Thank you to whomever wrote this headline for the Oct. 22, 2013 US National Institute of Standards and Technology (NIST) news release, also on EurekAlert, titled: The Reins of Casimir: Engineered Nanostructures Could Offer Way to Control Quantum Effect … Once a Mystery Is Solved, for getting the word ‘reins’ correct.
I can no longer hold back my concern over the fact that there are three words that sound the same but have different meanings and one of those words is often mistakenly used in place of the other.
The first one, reins, refers to narrow leather straps used to control animals (usually horses), as per this picture, It’s also used as a verb to indicate situation where control must be exerted, e.g., the spending must be reined in.This ‘reign’ usually references people like these, And, Kings, Queens, etc. reign over or rule their subjects or they have reigns, i.e., the period during which they hold the position of queen/king, etc. There are also uses such as this one found in the song title ‘Love Reign O’er Me’ (Pete Townshend)
I’ve lost count of the times I’ve seen ‘reigns’ used in place of ‘reins’, the worst part being? I’ve caught myself making the mistake. So, a heartfelt thank you to the NIST news release writer for getting it right. As for the other ‘rains’, neither I not anyone else seems to make that mistake (so far as I’ve seen).
Now on to the news,
You might think that a pair of parallel plates hanging motionless in a vacuum just a fraction of a micrometer away from each other would be like strangers passing in the night—so close but destined never to meet. Thanks to quantum mechanics, you would be wrong.
Scientists working to engineer nanoscale machines know this only too well as they have to grapple with quantum forces and all the weirdness that comes with them. These quantum forces, most notably the Casimir effect, can play havoc if you need to keep closely spaced surfaces from coming together.
Controlling these effects may also be necessary for making small mechanical parts that never stick to each other, for building certain types of quantum computers, and for studying gravity at the microscale.
In trying to solve the problem of keeping closely spaced surfaces from coming together, the scientists uncovered another problem,
One of the insights of quantum mechanics is that no space, not even outer space, is ever truly empty. It’s full of energy in the form of quantum fluctuations, including fluctuating electromagnetic fields that seemingly come from nowhere and disappear just as fast.
Some of this energy, however, just isn’t able to “fit” in the submicrometer space between a pair of electromechanical contacts. More energy on the outside than on the inside results in a kind of “pressure” called the Casimir force, which can be powerful enough to push the contacts together and stick.
Prevailing theory does a good job describing the Casimir force between featureless, flat surfaces and even between most smoothly curved surfaces. However, according to NIST researcher and co-author of the paper, Vladimir Aksyuk, existing theory fails to predict the interactions they observed in their experiment.
“In our experiment, we measured the Casimir attraction between a gold-coated sphere and flat gold surfaces patterned with rows of periodic, flat-topped ridges, each less than 100 nanometers across, separated by somewhat wider gaps with deep sheer-walled sides,” says Aksyuk. “We wanted to see how a nanostructured metallic surface would affect the Casimir interaction, which had never been attempted with a metal surface before. Naturally, we expected that there would be reduced attraction between our grooved surface and the sphere, regardless of the distance between them, because the top of the grooved surface presents less total surface area and less material. However, we knew the Casimir force’s dependence on the surface shape is not that simple.”
Indeed, what they found was more complicated.
According to Aksyuk, when they increased the separation between the surface of the sphere and the grooved surface, the researchers found that the Casimir attraction decreased much more quickly than expected. When they moved the sphere farther away, the force fell by a factor of two below the theoretically predicted value. When they moved the sphere surface close to the ridge tops, the attraction per unit of ridge top surface area increased.
“Theory can account for the stronger attraction, but not for the too-rapid weakening of the force with increased separation,” says Aksyuk. “So this is new territory, and the physics community is going to need to come up with a new model to describe it.”
For the curious, here’s a link to and a citation for the research paper,
Strong Casimir force reduction through metallic surface nanostructuring by Francesco Intravaia, Stephan Koev, Il Woong Jung, A. Alec Talin, Paul S. Davids, Ricardo S. Decca, Vladimir A. Aksyuk, Diego A. R. Dalvit, & Daniel López. Nature Communications 4, Article number: 2515 doi:10.1038/ncomms3515 Published 27 September 2013.
This article is open access.