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US Nuclear Weapons Lab Discovers How To Suppress the Casimir Force
KentuckyFC writes "One of the frustrating problems with microelectromechanical (MEM) devices is that the machinery can sometimes stick fast, causing them to stop working. One of the culprits is the Casimir effect — an exotic force that pushes metallic sheets together when they are separated by tiny distances. Now physicists at the Los Alamos National Laboratory in New Mexico have worked out and demonstrated how to suppress the Casimir force. The trick is to create a set of deep grooves and ridges in the surface of one sheet so that the other only comes close to the tips of the ridges. These tips have a much smaller surface area than the flat sheet and so generate much less force. That could help prevent stiction in future MEMs devices. But why would a nuclear weapons lab be interested? MEM devices are invulnerable to electromagnetic pulse weapons that fry transistor-based switches, and so could be used as on-off switches for nuclear devices."
"MEM devices are invulnerable to electromagnetic pulse weapons that fry transistor-based switches,"
I don't know why that would be true. We're talking about a very small mechanical switch, right? Two metallic surfaces (presumably at the end of wires or traces) that connect to close a circuit? The high voltage surge usually associated with an EMP would jump (and weld) micro-teensy-tiny switches just as easily as big ones. You've never seen a mechanical switch welded by an unexpected high voltage or amperage surge? I have. No reason why that won't happen with an MEM device. I'll have to see a better reference to proof of that surge invulnerability before I buy into this.
reduction of surface area leads to reduction of effect. imagine that. duh. why didn't they try that sooner? that woulda been top on my list.
Then it is most unfortunate you didn't share this information with them years ago, asshole.
Totally immune to EMP. Besides, we need people to magnify the Casimir effect if we're to ever get wormhole technology. And, trust me on this, you do NOT want an evil general on the other side to go around suppressing it when you're half-way through.
It's a small world and it smells funny; I'd buy another if it wasn't for the money; Take back what I paid (SoM)
Los Alamos is a National Laboratory. It's not a "Nuclear Weapons Laboratory". It sequences Genomes, it works on carbon nanotubes, it develops remote sensing, it does particle physics, it works on biofuels, and proteins, and medicine. You might as well say Stanford University is a place where they develop internet search engines, and General electric makes nuclear reactors.
Some drink at the fountain of knowledge. Others just gargle.
So they are making Babbage mechanical computers in them nukes! Got to love problem solving. But the G loads have to cause problems on those devices, don't they? Timing errors and such?
It all starts at 0
An isolated MEMS is immune to electromagnetic pulses as the atmospheric saturation voltage is too low to produce sufficient potential in a system that small to damage it. If the MEMS is electrically connected to larger external systems, the potential across the contact points could be sufficient to cause damage.
I once had an similar idea about reducing the force of gravity on rockets. Basically make them with less mass, and as mass goes to zero then the force required to launch them into space also goes to zero. Genius.
Not sure if I agree. I think the research is interesting. (Also, the Casimir force is _not_ like friction: it appears in conductive materials only.)
1. They've managed to make the super-tiny grooves needed at an unheard of precision. Sub-100 nm features have little in common with grooved surfaces.
2. The grating they've developed confirms the prediction that Casimir force is proportional to area.
3. The grating has effects going beyond existing theory:
Replacing a flat surface with a deep metallic lamellar grating with sub-100 nm features strongly suppresses the Casimir force and for large inter-surfaces separations reduces it beyond what would be expected by any existing theoretical prediction. (Abstract)
So they didn't really suppress anything, they just prevented the circumstances that would be subject to the effect.
Wouldn't it be the case that if they actually manipulated a fundamental nuclear force that it would be a very notable achievement? Rght up there with negating gravity or something.
When Fascism comes to America, it will call itself Anti-Fascism, and tell you to give up your guns.
You work for the US congress, don't you.
Is it just my observation, or are there way too many stupid people in the world?
Ah, Los Alamos. Once it had more great scientists in one place than anywhere else in the world. There was a tradition in the early days that the head of Los Alamos must have a Nobel Prize. That ended in the 1980s when Ronald Reagan put a lawyer in charge.
The US has a strange approach to "national laboratories". The original ones (Los Alamos, Lawerence Livermore, Sandia, Oak Ridge, Savannah River, etc.) were originally all Atomic Energy Commission operations. The Department of Energy got the AEC operations when it was formed. So the US still has a huge nuclear weapons R&D operation, despite the fact that the US hasn't built a new nuclear weapon in decades.
This project sounds more like an excuse for funding basic research than a component needed in a nuclear weapon. EMP shielding isn't that hard. This MEMS device doesn't seem to be a likely choice for the firing switch in a nuclear weapon. Nuclear weapons require a symmetrical implosion squeeze, which is initiated with multiple detonators, all of which have to go off at the same time within 1ns or so. This is done with a setup like a photoflash, but more powerful - a capacitor bank is charged up, and then dumped into thin wire detonators when the discharge switch closes. It's a few KV at a few thousand amps for a nanosecond or so. That discharge switch is what the article probably refers to.
The classic device for that is a krytron. Although using a gas-filled tube is kind of retro, it works. It's probably possible to build some MOSFET device to replace krytrons, as this work at SLAC indicates. But a microscopic MEMS device? Too tiny to handle the current.
not in the part (the 'pointy' bits) that's closest to the other (flat) surface...
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"Breakthrough?
This technique has been used for years in the manufacture of MEMS sensors."
There are other uses of it too, here's the link to the video from the Orchid orientation tape.
http://www.youtube.com/watch?v=NY3dY3Cx-DM
So, to paraphrase quite a few comments on this article:
"Duh, Los alamos are so stupid - less material in contact, less force, just like friction. I can't believe they only just worked that out. I mean DUH, they could've asked me THAT. Oh, and they make nukes. Eurgh, I hate them!"
Really? You seriously think that's all there is to it? I only read the abstract, and it states that the decrease in the Casimir force is far beyond theoretical predictions. But pffth, they probably got that wrong too, right?
I dunno, the misplaced arrogance I read on here sometimes really depresses me.
http://www.lanl.gov/about/facts-figures/budget.php#.UlhzcVCshcY
NNSA Weapons programs 57%: 1.263B
NNSA Nonproliferation (also about nuclear weapons): 9% 210M
NNSA Safeguards & Security (also about nuclear weaopns) 7% 152M
DOE Environmental Management (cleanup junk) 8% 187 M
DOE Energy and other Programs, 4% 84M (unclear, nuclear reactors perhaps?)
DOE Office of Science, 4% 94M
Work For Others, 4%, 98M
Work For Others (National Security), 7% 154M
So by far most of LANL's budget involves nuclear weapons, and cleaning up from producing and testing nuclear weapons. Then after that unspecified work for "National Security", which is probably scientific services to the Intelligence Community.
Then, there's the 4% which is basic science like "particle physics, it works on biofuels, and proteins, and medicine" and there may be some science in the 4% of "DOE Energy and Other Programs".
I too was pretty surprised how small the basic science budget is, and I'm a physicist.
Calling LANL a "Nuclear Weapons Laboratory" is about as correct as calling Microsoft a "software company", even though they do make keyboards and mice and a tablet.
The idea that the so-called Casimir force could be made small or negative with a geometry change has been around for a long time. The outcome for a particular geometry is not easy to theoretically predict though.
The summary is bad. For the most part its not about reduction in surface area. So all the comments about how obvious it is that the force should go down with surface area are ignorant.
Almost everything one reads about the Casimir force is based on a misunderstanding of the math tricks used to derive it for parallel plates. Its the van der Waals force, with nothing meaningful going on with 'infinite vacuum energy'. Some scientists are to blame for the confusion, because they exploit the misunderstanding to get funding from ignorant DoE and DoD program managers.
So the summary is misleading, as always, and many of the slashdot comments are off base, as always. The study itself may or may not be stupid or spun in a dishonest manner, I'd have to read the paper and get up to date on other research in the last ten years in order to know. Based on past experience, I would not be surprised either way.
The Casimir force occurs for non-conductive materials too. Lifshitz did a famous treatment for dielectric slabs.