Physics
pontiff | January 17, 2008Through my computer science "information is king" eyeglasses, there are really only two notions which thoroughly distinguish quantum theory from classical theories of how the world works: the nonlocal nature of quantum correlations as exemplified by Bell's theorem and the much less well known contextual nature of quantum measurements as exemplified by the Bell-Kochen-Specker theorem. While the former is well known (and hence, to paraphrase Gell-Mann, what you've heard about it is mostly wrong), the later is less well known. Is that because it is a complicated idea? I don't think so!…
drorzel | January 17, 2008I've been in a bit of a funk this week, for reasons that don't bear talking about, and everything in blogdom has seemed indescribably tedious: the same boring people having the same stupid arguments over and over, with no end in sight. And don't get me started on politics.
In an effort to shake myself out of this, I've been poking around with Technorati, and stumbled across Confused at a Higher Level, a blog by a physics professor at Carleton. It's familiar material to me-- he even started there the same year I started here-- but he's got some good thoughts on physics, teaching, and academia…
pontiff | January 16, 2008Graphene quantum dots as qubits, Quantum Zeno effect, and the APS March meeting.
A group in Zurich has made quantum dots in graphene and demonstrated Coulomb blockade opening up yet another material of promise for quantum dot qubits. Journal article here.
Lev Vaidman has an itneresting News and Views on some recent work related to the quantum Zeno effect and in particular on this recent Physical Review A article.
The March meeting of the APS now has its program online. The best way I can figure out of finding sessions sponsered by GQI is going to this page and searching the text of that…
drorzel | January 16, 2008The second half of the NOVA special on "Absolute Zero" aired last night. Like the first installment, it was very well done, avoiding most of the traps of modern pop-science television. There were some mysterious shots of amusement park rides when they started talking about quantum mechanics, and I'm not sure why, but they kept the "re-enactments" to a minimum, and didn't overdo the CGI.
They also deserve special mention for not insulting the viewers' intelligence with constant recaps.
As you can guess from the title, this part of the story covered the history of attempts to reach ever-lower…
drorzel | January 15, 2008The second part of the NOVA program Absolute Zero airs tonight on PBS stations. The first part, "The Conquest of Cold" covered the theory and technology of refrigeration, while this segment, "The Quest for Absolute Zero" will include all the fun atomic physics stuff leading up to the achievement of Bose-Einstein Condensation in 1995.
Check your local listings, and set your schedules appropriately.
purepedantry | January 15, 2008Dennis Overbye of the NYTimes had this to say of cosmologists who are speculating about disembodied brains spontaneously generated in empty space:
If you are inclined to skepticism this debate might seem like further evidence that cosmologists, who gave us dark matter, dark energy and speak with apparent aplomb about gazillions of parallel universes, have finally lost their minds. But the cosmologists say the brain problem serves as a valuable reality check as they contemplate the far, far future and zillions of bubble universes popping off from one another in an ever-increasing rush through…
pontiff | January 11, 2008Sean watches a panel discussion on whether the universe is a computer, looks up the definition of a computer, and decides that instead the universe is a calculation. If thinking about the universe as a computer is designed to make computer scientists feel important, thinking about the universe as a calculation seems designed to make theoretical physicists feel important :) But what I find interesting is that Sean points to a question asked by Tony Leggett: "What kind of process does not count as a computation?"
Now first of all, let me preface this by saying that the word "computation" has…
drorzel | January 11, 2008It's been a while since I did one of these (see "How to Tell a True Lab Story" for an explanation), but yesterday's laser tech story reminded me of one.
The lab next to mine in grad school also used an argon ion laser to pump another laser, but they were much more cramped for table space than we were. Instead of putting the argon ion laser (which was about 6' long) on top of the table, they put it on a bench that slid under the optical table, then used mirrors to direct the beam up onto the table top. Since the ion laser is pretty much a black box, this worked great, and they could drag it…
drorzel | January 10, 2008As I mentioned a few days ago, a colleague asked me if I'd be interested in doing a guest lecture for a class on science fiction. She suggested that a good way to go might be to pick one story to have the class read, and talk about that.
Kicking ideas around with Kate, I latched onto the Ted Chiang story "Story of Your Life," from the Starlight 2 anthology (and also his collection Stories of Your Life and Others), because it's got a lot of great stuff in it-- linguistics, physics, math, really alien aliens, and fantastic human characters and interactions. If you haven't read it, it's a great…
drorzel | January 10, 2008Back when I was a grad student at NIST, we had a large frame argon ion laser that put out 10-15 watts of green light that we then used to pump a Ti:Sapph laser to produce the infrared light we used for laser cooling. This particular type of laser had a small design flaw-- the energy needed for laser operation was pumped into the medium by exciting a plasma discharge in the tube using a high-voltage filament, which was coiled around the beam line. Over time, the filament would soften slightly from the heat of the plasma, then droop into the beam line, and mess up the laser mode, rendering it…
drorzel | January 9, 2008The first half of NOVA's Absolute Zero program aired last night, and I was able to watch the whole thing. Well, more or less-- it was a long day, so I was drifting off a little bit about fifteen minutes in, and didn't get all of the Michael Faraday story, but a phone call woke me up, and I watched the rest of it.
This half was mostly devoted to the history of ideas about cold, and the technology of making things cold. It didn't include any of the atomic physics topics of most immediate interest to me-- those will be in next week's installment-- but it did present a lot of fascinating…
pontiff | January 9, 2008Can markets predict elections? Alea summarizes last night's primary results: Ooops! From my perspective, I find the ideas of markets predicting future events fascinating, if for no other reason than my original motivation for studying physics was tied up deeply in questions about predicting the future.
I believe that, fundamentally, we cannot predict the future. Why? Not necessarily because of quantum theory (did I surprise you there?) and not because of arguments based on chaos theory (and I worked at the Santa Fe Institute ;) ), but because of the locality of physics. In a world with…
drorzel | January 9, 2008Via a back channel, the Gardner Project of EniTech Research. They have an argon laser, so you know it's science!
(This is way too slick to be the work of real crazy people, and, of course, there's this ad... This is almost certainly either performance art or viral marketing for an upcoming tv show, but it's pretty amusing. Make sure to at least skim through the comments.)
drorzel | January 8, 2008Having made a snide comment or two about engineers earlier, I feel like I should relate a positive experience today:
Over the Christmas break, there was a power outage in my lab. Not an accidental outage, but a planned outage that nobody told me about-- a contractor cut the breakers in order to do some work down the hall. After the outage, a piece of laser diagnostic equipment wasn't working. After exhausting the really sketchy information in the manual about the particular failure mode of this device, I tried to call the manufacturer. Of course, the original company got bought by a different…
drorzel | January 8, 2008Tonight at 8pm (Eastern) is the premier of the NOVA program "Absolute Zero". This is the first of two one-hour specials talking about the physics and technology of ultra-low temperatures. I haven't seen nearly enough hype for this on the Internet-- actual results aren't as sexy as wild speculation-- but the science here is fascinating, if I do say so myself, and at the very least, they have an impressive list of participants, and a nice Q & A about BEC with Luis Orozco of the University of Maryland (who was at Stony Brook when I was a grad student, but spent part of a sabbatical working…
drorzel | January 5, 2008Tommaso Dorigo, in reviewing an assessment scheme for science projects:
Ironically, in the same table Knuteson includes the SBFB ["Scientific Bang for the Buck" factor] of the experiment of flipping a coin: the SBFB of the experiment is zero, not that different from the global search for new physics at the LHC!, although, to be fair, zero and 0.001 are indeed quite different when you take the logarithm.
drorzel | January 4, 2008Wow, am I cranky today, or what?
To make up for the previous three tediously political posts, here's a more light-hearted physics poll question:
What's the dorkiest term in physics?
Physicists have no real flair for naming things-- either you get dull and prosaic names ("up" and "down" quarks), or strained attempts to be cute ("strange" and "charm" quarks). As a result, there are lots of dorky terms in physics, but what is the very dorkiest?
My vote goes to the Dirac notation for wavefunctions.
This one requires a little explanation: the Dirac notation comes out of the fact that certain…
grrlscientist | December 27, 2007tags: slow motion, streaming video
Have you ever seen the details how a lighter lights up? How a face is deformed after a punch or slap? How a water balloon explodes? How a rocket is fired and how a gun is fired? How an apple, banana, golf ball, concrete slab and other things are shot through with a bullet? How an arbalest is fired? How a bomb explodes? All these things and more can be seen on this streaming video. My favorite is watching the pigeon take off from its perch. [6:33]
pontiff | December 22, 2007Superexchange in optical lattices, factoring 15 in a linear optics quantum computer, quantum plagarism peaceful resolution, silicon and gallium arsinide quantum computers, and quantum mumbo jumbo in support of the ideas popularly known as God.
Superexchange demonstrated in an optical lattice by Immanuel Bloch's group in Germany.
Quantum leaps: Brisbane Times and UQ News Online report on Andrew White factoring 15 with a linear optics quantum computer. The preprint for this paper is arXiv:0705.1398. I didn't check, but I bet they got 15 equals 3 times 5.
A resolution to the quantum…