Slow blogging + interesting links

The end of our academic year + travel + some major writing has cramped my blogging of late.  Things should pick back up to a more regular pace in a couple of weeks.  In the meantime, here are some links that caught my eye lately:

• On Sir Harold Kroto's website, here are some interesting lectures by Richard Feynman.  It's absolutely worth browsing around the rest of the site, too - lots of cool videos.
• This preprint by Sean Hartnoll looks very interesting.  There are materials out there that act like metals (in the sense of having lots of low energy excitations available, and an electrical resistivity that falls with decreasing temperature), but the electrons interact so strongly and in such a complex way that it no longer makes sense to think about "quasiparticles" that act basically like ordinary electrons.  The challenge is, if the quasiparticle picture (which works spectacularly well for materials like gold, copper, aluminum, doped semiconductors) fails, what's the right way to treat these systems?  This paper tries to look at what features would have to be there in such a system.
• This video is cute.  The material used in this LED has a bandgap that apparently increases a fair bit upon cooling.  As a result, the light emitted from the diode shifts toward the blue when the device is dipped in liquid nitrogen, and comes back toward the red when it's warmed.
• We still really don't understand triboelectricity, the "static electricity" you see when you rub a balloon against your hair or rub a glass rod with rabbit fur.  News story here.  It's amazing to me that we still don't know how this kind of charge transfer works, given that it was discovered thousands of years ago.  (As Pauli said, "God made the bulk; surfaces were the work of the devil.")