Physics "News": Precision Measurements Edition

I'm on vacation this week, and taking this opportunity to clear out a large backlog of news items that I flagged as interesting, but never got around to commenting on. I'll group them thematically, just to spread things out over a few days, and this lot is a bunch of articles about fiendishly difficult experiments to make or detect something really hard to see:

• This one's from email: ages ago, Geoff Koch from Michigan State sent me a pointer to an experiment in which they produced the heaviest isotope of silicon ever detected. I keep forgetting to post something about it, because I'm a bad person.
• "Two relativity tests are better than one": groups in Europe and Australia did simultaneous Michelson-Morley type experiments to put new and improved limits on possible violations of Lorentz invariance. You'll be happy to know that the speed of light is still a constant in all directions. Or maybe you won't. Of course, it doesn't really matter what you think...
• "Axions ruled out by PVLAS": This is a re-analysis of an experiment from last year which might've shown a signature of the production of exotic dark matter particles. After a new round of tests, they've concluded that the signal they saw was some sort of glitch, much to the relief of theorists everywhere.
• "New limit placed on photon charge": There's really no end to the list of odd effects that might arise from new physics theories, nor the list of clever ways to put limits on them. One such effect that I had never encountered before is the idea that a photon might carry electric charge, which has now been ruled out at the level of a part in 10⁴⁶. That's 10⁴⁶, a whopping thirteen orders of magnitude better than the previous measurement. That's very cool indeed.