Five years ago, there was a controversy in the pages of Nature regarding this paper from 1993, the first to claim atomic-resolution chemical analysis via scanning transmission electron microscopy. At issue was whether or not the data in the paper had been reprocessed (in response to referee concerns) in a legitimate or misrepresentative way, and whether the authors had been honest and forthcoming with the journal and the reviewers about the procedures they'd followed. The reason that matters came to a head more than 12 years after the original paper was the appearance of a preprint in the arxiv and subsequently submitted to Nature Physics, sharing two of the authors of the original paper, with further questions raised about the handling and analysis of data and images. This was all discussed clearly and succinctly by ZZ at the time. Nature allowed the authors to publish a corrigendum, a correction rather than a retraction, regarding the original '93 paper. This was sufficiently controversial that Nature felt the need to write an editorial explaining their decision. Oak Ridge did an investigation of the matter, and concluded that there was no fabrication or falsification of data; that report and a response by the authors are linked here. Judging from the appearance of this on the arxiv last night, it would appear that this isn't quite the end of things.
Wednesday, June 15, 2011
Summer blogging has been and will continue to be light, as I try to get some professional writing done. In the meantime, though, I have to give my elevator pitch for the awesome new TV show that would be great fun. It's "Chopped" meets "Mythbusters" meets "Scrap Heap Challenge"/"Junkyard Wars". Start off with three teams. Give them a physics- or engineering-related task that they have to accomplish (e.g., write the opening crawl from Star Wars in one mm^2; weigh a single grain of salt), some number of tools that they have to use (e.g., a green laser pointer and an infrared corrected microscope objective), and access to a stocked "pantry" (including a PC, electronics components, etc.). Give them a time limit (4 hours, cleverly edited down to half an hour in broadcast). Points awarded for success at the task, time used, and elegance. I think it could be a hit, particularly if there are explanations (narrated by cool resident experts) delivered in a fun, accessible tone. It'd be fun, even if it did conjure up images of Guy Fleegman in Galaxy Quest.
Posted by Douglas Natelson at 9:52 PM
Monday, June 06, 2011
I am interested in reading good books or review articles on two particular topics, and I'm hoping that by "crowd-sourcing" to my readership, I might do better than wandering through the literature. First, I want to find an authoritative discussion of the physics behind the electrochemical potentials of battery materials - not the lore of decades of electrochemistry, but a real hashing out of the physics. Second, I would like to find a thorough, authoritative discussion of the physics behind catalysis. Again, I'm not interested in handwaves and parametrized empirical knowledge, but would prefer a physics-based discussion that explains, e.g., why Pd is good at splitting H2, while Ti is not. Any help would be greatly appreciated.
Posted by Douglas Natelson at 9:33 PM
Sunday, June 05, 2011
I returned late last week from Germany, where I spoke at a summer school. One fun part of the trip was a tour of the main experimental facility at the neighboring Max Planck Institute for the Chemical Physics of Solids. The facility was a large high-bay lab space, with 9 (!) dilution refrigerator apparatuses, as well as a 0.3K scanning tunneling microscope with 12 Tesla magnet. Very impressive infrastructure, and the place was neat as a pin - the very model of a lab. Note to self: figure out how to instill Germanic ultraprecise lab notebook habits in all incoming grad students...,
Other news this week that is interesting: the US National Academies have decided to make many of their books available for pdf download free of charge. I'm a particular fan of one or two of these. For example, with reference to recent discussions about helium as a resource, check this out.
There is also a great deal of attention being paid to a paper from this week's Science by the group of Aephriam Steinberg. The experiment sends single photons one at a time through a two-slit type apparatus. This is one of those experiments meant to blow the minds of undergrad physics majors taking quantum for the first time: you still build up an interference pattern from the slits, even though there's only one photon in there at a time. That means the photon must be interfering with itself(!). In the new work, the group uses optics techniques (that I freely admit I do not fully understand) to correlate, after the fact, the ("weakly" measured) momentum of the photon while in the apparatus with the (strongly measured) final position of the photon on a CCD. This does not violate the uncertainty relation, since it basically finds a quantum mechanical ensemble average of the momentum as a function of final position. Still, very neat, and discussed in some detail here and here.
I've liked Steinberg's work for years. This business about quantum measurement and post-selection is very fun to think about. For example, this comes up when considering the question, "how long does it take a quantum particle to tunnel through a classically forbidden region?". What you're basically asking is, given the successful measurement of a quantum particle at some position beyond the classically forbidden region, when did the particle, in the past, impinge upon that region in the first place? This is a very hard question to answer experimentally.
Posted by Douglas Natelson at 2:05 PM