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The Military Science

US Nuclear Weapons Lab Discovers How To Suppress the Casimir Force 112

Posted by Soulskill
from the requires-application-of-Casimir's-Oil dept.
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."
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US Nuclear Weapons Lab Discovers How To Suppress the Casimir Force

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  • by Toad-san (64810) on Friday October 11, 2013 @03:16PM (#45103997)

    "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.

    • 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.
      • ...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.

        • 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.
          • 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.

            • 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.
              • by HiThere (15173)

                That sounds like a benefit alright, but wouldn't transistors work just as well?

      • by fuzzywig (208937)
        Nuclear weapons are designed to survive EMPs because there's a strong possibility that they will be used in an environment where other nuclear weapons are being detonated, either with intent to stop incoming weapons, or as part of a barrage.

        So, yeah, they are expecting nukes to have to survive being nuked.

    • by wagnerrp (1305589) on Friday October 11, 2013 @03:31PM (#45104109)
      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
    • 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.

    • by afxgrin (208686)

      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.

  • 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...

    • 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...

      Engineered plague would be the obvious solution; no need to worry about nukes if there's no one alive to launch them!

      OK, so maybe not an ideal solution, but hey - it solves the problem. I call that a win.

      • You work for the US congress, don't you.

        • Not yet, although I do admit I've been considering taking a run at it.

          Do you think a general lack of respect for human life is enough to overcome the absence of campaign funding, or do I need to pick some pet issue to go 50-kinds-of-stupid with as well?

      • If you want to appeal to the floating voters then you need to acknowledge that it is only half a solution: present yourself as the reasonable middle ground candidate, willing to compromise on an engineered super-plague apocalypse.

  • by jd (1658) <imipak&yahoo,com> on Friday October 11, 2013 @03:21PM (#45104035) Homepage Journal

    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.

    • by fuzzyfuzzyfungus (1223518) on Friday October 11, 2013 @03:34PM (#45104123) Journal

      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.

      Plus, ICBMs controlled by valves just have a 'warmer' trajectory. It's hard to describe; but the flight path just isn't nearly as 'harsh' as semiconductor ICBMs.

    • 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".

    • by xupere (1680472)

      Besides, we need people to magnify the Casimir effect if we're to ever get wormhole technology.

      Increase the surface area with a series of (complementary) deep grooves and ridges?

    • by Grog6 (85859)

      Oddly enough, Nukes DO run on tubes, lol.

      http://en.wikipedia.org/wiki/Krytron [wikipedia.org]

      There are much newer variants, I'd bet, since the 40's.

      It's really hard to set off that many explosives to within a few nanoseconds of "exactly the right time"; an electric plasma pretty much wins out every time. :)

  • 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?
  • This is centuries-old hat in all kinds of precision equipment. Just think about the slides on the massive old machine tools. They are crisscrossed with grooves and the flat surfaces are flaked to reduce contact and let slide oil help keep the metal surfaces apart.

    Whoever launched this as an amazing new discovery should be painfully embarrassed. Don't even want to spend time for links - just search if you're interested.

    • Re:Prior Technology (Score:5, Interesting)

      by Anonymous Coward on Friday October 11, 2013 @03:45PM (#45104191)

      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)

      • The Casimir force occurs for non-conductive materials too. Lifshitz did a famous treatment for dielectric slabs.

    • by sumdumass (711423)

      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.

      • by EETech1 (1179269)

        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

  • by Anonymous Coward

    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?

  • Good old LANL (Score:5, Insightful)

    by Animats (122034) on Friday October 11, 2013 @04:00PM (#45104277) Homepage

    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 [fnal.gov] indicates. But a microscopic MEMS device? Too tiny to handle the current.

    • 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.

    • by Grog6 (85859)

      I'd also agree with the funding thing; that's all I hear about is the constant chasing of funding from people at the lab here.

      I'd bet the tech is a more resistant upgrade of the PAL system; from what I've heard, punching in the wrong code a certain number of times renders the bomb useless, until the board is replaced. Unless you're McGuyver, lol.

      A mems keylock would be pretty hard to pick... but easy to break. :)

    • by mbkennel (97636)
      "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."

      Well, it ended after zero, none of them won a Nobel Prize, but all of them have been PhD's in science. Oppenheimer won the Fermi award.

      One of the more recent problems was the transition from light management by the University of California to a commerical contractor (With minority UC involvement) at 10x the price, but an emphasis on compliance and n
  • could be used as on-off switches for nuclear devices

    On-off switches? What exactly is the function of an “off” switch on a nuclear bomb?

  • 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 wit

  • Its the van der Waals force derived for a bulk material. The rest is marketing.

    • Also....For a non-flat surface, the force can't be estimated from surface area and distance, it doesn't work like that. The resonances are different depending on the shape. A good estimate of the force of attraction (or repulsion) would have to be derived from first principles, which would be prohibitively difficult for all but the most trivial of geometries. Its not right to say that the reduced force is due to the reduced surface area.

  • by taylorius (221419) on Friday October 11, 2013 @05:18PM (#45104859) Homepage

    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.

    • by RedBear (207369)

      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

    • by AK Marc (707885)

      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 Casimir effect â" an exotic force that pushes metallic sheets together when they are separated by tiny distances.

    So, the solution is to make one of them not-a-sheet!

    This isn't "suppressing the Casimir force," it's avoiding it.

  • Look up PAL. I think Bellovin is the CS expert.
  • 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.

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