A month and a half ago, I reported on a simple experiment to measure the performance of a timer from the teaching labs. I started the timer running at a particualr time, and over the next couple of weeks checked in regularly with the Official US Time display at the NIST website, recording the delay… Continue reading The Test(ing) of Time 2: Freezing Time
Tag: precision measurement
What’s So Interesting About AMO Physics?
That’s the title of my slightly insane talk at the DAMOP (Division of Atomic, Molecular, and Optical Physics of the American Physical Society) conference a couple of weeks ago, summarizing current topics of interest in Atomic, Molecular, and Optical Physics. I’ll re-embed the slides at the end of this post, for anyone who missed my… Continue reading What’s So Interesting About AMO Physics?
Commanding the Power of Thor…ium: “Wigner Crystals of 229Th for Optical Excitation of the Nuclear Isomer”
I have to admit, I’m writing this one up partly because it lets me use the title reference. It’s a cool little paper, though, demonstrating the lengths that physicists will go to in pursuit of precision measurements. I’m just going to pretend I didn’t see that dorky post title, and ask what this is about.… Continue reading Commanding the Power of Thor…ium: “Wigner Crystals of 229Th for Optical Excitation of the Nuclear Isomer”
What Goes Around Is Really Round: “Improved measurement of the shape of the electron”
The big physics story of the week is undoubtedly the new limit on the electric dipole moment (EDM) of the electron from Ed Hinds’s group at Imperial College in the UK. As this is something I wrote a long article on for Physics World, I’m pretty psyched to see this getting lots of media attention,… Continue reading What Goes Around Is Really Round: “Improved measurement of the shape of the electron”
Measuring Gravity: Ain’t Nothin’ but a G Thing
There’s a minor scandal in fundamental physics that doesn’t get talked about much, and it has to do with the very first fundamental force discovered, gravity. The scandal is the value of Newton’s gravitational constant G, which is the least well known of the fundamental constants, with a value of 6.674 28(67) x 10-11 m3… Continue reading Measuring Gravity: Ain’t Nothin’ but a G Thing
Protons: Even Smaller Than We Thought
The big physics story at the moment is probably the new measurement of the size of the proton, which is reported in this Nature paper (which does not seem to be on the arxiv, alas). This is kind of a hybrid of nuclear and atomic physics, as it’s a spectroscopic measurement of a quasi-atom involving… Continue reading Protons: Even Smaller Than We Thought
Amazing Laser Application 11: Frequency Combs!
What’s the application? An optical frequency comb is a short-duration pulsed laser whose output can be viewed as a regularly spaced series of different frequencies. If the pulses are short enough, this can span the entire visible spectrum, giving a “comb” of colored lines on a traditional spectrometer. This can be used for a wide… Continue reading Amazing Laser Application 11: Frequency Combs!
Amazing Laser Application 3: Lunar Laser Ranging!
What’s the application? Measuring the distance from the Earth to the Moon by bouncing a laser off one of the retro-reflector arrays left there by the Apollo missions. What problem(s) is it the solution to? 1) “How does the distance from the Earth to the Moon vary over time due to things like tidal drag?”… Continue reading Amazing Laser Application 3: Lunar Laser Ranging!