G-whizzes disagree over gravity
[T]he relentless honing of G may have hit a stumbling block. Two recent experiments are in striking disagreement with earlier findings, and the overall uncertainty in the value of the constant may be set to increase.
Monthly Archives: August 2010
Eddy's Back
Fun stuff. The nonmagnetic but conductive materials will see a changing magnetic field, or will “break” field lines, as the jargon goes, which induces eddy currents to flow and produce a field (that’s Faraday’s Law), with the induced field opposing the change (Lenz’s Law). This gives a braking effect, as you can see. Interesting that the nickel is largely unaffected by this; the composition is 75% copper and 25% nickel, while for the quarter, it is 91.67% and 8.33%.
I’ve linked to eddy current effects before, but still wanted to do my own video. I tried to narrate it while filming, but keeping everything in the frame and talking (while my hands were occupied with the demo) was too tough. I did a couple of disastrous takes and then had a fit and stormed off to my trailer, vowing to never work with myself again. I finally calmed myself down and did the silent shot, then waited impatiently for me to do the post-production.
Strange Things Done 'neath the Midnight Sun
The strange case of solar flares and radioactive elements
As the researchers pored through published data on specific isotopes, they found disagreement in the measured decay rates – odd for supposed physical constants.
Checking data collected at Brookhaven National Laboratory on Long Island and the Federal Physical and Technical Institute in Germany, they came across something even more surprising: long-term observation of the decay rate of silicon-32 and radium-226 seemed to show a small seasonal variation. The decay rate was ever so slightly faster in winter than in summer.
Was this fluctuation real, or was it merely a glitch in the equipment used to measure the decay, induced by the change of seasons, with the accompanying changes in temperature and humidity?
“Everyone thought it must be due to experimental mistakes, because we’re all brought up to believe that decay rates are constant,” Sturrock said.
The Pièzo de Résistance
“The piezoelectric effect has never been manipulated at this scale before, so the range of possible applications is very exciting,” explained Pooja Tyagi, a PhD researcher in Professor Patanjali Kambhampati’s laboratory. “For example, the vibrations of a material can be analyzed to calculate the pressure of the solvent they are in. With further development and research, maybe we could measure blood pressure non-invasively by injecting the dots, shining a laser on them, and analyzing their vibration to determine the pressure.”
(The title was the pun I forgot to use in my thesis defense talk, in describing our homemade diode laser systems)
In the Whole, I'm Glad I'm not in Philadelphia
After dutifully reporting even the smallest profits on their tax filings this year, a number — though no one knows exactly what that number is — of Philadelphia bloggers were dispatched letters informing them that they owe $300 for a privilege license, plus taxes on any profits they made.
Even if, as with Sean Barry, that profit is $11 over two years.
My blog is purely a hobby, but I’d probably get nabbed for selling a t-shirt
Nobody Can Do the Triple Lindy
Bee has a short post on the triple-slit interference experiment: Testing the foundations of quantum mechanics. Contrary to the prediction of the writers at Nature, she does not appear to be “flummoxed” by QM.
If you know one thing about quantum mechanics, it’s Born’s rule: The probability of a measurement is the square of the amplitudes of the wave-functions. It is the central axiom of quantum mechanics and what makes it quantum. If you have a superposition of states, the amplitudes are sums of these states. Taking the square to obtain the probability means you will not only get the square of each single amplitude – which would be the classical result – but you will get mixed terms. These mixed terms are what is responsible for the interference in the famous double-slit experiment and yield the well-known spectrum with multiple maxima rather than one reproducing the two slits, as you’d get were the particles classical.
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The View from Up There
“Earth From Above” is the result of the aerial photographer Yann Arthus-Bertrand’s five-year airborne odyssey across six continents. It’s a spectacular presentation of large scale photographs of astonishing natural landscapes. Every stunning aerial photograph tells a story about our changing planet.
Overheard in the Lab of the Day
A laser recently died a violent death (probably natural, though foul play has not been ruled out; we are interviewing a component of interest), and during the autopsy we got a whiff of the tell-tale smell of burnt insulation and saw where the circuitry had failed. One colleague wondered aloud of the viability of selling an air freshener that smelled that way. This is the same one who thought that the scent of acetone would make a good cologne.
From the geek collection
