Experiment
drorzel | April 16, 2007The big physics news of the week last week came while I was in transit on Wednesday: The MiniBooNE (the odd capitalization is because it's sort of an acronym) neutrino experiment released their first results on the neutrino oscillation studies they've been doing, and found, well, nothing new. In contrast to a previous experiment that hinted at the possible existence of a fourth type of neutrinos, the MiniBooNE results were entirely consistent with having only the three previously known types. There's a news article here, and one of the MiniBooNE experimenters did a excellent guest post…
drorzel | April 14, 2007Physical Review Letters this week features a paper on a topic that might not seem to be in dispute: Newton's Second Law of Motion:
We have tested the proportionality of force and acceleration in Newton's second law, F=ma, in the limit of small forces and accelerations. Our tests reach well below the acceleration scales relevant to understanding several current astrophysical puzzles such as the flatness of galactic rotation curves, the Pioneer anomaly, and the Hubble acceleration. We find good agreement with Newton's second law at accelerations as small as 5Ã10-14 m/s2.
I'm writing this on…
drorzel | March 31, 2007As you undoubtedly already know, the Large Hadron Collider suffered a setback this week:
The start-up of the Large Hadron Collider (LHC) at CERN could be delayed after three of the magnets used to focus and manipulate the accelerator's proton beams failed preliminary tests at CERN earlier this week. The magnets were built at Fermilab in the US, which announced the failure on its Web site. Although CERN has not yet issued a formal statement on the set-back, it looks increasingly unlikely that the LHC will come on-line this year as planned.
(See also the official Fermilab release on the…
drorzel | March 15, 2007After a short post-March Meeting lag, Physics World is back to announcing really cool physics results, this time highlighting a paper in Nature (subscription required) by a French group who have observed the birth and death of photons in a cavity. I'm not sure how it is that the French came to dominate quantum optics, but between Serge Haroche and Alain Aspect, most of the coolest experiments in the field seem to have been done in France.
In this particular case, they set up a superconducting resonant cavity for microwaves. Basically, this is like two mirrors facing one another, and a photon…
drorzel | March 6, 2007Physics World has a story today about a new addition to the now-you-see-it, now-you-don't maybe-it's-a-Higgs-boson signals seen at Fermilab. (See here and here for a flavor of the earlier discussions). This one is a beyond-the-Standard-Model particle that would require a supersymmetric theory to explain.
Of course, the evidence at this point consists of a whopping three events. Color me skeptical.
drorzel | February 22, 2007This is an approximate transcription of my physics talk from Boskone, titled "Spooky Action at a Distance," in which I attempted to give a reasonable explanation of the Einstein-Podolsky-Rosen ("EPR" hereafter) paper and Bell's Theorem. This was sort of a follow-on from last year's "Weird Quantum Phenomena," meant to highlight a specific class of weird quantum phenomena.
There's some SF relevance to the ideas involved in EPR and Bell's Theorem. A number of authors have name-checked the idea, most notably Charlie Stross citing "entangled particles" as the mechanism for FTL communications in…
drorzel | February 21, 2007The AIP's Physics News Update this week highlights a paper on the laser cooling and trapping of radium by a group at Argonne National Laboratory. This is a new record for the heaviest atom ever cooled and trapped.
It's not quite as cool as the previous record, which involved the trapping of francium atoms that were produced using an accelerator-- you need to do a bit more work to get radium than just scraping off a bunch of old watch dials, but the basic apparatus is a fairly standard atomic beam system. It's still pretty cool stuff, and a good bit of work has gone into it-- before they could…
drorzel | February 19, 2007We're back from Boskone, which included lots of fun stuff, and not enough sleep. I also cleverly forgot to bring my lecture notes home from work, which means I need to go in early to figure out what the hell I'm talking about in class today, so there's not much time for blogging at the moment.
I would be remiss in my physics-blogging duties, though, if I failed to point people to this Physics Web story about a new single-photon interference experiment (you'll need a subscription to read the Science article). A French group including Alain Aspect (who else?) has done a beautifually clean…
drorzel | February 16, 2007There's a press release on EurekAlert about new measurements limiting the change in the fine structure constant from the Time and Frequency division of NIST in Boulder:
Some astronomical and geological studies suggest there might have been very small changes in the values of fundamental constants over billions of years, although the results have been inconsistent and controversial. If fundamental constants are changing, the present-day rates of change are too small to be measured using conventional methods. However, a new comparison of NIST's cesium fountain and mercury ion clocks, scheduled…
drorzel | February 14, 2007Over at metadatta, Sujit is doing spectroscopy experiments with interferometers, and has posted a very nice introduction to the technique. Basically, if you have a light source emitting two different wavelengths that are very close together, you can determine the wavelength difference by shinging the light into an interferometer, and seeing how far you need to change things to make the interference patterns of the two wavelengths overlap.
That's a really sketchy description, so you should follow the link, and read Sujit's description which is, as I said, very nice. And if I find myself…
drorzel | February 13, 2007PhysicsWeb has a
story about a new theory of axions that claims to resolve some discrepancies between past experiments. Two previous experiments looking for axions-- hypothetical weakly interacting particles that might be an explanation for dark matter-- have found conflicting results: the CAST experiment looking for axions produced in the Sun found nothing, while the PVLAS experiment looking for axions by studying the rotation of polarized light in a magnetic field may have seen something. (I talked a bit about the latter here.)
Of course, the new theory is not without its complications:
Now…
drorzel | February 13, 2007The New York Times reports that Purdue has officially cleared Rusi Taleyarkhan of charges of scientific wrongdoing over his claim to have produced nuclear fusion on a tabletop through the magic of sonoluminescence. You might recall that these claims were made a couple of years ago, but nobody else has been able to replicate them.
Purdue has conducted some sort of inquiry into the matter, and declared that there was nothing dishonest about the results. The inquiry was not what you'd call a model of transparancey, though:
Purdue did not reveal what allegations the committee had considered. It…
drorzel | February 10, 2007Piled Higher and Deepr nails it this week:
A Pofessor's Negation Field is the unexplained phenomenon whereby mere spatial proximity to an experimental set-up causes all working demonstrations to fail, despite the apparent laws of Physics or how many times it worked right before he/she walked in the room.
I haven't been on the faculty long enough to develop a really effective Negation Field, but my boss when I was a post-doc was the absolute king of this. I eventually stopped telling him when things were working well, because he'd invariably want to come see it, and then something would go…
drorzel | February 9, 2007A marginally less cranky physics post than the previous: the big story in my area of physics this week is probably the Harvard experiment involving the storage and transport of light pulses. Like the ILC announcement, this has been written up in the Times, and you can also read the Harvard press release or the much more informative PhysicsWeb report.
The basic idea here is an extension of the "stored light" trick that Lene Hau's group at Harvard did a few years ago. They illuminate a sample of atoms with two different laser beams, which leads to the absorption of one of the two. They then…
drorzel | February 6, 2007SDL 5401-G1, October 2001- February 6, 2007
SDL 5401-G1 ("Sid" to friends) died today of static shock, after five years of service in a grating-locked diode laser system. He had survived three lab floods, and more than a dozen power outages, but succombed to electric shock following a mishap with a Tesla coil.
He is survived by three siblings from the same batch, one of whom has already taken his place in the grating-locked laser mount. In lieu of flowers, the family asks that you send research grants.
Sic transit gloria laseri.
drorzel | February 2, 2007
Time spent locating the parts for the Compton Effect experiment: 15 minutes.
Time spent dragging lead bricks for radiation shielding into the lab: 10 minutes.
Time spent bulding little lead houses for the hot 137Cs source and Photo-Multiplier Tube (PMT): 15 minutes.
Time spent trying to find somebody who knew the administrator password for the computer: 20 minutes.
Time between saying "What happens if you just click 'Cancel?'" and getting the computer working: 2 seconds.
Time spent connecting the detector, amplifiers, and high-voltage power supply: 5 minutes.
Time spent swapping…
drorzel | February 2, 2007Late spring/ early summer is Conference Season in academic science, with lots of meetings scheduled during the academic break, so that everybody can attend without cutting into their teaching responsibilities (of course, our trimester calendar means we're still in session for most of these, but whatever...). The peak time for conferences in my subfield is late May and early June-- the main meeting I go to, the Division of Atomic, Molecular, and Optical Physics is actually later than usual this year, presumably because it's in Calgary, and they need an extra week or two to thaw out.
Of course…
drorzel | February 2, 2007Eurekalert has a press release about new results involving "articifical atoms" at Yale. This is new work appearing in this week's Nature from the Schoelkopf lab.
The term "artificial atoms," while evocative, doesn't really mean what you might think (the name they give it on their own page is Circuit Quantum Electrodynamics, which is more accurate, but too technical for the mass media). What Schoelkopf and his group have done is to fabricate very small structures on silicon chips that act in a manner similar to atoms, with discrete allowed states for the electrons, and absrobing or emitting…
drorzel | February 1, 2007In the comments to the post where I noted how many more people had least favorite textbooks than favorite ones, dr. dave writes:
Textbooks... particularly SCIENCE textbooks, are not really written to be ENJOYED by anyone. They tend to be purely utilitarian. Asking for someone's favorite textbook is kind of like asking someone to choose their favorite screwdriver.
To which my reaction is: "What's wrong with having a favorite screwdriver?"
So here's a new dorky poll. We'll broaden the category a little, so as to be more inclusive, but inspired by dr. dave:
What's your most essential tool?
I'm…
drorzel | January 26, 2007Cosmic Variance finally got themselves an experimentalist, John Conway of CDF, and he hits the ground running with a nice post about the search for the Higgs boson:
I've been looking for the Higgs boson for almost 20 years.
So there I was, on a Saturday morning in December, at CERN as it so happened, when I saw the graph we'd been working towards all year. At first I thought it was some mistake - the hair literally rose up on the back of my neck, and I said: "Holy crap! What's that?"
This is only part one of the description, and like a good author, he leaves the reader in suspense. It's a…