One of my favorite experiments in physics has released a new set of results in Physical Review Letters, putting experimental limits on the size of any extra dimensions of the sort predicted by string theory: We conducted three torsion-balance experiments to test the gravitational inverse-square law at separations between 9.53 mm and 55 µm, probing… Continue reading Extra Dimensions Get Smaller
Category: Experiment
Mirror, Mirror
A little bit before Christmas, I spent an afternoon swapping mirrors out of one line of the apparatus. I was losing too much of the laser light before it went into the chamber, and replacing the mirrors increased the power entering the apparatus by a factor of two or so. Here’s a picture of the… Continue reading Mirror, Mirror
Bose, Fermi, Hanbury Brown, and Twiss
Via Doug Natelson, a very nice paper from the arxiv on Hanbury Brown and Twiss experiments with atoms. The Hanbury Brown and Twiss experiment (that’s two guys, one with a double unhyphenated last name) is a classic experiment from the field of quantum optics, which can be interpreted as showing the bosonic nature of photons.… Continue reading Bose, Fermi, Hanbury Brown, and Twiss
You Can’t Cook a Cow: The Problem with Raw Data
Bill Hooker is a regular advocate of “open science,” and is currently supporting a new subversive proposal: to make all raw data freely available on some sort of Creative Commons type license. It sounds like a perfectly reasonable idea on the face of it, but I have to say, I’m a little dubious about it… Continue reading You Can’t Cook a Cow: The Problem with Raw Data
Single Top Quark, Seeking Antiquark. No Freaks.
The physics story of the moment is probably the detection of single top quarks at Fermilab. Top quarks, like most other exotic particles, are usually produced in particle-antiparticle pairs, with some fraction of the kinetic energy of two colliding particles being converted into the mass of the quark-antiquark pair (see this old post). There’s a… Continue reading Single Top Quark, Seeking Antiquark. No Freaks.
Defying the Nobel Prize Jinx
I’m lecturing to our first-year seminar today about Bose-Einstein Condensation, using slides that haven’t been updated since 2002. Given the pace of research in the field, that’s a little crazy, so I spent a good while last night looking at pretty pictures on the Ketterle group web site, among others, so I can report on… Continue reading Defying the Nobel Prize Jinx
Because I Need More Stress
Steinn reports a new metric for research productivity that some people are using: the “H-number”: The H-score, takes all your papers, ranked by citation count; then you take the largest “k” such that the kth ranked paper has at least k citations. So, you start off with a H-score of zero. If your 5th highest… Continue reading Because I Need More Stress
Local Realism, Loopholes, and the God Delusion
The recent discussion of reviews of The God Delusion has been interesting and remarkably civil, and I am grateful to the participants for both of those facts. In thinking a bit more about this, I thought of a good and relatively non-controversial analogy to explain the point I’ve been trying to make about the reviews… Continue reading Local Realism, Loopholes, and the God Delusion
Accepted Paper Happy Dance
I got word yesterday that the last leftover part of the work I did as a post-doc has been accepted for publication as a Rapid Communication in Physical Review A. It’s not up on the web yet, but you can find an old draft on the ArXiV that will give you the basic idea. “But… Continue reading Accepted Paper Happy Dance
College Choice
Sean Carroll is offering more unsolicted advice (though it is in response to a comment, which makes it borderline solicited…), this time about choosing an undergraduate school. He breaks the options down into four categories, with two small errors that I’ll correct in copying the list over here: Liberal-Arts College (LAC), such as Williams or… Continue reading College Choice