Physics
purepedantry | October 10, 2006News@Nature has the best summary of what is known about North Korea's missile test that I have read thus far.
How big was the blast?
Estimates for the bomb's yield (the amount of energy discharged when the weapon is detonated, in the equivalent mass of trinitrotoluene, or TNT) differ widely, from 550 tons of TNT to 5-15 kilotons (this last a Russian estimate). By comparison, the Hiroshima bomb was about 12.5 kilotons.
The lower estimate is very small: it would be difficult to build a bomb with a critical mass of plutonium that creates a blast like this. It may be that the bomb didn't…
drorzel | October 10, 2006Lee Smolin's The Trouble With Physics is probably the hot physics book of the year. Granted, that's not saying very much, relative to whatever Oprah's reading this week, but it's led to no end of discussion among physics types. And also, frequently, the spectacle of people with Ph.D.'s squabbling like children, so reviewing it is a subject that I approach with some trepidation.
I'm coming to this late enough that it's hard to talk about the book without also talking about the various responses to the book. I'll do my best to split that material off into a separate post (if I post it at all),…
drorzel | October 8, 2006I finished Lee Smolin's The Trouble With Physics last night, and will write up a full review in the next couple of days. On the whole, I thought it was a well-done book, and he makes some good points. It's not without its problems, though, chief among them being the fact that the title is missing some words.
The book is really The Trouble With [Theoretical Particle] Physics, but Smolin, like the string theorists he criticizes for arrogance and narrow-mindedness, consistently talks about string theory and quantum gravity as if they were the only areas of physics that matter, and about physics…
drorzel | October 7, 2006Sean Carroll comments on an item in the Atlantic Monthly on test scores compared across nations. There are two things that really bug me about this item, the most important of which is the deeply dishonest graphic the Atlantic did to illustrate the item.
Here's the honest version of the graph, redone using data from this table (the relevant figures don't appear in the report cited in the original piece). (Click on the graph for a larger version.)
I've plotted the normalized test score (the score for each country divided by the reported maximum score, because I'm a physicist and like…
drorzel | October 6, 2006Third and final post in a series about "teleportation" from July 2002. This one is mostly dedicated to voicing the same complaints I have about the more recent stories that kicked this whole repost business off.
The more things change, the more I keep repeating myself.
So, having discussed how to do "quantum teleportation," how does this get us to "Beam me up, Scotty?" Well, that's the thing. It doesn't, not in any meaningful sense. What gets "teleported" is just the state of the initial quantum particle, not the particle itself. There's no reason why you couldn't do "teleportation" with…
drorzel | October 6, 2006Part two of three of an explanation of "quantum teleportation" experiments, from July of 2002. This one goes through the basics how teleportation works. I might be able to do better now, having worked through it in more detail in order to teach about it in my Quantum Optics class, but it's been a busy week, so I'll just repost the old entry for now.
So, the last whopping huge physics post here covered the idea of quantum entanglement-- how do you get from entanglement to "quantum teleportation", which is what the article that kicked the whole thing off was about?
The first step here is to…
drorzel | October 6, 2006As threatened in the previous post on new "quantum teleportation" results, here's the first of three old articles on teleportation. This one discusses EPR states and "entanglement." It's somewhat linkrotted-- in particular, the original news article is gone, but the explanation is still ok.
This dates from July of 2002, which is like 1840 in blog years.
Yet again, SciTech Daily provides me with weblog material, this time in the form of an oddball article in the Las Vegas City Life archives (how do they find this stuff? It never would've occurred to me to look there...). The article is mostly…
drorzel | October 6, 2006The latest physics news is an experimental demonstration of "teleportation" involving both light and atoms, done at the Niels Bohr Institute in Copenhagen, and reported on by the Institutes of Physics and CNN, among others, and remarked on by Dave, among others.
I wrote up some stuff about teleportation in the early days of this blog, and I'll Classic Edition those posts in a little while. "Teleportation" stories always kind of annoy me, though, because the reality isn't nearly as cool as the image that the term evokes. To some degree, it's a triumph of marketing more than a scientific…
drorzel | October 5, 2006So, there's a new issue of Physics World magazine out, with a bunch of feature stories on the Large Hadron Collider. Three of these are available free online:
Life at the high-energy frontier, a sort of overview of the accelerator and the people involved.
Expedition to inner space, a discussion of what they hope to discover at the LHC.
How the US sees the LHC, which is obvious.
I'm particularly interested in one of the articles that isn't free online, though: "Beyond the Higgs" discussing what would happen if the LHC fails to find the Higgs boson. My interest stems from the fact that the…
drorzel | October 5, 2006Last week, Mike Dunford was struggling with some teaching issues, relating to what level of effort he should expect from his students. His original decision drew some harsh criticism, both in his comments and from Sandra Porter, leading Mike to reconsider matters.
I meant to comment at the time, but I gave an exam last Thursday, which kept me kind of busy, and then there was the SAT Challenge to get ready.The issues Mike raises present some tough questions: on the one hand, you want students to learn to learn for themselves, and that occasionally runs counter to their immediate impulses,…
drorzel | October 4, 2006The Paper of Record provides the Story of Record for yesterday's Nobel Prize in Physics for Mather and Smoot, including recent photographs of both. One of my favorite bits of the 1997 Nobel was seeing the media circus that went on around the Prize-- I'll put some amusing anecdotes into another post.
All the usual blogger suspects have weighed in with comments, including but not limited to Sean, Rob, Steinn, Clifford, and Jennifer Ouellette. Most of them took the time to find the appropriate COBE graphics to illustrate their posts, which I was too lazy to do.
Janet Stemwedel deserves special…
drorzel | October 3, 2006A little while back, I offered a Nobel betting pool, and promised to allow anyone who successfully predicted the name of at least one of the winners of the Physics prize to pick a post topic here:
If you correctly predict the name of at least one of the winning physicists, I'll post an article on a topic of your choosing (within reason-- I reserve the right to refuse to write on offensive or inflammatory topics) on Uncertain Principles.
Much to my surprise, Tom Renbarger got two names right.
So, congratulations, Tom. Feel free to gloat, and leave your topic request in the comments.
drorzel | October 3, 2006Hot off the presses: The Nobel Prize in Physics goes to John C. Mather and George Smoot "for their discovery of the blackbody form and anisotropy of the cosmic microwave background radiation." This is recent enough that they don't even have much on the Nobel site, but happily for me, it's something I know a tiny bit about.
The prize here is for the COBE ("Cosmic Microwave Background Explorer") mission back in the early 1990's, which made extremely precise measurements of the radiation left over from the Big Bang (the discovery of which led to a previous Nobel for Penzias and Wilson). Mather…
drorzel | September 28, 2006The fourth and final post in my 2003 series attempting to explain experimental particle physics to the lay reader. This one talks about the specifics of the "pentaquark" experiment that was announced that year, and provided the inspiration for the whole thing.
It should be noted that that discovery is by no means certain, but I'm still fairly happy with the explanatory aspects of these posts. I'm certainly not bothered enough to re-write them.
So feel free to ignore pentaquark-specific comments in these reposts. If you'd like a more recent experimental hook for this, Tommaso Dorigo has you…
purepedantry | September 28, 2006I love YouTube -- so many ways to waste time at work.
Check out this video of a popped balloon in zero gravity.
drorzel | September 28, 2006This is the third in a series of posts covering the basics of particle physics, originally posted back in 2003. In this installment, I talk about some of the hardware involved, specifically the CLAS detector at Jefferson Lab, because I've heard a good number of talks about that.
It should be noted that the inspiration for this whole thing was the announcement of the discovery of a "pentaquark" particle at a couple of accelerators. That discovery is by no means certain, but I'm still fairly happy with the explanatory aspects of these posts. I'm certainly not bothered enough to re-write them.…
drorzel | September 28, 2006Blogging will be light today, as I'm giving an exam and making another magnet coil. I've also been working on getting the Blogger SAT Challenge results ready to go-- big roll-out coming soon!-- so I haven't been able to pre-schedule posts.
All I have time for this morning is a quick follow-up to yesterday's betting pool post, noting some other people trying to guess the winner's of this year's dynamite money.
First, guessing the Nobel winners is the topic for this week's Ask a ScienceBlogger (archival link here), so you can see what my colleagues have to say. Not much, yet, but maybe they'll…
purepedantry | September 27, 2006Lee Smolin -- author of The Trouble with Physics -- was interviewed on the Leonard Lopate Show (on WNYC) talking about string theory and why he thinks we shouldn't change scientific standards because of experimental difficulties. A really interesting interview. You can listen here (it is a streaming mp3).
drorzel | September 27, 2006Well, not really. That wouldn't be legal.
But the Nobel Prize in Physics for 2006 is scheduled to be announced next Tuesday, and this clearly calls for some irresponsible speculation. Who do you think will win? How about a guess as to what field of physics will be honored this year?
If you think it'll help, the last five prizes were:
2005: Quantum optics
2004: Asymptotic freedom
2003: Superconductivity theory
2002: Neutrino and X-ray astronomy
2001: Bose-Einstein Condensation in atomic vapors
I wouldn't bet on anything from the AMO realm this year, as they've got two of the last five.…
drorzel | September 27, 2006This is the second of a set of old posts, dating back to 2003, discussing the business of experimental particle physics. In this installment, I talk about how you get exotic particles by slamming ordinary ones together at high speed.
In a previous post, I gave a quick outline of the Standard Model of elementary particles, and how it relates to the recent discovery of a new particle. The best illustration of the process is probably the picture on the Ohio University reference page: A deuterium nucleus (one proton and one neutron) is sitting there, minding its own business, when a photon comes…