Physics
drorzel | January 7, 2010A number of people have commented on this LA Times op-ed by Steve Giddings about what physicists expect to come out of the Large Hadron Collider. It includes a nice list of possible particle physics discoveries plus a few things that will annoy Peter Woit, and also includes the obligatory note about spin-offs:
All this may seem like impractical and esoteric knowledge. But modern society would be unrecognizable without discoveries in fundamental physics. Radio and TV, X-rays, CT scans, MRIs, PCs, iPhones, the GPS system, the Web and beyond -- much that we take for granted would not exist…
drorzel | January 6, 2010I forgot to include an option about this in the previous Dorky Poll, but this is one of the best ways I know to sort out righteous physicists from heathen mathematicians:
How do you like your angular coordinates?(polls)
Choose wisely.
drorzel | January 6, 2010Today's lecture in intro mechanics is a whirlwind survey of vectors. While I struggle to clear my head enough to be able to teach this stuff, here's a Dorky Poll to pass the time:
What's your favorite three-dimensional coordinate system?(survey)
This is a strictly classical subject, so please choose only one.
drorzel | January 6, 2010Not a whole lot new, but it's been a few days. Also, it's a challenge to remain ambulatory at the moment, thanks to this cursed cold, so I'm not really prepared to turn out Significant Blogging.
-- This morning's vanity search (why yes, I am searching for "How to Teach Physics to Your Dog" on a daily basis. Aren't you?) turned up this Current Geek podcast, which talks about the book. They haven't read it yet, but picked up the BoingBoing mention, and are enthusiastic about the idea. They pretty well nail the thinking behind the book.
-- The vanity search also turned up this discussion of my…
drorzel | January 5, 2010"Slow light" is in the news again. The popular descriptions of the process usually leave a lot to be desired, so let's see if we can't do a slightly better job of explaining what's going on. The key idea is using one light beam to control the transmission of another.
Let's say you have a bunch of atoms in a gas and a laser. The laser happens to be at exactly the right frequency to be absorbed by the atoms, meaning that if you try to shine the laser through the gas, it'll be absorbed, and won't make it out the other side. This is traditionally represented by a diagram like to one to the right…
oracknows | January 4, 2010Over the holidays, I stayed at home for a combination of some relaxation and some grant writing. (I know, weird.) As I was perusing some of the links I saved during that time, it occurs to me that I totally forgot about one particularly amazing bit of hilarity, courtesy of our old "friend" Deepak Chopra. Given that it was over a week ago, it's probably not worth going into the full Orac mode on it any more, old news and all, but I couldn't let it go completely unremarked upon because it's just so amazingly, hysterically funny. Appearing two days after Christmas, Chopra's post was entitled Woo…
rallain | January 4, 2010This is great. Many people have already reported google's apple-dropping homepage in honor Newton's birthday. In case it disappears, here is a screen shot.
So, I got this awesome note from Dale Basler. He said that his class had analyzed this falling apple animation. What a very Dot Physics-y idea (check out his analysis). He said they were questioning the results which might be due screen capture issues. I decided to reproduce this.
I captured the motion with Apple's Quicktime X screen recording feature. I then used Tracker Video Analysis - which now has an autotracking feature that…
drorzel | January 4, 2010I spent most of Saturday in the lab, swapping out a turbopump that was starting to die. How could I tell? Well, for one thing, it made an awful noise, even more than usual for a noisy pump. But after it was stopped and unmounted from the chamber, there was a simple test: comparing the rotation to a second pump that I knew was in better shape:
The pump on the left (with the copper gasket stuck to it) is the old one; the pump on the right is the one that I replaced it with. As you can tell, even with a bearing starting to go, it's a pretty damn good rotor, but clearly worse than the…
drorzel | January 4, 2010Let's say you have some liquid that you want to contain without leaks, say, milk for a baby. What do you do?
Well, you put it in something like a baby bottle, the components of which are shown here:
You have a hard plastic bottle, a soft silicone nipple, and a hard plastic ring that screws onto the bottle. When you put it together and screw the cap down tight, it compresses the silicone between the two plastic bits, squeezing it into the small gaps, and plugging any leaks. Done properly, this will ensure that milk doesn't leak out of the bottle except through the whole in the nipple.
Now,…
drorzel | January 4, 2010Today is the first day of classes, and to celebrate, I've come down with the Martian death virus that Kate and SteelyKid have had the last few weeks. Joy.
This calls for a How to Teach Physics to Your Dog update, to distract myself from the cotton balls and vacuum pump oil that have apparently been stuffed into my sinuses:
The primary news is that Peter Woit has posted a review, in which he says mostly good things:
While Brian Greene in his Elegant Universe Nova special introduced general relativity by trying to discuss it with a dog, concluding that "No matter how hard you try, you can't…
rallain | January 3, 2010Wow. In xkcd 681 comic, there is an impressive illustration of the common term "gravity well". Here is a small part of that large image:
I can't resist. I must talk about this awesome illustration. My goal for this post is to help someone understand that comic (although the comic itself does a pretty good job).
Energy
Energy is the key here. Here, I will talk about two types of energy - kinetic energy and field energy. In this case, kinetic energy is basically just the energy associated with something moving. Field energy is the energy stored in the gravitational field. You could…
drorzel | January 3, 2010Over at Faraday's Cage, Cherish has a very nice post on Fourier series, following on an earlier post on Fourier transforms in the Transformers movie. She gives a nice definition of the process in the earlier post:
A Fourier Transform takes a signal and looks at the waves and then shows us the frequencies of all the waves. If we only have a single sine wave, like above, we will have a frequency that is zero everywhere except for the frequency of that sine wave. More complicated signals will be made up of several of these different frequencies and thus will have several peaks. The idea is that…
drorzel | January 2, 2010In talking to a reporter about How to Teach Physics to Your Dog on Wednesday, I learned of a mistake in the text of the book-- a footnote on page 71 says that Scientific American published an article on how to make your own "quantum eraser" in April 2007, when in fact it was May 2007.
If that's the worst mistake in the published book, I'll be very happy. It is a mistake, though, and needs to be corrected. This also reminded me that I never did post the scholarly references that go with the book, so maximizing the birds killed per stone, I have added a References and Errata page to DogPhysics.…
jstemwedel | January 1, 2010Dr. Free-Ride: So tell me about that device of yours? How did you make it and what does it do?
Elder offspring: There is a cut piece of a drinking straw. You also need two pieces of tin foil and a long string.
Dr. Free-Ride: That's really aluminum foil, isn't it?
Elder offspring: They call it tin foil.
Dr. Free-Ride: Well, I've been meaning to have a word with "them" about that. Anyway, how did you assemble the device.
Elder offspring: First, you put the string through the piece of straw. Then, you pinch the pieces of foil into bow shapes (like bow-ties), and then you tie the ends if the…
drorzel | January 1, 2010There isn't all that much news for a real obsessive update, so I'll lump in a few writing-related items of possible interest to people who read books other than mine.
A real obsessive update item: BradDeLong doubts my book can help his dog.
How to Teach Physics to Your Dog gets four out of five stars as part of a good books round-up in the Timmins Daily Press in Ontario. (Google News search is nifty).
A fortuitous discovery thanks to, of all things, an ad in GMail: QM for cat lovers, part of an old blog of imaginary conversations with Einstein. I doubt this will change anybody's mind about…
rallain | January 1, 2010It's odd that I have talked about these forces so much. First, I talked about how centrifugal forces were not real and the difference between centrifugal and centripetal forces. Then I talked about how sometimes, fake forces are good. Finally, I talked about the origin of the words centrifugal and centripetal. (note: "talked about" means wrote a blog post)
In thinking about centripetal forces, I realized that I could come up with a situation in which the centrifugal force is the centripetal force. This is great. I can end all the confusion between centrifugal and centripetal by making a…
esiegel | December 31, 2009Blue Moon
You knew just what I was there for
You heard me saying a prayer for
Someone I really could care for... -Richard Rodgers & Lorenz Hart
Tonight is the last night of 2009, there's a full Moon, there's a sliver of a partial lunar eclipse, and it's the second full Moon this month.
Q: Does having two full Moons in a month make it a Blue Moon?
A: In our modern times, yes, that's what we use that colloquialism to mean. The phrase "Blue Moon" is much older than that, dating back to at least 1528, where a pamphlet attacking the dogmatism of the church states:
Yf they say the mone is…
drorzel | December 31, 2009A couple of days ago, the LHC Blog asked about the future funding of the arxiv pre-print server, currently hosted at Cornell. Cornell is looking to get some external funding, though:
Currently the plan is to ask the "heaviest user institutions" (other university library systems) to voluntarily contribute to support arXiv operational costs. The FAQ states that the library has already secured commitments from 11 of the 20 institutions that make the most use of the arXiv. (I've seen an unofficial list; these include many of the 'big name research institutes' around the world.) In return, besides…
rallain | December 31, 2009A couple of commenters expressed concern over the use of centrifugal force after my rant on the use of the word force. So, what is the deal with these two terms? Are they ok to use? Are they real forces?
First, are they real forces?
It depends on what you mean by real. What is a force? Here is a quick overview of what a force is. I previously talked about real vs. non-real forces. For me, I say that if the force is essentially one of the 4 fundamental forces then it is "real". With this definition, centripetal force would be real and centrifugal not real.
Centripetal Force
Centripetal…
esiegel | December 30, 2009Oh the weather outside is frightful,
But the fire is so delightful,
And since we've no place to go,
Let It Snow! Let It Snow! Let It Snow! -Sammy Cahn and Jule Styne
Yesterday in the late afternoon (and yes, it's dark by late afternoon here in Portland, OR), I looked out the window and saw a rare sight for this part of the world.
That's right, it snowed here! So, what did we do? We went out and played in it, like children, because it's fun.
It was a good snow. For me, that means it wasn't too powdery, and didn't fall apart when you tried to make snowballs out of it. (Clearly.) In fact, it…