Theory
drorzel | October 5, 2011If you want to know how stressed and busy I've been lately, you don't have to look any farther than the fact that I've totally fallen down on the shameless self-promotion front: I was on a radio show, and forgot to post about it here. I know, bad blogger, no pageviews...
Anyway, I talked about the fast neutrino experiment on the phone to Clay Naff, who runs the Science Odyssey show on KZUM in Nebraska, and he used it as part of this past weekend's show. My interview is in Part 1, and Part 2 is Alan Kostelecky, who is an actual expert on this sort of thing.
For some odd reason, it…
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 14, 2011I really ought to be doing other things, but this roller slide business kept nagging at me, and I eventually realized I could mock up a crude simulation of the results. This led to the production of this graph:
This looks pretty similar to the Tracker Video data from the previous post, which I'll reproduce below the fold, along with an explanation of the math that went into the model:
The two graphs are qualitatively similar, other than, you know, the godawful Excel aesthetic of the simulation results graph. One line looks relatively straight, like motion at constant speed, while the others…
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 11, 2011We took SteelyKid to the playground at one of the local elementary schools on Sunday morning. this one includes an odd sort of slide, made of dozens of rollers that are 1-2 inches in diameter (they're all the same size-- the range is just because I didn't measure them carefully). They're on really good bearings, and while it's kind of noisy, it's a reasonably smooth ride.
There is, however, one slightly mysterious aspect to this slide, clearly visible in this video that Kate was good enough to shoot for me:
SteelyKid takes something like 6 seconds to go down the slide, while it only takes me…
drorzel | July 1, 2011Third of the five research categories within DAMOP that I talked about is Quantum Phenomena. This is a little bit of a catch-all, as there are a few different things going on in this area. They are all unified, though, by the fact that they end up making quantum mechanical effects manifest in some way, either as a means to an end, or just for the sake of showing that quantum mechanics is really weird.
What do I mean "making quantum mechanical effects manifest?" Basically, demonstrating one of the essential elements that I talked about last year: showing the wave nature of matter,…
drorzel | June 29, 2011The first of the five categories of active research at DAMOP that I described in yesterday's post is "Ultracold Matter." The starting point for this category of research is laser cooling to get a gas of atoms down to microkelvin temperatures (that is, a few millionths of a degree above absolute zero. Evaporative cooling can then be used to bring the atoms down to nanokelvin temperatures, reaching the regime of "quantum degeneracy." This is, very roughly speaking, the point where the quantum wavelength of the atoms becomes comparable to the spacing between atoms in the gas, at which point the…
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 2, 2011This is the alst week of the academic term here, so I've been crazy busy, which is my excuse for letting things slip. I did want to get back to something raised in the comments to the comments to the Born rule post. It's kind of gotten buried in a bunch of other stuff, so I'll promote it to a full post rather than a comment.
The key exchange starts with Matt Leifer at #6:
The argument is about why we should use the usual methods of statistics in a many-worlds scenario, e.g. counting relative frequencies to estimate what probabilities we should assign in the future. It is not simply about…
drorzel | May 30, 2011Last week's post about the Many-Worlds variant in "Divided by Infinity" prompted the usual vigorous discussion about the merits of the Many-Worlds Interpretation. This included the common objection that we don't know how to obtain the probability of measurement outcomes in the Many-Worlds Interpretation.
This is one of those Deep Questions that lots of people expend lots of time talking about, and I can never quite understand what the problem is. How do we obtain the probability of events in the Many-Worlds Interpretation? Using the Born rule, of course: the probability of a particular…
drorzel | May 25, 2011If I ever decided to abandon any pretense of integrity or credibility, and just shoot for making a bazillion dollars peddling quantum hokum, the particular brand of quantum philosophy I would peddle has already been laid out, in Robert Charles Wilson's Divided by Infinity. In the story, the narrator is given a copy of a "crank book" by Carl G. Soziere, titled You will Never Die, which makes an argument that is essentially a variant of the Many-Worlds Interpretation of quantum mechanics:
And the argument was seductive. Shorn of the babble about Planck radii and Prigogine complexity and the…
drorzel | May 11, 2011While Kenneth Ford's 101 Quantum Questions was generally good, there was one really regrettable bit, in Question 23: What is a "state of motion?" When giving examples of states, Ford defines the ground state as the lowest-energy state of a nucleus, then notes that its energy is not zero. He then writes:
An object brought to an absolute zero of temperature would have zero-point energy and nothing else. Because of zero-point energy, there is indeed such a thing as perpetual motion.
This is really the only objectionable content in the book, but he certainly made up in quality what it lacks in…
drorzel | May 10, 2011When I was looking over the Great Discoveries series titles for writing yesterday's Quantum Man review, I was struck again by how the Rutherford biography by Richard Reeves is an oddity. Not only is Rutherford a relatively happy fellow-- the book is really lacking in the salacious gossip that is usually a staple of biography, probably because Rutherford was happily married for umpteen years-- but he's an experimentalist, and you don't see that many high-profile biographies of experimental physicists.
When you run down the list of famous and relatively modern scientists who have books written…
drorzel | May 9, 2011While I've got a few more review copies backlogged around here, the next book review post is one that I actually paid for myself, Lawrence Krauss's Quantum Man: Richard Feynman's Life in Science, part of Norton's Great Discoveries series of scientific biographies. I'm a fan of the series-- past entries reviewed here include Richard Reeves's biography of Rutherford, Rebecca Goldstein's biography of Goedel, and David Foster Wallace on Cantor's work on infinity (which is less of a biography than the others). I'm not a huge reader of biographies, but I've liked all the books from this series that…
drorzel | May 6, 2011In comments to yesterday's post about precision measurements, Bjoern objected to the use of "quantum mechanics" as a term encompassing QED:
IMO, one should say "quantum theory" here instead of "quantum mechanics". After all, what is usually known as quantum mechanics (the stuff one learns in basic courses) is essentially the quantization of classical mechanics, whereas QED is the quantization of classical electrodynamics, and quantum field theories in general are quantizations of classical field theories. I think saying "quantum mechanics" when one talks about something which essentially has…
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 | February 27, 2011A few lines of dialogue that I wrote today:
"So, the treats I eat represent the matter falling into the black hole, while my poop--"
"You are not coming to my class and pooping to demonstrate Hawking radiation. Don't even think about it."
"I guess that means you don't want to hear my take on the black hole information paradox, then?"
My life is very strange.
drorzel | February 16, 2011Sean Carroll and Brad DeLong have each recently asserted that relativity is easier to understand than quantum mechanics. Both quote Feynman saying that nobody understands quantum mechanics, but Sean gives more detail:
"Hardness" is not a property that inheres in a theory itself; it's a statement about the relationship between the theory and the human beings trying to understand it. Quantum mechanics and relativity both seem hard because they feature phenomena that are outside the everyday understanding we grow up with. But for relativity, it's really just a matter of re-arranging the concepts…
drorzel | January 14, 2011The physics book generating the most bloggy buzz in the latter part of 2010 would have to be Ian Sample's Massive: The Missing Particle that Sparked the Greatest Hunt in Science, about the as yet undetected particle known as the Higgs boson. Detecting the Hiigs is the most immediate goal of the Large Hadron Collider, so it's a topic that's in the air at the moment, so this book was inevitable-- in fact, the publisher sent me not one but two review copies. I gave one away, but that makes me feel even more guilty for taking months to get around to reviewing it.
This is, basically, a concise…
drorzel | January 6, 2011I've reached a point in the book-in-progress where I find myself needing to talk a little about particle physics. As this is very much not my field, this quickly led to a situation where the dog asked a question I can't answer. But, hey, that's why I have a blog with lots of smart readers...
The question is this:
What are all these extra particles for?
Or, to put it in slightly more physics-y terms: The Standard Model contains twelve material particles: six leptons (the electron, muon, and tau, plus associated neutrinos) and six quarks (up-down, strange-charm, top-bottom). The observable…