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.
More like this
In which we do a little ResearchBlogging to look at a new paper about weir
Over at Dot Physics, Rhett is taking another whack at photons.
A reader emailed me with a few questions regarding How to Teach Physics to Your Dog, one of which is too good not to turn into a blog post:
Part two of three of an explanation of "quantum teleportation" experiments, from July of 2002. This one goes through the basics how teleportation works.
Wooo! Go State!
And Geoff Koch is a BAMF. :)
I personally love the photon charge (and mass) experimental limits because the mere fact that people try to measure the charge on a photon has a tendency to blow the minds of sophomore physics students. They assume these are all given in books, not by experiment. I'll be sure to include this new experiment as justification for teaching Coulomb's law when the fall semester starts up!
The Michigan State facility is awesome. They recently detected an N=Z isotope of Ge (Ge-64), a very heavy "mirror" nucleus which is on the neutron-poor side of the stable nuclei in a region of great astrophysical interest.