Precision Measurement
drorzel | March 13, 2012I finally got a copy of Cox and Forshaw's The Quantum Universe, and a little time to read it, in hopes that it would shed some light on the great electron state controversy. I haven't finished the book, but I got through the relevant chapter and, well, it doesn't, really. That is, the discussion in the book doesn't go into all that much more detail than the discussion on-line, and still requires a fair bit of work to extract a coherent scientific claim.
The argument basically boils down to the idea that the proper mathematical description of a universe containing more than one fermion is a…
drorzel | March 6, 2012My course on the history and science of timekeeping has reached the home stretch, with students giving presentations in class for the remainder of the term. My portion of the course was wrapped up with two lectures on "quantum timkeeping," as it were: a lecture on the development of quantum mechanics:
History of Quantum Mechanics
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And one on the development of atomic clocks:
A History of Atomic Clocks
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These are pretty fast-moving, but by this point in the course, students were already working on their final…
drorzel | February 24, 2012It's not a good week for me to be writing about anything remotely controversial, but if I want to keep my physics blogging license, I need to say something about the latest fast neutrino news. This has followed the usual trajectory of such stories, with the bonus farcical element of people who blasted the media for buying into the initial release seizing triumphantly on an initial rumor in the press that was garbled into incomprehensibility. With a little more time, it's become more clear how their result has become less clear, and the best place to look for a description of this is Matt…
drorzel | December 23, 2011A week and a half ago, when the advent calendar reached Newton's Law of Universal Gravitation, I said that it was the first equation we had seen that wasn't completely correct. Having done our quick swing through quantum physics, the time has come to correct that equation:
If you say "Einstein equation" to a random person on the street, odds are they'll immediatley think of "E=mc2." If you ask a physicist to think of the Einstein equation, though, this is the one they'll think of. This is the Einstein field equation from general relativity, and while it's not as well known as E=mc2, it's…
drorzel | October 16, 2011In a lot of ways, the OPERA fast-neutrino business has been less a story about science than a story about the perils of the new media landscape. We went through another stage of this a day or two ago, with all sorts of people Twittering, resharing, and repeating in other ways a story that the whole thing has been explained as a relativistic effect due to the motion of GPS satellites. So, relativity itself has overthrown an attack on relativity. Huzzah, Einstein! Right?
Well, maybe. I'm not quite ready to call the story closed, though, for several reasons. First and foremost is the fact that…
drorzel | August 22, 2011A few people last week were linking to this press release from Fermilab, which probably says more about the state of American particle physics than anything else: it's about an experiment that they expect to be approved in 2012, to break ground in 2013, and start running in 2016. I guess with the Tevatron shutting down and nothing noteworthy from the LHC yet, this is what you have to talk about.
The experiment in question is an update of an experiment from Brookhaven in 2001, which measured the anomalous magnetic moment of the muon. The value they get differs from the best theoretical value…
drorzel | July 12, 2011Among the articles highlighted in this week's Physics is one about a new test of QED through a measurement of the g-factor of the electron in silicon ions. This comes on the heels of a measurement of proton spin flips (this includes a free PDF) a couple of weeks ago, and those, in turn, build on measurements of electrons from a few years back, which Jerry Gabrielse talked about at DAMOP. Evidently, it's magnetic moment season in the world of physics.
The media reports on the proton experiment tend to be a little garbled in a way that reveals the writers don't quite understand what's going on…
drorzel | July 12, 2011A month and a half ago, I reported on a simple experiment to measure the performance of a timer from the teaching labs. I started the timer running at a particualr time, and over the next couple of weeks checked in regularly with the Official US Time display at the NIST website, recording the delay between the timer reading and the NIST clock.
As a follow-up experiment, I did the same thing with a different timer, this one a Good Cook brand digital timer picked up for $10 in the local supermarket, and the same Fisher Scientific stopwatch/timer as the first experiment, with the Fisher…
drorzel | July 8, 2011The final content area from my DAMOP overview is Precision Measurement. This is also the smallest area, with only one invited session on the topic on Fundamental Symmetry Tests, though two of the "Hot Topics" talks (by Zheng-Tian Lu and Ed Hinds) were precision measurement talks. You might be able to make an argument that this doesn't really deserve its own category, but I was the one giving the talk, and I love this stuff (though I absolutely do not have the temperament necessary to do it), so it gets its own category.
I also think there is a fairly distinct culture to precision measurement…
drorzel | June 28, 2011That's the title of my slightly insane talk at the DAMOP (Division of Atomic, Molecular, and Optical Physics of the American Physical Society) conference a couple of weeks ago, summarizing current topics of interest in Atomic, Molecular, and Optical Physics. I'll re-embed the slides at the end of this post, for anyone who missed my earlier discussion.
I put a ton of work into that talk, and had a huge amount of material that I didn't have time to include. I'd hate for that to go to waste, so I'm going to repurpose it for blog content over the next week or so. It'll probably be about a half-…
drorzel | June 16, 2011One of the odd things about going to conferences is the unpredictable difference between talks and papers. Sometimes, when you go to a talk, you just get an exact repetition of what's in the paper; other times, you get a new angle on it, or some different visual representations that make something that previously seemed dry and abstract really click. And, of course, sometimes you get new hot-off-the-apparatus results that haven't made it into print yet.
Maddeningly, there doesn't seem to be any way to know in advance which of these things you're going to get from the title and abstract. It…
drorzel | June 14, 2011That's the title of my talk this morning at DAMOP, where I attempt the slightly insane feat of summarizing a meeting with over 1000 presentations in a single 30-minute talk. This will necessarily involve talking a little bit like the person reading the legal notices at the end of a car commercial, and a few of the guide-to-the-meeting slides will have to flash by pretty quickly. Thus, for the benefit of those who have smartphones and care about my categorization of talks, I have put the slides on SlideShare in advance, and will embed them here:
What's So Interesting About AMO Phyiscs?…
drorzel | June 7, 2011I have to admit, I'm writing this one up partly because it lets me use the title reference. It's a cool little paper, though, demonstrating the lengths that physicists will go to in pursuit of precision measurements.
I'm just going to pretend I didn't see that dorky post title, and ask what this is about. Well, it's about the trapping and laser cooling of thorium ions. They managed to load thorium ions into an ion trap, and use lasers to lower their temperature into the millikelvin range. At such low temperatures, the ions in the trap "crystallize."
So, they've demonstrated that if you get…
drorzel | May 27, 2011The big physics story of the week is undoubtedly the new limit on the electric dipole moment (EDM) of the electron from Ed Hinds's group at Imperial College in the UK. As this is something I wrote a long article on for Physics World, I'm pretty psyched to see this getting lots of media attention, and not just from physics outlets.
My extremely hectic end-of-term schedule and general laziness almost make me want to just point to my earlier article and have done with it. But really, it's a big story, and one I've been following for a while, so how can I pass up the chance for a ResearchBlogging…
drorzel | May 26, 2011As I've mentioned before, I'm schedule to teach a class on "A Brief History of Timekeeping" next winter term as part of the Scholars Research Seminar program. Even though I have a hundred other things to do, I continue to think about this a lot.
One of the goals of the course is to introduce students to the idea of doing research. This was primarily conceived as a humanities/ social sciences sort of thing, so most of the discussion I've seen about these has been in terms of library research. Of course, as a physicist, I very rarely need to look things up in the library. when I think about…
drorzel | May 5, 2011NASA held a big press conference yesterday to announce that the Gravity Probe B experiment had confirmed a prediction of General Relativity that spacetime near Earth should be "twisted" by the Earth's rotation. A lot of the coverage has focused on the troubled history of the mission (as did the press conference, apparently), but scientifically it's very impressive.
The shift measured is very, very small-- 0.04 arcseconds over the course of a year, or 0.000011 degrees-- but agrees nicely with the predictions of relativity. I'm not sure whether to try to work this into the book-in-progress as I…
drorzel | March 11, 2011I've got three months to decide. I'll be giving an invited talk at the Division of Atomic, Molecular, and Optical Physics (DAMOP) with this title, with a goal of introducing the field to students and physicists from other fields:
In recent years, DAMOP has expanded to the point where the meeting can be quite daunting for a first-time attendee. This talk will provide an introduction to some of the most exciting current areas of research in Atomic, Molecular, and Optical physics, intended to help undergraduates, beginning graduate students, or physicists from other fields attending their first…
drorzel | January 12, 2011Another response copied/adapted from the Physics Stack Exchange. The question was:
What are the main practical applications that a Bose-Einstein condensate can have?
Bose Einstein Condensation, for those who aren't familiar with it, is a phenomenon where a gas of particles with the right spin properties cooled to a very low temeprature will suddenly "condense" into a state where all of the atoms in the sample occupy the same quantum wavefunction. This is not the same as cooling everything to absolute zero, where you would also have everything in the lowest energy state-- at the temperatures…
drorzel | December 28, 2010It's the last week of the (calendar) year, which means it's a good time to recap the previous twelve months worth of scientific news. Typically, publications like Physics World will publish a list of top ten physics stories of 2010, but we're all Web 2.0 these days, so it seems more appropriate to put this to a poll:
What is the top physics story of 2010?survey software
I've used the Physics World list as a starting point, because you have to start somewhere. I added a few options to cover the possibility that they left something out, and, of course, you know where the comments are.
This poll…
drorzel | November 30, 2010Somebody asked a question at the Physics Stack Exchange site about the speed of light and the definition of the meter that touches on an issue I think is interesting enough to expand on a little here.
The questioner notes that the speed of light is defined to be 299,792,458 m/s and the meter is defined to be the distance traveled by light in 1/299,792,458 seconds, and asks if that doesn't seem a little circular. There are actually three relevant quantities here, though, the third being the second, which is defined as 9,192,631,770 oscillations of the light associated with the transition…