The Quantum Chymist
Incoherent thoughts on quantum coherence and other points of interest.
Sunday, February 19, 2017
Thursday, September 4, 2014
Scientists (or at Least Theoreticians) as Cartographers
When non-scientist friends and family ask me the dreaded question "What's the aim of your work?", I'm never quite sure how to frame my answer. This is particularly true when I'm asked "Aren't scientists looking for the ultimate truth?" (no, we're looking for grant money and pizza). Lately, I've come up with a reply that I think helps me explain my aims while remaining relatively agnostic about the realist vs. instrumentalist debate:
I tell them I'm a cartographer.
Sunday, June 8, 2014
Midwest Theoretical Chemistry Conference
As to one of those obligations, I will be presenting a poster at the upcoming Midwest Theoretical Chemistry Conference (MTCC) at Northwestern University on Sunday, June 15th. I will be presenting poster number 14 in session B from 4:30 to 6:00 PM in Silverman Hall . The title of my poster is Interplay of Coupling Strength and Dephasing Noise in Excitonic Transfer in One- and Two-Dimensional Homogeneous Systems. The research is still very much ongoing, but when's the last time you heard of a complete and finished scientific work?
If you're attending the MTCC please do drop by. Since I'd imagine only a handful of readers will be attending, I will try to publish the content of my poster on the blog at some point, although unfortunately that may not be for a while.
Friday, May 2, 2014
Further Evidence of Element 117
In the paper, the evidence of the existence of E117 relies on observing a small number of decay events. There's plenty of interesting nuclear physics, including the discovery of a previously unknown isotope of lawrencium, but don't expect any chemistry for the foreseeable future.
Nevertheless, if I may be so bold allow me predict that E117 will be essentially entirely metallic with little to no halogen character. Its spin-orbit coupling will be so extreme that it will only be possible to describe it with a j-j like scheme, and as such it will have almost no similarity to the halogens fluorine through iodine. For more on this, see my posts on astatine, especially Astatine: Halogen or Metal? Part 3: Electronic Structure Calculations. Anything that applies to astatine will apply even more strongly to E117.
Wednesday, April 9, 2014
Discovery of a Tetraquark
The scientists claim they discovered a four-quark particle, or tetraquark, composed of a charm, anti-charm, down, and an anti-up quark. The particle would appear to be roughly (or possibly even exactly) a bound state of two mesons, that is two pairs of color-anticolor quarks; for example red-antired and blue-antiblue. The charges of the charm and anti-charm obviously cancel, leaving -1⁄3 from the down and -2⁄3 from the anti-up, for a total charge of -1.
I can't speak to the quality of this research per se, but I do remember the excitement and subsequent let down over the pentaquark, so I'm going to wait to hear what the wider particle physics community concludes about this latest finding. Still, it's a pretty cool finding.
Tuesday, April 1, 2014
Is Spin a Relativistic Effect? Levy-Leblond and First Order Wave Equations
In the nonrelativistic quantum mechanics to which we are confining ourselves, electron spin must be introduced as an additional hypothesis.
Other undergraduate and graduate texts on quantum mechanics I have examined appear to take more or less the same view. But is it really true? Is it really impossible to justify spin without invoking relativity? In this post I plan to demonstrate that it is not. But first, a little background.
Background: The Discovery of Spin
In retrospect, spin was first discovered in 1922 by Otto Stern and Walther Gerlach, though they didn't realize it at the time. In the now famous Stern-Gerlach experiment, they found that an electron passing through a magnetic field will be deflected in one of two possible directions. (Historically, they found this to be true for gaseous silver atoms, but the reason was later established to be because of the spin of the single unpaired electron.)
Thursday, March 27, 2014
Discovery of Oxygen
It shows each element by its nation(s) of initial discovery, except of course elements like iron which date to antiquity. Europe claims most of the 18th and 19th century elements, while the U.S. seems to dominate in the modern ones, i.e. astatine plus the transuranium elements.
RT @greatbritain: UK discovered more elements in periodic table than any other country pic.twitter.com/yjN2BQ3QWx #museumweek— UKTI (@UKTI) March 27, 2014
Overall I think it's a fascinating chart, but I do have a couple of problems with it. One, it lists element 117 as undiscovered, despite the fact that it was synthesized by a joint U.S.-Russian team in 2010. Still, element 117 hasn't been officially accepted by the IUPAC/IUPAP, so I suppose the creators are just playing it safe.
But more importantly, I feel the chart's creators err when they assign the discovery of oxygen to England and Sweden. For the historical record, Carl Wilhelm Scheele of Sweden in 1772 and Joseph Priestley of England in 1774 both independently isolated oxygen by heating HgO and the like. Although Scheele performed his experiment first, Priestley published first, so there's some question as to which one deserves more credit-this chart seems to split the difference.