Slashdot Mirror

← Back to Stories (view on slashdot.org)

Is It Really GPS If It Doesn't Use Satellites?

Posted by Soulskill on from the is-it-really-a-hot-dog-if-it's-not-made-from-dogs? dept.

cartechboy writes: "GPS was originally developed by the military, but today it's in your smartphones, and soon, possibly your watches. Now the British military is developing something called quantum compass. The concept is a GPS-style navigation for submarines that doesn't use satellites. The quantum compass uses the movements of super-cooled subatomic particles to pinpoint a vessel's location. These particles, stored in a vacuum, react to the Earth's magnetic field. The movements caused by this interaction can be used for location positioning. At the moment, the Ministry of Defense's prototype resembles a '1-meter long shoe box,' so the next step is to miniaturize it. It could then be used by individual soldiers, as well as huge ships and submarines. Not only is it useful, but it's secure too—the technology is apparently interference-proof. Is this the future of navigation systems, or the reinvention of the compass? Possibly both."

58 of 298 comments (clear)

  1. Man-portable supercooling? by GameboyRMH · · Score: 4, Insightful

    Good luck with that.

    --
    "When information is power, privacy is freedom" - Jah-Wren Ryel
    1. Re:Man-portable supercooling? by tippe · · Score: 5, Interesting

      The supercooling is apparently done using lasers, so something that is man-portable is maybe realistic

      The DSTL's team was inspired by the Nobel-prize winning discovery that revealed that lasers can trap and cool a cloud of atoms placed in a vacuum to less than a millionth of a degree above absolute zero

    2. Re:Man-portable supercooling? by jellomizer · · Score: 4, Funny

      Doesn't anyone listen to the Doctor. Whenever the Brits make advanced technology meant to be shared with the world for the common, it is part of some evil plot to take over the human race! Why don't they just call it Asmos.

      --
      If something is so important that you feel the need to post it on the internet... It probably isn't that important.
    3. Re:Man-portable supercooling? by DougOtto · · Score: 2

      Indeed. The ones I used to work with, (GDIT VZ series), used compressors running helium as refrigerant. That said, they fit just fine in the 1 meter shoebox scenario but on the wrist might be a little tougher.

      --
      Solving Unix problems since 1989...
    4. Re:Man-portable supercooling? by Wootery · · Score: 2, Funny

      Is a shark-portable version a possibility?

    5. Re:Man-portable supercooling? by Anonymous Coward · · Score: 2, Informative

      Just the ultra high vacuum vessel and the turbo pumps, allowing you to reach vacuum better than in orbit at 200 km altitude, are enough... and you haven't started to cool yet.

      You don't need a large pump for a small volume, especially if the vessel will not be opened regularly during normal operation. Ten years ago I was a on a project using a small vacuum vessel, and we had a self contained commercial vacuum system in a box the size of a shoe box that included a turbo and a two stage oil-free roughing pump. We regularly got down to 10^-7 with that setup, and if purpose built it could have been smaller for our use. With a high quality turbo, you can get down to the 10^-9 needed for laser trapping of atoms, but a small cryopump setup would work well to augment a cheaper/smaller turbo. Self contained cryopump setups were already shoe box sized years ago, and again used on something with larger volume than what they would need here for a purpose-built system. Small, ultra high vacuum systems are straightforward to build and have commercial sources, although you don't see them in a lab as often because the smallest have very tiny pumping rates that are not useful for labs that need to open their vacuum vessel from time to time.

      The equipment volume and weight isn't so much an issue for making something man portable, as is having the power to run them for any length of time. Batteries to supply a couple hundred watts continuously get kind of heavy for any decent amount of time.

    6. Re:Man-portable supercooling? by Kuroji · · Score: 2

      Sure, you just need to get the shark to eat someone wearing the man-portable version.

  2. Well ... by gstoddart · · Score: 4, Insightful

    Does it provide you with an accurate position on the globe?

    As far as I know GPS means "global positioning system", and doesn't include the word satellite.

    --
    Lost at C:>. Found at C.
    1. Re:Well ... by CastrTroy · · Score: 5, Insightful

      GPS specifically refers to the system created by the US military for tracking your position using a bunch of satellites they put up there. Just because the acronym expands out to something rather generic doesn't mean it doesn't mean a specific implementation. FTP expands out to File Transfer Protocol. That doesn't mean that bittorrent is FTP because it's also a protocol for transferring files. There are other systems like GLONASS that help you determine you position, and also use satellites. But it would be confusing to call them both GPS, because GPS refers to a specific implementation. If you're going to call things that aren't GPS as GPS, then you might as well call navigating by the stars GPS.

      --

      Anthropic principle: We see the universe the way it is because if it were different we would not be here to see it.
    2. Re:Well ... by NatasRevol · · Score: 4, Funny

      you might as well call navigating by the stars GPS

      That'd be galactic positioning system.

      --
      There are two types of people in the world: Those who crave closure
    3. Re:Well ... by Lumpy · · Score: 3, Insightful

      Exactly, and when you use the Russian system you dont use GPS. you use GLONASS. http://en.wikipedia.org/wiki/G...

      --
      Do not look at laser with remaining good eye.
    4. Re:Well ... by gl4ss · · Score: 4, Insightful

      "Non-Satellite GPS Could Soon Be A Thing"

      that's the only fucking thing on the article that refers to it as "gps". other references are "gps like".

      if wanting to be a total troll about it, I think it remains to be seen if us military will call this sort of positioning GPS or not.

      --
      world was created 5 seconds before this post as it is.
    5. Re:Well ... by Nosretep1 · · Score: 2

      It like using kleenex instead of tissue, or hoovering instead of vacuum. It is a brand name.

    6. Re:Well ... by DougOtto · · Score: 5, Funny

      No. In Russia, GLONASS uses you!

      --
      Solving Unix problems since 1989...
    7. Re:Well ... by fahrbot-bot · · Score: 2

      Exactly, and when you use the Russian system you don't use GPS. you use GLONASS.

      To be clear, in Soviet Russia, GLONASS uses you. (and the acronym actually includes the word "satellite".)

      From Wikipedia:

      GLONASS acronym for "Globalnaya navigatsionnaya sputnikovaya sistema" or "Global Navigation Satellite System" ...

      --
      It must have been something you assimilated. . . .
    8. Re:Well ... by itsdapead · · Score: 3, Informative

      GPS specifically refers to the system created by the US military for tracking your position using a bunch of satellites they put up there.

      So, its a System that gives you your Position on the Globe, but not a GPS(TM). Thanks for the clarification...

      Unless its just a super-accurate way of finding out which way is North in which case it is probably a compass (not trademarked, at least in that context, AFAIK). Carefully analysing the name "quantum compass" suggests that maybe, just maybe, that's the case - although it could still form part of a System that gives your Position on the Globe.

      Maybe the key distinction is that a GPS (TM-or-otherwise) will work out your position from scratch, whereas the sort of hyper-accurate dead reckoning/inertial navigation system that TFA appears to describe would need to know where you started from...

      --
      In a survey of 100 programmers, 111111 thought that duck-typing was a good idea.
    9. Re:Well ... by rogoshen1 · · Score: 2

      wasn't that only useful for finding the latitude? accurately finding longitude wasn't really possible until accurate clocks/watches were developed?

    10. Re:Well ... by The+Grim+Reefer · · Score: 5, Interesting

      This is only true because before the array of satellites deployed by the US military, there was no other system for finding your global position.

      Not true. From the Wikipedia entry on the SR-71"Nortronics, Northrop's electronics development division, had developed an astro-inertial navigation system (ANS), which could correct navigation errors with celestial observations, for the SM-62 Snark missile, and a separate system for the ill-fated AGM-48 Skybolt missile, the latter of which was adapted for the SR-71.[50][citation needed]

      Before each takeoff, a primary alignment brought the ANS's inertial components to a high degree of accuracy. Once in flight, the ANS, which sat behind the Reconnaissance Systems Officer (RSO)'s position, tracked stars through a circular window of quartz glass set in the upper fuselage.[37] Its "blue light" source star tracker, which could see stars during both day and night, would continuously track a variety of stars as the aircraft's changing position brought them into view. The system's digital computer ephemeris contained data on 56 (later 61) stars.[51] The ANS could supply altitude and position to flight controls and other systems, including the Mission Data Recorder, Auto-Nav steering to preset destination points, automatic pointing and control of cameras and sensors, and optical or SLR sighting of fix points loaded into the ANS before takeoff.[52] Former pilot Richard Graham told an interviewer at the Frontiers of Flight Museum that the navigation system was good enough to limit drift to 1,000 feet off the direction of travel at Mach 3."

      I knew a guy who worked on this system. He told me about a time when they pulled one out of a plane for routine maintenance and they thought it was malfunctioning as it locked onto a star while in the hanger. After they couldn't find the fault they put a guy on a lift and turned all of the lights off in the hanger. Sure enough they found a pin hole in the roof that could only be seen close up in the dark. After they patched the hole, everything checked out fine.

    11. Re:Well ... by worip · · Score: 2

      Typically the different systems of GPS, GLONASS, Galileo, Beidou, etc. is referred to as GNSS (global navigation satellite systems).

      --
      A picture is worth exactly 1024 words.
    12. Re:Well ... by worip · · Score: 2

      The general term is GNSS - Global Navigation Satellite System.

      --
      A picture is worth exactly 1024 words.
    13. Re:Well ... by donscarletti · · Score: 3, Informative

      A sextant can find longitude through the lunar distance method, comparing the moon's position to that of a reference star and looking up that position in a Nautical Almanac to find Greenwich Time. This method was actually discovered a few years after the marine chronometer was invented, but was the dominant method during the 18th century because of the insane cost of chronometers at the time.

      A sextant is also needed to find the local time at your current location regardless of whether you use a chronometer or the moon to find GMT, so it's at the least half of the process in finding longitude either way.

      --
      When Argumentum ad Hominem falls short, try Argumentum ad Matrem
    14. Re:Well ... by dnavid · · Score: 2

      Unless its just a super-accurate way of finding out which way is North in which case it is probably a compass (not trademarked, at least in that context, AFAIK). Carefully analysing the name "quantum compass" suggests that maybe, just maybe, that's the case - although it could still form part of a System that gives your Position on the Globe.

      Maybe the key distinction is that a GPS (TM-or-otherwise) will work out your position from scratch, whereas the sort of hyper-accurate dead reckoning/inertial navigation system that TFA appears to describe would need to know where you started from...

      Everything I've read suggests it is in fact a form of inertial navigation system, or more precisely a type of sensor that could be used to create one. Although its being called a "quantum compass" it appears to be a really a hyper-accurate accelerometer that can be calibrated to measure inertial effects, gravitational effects, and magnetic effects on a laser cooled Bose-condensate cluster.

  3. Does it give you a position on the globe? by Missing.Matter · · Score: 2

    Then it's a "Global Positioning System"... GPS.

    1. Re:Does it give you a position on the globe? by Missing.Matter · · Score: 4, Informative

      A map is not a system.

    2. Re:Does it give you a position on the globe? by drinkypoo · · Score: 2

      A map gives you a position on a globe.

      It doesn't just give it to you, although it may let you find it.

      --
      "You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
    3. Re:Does it give you a position on the globe? by Missing.Matter · · Score: 2

      Cartography produces a map, not a localization.

    4. Re:Does it give you a position on the globe? by Anonymous Coward · · Score: 2, Interesting

      Mine must be broken then. I keep asking it to tell me where I am, but the dumb piece of paper just lays there.

    5. Re:Does it give you a position on the globe? by Anonymous Coward · · Score: 2, Insightful

      No but a map, compass, and trained operator are.

  4. What kind of question is that? by Enry · · Score: 3, Interesting

    Of course it is. It's Global Positioning System, not GLONASS Points South. Doesn't matter how you know where you are, as long as you know where you are with some accuracy. It's unlikely this method will be as accurate as using an actual satellite-based GPS, but probably good enough for submarines that can stay under for months at a time.

  5. Not GPS by Megane · · Score: 5, Informative

    Nope.

    Sounds like more like an inertial navigation system, but one that uses the Earth's magnetic field instead of just being shaken around.

    --
    #naabhaprzrag, #sverubfr-000, #agi-fcbafberq, negvpyr[pynff*=' negvpyr-ary-'] { qvfcynl: abar !vzcbegnag; }
    1. Re:Not GPS by timeOday · · Score: 4, Insightful
      It is not clear from the article whether or not this is ultimately an inertial system, but if so it's a huge leap beyond the current ones:

      It's a great deal more accurate than the current method used by submariners, which relies on accelerometers to pick up a vessel's movement while underwater. The accuracy difference is enough that a vessel surfacing after a day could be within three feet of its intended position--rather than up to a mile off.

      It sounds potentially very exciting. (Yet once again, 99% of the slashdot comments are debating the phrasing of the clickbait headline, instead of talking about the technology itself and potential impacts. It's really disappointing.)

    2. Re:Not GPS by Anonymous Coward · · Score: 2, Informative

      Wow. This story has migrated from one new website to another and it has been like a game of telephone. The ones linked from Slashdot came from via a Russian website which is full of non-scientific babble like "subatomic fluctuations of the Earth's magnetic field". New Scientists has a reasonable article which says, yes, it's a very accurate INS and has nothing to do with the Earth's magnetic field. That story is much better.

      Currently subs need very accurate gravity maps to deal with local differences in the gravity field. With this they will need even more accurate ones. An INS and a gravity meter are in some ways the same instrument. The better they are, the more similar they are.

  6. depends. by gandhi_2 · · Score: 4, Informative

    Are we saying Global Positioning System, capitalized and considered a Proper Noun?
    Then, no.

    Are we saying global positionin system, a generalized term for systems that give you position data on the globe?
    Then yes.

    LORAN, EPLRS (when used as it was actually created for instead of a mesh data network), VORTAC, and probably many other systems were all generic positioning systems.

    If the earths magnetic field moves (and it does), then won't this system also be affected?

    --
    THL phish sticks
    1. Re:depends. by arth1 · · Score: 4, Insightful

      Are we saying global positionin system, a generalized term for systems that give you position data on the globe?
      Then yes.

      In that case, we're causing confusion, and should be using the already existing word - geodesy/geodesics.

      Using a well-known noun as if it were a generic term causes problems. People who ask what brand of xerox machine you have should be taken out and shot, and so should people who say GPS for other things than, well, GPS.

    2. Re:depends. by DERoss · · Score: 2

      If the earths magnetic field moves (and it does), then won't this system also be affected?

      I was going to ask the same question. It's bad enough that the earth's poles of rotation describe circles, loops, and spirals some meters across over a year. The earth's magnetic field is even more dynamic. Responding to solar storms, the magnetic field lines can shift many meters in a few hours.

      In my lifetime, the north magnetic pole has shifted several kilometers, from an island in the Arctic Ocean to a peninsula in Canada. Furthermore, shifts by the south magnetic pole are not synchronized with shifts by the north magnetic pole.

      From the description, the device would say that you are moving while you are actually standing still.

    3. Re:depends. by Rei · · Score: 2

      They talk about magnetic fields, but I think what they're proposing is actually based on fluctuations on the gravitational field. You can build a precise map of local gravitational fields and combine it with dead reckoning and/or other rough positioning mechanisms to determine a precise position. And there's no plausible way to tamper with the local gravitational field.

      If it's doing an ultraprecise measurement of the magnetic field too, that's a possibility, although I can't picture a system that works only based on the magnetic field because you could just be moving along field lines and show no change, and the weak magnetic field of Earth is easy to tamper with. Drift is the least of your worries; I'm sure they could come up with some compensation system for that.

      As mentioned elsewhere, if you're keeping supercooled particles in your home GPS, that means a source of power. However, it doesn't sound like it needs to be an always-on source of power, you could just re-cool the particles as needed. If it's just a miniscule quantity of particles requiring cooling, it could conceivably be fast and low power to cool them - then you take your field measurement(s), then let them thermalize again until you want your next reading. Assumedly the cooling lasers would be diode lasers, as they're very efficient and you can make them very small. I can easily picture something like that mounted on a chip. The system could even conceivably be much lower power than GPS - if you only need it on for a fraction of a millisecond, for example, that'd be a huge advantage over GPS where you have to leave it on for long periods while it tries to receive and download the low-gain data from GPS satellites.

      --
      For the love of Crom, am I the only one here who wants to keep the U.S. technologically competitive?
    4. Re:depends. by gandhi_2 · · Score: 2

      In the early days of the FBCB2 systems that were put into the Stryker vehicles, the computers talked via EPLRS and could get position via GPS or EPLRS (but never did). In some class, the contracted trainer explained that the EPLRS was sort-of like a portable, land-based LORAN radio triangulation setup that was basically got forgotten about when GPS became the new hotness, about the time the PLGRs (AN/PSN-11) were good enough to replace the SLGR that no one wanted to ruck.

      The serial number on my striker was 8. As in something like 000008.

      --
      THL phish sticks
  7. Light on facts by Captain_Chaos · · Score: 4, Insightful

    The article is very unclear about how exactly these supercooled atomic particles tell them where they are on the globe. The impression I get is that it's just a more accurate form of inertial navigation. Or perhaps it compares the local magnetic and gravitational fields against some map of the Earth? I don't see how that would be immune to interference though, especially the magnetic part. And it would rely on an extremely accurate magnetic/gravitational map of the entire planet, which would have to be kept up to date as well as both those fields are constantly changing. Sounds very unpractical.

    I'll be very interested to see if something comes of this or if it will just turn out to be hot air and/or inaccurate reporting...

  8. stable magnetic field by DoofusOfDeath · · Score: 4, Interesting

    I'm kind of surprised that Earth's magnetic field is stable enough for this to work well. Or if nothing else, wouldn't local magnetic field disturbances goof it up?

    1. Re:stable magnetic field by NotInHere · · Score: 2

      I assume they will need some sort of a "magnetic map" of the earth.

    2. Re:stable magnetic field by Anonymous Coward · · Score: 2, Informative
      The best we have is the IGRF, but this would be no where near accurate enough. From NOAA:

      If you measure the magnetic field at a point on the Earth's surface, do not expect to get the value predicted by the IGRF! Quite apart from the errors discussed above, there might be fixed contributions from buildings, parked cars, etc., and the magnetization of crustal rocks will certainly add its own local, small-scale, field, typically of magnitude 200 nT, but often much larger. There are also a large variety of time-varying fields, both man-made (traffic, DC electric trains and trams, etc.) and natural (from electric currents in the ionosphere and magnetosphere), and the associated induced fields from currents induced in the conducting earth. The ionospheric and magnetospheric fields occur at time scales mostly ranging from seconds to hours; in "quiet" conditions they may be as small as 20 nT (though enhanced near the geomagnetic equator and over the polar caps), but up to 1000 nT and more during a magnetic storm. On a longer time scale (days to years), the large-scale magnetic field of the external ring current (approximately represented by the Dst index) will give perhaps 1000 nT during and after a magnetic storm.

    3. Re:stable magnetic field by Galt_Drakor · · Score: 2

      Local magnetic field problematic(within low hundreds of meters)? yes.
      In the middle of the ocean where submarines cruise, not so much. The closer they go to an anomaly(concentration of ferrous material) the worse it will be (inverse square law and all that).
      Earth field stable enough: majority of the time, yes. One exception magnetic storm- but those can be forecast to some degree.

      To counter problems they need inertial trackers in additionally. Better yet multiple units so they know when they are close to a magnetic anomaly.

      Example similar consumer unit: CH Robotics um6.

      Relevant knowledge: I have done surface(ground) magnetic surveys.

    4. Re:stable magnetic field by The+Raven · · Score: 4, Informative

      This is not a compass. This measures the atoms passing through lines of magnetic flux. The magnetic flux lines are remarkably uniform when you are not within range of a competing magnet; I suspect that is just as true underwater. It's like measuring your distance from the center of a record by counting the track grooves you have scratched over. It does mean it's more accurate at east-west than it is at north-south.

      --
      "I will trust Google to 'do no evil' until the founders no longer run it." Hello Alphabet.
  9. How new is this? by wisebabo · · Score: 2

    A long time ago I saw something that (according to the caption on the photo) was an inertial guidance unit for SLBMs. It was an instrumented(?) sphere that floated in liquid helium 4 which, at that temperature, was a superfluid (which I guess is a kind of quantum effect). This was to compensate for the motion of the submarine AND the flight of the SLBM because in a nuclear war I guess you can't count on any external sensors like a star tracker working. Since this sphere was suspended in a frictionless fluid presumably any frictional losses would be zero (and I guess very precise accelerometers could do the rest).

    Now that I think of it, this might have been B.S. (how does one keep liquid helium 4 a liquid in a device, a solid fueled rocket, that you don't want to have to keep constantly maintained?). Still, "maybe" it actually worked, in which case why don't they just use this system in the sub? Are the running out of helium-4? (I think it's a rare isotope of a scarce gas).

    1. Re:How new is this? by Anonymous Coward · · Score: 2, Interesting

      Sounds like a lot of trouble to create a system that's ultimately inferior to the Ring Laser Gyroscope (which was made for this very purpose).

  10. I'm skeptical by fewnorms · · Score: 3, Informative

    These particles, stored in a vacuum, react to the Earth's magnetic field.

    ... it's secure too—the technology is apparently interference-proof.

    I work for a company that deals with inertial navigation systems, specifically systems based on mechanical gyroscopes. The reason we use gyroscopes is because testing, running, and updating our tools for the last 30 years has shown us that we are inherently more precise than a magnetic measurement tool that measures the Earth's (local) magnetic field. Contrary to our tools, a magnetic measurement device is easily influenced by outside interference. Events like variations in the solar wind, such as solar flares, can easily interfere with the local magnetic field, which in turn changes your measurement of the field. Of course you can compensate for this with a lot of math, but even then those tools are still not as accurate as the tools we provide. I'd really like to know how they solved that problem, if they actually did.

    --
    Veni, Vidi, Velcro!
    1. Re:I'm skeptical by Rei · · Score: 4, Interesting

      I think the emphasis has been misplaced; I think based on the process describe that they're actually measuring the *gravitational* field, which is not readily tampered with. It'd be like navigating based on a topo map, except instead of altitude it'd be using the local gravitational field below the device.

      Supercooled superconducting gravimeters can be amazingly sensitive, to the point that one in Finland reportedly detected the increase in local gravity as workmen removed snow from the roof of the building it was housed in ;) If one can make use of tiny diode lasers to supercool a tiny group of particles, it could conceivably yield a low power, portable, super-precise, tamper-immune GPS when combined with dead-reckoning and/or other rough positioning mechanisms to help determine how you're moving over the "topographical" gravity map.

      At least that's my take.

      --
      For the love of Crom, am I the only one here who wants to keep the U.S. technologically competitive?
  11. Re:Durability? by gstoddart · · Score: 2

    Existing GPS systems can be essentially all solid-state. There are no moving parts, and the temperature tolerance can be made to handle pretty extreme tempteratures.

    So, honest question ... at what depth does the satellite signal from the GPS system penetrate water? Is it affected by surface conditions? Is it less than the average depth of a submarine?

    My guess, if the existing GPS stuff was adequate for their needs, they wouldn't be looking into doing this.

    From the article:

    The movements caused by this interaction can be used for location positioning. It's a great deal more accurate than the current method used by submariners, which relies on accelerometers to pick up a vessel's movement while underwater. The accuracy difference is enough that a vessel surfacing after a day could be within three feet of its intended position--rather than up to a mile off.

    Sounds to me like they don't rely on GPS at all, and quite likely because it's useless under water.

    --
    Lost at C:>. Found at C.
  12. Re:Summary Doesn't Make Sense by arth1 · · Score: 2

    If it's a magnetic compass, how could it be immune to interference?

    Electromagnetic fields peter off very quickly, so while interference is certainly possible, you either have to be quite close or be able to produce an enormous sized field to be able to override the earth's magnetic field. Creating country-sized EM fields is to my knowledge not technology available to any military.

  13. Re:Durability? by Lumpy · · Score: 4, Informative

    About 3 inches. The GPS satellites transmit signals on two carrier frequencies. The L1 carrier is 1575.42 MHz and carries both the status message and a pseudo-random code for timing. The L2 carrier is 1227.60 MHz and is used for the more precise military data stream

    Salt water attenuates 1.5ghz signals quite effectively.

    --
    Do not look at laser with remaining good eye.
  14. Re:Durability? by SuricouRaven · · Score: 3, Funny

    Could build the input stage with valves. It'll make your location sound better.

  15. Vacuum? by Forthan+Red · · Score: 3, Interesting

    "These particles, stored in a vacuum, react to the Earth's magnetic field." Is it actually possible to store anything in a vacuum? If a vacuum is, by definition, a space that is devoid of matter, once you put something in it, it's not a vacuum anymore.

    1. Re:Vacuum? by Rob+the+Bold · · Score: 2

      "These particles, stored in a vacuum, react to the Earth's magnetic field." Is it actually possible to store anything in a vacuum? If a vacuum is, by definition, a space that is devoid of matter, once you put something in it, it's not a vacuum anymore.

      I guess if I store my clothes in a closet, it's no longer a "closet," but a "closet with clothes in it." And really, it's gonna be filled with the same atmosphere as the rest of the house even before I unpack my pants. Probably dust, too. At least if I go on like this for long enough, my wife will put my things away just to get me to shut up.

      --
      I am not a crackpot.
  16. Re:Jamming proof???? by fustakrakich · · Score: 2

    You only need a tiny disturbance. Drop magnetized microscopic chaff that stays aloft, or in solution...

    --
    “He’s not deformed, he’s just drunk!”
  17. Re:Durability? by SuricouRaven · · Score: 3, Interesting

    Salt water attenuates all radio quite effectively, except for VLF, which is cumbersome to work with.

  18. Next Up! by Rob+the+Bold · · Score: 3, Funny

    Next up in our quest to solve the world's semantic quibbles: is it a metric system if it isn't SI?

    Discuss among yourselves.

    --
    I am not a crackpot.
  19. Article is lame blogspam. Here's the real info. by Animats · · Score: 4, Informative

    Lame article, which points to a blog, which points to another blog, which points to the wrong place on a Russian site, which copied the article from The Daily Mail. The Daily Mail, even though a tabloid, has a halfway decent article.

    I'm not going to explain inertial guidance; that's what Wikipedia is for. This is better inertial guidance. Here's a popular article which describes this new class of "gyros" and accelerometers. If you really want to know what's going on here, read Advances in Atomic Gyroscopes: A View from Inertial Navigation Applications

    Laser "gyros", which work by interferometery and have no moving parts, have been around for decades. The best laser gyros still have more drift, by about 2 orders of magnitude, than the best mechanical gyros. Laser gyro technology has hit the limits of what you can do with photons. The idea here is to do interferometry with coupled atoms, rather than photons. That technology has been slowly improving for a decade or so, and it looks like it's getting close to deployment for high-end applcations.

    One of the more interesting possibilities here is chip-scale gyros of moderate precision. Here's a Honewell patent from 2006 for one.

  20. Re:THIS JUST IN by wonkey_monkey · · Score: 2

    THIS JUST IN

    Slashdot reader skims article and misunderstands new technology.

    --
    systemd is Roko's Basilisk.