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 nifty new widgets made in various labs:
- "NMR Gets Seriously Small": a French group has managed to demonstrate NMR spectroscopy on tiny solid samples. This has been a problem in the past because the small signal gets washed out by thermal noise, but they've played some tricks to allow NMR on nanoliter-scale samples. Which is potentially really useful for things that are hard to acquire or synthesize.
- "Turning Heat Into Electricity Through Sound": pretty much what it sounds like. A group in Utah has made a gadget where thermal gradients drive air currents that produce sound waves, which are turned into electrical signals by piezoelectric transducers. One of our students made a pipe organ based on the sound part a couple of years ago, which was kind of cool.
- "All-Optical Magnetic Recording: a Dutch group has written information onto a magnetic material using polarized light rather than the usual magnetic heads (like in a hard disk). This could potentially allow faster disk writing on smaller scales than can be done with magnets. Just think how small your next iPod could be...
- "A Highly Efficient Room-Temperature Nanolaser": a Japanese group has made a nanoscale diode laser system that produces light with very little power input, using a photonic crystal structure. This seems like more of an incremental improvement than a conceptual leap, but I'm enough of a laser geek to find it interesting all the same.
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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 post highlights a couple of new things in the…
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I didn't think head size was a significant limiter on HD size, these days...the development of perpendicular media, for example, seems to indicate we're already pushing close to the smallest resolution at which a signal could be written and read...
This is a clever, and important, experiment, with really simple gadgets!
http://www.sciencedaily.com/releases/2007/07/070727212344.htm
Molecular Chaos Observed For The First Time
Source: Baylor University
Date: July 31, 2007
Science Daily -- A Baylor University researcher has created the first experimental observation of molecular chaos, providing evidence that a widely accepted, yet unproven, assumption is indeed accurate.
Still image from a movie made of the molecular chaos experiment. (Credit: G. W. Baxter and J. S. Olafsen)
Molecular chaos is an assumption that the velocities of colliding particles are uncorrelated and independent of position. An example of molecular chaos is the air in any room. While the nitrogen and oxygen atoms are flying around with some average square speed because of the temperature in the room, they are not related, so the air does not spontaneously fly off in one direction of the room without some sort of external pressure change, like a window opening.
The molecular chaos assumption, which is part of the kinetic theory of gases, is widely thought to be true because everything else that arises and follows from that assumption works so well. However, it has been nearly impossible to prove the assumption, until now.
"It was very exciting when we first happened upon the observation," said Dr. Jeffrey Olafsen, associate professor of physics at Baylor and a lead investigator on the project. "Prior observations have been made in computer simulations, but this is the first time it has been measured in an experimental system."
Olafsen, in collaboration with Dr. G. William Baxter, associate professor of physics at Pennsylvania State University - Erie, constructed two "gases," or layers, of ball bearings. In the layer where molecular chaos held, researchers measured Maxwell Boltzmann statistics, like those that predict the mean square speed of particles in the air in the room. In the layer where the assumption of molecular chaos failed, the statistics did not obey Maxwell Boltzmann statistics. Perhaps the most interesting part, researchers said, is that the two "gases" were in contact with each other while simultaneously demonstrating their respective behavior.
"The two layers can be thought of as two gases simultaneously in thermal contact, and yet, one of the gases demonstrates molecular chaos while the other does not," Olafsen said. "It means that the particulars of how energy is injected and distributed within the two gases is important to understanding when a system will demonstrate molecular chaos."
Olafsen said the results also are beneficial to building a fundamental thermodynamics for systems driven far from equilibrium.
Note: This story has been adapted from a news release issued by Baylor University.
Copyright © 1995-2007 ScienceDaily LLC -- All rights reserved -- Contact: editor@removeme.sciencedaily.com
@Skwid:
The limit is not so much on the read head size, but the size of the writer head - you need it strong enough to be able to switch the bits, but confining such a strong field to a small region (ie the area over the bit) is quite difficult. Stray flux can easily erase bits on adjacent tracks, hence one of the big problems in HDD research is on new writing schemes that will minimise this cross-track erasure problem.
Ah, makes sense. Thanks, Lab Rat.