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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.
Neutralizing all weapons is a worthwhile goal. How are we going to defend ourselves against them now? More nukes? I'm hoping for something a little less harmful...
“He’s not deformed, he’s just drunk!”
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.
Breakthrough?
This technique has been used for years in the manufacture of MEMS sensors.
Ridges, bumps and non-perpendicular geometries all tend to reduce the surface
to surface contact area and are standard in MEMS gyroscope and accelerometer
designs, used to combat "Stiction".
While interesting, this is not new news.
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
the switch itself will survive. Also, when they say EMP they mean on microscopic scales, not like the emp that is emitted when a nuke goes off. Transistors won't work here because of how they're made, but all this is, essentially, is a piece of metal.
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'd imagine that 'invulnerable' is hyperbole; but I would tend to suspect that MEM gear is less touchy than semiconductors, especially modern very-high-density compute logic(on recent x86 CPUs, loss of magic smoke is a distinct possibility at vCore of 2 volts or less (never mind if you do something genuinely impolite like reversing power and ground...))
I assume that the nuke jockies use older, better hardened, stuff; but semiconducters small enough for serious computing purposes are real wimps(SCR pucks large enough to be used as blunt weapons, not so much; but we need to fit the computer inside the missile, no?).
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.
Did you read the link? Quoting: "Various physicists speculate that by choosing the right combination of geometries, it may be possible to make the force repulsive. That would be handy in preventing problems such as stiction. But nobody has been able to say for sure how this might be done." Explain that O Wise One. Maybe it's not possible, but those ignorant think everything is simple but what they do... let me guess, you are a wannabe hacker.
Maybe you should read the article first.
The high voltage surge usually associated with an EMP would jump (and weld) micro-teensy-tiny switches just as easily as big ones
Electrical fields are expressed in V/m. If you have a micro-switch, you get a microvoltage. Now, the air breakdown is also in V/m, so you may still get a spark in all things are proportional, but the energy won't be there to weld anything shut.
Totally immune to EMP.
Nothing made of atoms is immune to EMP. A sufficiently large EM field will rip atoms apart and convert the object to plasma. The words you are looking for are "less susceptible".
Also, this is about testing theories. They mean nothing without experimental backup. Add to that the ability to make uniform 0.1 micron ridges that are 0.2 microns deep. Let's see if you even know how to begin to do that first before you speak. Clearly the nuance of science is lost on you. If you have a PhD, I wish to take it back.
is that they've made something so small that they have to account for the Casimir force at all.
It's like General Relativity and the GPS satellites. I wonder if they launched the GPS satellites before general relativity was understood, how long would it have taken to figure out why the clocks were running slow?
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)
...when they say EMP they mean on microscopic scales, not like the emp that is emitted when a nuke goes off.
The use of the phrase "electromagnetic weapons" in the summary kinda belies that hypothesis.
An enigma, wrapped in a riddle, shrouded in bacon and cheese
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?
Um, it is a INCREASE in the surface area.
It's that very increase in the area, coupled with the geometry of the object that negates the force as the average space between the two objects is now large enough to allow enough virtual particles to form and negate the the push of the virtual particles on the outside of the objects.
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.
On-off switches? What exactly is the function of an “off” switch on a nuclear bomb?
Funny, given the Casimir effect, I would have thought that non-perpendicular geometries (such as parallel) increase risk of surface to surface contact.
Views expressed do not necessarily reflect those of the author.
Took a look at the article; their conclusion is that a significant reduction of the Casimir force can be achieved using metal gratings, at relatively large separation distances (> 200 nm). Unfortunately this does not solve the problem of high nano-scale adhesion in MEMS devices, because that implies the state is in contact (which is ~1 nm separation, depending on how you define how the atoms of different surfaces "touch" each other). At these small contact distances, the adhesion forces do not reduce with the grating approach. However, using the gratings can slightly reduce the risk of a MEMS component from collapsing when at larger distances from an opposing surface. Essentially, the approach can a device that should not touch an opposing surface, but will not help a device that needs to touch an opposing surface (i.e. a MEMS RF Switch).
Yes, but can you explain friction?
not in the part (the 'pointy' bits) that's closest to the other (flat) surface...
___ ___
--- ^^^
I believe what you are talking about is called knurling. It is commonly used on valve guides for high performance engines to specifically decrease what is known as sticktion. But it is often used as you say also. It has been around for a long time.
But you still need a triggering mechanism for that weapon that is immune to EMP surges. Think about it: if the bomb goes off then you don't really worry about what condition the switch is in, because it going to be vaporized. You can alternatively not park your weapons next to emp sources but you need to make sure they won't accidently detonate if they are.
Oops, you are right. That should have read "non-parallel surfaces"
Thanks for the feedback
Well technically, the technique increases surface area (they use something similar on solar cells to increase efficiency), but yeah - otherwise good point. :)
Quo usque tandem abutere, Nimbus, patientia nostra?
"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
Its the van der Waals force derived for a bulk material. The rest is marketing.
My point was that an electromagnetic pulse weapon would not be microscopic in scale, thus negating OP's conjecture. Granted, it probably wouldn't give off nuclear-detonation-levels of EMR, but it sure as hell wouldn't be "microscopic" either.
An enigma, wrapped in a riddle, shrouded in bacon and cheese
i was actually thinking the same thing
Me too.
But a microscopic MEMS device? Too tiny to handle the current.
Thing about MEMs is, if they're made using semiconductor manufacturing techniques you can make huge numbers of them all at once (unless it's a one-off deviced carved with an electron beam or such). Solid-state power-handling devices can have arrays of millions of mass-produced micro-circuits on an IC, handling macro-sized load in parallel.
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.
Perhaps, though, I was thinking about this, and its not that the switch will accidentally activate, its that it will nullify itself so it will NEVER activate, making the bomb a 1 billion dollar dud. Think about it: If you're busy nuking the landscape, what happens if one bomb goes off and burns all the triggers for the rest of the bombs? Then your entire war strategy has to be adjusted or scrapped.
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.
There is no information to share.
Contact surface area has always been a major factor in static and dynamic friction forces in conventional mechanics (ex.: ball bearings) so this "discovery" is nothing more than scientists re-discovering something obvious that they forgot for some reason: reducing contact surface area works at microscopic scales too.
On macroscopic mechanics, surface roughness is a major contributor to friction. On a microscopic scale, roughness is replaced by atomic forces but the rest is still the same.
Read the actual paper, they did more than TFS implies.
So, the solution is to make one of them not-a-sheet!
This isn't "suppressing the Casimir force," it's avoiding it.
"National Security is the chief cause of national insecurity." - Celine's First Law
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.
Look up PAL. I think Bellovin is the CS expert.
While the idea is trivially obvious, the implementation is a bit difficult. What they've discovered isn't theory, but technology. And telling them what they should try first wouldn't help if you don't also tell them how to try it.
FWIW, the Casimir effect is normally quite difficult to observe, because it only appears when two extrememly flat pieces of conductor are brought close enough together to suppress virtual particle pair production. This causes the space between the two flat pieces of metal to have a lower energy level that the space outside, where virtual pair production isn't suppressed. And THAT is what tries to push the two pieces of conductive material closer together.
Now for a mem, this will generally be in the form of a cylinder within a cylinder, which will tend to be dynamically pushed off center. So you're talking about doing machining on smooth pieces of metal that are extremely small, and which will still end up with making contact on one side. Rails, which is what this sounds like, then need to be not only small, but smooth and sharp. Not a simple machining problem. And you probably need three or four of them on each cylinder. And they must be extremely smooth, because ordinary lubricants won't work in this environment. (Think vacuum contact welds.) This probably means that the rails need to be of a different material than the thing they make contact with, but with the same default electric charge. (At this point I'm guessing wildly. But you get the kind of thing that needs to be considered.)
Just saying rails doesn't help that much.
I think we've pushed this "anyone can grow up to be president" thing too far.
That sounds like a benefit alright, but wouldn't transistors work just as well?
I think we've pushed this "anyone can grow up to be president" thing too far.
The Casimir force occurs for non-conductive materials too. Lifshitz did a famous treatment for dielectric slabs.
The problem with the Casimir force is that it is difficult to measure experimentally and difficult to calculate theoretically. The research in the past several years has focused on expanding the class of geometries and materials that can be simulated in addition to devising more accurate experiments and methods of fabricating the nanoscale structures.
With Intravaia et. al's paper, they are dealing with a phenomenon that has been predicted theoretically, but has not been verified experimentally. The novelty here would be in being able to construct a periodic nanoscale grating and incorporating it into a measurement device. They also note a deviation in the theoretical force with their plates for large separations. It seems that this comes about due to their use of the Proximity Force Approximation as the kernel in their calculations. The disparate length scales that they are working with in terms of the object size, feature size, and separations are too much for current numerical methods.
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.
There's arrogance, but then there's also the fact that this really does seem perfectly intuitive. If your surfaces have a tendency to stick to one another due to some kind of oddball "force" not quite the same as but similar to the static friction force, how is it not obvious that it might be helpful to reduce the amount of surface area that comes together between the two surfaces? After all, it works well with static friction.
I'm thinking this came out because A) they found a good way to create a micro- or nano-scale surface with sufficiently reduced area, and B) the positive result seems to significantly exceed the predicted effect, and they don't know why. That's why it's interesting. Not because the underlying concept is an amazing new idea. I'll bet the idea has been around for a long time, which is what prompted them to try to take the steps that created this result.
I don't think there's any need to be so offended by peoples' intuitive response in this particular case. They're just reacting to an article and summary that makes it seem like the simple part if the story (the idea of reducing surface area in contact) is a new, breakthrough idea when it really isn't, instead of emphasizing the parts of the story that are actually new and interesting (the actual results that exceed predictions).
it's called frosting, and it's done with a scraper. I took a machine rebuilding class, and we had to scrape and frost the ways. It is very tedious work, but cool to know how to do.
en.wikipedia.org/wiki/Hand_scraper
I got excited when I read the title, as suppression of the Casimir effect implies some way to manipulate virtual particles and would be required some breakthrough in our understanding of profound processes. But the article means that they discovered a way to minimize the force the effect applies, not suppress the force itself.
If Slashdot were chemistry it would look like this:Cadaverine
Yeah I don't understand that either, any MEMs device I've dealt with, like a DLP chip had strong warnings about electro static charge. I imagine an EMP wouldn't be much better.
less material in contact, less force, just like friction.
The funny thing is I read that too, but friction is based on forces, not surface area. Sliding a bed that has a flat bottom (or a square frame bottom) will take no more force on a smooth floor than one with four posts (ideal world, frictionless friction and all that apply). In reality, the 4-post bed is easier to move because we don't just push, we lift as we push, so we put some meaning behind that, and moving one (well, 3) of the posts at a time reduces friction by reducing the force. That and carpets. The 4-post will be much easier to move on carpet, but it isn't because of friction.
So if reduction in area changes the force, it's very much *not* like friction, but most don't understand friction, so what's the point.
This is a stiction, not sliding friction issue, and friction doesn't explain stiction, which is caused by materials issues, not friction at all (often a weak bond, or other micro forces holding them together).
I dunno, the misplaced arrogance I read on here sometimes really depresses me.
My favorite is the "I can't think of a solution, so I take that as proof that no solution exists" arrogance.
Learn to love Alaska
So, yeah, they are expecting nukes to have to survive being nuked.