was amazed at what the physical world can do when I saw this video.
(Video courtesy of Wimp.com.) What's going on here? Well, you've got:
a series of bar magnets on the bottom,
a ceramic cylinder,
an insulating, non-magnetic piece of plastic between the magnets and cylinder,
and liquid nitrogen being poured into the cylinder before the insulator's removed.
Amazing! For those of you who like puzzles, you've got until tomorrow's post goes up to figure it out. (I'll give you a hint: Walther…
rallain | October 20, 2009I don't really know what that title actually means. So, I have been having problems with my PASCO projectile launcher devices. I will just call them launchers (they are really cannons). In my previous post, I looked at the launch speed from a launcher shot horizontally and vertically. The problem was that I was getting different launch speeds for the vertical and horizontal shot. So, here is my plan: shoot the ball and a variety of angles from 0 to 90 degrees and see how the launch speed changes. I will only use the data from video analysis (of course using Tracker Video Analysis)…