Happenings – 24 March

Last week’s happenings post was written Saturday. Later that day I had a great idea for controls. At the beginning of this weekend I found a great example in quantum mechanics; and yesterday afternoon I had a breakthrough in PCA / FA. I think I will describe the first two in separate posts; the PCA will show up soon, in sequence. (The quantum mechanics and controls will not be in one big “happenings” post. my primary reason for keeping posts smaller rather than larger is so that the latex translation is of manageable size.)
Last Monday I went to the annual Oppenheimer Lecture at Cal. it was about quantum mechanics, “spooky actions at a distance”. The speaker’s overheads are available on his webpage http://people.ccmr.cornell.edu/~mermin/homepage/spooky-berk.pdf
He was a lively and knowledgeable speaker; it was a fine lecture.
Despite the title, I thought the lecture had more to do with “hidden variables”, but that’s not quite it either. The question he answered was, I think: can I infer from a measurement of one property, the value of a second property which I have not measured? What he seems to show is that, experimentally, there is no consistent assignment of the value of the second property on the basis of measurements of the first one. We cannot assert that it “has” a value of the second property until we measure it in a separate experiment. That’s what i think he showed. 
I cleaned up the final computations for the Davis example in PCA / FA. I moved forward in special relativity. I did not get to geometry / topology, and I did not actually get to control theory, although I did figure out how to do in fact what I thought I could do in principle in Mathematica.
All in all, I’m rather pleased with the past week. I got to cry “Eureka!” three times. (No, I wasn’t in the bathtub at the times, but that’s not a requirement. Hmm. Come to think of it, maybe I was in the shower when the control theory idea hit.)
On a blog-technical note, I have encountered a serious change in the behavior of the wordpress editor. It now eats carriage returns, and I am afraid to edit the bibliography page. Oh, I have a workaround for getting blank lines – you can see that! – but all the boldface book titles would have to be set one at a time in the editor. I really want the titles in bold, but I don’t want to have to set them individually again. I’m looking for a workaround for that.

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