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Slashback: Iridium, Synthesis, Drives 316

Posted by timothy from the world-is-world dept.
Slashback tonight with word on the (groan) fate of Iridium, more Speak n' Spell modding, examples of Serial ATA oozing to market, the RIAA versus mandatory DRM, and more. Read on for the updates.

In this household, we obey the laws of physics! Tuesday before last, we mentioned that two scientists had announced what they claim is the first accurate measure of the speed of gravity.

Now, Emperor_Alikar writes "In an article on Space.com, many physicists have criticized the current work on the speed of gravity, calling it 'nonsense' and 'simply incorrect.' Many of them still doubt the claims made by Fomalont and Kopeikin even before the results were even announced. Many of the physicists still hold on to the idea that gravity works instantaneously no matter what the distance, an idea that originated by Newton, but that was argued against by Einstein."

Back from the back from the back from the dead. Checkers writes "Spacedaily.com posted the following two stories about Iridium today. The first story is about the DoD committing the first of three renewal options that will use Iridium through 2005. The second story related story is about an agreement inked between Iridium and Harris Corp. that allows Iridium the right to use Harris' OS/COMET satellite command and control system for the life of the Iridium satellite network."

E.T. was also into this scene. In re: matt simpson writes "Another fantastic Speak & Spell modder is Dave Wright of the band "not breathing". You can check his work out, among other modifications to toys, at www.carrionsound.com Dave has made speak & spell/math/read for Nine Inch Nails, Meat Beat Manifesto, and many other bands. Figured you might be interested in other neat synth hackers :)"

Further evidence, never a good time to buy. SpinnerBait writes "It's seems like Serial ATA Controllers have been on the market forever but where have all the Serial ATA Hard Drives been? The wait seems to finally be over, as HotHardware shows with this review and showcase on a pair of new Seagate Barracuda V Serial ATA drives. This article covers benchmarks with the product in single drive configurations, as well as RAID 0. In addition, they show performance on two different SATA controllers, from Promise and Silicon Image. And oh, those nice thin neat little SATA cables! Gotta love 'em."

We've had a few articles about Serial ATA; I hope it lives up to its reputation.

Just to add to the confusion ... probejockey writes "A current article in the Globe and Mail claims SCO will start collecting licensing fees from some Linux users, not all Linux vendors as previously reported here."

Birds of a feather, separate rooms. Finally, Declan McCullagh sent in a few interesting links yesterday regarding the RIAA and its announced opposition to mandated DRM technologies:

"First, here are the photos from today's press conference.

Second, the supposed news of today's announcement was that the RIAA would no longer pursue mandatory-DRM technologies like the Hollings bill. But it was the MPAA that was behind Hollings from the beginning (September 2001). And when Hollings finally introduced his bill in March 2002, it was the MPAA that endorsed it, while the RIAA pointedly did not."

Thanks to Declan for the links.

Wasn't smart enough to get in, either ... Finally, thanks to the several readers who alerted me by email and in comments that the school variously rendered Cal Tech, CalTech and other things even worse is in fact properly spelled "Caltech."
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Slashback: Iridium, Synthesis, Drives More

Slashback: Iridium, Synthesis, Drives

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  • "In this house, we obey the laws of thermodynamics!" Homer mutters this when Lisa, bored at being out of school, creates a perpetual motion machine.

  • Iridium and GPS (Score:3, Interesting)

    by The Bungi ( 221687 ) <thebungi@gmail.com> on Thursday January 16, 2003 @08:09PM (#5098779) Homepage
    1. Put satellites in orbit
    2. ???
    3. Profit!!
    It seems they've filled in the '???' part - sell 'em to the DoD.

    I couldn't help but think about the GPS system though. As the military shifts from laser guidance systems for bombs and cruise missiles to GPS-based ones, the GPS network becomes more and more critical and overloaded. Is the Iridium network being used only for simple voice/data communications or is there a dual-use capability (targeting, whatever) in the network as well?

    • Me fail GPS ? That's unpossible! (Score:5, Informative)

      by OldMiner ( 589872 ) on Thursday January 16, 2003 @08:12PM (#5098801) Journal
      GPS is a passive system [lmv.lm.se]. It can't be overloaded.

    • Re:Iridium and GPS (Score:5, Informative)

      by axjms ( 167179 ) on Thursday January 16, 2003 @08:14PM (#5098813) Homepage
      I am not sure if you completely understand how the GPS system works. I am not sure if I do either for that matter but the GPS system is in very little danger of being "overloaded". It is the actual GPS device that does the triangulation calculations. All the sats do is keep track of their relative position to their peers and broadcast a unique signal. Doesn't matter if 1 device or 1 million devices are earthside it is just a broadcast.

      • "Overloaded" - bad wording. I read an article somewhere about Iraq planning to jam GPS signals, especially around cities in the event of war. Supposedly it was cheap and simple to do that (as in, just a few hundred bucks per jamming device). The article went on to say that the AF might resort to laser-guided weapons if that was the case, which of course is problematic if there's smoke or clouds and so on.

        Not that they would use the Iridium sats for GPS, but perhaps some other targeting system.

        • Re:Iridium and GPS (Score:5, Informative)

          by angst_ridden_hipster ( 23104 ) on Thursday January 16, 2003 @09:08PM (#5099135) Homepage Journal
          The problem with jamming GPS is that, to do that, you need to transmit a signal.

          When you transmit a signal, you make yourself vulverable to things that can sense that signal; e.g., missiles that home in on radio transmissions.

          So yes, you could jam a wave of GPS-guided weapons. But if the wave of attacks includes a handful of gravity bombs or other weapons that seek those frequencies, you couldn't do it twice...

          Still, a smart jamming strategy might help protect a hardened target.

          .
          • If you can really make a GPS jammer for a few hundred bucks, and the components are easily accquired, then the jammers are disposable. You don't place them just at potential targets. You just blanket the city with them in a 1 mile grid, favoring vacant lots and open fields. These targets are not valuable enough to use a radio-seeking missle on, nor would you want to expose your aircraft to danger to destroy stupid little GPS jammers. It is a pretty good idea, since it is a low cost system that frustrates a high-cost system.

            The the previous post that suggested that the US military might want to have a system that doesn't rely on GPS seems pretty sharp to me.
            • Except the only thing that interferes with is your ground troops. A GPS guided bomb can easily have it's antena situated to block ground signals. Even at the height they are dropped this would not significantly reduce the GPS satelite recept (assuming 90 degrees.

              A quick redesign should minimize that risk.

              Jammers also have to jam 2 frequencies, both civilian and military. If either of them work the results can be accurate enough for military operations.

              (There is an advantage to turning off civilian signals in the area, but in the past during conflicts the signals were upgraded, not degraded because the U.S. military used civilian receivers in many instances.)

        • Re:Iridium and GPS (Score:3, Interesting)

          by Wyatt Earp ( 1029 )
          The problem with jamming GPS munitions is the fact that the aircraft dropping a GPS bomb has GPS up above the jamming.

          The aircraft is connected to the bomb in flight with a databus. The plane gives the weapon updated location via the bus up to the point of release.

          The bomb knows where it was, the bomb also has a ballistics computer updating the rate of decent and distance to target.

          So when the weapon gets into the jamming region, it still knows where it was when it was dropped, and knows how fast/far is dropped and where the target was. The weapon still falls relativly close to the target, the CEP just increases.

          I've read the CEP doubles when GPS is off/jammed. Which is still much better than a dumb iron bomb.

          http://www.google.com/search?q=jdam+gps+jamming& ie =UTF-8&oe=UTF-8

          http://www.darpa.mil/spo/programs/gpsguidancepac ka ge.htm

          http://www.globalsecurity.org/military/systems/m un itions/jdam.htm

          "Once released, the bomb's INS/GPS will take over and guide the bomb to its target regardless of weather. Guidance is accomplished via the tight coupling of an accurate Global Positioning System (GPS) with a 3-axis Inertial Navigation System (INS). The Guidance Control Unit (GCU) provides accurate guidance in both GPS-aided INS modes of operation (13 meter (m) Circular Error Probable (CEP)) and INS-only modes of operation (30 m CEP). INS only is defined as GPS quality hand-off from the aircraft with GPS unavailable to the weapon (e.g. GPS jammed). In the event JDAM is unable to receive GPS signals after launch for any reason, jamming or otherwise, the INS will provide rate and acceleration measurements which the weapon software will develop into a navigation solution."

          http://www.boeing.com/news/releases/1998/news_re le ase_980423n.htm

          "A new anti-jam Global Positioning System (GPS) developed by Boeing has successfully defeated jammed environments in two successive drop tests, allowing the test vehicles to strike well within their designated target areas."

          "In the most recent test, the AGTFT test vehicle was dropped into a high-power GPS-jammer environment from 44,000 feet and achieved direct military code GPS acquisition within 8 seconds. While descending through wind shears of up to 110 mph, the test vehicle continued to track GPS satellites in the jammed environment and ultimately struck within 6 meters of the target.

          In an earlier test, the AGTFT test vehicle was dropped from 44,000 feet into a low-power GPS-jammer environment and achieved direct military code GPS acquisition within 12 seconds. The test vehicle descended in the jammed environment through wind shears of up to 105 mph, continuously tracking GPS satellites and striking within 3 meters of the target."

          Those tests were conducted in 1998.

    • Re:Iridium and GPS (Score:5, Informative)

      by Russ Steffen ( 263 ) on Thursday January 16, 2003 @08:18PM (#5098839) Homepage

      GPS can never be overloaded like that. The SVs are broadcast only, they don't give a rat's arse how many things are using them.

      And, GPS would never be the sole means of guidance for all weapons, by virtue of the fact that it only really works well against targets at known positions. Only laser and TV guidance work well against moving targets.

    • Re:Iridium and GPS (Score:2, Interesting)

      by cristofer8 ( 550610 )
      About the GPS missiles, I recently took a tour of the Trident Missile facility in California (Moffet Field) with my school. The trident missiles, which are basically our doomsday machine, not only don't rely on GPS, but don't even really have any electronics. The gov is so worried about radiation and interference and such, that they use pressurized tubes to send signals, and orient themselves by actually looking for certain stars through a little hole in the side. Of course, they refused to explain how the "magic inertia" device worked.

  • Okay, answer me this: (Score:3, Interesting)

    by TClevenger ( 252206 ) on Thursday January 16, 2003 @08:10PM (#5098781)
    If the Sun suddenly disappears (hypothetically), would the Earth continue to hold its orbit for 8 or so minutes, or would it go whizzing off into space instantly? Does this new "Speed of Gravity" research change that answer from what it was, say, a year ago?

    • Re:Okay, answer me this: (Score:2, Funny)

      by Anonymous Coward
      Does this new "Speed of Gravity" research change that answer from what it was, say, a year ago?

      No, it just changes what the physicists tell you.

    • Re:Okay, answer me this: (Score:4, Funny)

      by DAldredge ( 2353 ) <SlashdotEmail@GMail.Com> on Thursday January 16, 2003 @08:20PM (#5098851) Journal
      That would be a BAD THING. I line with current US economic thinking BAD THINGS do not exist. So your question is not a valid question. You must be a terrorist supporter...
    • The thing is, you wouldn't know the Sun disappeared till 8 minutes after the fact anyways. Wouldn't it be so cool that here we are whizzing off into space for 8 minutes while the sun is still shining brightly.

      "What's this strange force pulling us off into space?"
      "It's actually the lack of the sun's gravity. The sun must've disappeared!"
      "Let's enjoy the last 8 minutes of sunlight while we can! Woohooo!"

      <tim><
    • An interesting question like that deserves an interesting answer. Too bad it's "we don't know".

      Welcome to the wonderfull world of science, where a smart person can ask more than a more informed person can answer :)

    • Re:Okay, answer me this: (Score:3, Informative)

      by dougmc ( 70836 )
      If the Sun suddenly disappears (hypothetically), would the Earth continue to hold its orbit for 8 or so minutes
      If you believe that gravity obeys the speed of light (I do), yes.

      would it go whizzing off into space instantly
      If gravity is instantaneous, yes.

      Of course, it's not that simple. The sun can't suddenly disappear.

      It could explode. Assuming that it forms a sphere with all the mass at the outer edge, the gravity that the Earth feels wouldn't change at all until the mass reached the Earth's orbit, and then it would immediately drop to zero (I forget the law that tells us that the gravity of a spherical body is the same as if all the mass was contained at one point in the center.)

      Unfortunately, the mass would come at the Earth at less than the speed of light, so this wouldn't be a good test. That, and it would kill us all, so if you do find a device to make the Sun blow up, I suggest not using it for this.

      The Sun could be grabbed away by some massive force -- but the source of this `massive force' (super massive spaceship? God? Galacticus?) would have gravity too, and that would affect us. That, and the Sun couldn't leave at more than the speed of light, so even that's not a good test.

      It's not easy to measure this :)

      • ... What if the sun were converted to energy instead? .. Since we can create anti-protons and anti-electrons now... Would it be possible to create some relatively equal small pockets of matter and anti-matter and have them combine to test this? A third party could observe the gravitational effects.. Can this not be used to measure gravity?? The matter would become energy .. and energy doesn't create gravity .. so .....
      • "The sun can't suddenly disappear."

        It can if you hook it up to an infinite improbability drive.

        (Douglas Adams books and Road Runner cartoons make more sense the more quantum you learn)
    • As I understand it (not particularly well :-) ), it would indeed - but the Earth wouldn't know the sun'd disappeared, as light, and any other information, is limited to, well, the speed of light..

      Thus from the earth's point of view, you could say it goes 'whizzing off' (a slightly dodgey concept in itself...) the moment it knows the sun's disappeared, and instantly from our perspective.

      - Chris

      P.S. I'm an engineer, not a physicist...
    • "would the Earth continue to hold its orbit for 8 or so minutes, or would it go whizzing off into space instantly?"

      Yes and yes.

      For an observer on Earth, the planet will start leaving the star system as soon as the sun vanishes.

      For an observer equidistant from both the sun and the earth, the earth will start flying out of the star system ~8.5 minutes after the sun vanishes.

      For an observer on/near the sun, the earth will start to leave its path ~17 minutes after the sun vanishes.

      And they're all right. Ain't relativity grand?
      • And they're all right. Ain't relativity grand?

        Just because no force can travel faster than c doesn't mean that time is all wacky.

        If you take two syncronized clocks, travel for one light-minute in opposite diretions at equal speeds, and then smash one of the clocks when it reads 9:00 a.m., the other clock can know that it lots its twin when IT says "9:00 a.m.", not when it says 9:02 a.m.

        *sigh* Of course, if you really understood it, you'd be correcting stuck up physicists, not harassing /. (Oh, wait, they understand it to--they just use an altered thinking state because it makes it easier to focus.)

    • Re:Okay, I'll try: (Score:5, Interesting)

      by glenebob ( 414078 ) on Thursday January 16, 2003 @09:09PM (#5099140)
      "...would the Earth continue to hold its orbit for 8 or so minutes..."
      There would be no clue that anything happened to the sun until 8 minutes after it happened. Or so the scientests are telling us. And if you think about it, it seems to make some sense when compared against other relativistic theories.

      For one thing, if gravity was instananeous it could conceivably be used to send information anywhere in the universe with zero ping time. Imagine a gravity-wave wireless link that would enable us to communicate with civilizations in other galaxies. Imagine playing Q3 with an alien on a planet in M3 and still having a 20ms ping.

      Now imagine sending energy via gravity waves. With the right technology you (in energy form) could be beamed, Star Trek style, to another galaxy. You could go visit your alien buddy for a lan party and be back in time for dinner.

      Unfortunately, the notion of energy (and indirectly, matter) moving at infinite velocity seems to violate the entire theory of relativity. Moving you from here to another galaxy instantly certainly seems to violate the theory of relativity.

      • There would be no clue that anything happened to the sun until 8 minutes after it happened.

        Unless we suddenly shift orbits 8 minutes before we see the sun go "blink."

        For one thing, if gravity was instananeous it could conceivably be used to send information anywhere in the universe with zero ping time.

        No. If Gravity is instantaenous, it's not a force, it's a property. (besides which, if we _could_ alter gravity, it'd be a bitch to find a sensor to pick up the minute graivty vibrations.)

        Unfortunately, the notion of energy (and indirectly, matter) moving at infinite velocity seems to violate the entire theory of relativity. Moving you from here to another galaxy instantly certainly seems to violate the theory of relativity.

        No, it'd just be in a differenet paradigm. If you achieve instant transmission you're not moving at instant velocity--you're taking a shortcut.
    • If the sun suddenly disappeard, the earth would not go whizzing off anywhere, since there is no opposing force pulling it out into space. An object in motion tends to stay in motion... yadda yadda yadda... (hereafter known as the yadda theory of motion) so the earth would continue along its present path through space, although it wouldn't be a spherical path anymore, it would be more like a straight line... so I guess the answer is... yeah, the earth would go whizzing off into space.

  • Infinite speed gravity? (Score:5, Insightful)

    by Doctor Fishboy ( 120462 ) on Thursday January 16, 2003 @08:11PM (#5098790)
    All general relativists (and for that matter, all physicists) I know think that gravity propagates at the speed of light. In the linked articles, the criticism is that they've measured the speed of light by virtue of the radio photons, not the speed of gravity, which they're claiming.

    There's nothing about 'infinitely' fast gravity in the article that I can see, and of the two physicists claiming to disagree with the results, the one who says it is 'nonsense' then refuses to comment any further.

    Dr Fish
    • That's the point, Doc Fishboy. Is general relativity correct about the propagation of gravity? After all, GR certainly doesn't agree with quantum mechanics--meaning that one of the theories will have to be revised. And does this experiment prove GR to be correct, or were they measuring the speed of light, as that Japanese dude, Hideki Asada, suggested in his paper last year?
      • What I was saying in my first comment was that the majority of physicists believe gravity has a finite propagation speed, whilst the /. tagline suggested that few physicists do. The experiment itself is being questioned by physicists thinking they're measuring the speed of light, not gravity. Apart from the Newton quote, none of the modern physicists thought that gravity propagated 'infinitely' fast - it's another usual /. not-quite-right headline.

        > After all, GR certainly doesn't agree with quantum mechanics

        Not sure if I agree with you there - I don't recall that QT is inconsistent with GR. The problem is that it is very, very hard to test a QT of gravity because the hypothesized quanta of gravity are 10^41 times smaller than those of electromagnetism and nuclear forces.

        Anyway, they came up with a speed of gravity (if that is what they measured) of plus or minus 20 percent of the speed of light, so if they were measuring gravity, it is consistent with GR.

        Dr Fish
        • True--I think that they are making more controversy over this than there probably is. On the other hand, Physicists' gut feeling doesn't stack up to observation, and everyone would like this to be settled by experiment.

          As for your other point, quantum mechanics isn't relativistically invarient. Quantum field theory is, but that's not finshed--though there are experimentally confirmed results. And quantum gravity remains a pipe dream
          • > quantum mechanics isn't relativistically invarient.

            Ah, my bad. It's been too long since my QM undergrad course. Thanks for the correction!

            Dr Fish
          • quantum mechanics isn't relativistically invarient.

            So it's quantum mechanics which needs to be changed, not relativity -- as physicists realized in the 1920s.

            Quantum field theory is, but that's not finshed

            True enough, but for all practical purposes (ie, to any level of experimental confirmation today or in the foreseeable future) it is finished. The standard model explains pretty much everything we know. The problem is some mathematical uglinesses and arbitrary parameters.

            • It was only last year that solar neutrino output from the sun was finally reconciled with theory--suggesting that neutrinos must have mass, even! Quantum field theory has no place for gravity. And quantum gravity has few experimental consequences that we can test, but it is fundamentally necessary to explain the initial stages of the big bang. Nobody seems to know whats up with supernova brightness results that seem to suggest that the universe is expanding faster and faster. Theory is not is such a splendid state at the moment.

              Now I'm not saying that our current theories will be overthrown--but they will certainly be revised.
    • They have actually measured the speed of gravity. however, the experiment assumes the speed of light and then deduces that the speed of gravity is same.

  • Can we turn gravity off? (Score:5, Insightful)

    by bleckywelcky ( 518520 ) on Thursday January 16, 2003 @08:16PM (#5098820)

    I think the real problem with determining the speed of gravity if indeed it does have a speed is the fact that we can not turn gravity on and off. Some of the first very very very rough measurements of the speed of light were made by a light source standing away from an oberserver and being turned off and on in a way that an algorithm they designed would use the information to tell them the approximate time it took for the light to get to the observer from the source. The problem with gravity is that we can not turn it off and on. Perhaps even like we can with a magnetic field. Just get a wire, run some current through it and use a switch to open/close the circuit. We could then measure the speed of a magnetic field (if it has one). The inability to turn gravity off and on is the key inhibitor to any substantial calculations on its part. And, I'm sure that when we can turn gravity off and on we really won't care that much anymore about trying to determine how fast it travels :) (although we probably will have already).
    • Couldn't you collide some matter and antimatter? If you had some mass and then it co-annihilates, it should be like turning gravity off. I'm sure the resulting gravity change is small, but there's a possibility that it could be measureable.

      • Re:Can we turn gravity off? (Score:4, Interesting)

        by Guy Harris ( 3803 ) <guy@alum.mit.edu> on Thursday January 16, 2003 @10:16PM (#5099450)
        Couldn't you collide some matter and antimatter? If you had some mass and then it co-annihilates, it should be like turning gravity off.

        No, it shouldn't. A matter-antimatter annihilation isn't really an "annihilation" in the sense that the "nihil" in "annihilation" might suggest; instead, if, for example, an electron and positron mutually annihilate, you get a pair of photons, and the total energy of the photons is equal to the total energy (rest energy, from rest mass, plus kinetic energy) of the incoming electron and positron.

        The photons have a gravitational field just as the electron and positron did. (Mass isn't the source of gravity - energy and momentum, and the flow thereof, are [ucr.edu].)

    • And, I'm sure that when we can turn gravity off and on we really won't care that much anymore about trying to determine how fast it travels :) (although we probably will have already).

      Actually if we could do that then knowing the speed at which it travels would be important if that speed were greater than the speed of light. That would mean that you could transmit information faster than the speed of light. I think that the ability to send and receive such transmissions has such obvious benefits that we would be very interested in the speed of gravity. What do you think?

  • Many of the physicists still hold on to the idea that gravity works instantaneously no matter what the distance, an idea that originated by
    Newton, but that was argued against by Einstein.

    So, if I put gravitons in a microwave will they go back in time?

    Man, this topic is so heavy...

  • Iridium Flares (Score:4, Interesting)

    by FrostedWheat ( 172733 ) on Thursday January 16, 2003 @08:26PM (#5098894)
    If you haven't already seen one, Iridium Flares [heavens-above.com] are really quite impressive.

  • SCO is toast (Score:5, Insightful)

    by legLess ( 127550 ) on Thursday January 16, 2003 @08:28PM (#5098906) Journal
    My brother used to run a motorcycle courier service in LA, and the only bill higher than his liability insurance (think about it - what type of guy wants to be a motorcycle courier? how safe is he going to be?) was his SCO license. These folks have been squeezing blood out of the turnip for years, and now that people have abadonded their turnip (to further torture the analogy) SCO is looking for other vegetables.

    They're toast, though, no matter what half-assed "intellectual property" scheme they come up with. I mean, really - who're you going to stay friends with? A girlfriend who gave you your toothbrush back and said, "Bye, and thanks for all the fish," or one who boiled your fucking cat alive? SCO is kicking its customers in the nuts while they walk out the door; they might squeeze a little cash out of them on the way, but they're only hastening the exit.
    Chris Sontag, hired in October as senior vice-president of SCO's Operating Systems division, leads the intellectual property organization, sources said. Earlier in his career, Mr. Sontag led marketing and product development for Novell...
    Did I mention that SCO is toast? That quote alone should get them on FC [fuckedcompany.com]
    Our Unix IP is a significant asset. And for several months, we have been holding internal discussions, exploring a wide range of possible strategies concerning this asset," the company said in a statement Monday. SCO hasn't decided how exactly to collect more Unix revenue, the company added.
    Translation: "We're desperate and rudderless, checking under sofa cushions for spare change. Got any?"

    • Re:SCO is toast (Score:5, Informative)

      by IntlHarvester ( 11985 ) on Thursday January 16, 2003 @11:24PM (#5099692) Journal
      Flame on, but read the article.

      Sources said SCO plans to charge for use of two software "libraries," ... A source said SCO libraries that accompany the SVR4 and OSR5 versions of Unix may be used with UnixWare and OpenServer, respectively, but using them in conjunction with Linux is prohibited by the software's licence.

      "There's a little bit of ignorance on the part of some customers," a source familiar with the plan said. But at the same time, the source added, "there are customers using the libraries that know they're not supposed to be using them."

      Using the libraries allows programs designed for SCO Unix to be run, unmodified, on Linux machines in conjunction with a package called Linux-ABI. That's a key step for companies moving servers from SCO Unix to Linux with minimum disruption.

      For those who don't know, "Linux-ABI" used to be called IBCS -- "Intel Binary Compatibility Standard" -- and you can guess from the name that it was an (old) attempt to standardize the ABI between different x86 Unixes. A long time ago, Linux users needed this to run commercial software like Oracle or WordPerfect.

      It sounds like either Linux-ABI steps on SCO patents, or certain customers are shipping SCO libraries to run on top of Linux-ABI (which is outright copyright violation). In either case, this only affects about 0.001% of Linux users.

      In short, all 2000 posts eariler were probably a massive over reaction.

      • Re:SCO is toast (Score:3, Funny)

        by js7a ( 579872 )
        all 2000 posts eariler were probably a massive over reaction

        Maybe those 2000 posters are the ones with software using Linux-ABI.

      • Well, you're closer, but you're still not on the money.

        It sounds like either Linux-ABI steps on SCO patents, or certain customers are shipping SCO libraries to run on top of Linux-ABI (which is outright copyright violation).

        They don't *need* patents. They just need for the SCO C library licence to say that programs developed using it may only be run on genuine SCO Unix. In that case, anyone running such a program would be in trouble -- they wouldn't have to redistribute it.

        I suspect the background for this story is that a few long-standing SCO customers with an eye to the future have had a bright young nerd look at how hard it would be to get their vertical application to run on Linux instead of SCO. (Perhaps it's a dental surgery management suite running on Ingres or something similar.) Probably in many cases the customer has a binary app without source access, but that can be fixed with Linux-ABI. It's probably not so hard in most cases.

        It's a good deal for the customer: they cut out their SCO licence costs, they get a platform with a bright future, and they have much less trouble finding people who can support and enhance it.

        This is a bit bad for SCO, though. Once word gets back to HQ that this is happening, they start to think about methods that can be used to keep their customers locked in. One technique is to exploit the licence that the customer's application vendor originally signed to get the SCO libraries. If SCO were smart enough to put in a "this can only be used on SCO" clause, then they're set!

        Anybody who has the source for their applications should be easily able to move to Linux, and probably most of the commercial applications like Oracle already have native ports. Linux-ABI and this licensing strategy really just apply to people with legacy SCO apps who can't, or don't want, to port to Linux.

        Microsoft could use such a clause in the Office (or DirectX or MSVC Runtime) licences to put an end to all this Wine, Crossover and Transgaming nonsense, if they wanted to. I think there are enough precedents for that kind of restriction in software licences that it would be possible. For example, lots of driver software comes with a licence saying it may only be used with the vendor's original software. I think this technique is a terrible abuse of customers, like most proprietary software licences. But it would probably work to shake down some more money.

  • CALTECH (Score:2, Funny)

    by Anonymous Coward

    Finally, thanks to the several readers who alerted me by email and in comments that the school variously rendered Cal Tech, CalTech and other things even worse is in fact properly spelled "Caltech."

    And of course, "Caltech" is pronounced: sall-TEESH

    Glad I could clear that up!

  • Measuring the speed of gravity (Score:2, Interesting)

    by Anonymous Coward
    Okay, we can't make the sun disappear and watch what happens to the earth's orbit (and really, why would you want to?)

    BUT - what if scientists create an amount of matter and anti-matter, and using very sensitive equipment measure the gravity effect it has on say a hanging weight (ala the two really heavy bags suspended next to each other). Then, all of a sudden combine the matter and anti-matter and measure how quickly the gravity "disappears". (BTW, the antimatter can be "held" in a magnetic field, as opposed to wearing really thick gloves)

    Okay, there's a lot of work to be done before this could even be considered, let alone be done in the garage of /.'ers, but are there any arguments against this being possible?

    I'm not sure if the energy released by the matter/anti-matter combination would interfere in any way (it probably would, for all I know). Also, it's probably not practical to generate a significant amount of anti-matter, and I believe it may have a very short half-life. Also, do we have equipment sensitive enough?

    There we go - I've suggested a better experiment, shot it to bits, admitted my ignorance and also taken the piss out of my suggestion a bit! This is the ultimate /. post - no replies necessary!!! (But the replies will still come. So sayeth the spider)

  • The speed of gravity, a consequence (Score:4, Interesting)

    by Traa ( 158207 ) on Thursday January 16, 2003 @08:39PM (#5098961) Homepage Journal
    Hypothesis: The speed of gravity == infinite

    If the above hypothesis where true then one could (theoretically) build the following device: At place A we have a measurement tool that measures the gravitational pull of an object at place B. At place B we move the object back and forth based on a coded pattern (sending information). At spot A the difference in gravitational pull allows us to decode the pattern (reading information). The time it takes to send this information is based on the time it takes for the gravity 'waves' to reach from point B to point A. Our hypothesis says that this time is 0 so it means that we can now build a device that can send information FASTER then the speed of light. Einstein allready proofed that there is nothing faster then the speed of light.

    Conclusion: The hypothesis is FALSE.

    (disclaimer: bah, I'm no physicist, so don't flame me for not writing the above proof in a perfect physicist lingo...I tried :-)
    • Well, you're thinking along the right lines...

      Here's the experiment you really want to perform:

      At place A, you place a massive object in front of a light, and move the object back and forth.

      At place B, you set up a light detector and a gravity detector (the means by which one builds the gravity detector is left as an exercise to the reader).

      You start off with points A and B really close to each other so you can calibrate your equipment (you need to be able to account for the difference between reading the gravity detector and the light detector). Once you do that, you move the points further apart.

      Now, if the speed of gravity is instantaneous, then the phase difference between the signal received by the gravity detector and the signal received by the light detector should change as you move the points away from each other.

      If the speed of gravity is the same as the speed of light, then the phase difference between the two signals should always be zero (after accounting for the equipment), no matter what the distance between points A and B.

      The relationship between the phase difference and the distance between points A and B will give you a clue as to the speed of gravity versus the speed of light, if that of gravity is finite but different from that of light.

  • Many of the physicists still hold on to the idea that gravity works instantaneously no matter what the distance, an idea that originated by Newton, but that was argued against by Einstein."

    I ain't no physicist, but I think i'm gonna go with Einstein on this one. It's like trying to block Jordan when he was in his prime.

  • IRIDIUM IS EVIL! BOYCOTT!! (Score:3, Funny)

    by sulli ( 195030 ) on Thursday January 16, 2003 @08:40PM (#5098965) Journal
    I can't believe there's another positive Iridium story on slashdot. Is this due to the visual studio .NET ads?

    People, we need to boycott this insidious attempt by Micro$haft and the evil **AA along with Senator Disney and the BSA to control our PCs! Join the EFF [eff.org], delete your Windows partition, and FIGHT BACK against this menace! Power to the people!



    oh, Iridium? oops, never mind.

  • Here is a case for why the speed of gravity could (and possibly is) instantaneous:

    To measure the speed of gravity you have
    1) point in space WHERE you measure
    2) an object in space THAT you measure

    the fastest that the object could ever travel is the speed of light, so the fastest change you could ever measure is the speed of the object, thus if we measure that the gravity changes with the speed of light, it might well be that the object changes position with the speed of light while gravity changes instantaneous.

    I know that the way the two physisist measured the speed of gravity was indirect, yet that still means that the fastest any object was moving in their experiment was with the speed of light.

    Does this make any sense? (just thought of it...not a lot of physics to back me up yet :-)

  • Um, why is this worthwhile? (Score:3, Insightful)

    by SuperDuG ( 134989 ) <be@@@eclec...tk> on Thursday January 16, 2003 @08:57PM (#5099083) Homepage Journal
    "In an article on Space.com, many physicists have criticized the current work on the speed of gravity, calling it 'nonsense' and 'simply incorrect.' Many of them still doubt the claims made by Fomalont and Kopeikin even before the results were even announced. Many of the physicists still hold on to the idea that gravity works instantaneously no matter what the distance, an idea that originated by Newton, but that was argued against by Einstein."

    There are still scientists that argue EVOLUTION. This is nothing new, scientists looking to ride the coat-tails of rising stars in the field by doubting them. Obviously with the results not out before the entire idea was refuted, but this doesn't surprise me. PhD's who are "experts" in their field tend to be arrogant asses when it comes to something they didn't "discover".

    Don't believe me, walk on to your local university and sit in on a graduate level class. Some people love to get paid to hear themselves speak.

  • Argh!!!!! (Score:5, Informative)

    by volsung ( 378 ) <stan@mtrr.org> on Thursday January 16, 2003 @08:57PM (#5099087)
    No, no, no! The contraversy over the results of the gravity measurement surrounds the MEASUREMENT TECHNIQUE, not the conclusion. You would have to look *really*, *really* hard to find a working physicist who thought that the influence of gravity was instantaneous. You'd have an easier time finding a "Pacifists for Bombing Iraq" organization to join.

  • SATA benchmarks pretty useless thus far (Score:5, Informative)

    by Tumbleweed ( 3706 ) on Thursday January 16, 2003 @09:11PM (#5099150)
    Out of every benchmark I've seen of the new Seagate Barracuda V S-ATA drives, _none_ of them benchmark against it's parallel ATA brother, but instead benchmark it against either an older generation drive, or a drive of another manufacturer completely.

    Look, if you want to know how SATA performs, benching one of these 'cuda V drives against a western digital p-ata drive isn't going to tell you anything. Those drives from Seagate aren't all that fast compared to drives from Maxtor or WD (or IBM/Fujitsu).

    Expecting SATA to speed anything up is pretty ridiculous - the drive mechanism is what determines performance in current hard drives - we're nowhere near ATA drives that can match even ATA100 speeds (even burst rates are only reaching ATA66 speeds, if that!).

    SATA won't increase your speed, PERIOD. New generation drives with higher data density, etc., are what speed up drives. The interface doesn't matter in speed.

    FYI.

  • Speed of gravity paradox (Score:5, Interesting)

    by nebbian ( 564148 ) on Thursday January 16, 2003 @09:18PM (#5099185) Homepage Journal
    If the speed of gravity isn't infinite, then I think you get a paradox when two bodies are orbiting each other.

    Let's say we have two bodies, body 1 and body 2, both orbiting a central point.

    Both of them are getting pulled in towards the central point by the other one. Right?

    But if the speed of gravity isn't infinite, each body will be pulled not exactly towards the center, but towards the point at which the other body used to be, a certain time ago.

    Try this experiment: You will need:
    1 friend
    2 tennis balls
    1 roundabout (the circular playground variety)

    Stand on a point on the circumference of the roundabout, and get your friend to stand opposite you. Spin the roundabout so you are both orbiting the central point.

    Now throw your tennis ball at your friend. Chances are you will miss, because your friend will have moved by the time the ball gets there. So now change your aim so that the ball actually hits your friend. Get your friend to do the same.

    When you've got things sorted, you should get the tennis balls hitting you from slightly 'front-on' compared to the center of the roundabout.

    So what this means is that if gravity has a speed, then each orbiting body will be pulled by the phantom ghost of the other one, which will appear to be slightly behind the center of rotation. Therefore, the two bodies will keep on accelerating, pulling themselves up by their shoelaces, until the orbits around the central point become so huge that the effect isn't very big at all.

    In other words, orbits won't be stable if gravity has a speed.
    If we assume that 2-body orbits are stable, then gravity must be instantaneous, but this introduces a communication paradox (as pointed out by many other posters).

    So we have a paradox! If you were God, would you make gravity have a speed, or not? Or do you make it so friggin' hard to measure that people give up and argue over which physicist has the bigger reputation? :-)
    • Cute thought experiment, but I don't think it matters. The end result of the vector math is still a point in between the bodies (the centre if they're of identical mass). The orbits will appear the same at all times regardless of whether gravity is constrained within light cones or not, and this is why it's such a pickle of a problem. In fact I suspect it's the sort of problem that will lead to other unexpected understanding simply because one has to be so devious to try and measure it.

      If you don't believe in the vector math method (that the bodies orbit a central gravitic point, just as, say, a dust ring or ringworld would) try thinking of it this way: each body is orbiting the [displaced phantom of] the other, but because their orbits are complimentary it still doesn't matter. That is, if only one body was affected then the binary system would go spinning crazily away, but because their respective motions necessarily complement one another, it again doesn't matter - with either method, the phantomicitys you're concerned about will exactly cancel each other out.

      Same applies if the bodies differ in mass, of course, though the math is a bit harder. ;)

    • Re:Speed of gravity paradox (Score:5, Interesting)

      by NanoProf ( 245372 ) on Friday January 17, 2003 @12:01AM (#5099819)
      I'm impressed. Very clever, but you've forgotten about the coordinate transformations of relativity. Assuming I remember my grad school E&M correctly, if one does a full calculation relativistically, the force arising from a body moving in a straight line at uniform speed does in fact appear to come from where the body would be predicted to be at the time that the signal is received, not the time that it is sent. Of course, if the body curves suddenly, this simple result breaks down (since own can't anticipate how it would curve). The situation with co-orbitting bodies is more complex, but the basic idea is the same: the full relativistic calculation with retardation effects (i.e. finite signal propagation) eliminates the naive nonphysical effects. One does, however, see things like precession of the perihelion from GR, which is absent in the Newtonian approximation.

  • Wolf! Wolf! Wolf! (Score:4, Interesting)

    by ScottForbes ( 528679 ) on Thursday January 16, 2003 @09:44PM (#5099324) Homepage
    Slashdot's articles make it sound like SCO is trying to claim intellectual property rights to "ls" and charge $2 per directory listing -- but all the linked article says is that they're planning to charge money for use of SCO's (non-GPLd, non-Free) libraries, which allow Linux users to run software written for SCO's proprietary Unix.

    I don't understand why Slashdot is crying wolf so loudly over this, especially when a bigger, badder wolf just ate 20 years of our intellectual property [google.com] -- is there something I'm missing here? Does Linux rely on the SCO libraries in some critical way, or is there reason to fear that SCO might actually try to assert IP rights over some part of Linux itself?

  • Maybe modern scientific equipment isn't sensitive enough to do this, but the following occurred to me as a possible way to test the speed at which gravity propagates.

    Take two weights, A (an extremely dense, very heavy spherical weight) and B (a tiny, tiny little weight). Mount B in a device that will detect any forces exerted on B. Put A some distance away from B, measure the forces on B, and then move A around as quickly as possible, and look at the changes in the forces B undergoes.

    The idea is that as A moves, the average vector of the gravitational force it exerts on B would move as well; the fastest rate of change would be if A was orbiting B. However, there are potential complications: The mass of the apparatus that moves A around, the mass of the device that holds B, the mass of the building this experiment is housed in, and of course any other massive objects that happen to be moving nearby. Plus, A has to be far enough away from B that, if gravity does propagate at the speed of light, the time lag will be detectable when B moves in response to A moving. But the farther away A is, the smaller the force, making it harder to detect a change (and to sort it from background "noise").

    Nonetheless, it still seems like it would be possible to construct some kind of relatively simple experiment of this nature to determine the speed of gravity. I'm not a physicist, so I'm sure there's a lot I'm missing here. Maybe someone more knowledgable can shed light (or gravity!) on the subject.

  • Speed of gravity is slower than speed of light (Score:3, Funny)

    by stretch0611 ( 603238 ) on Thursday January 16, 2003 @09:52PM (#5099349) Journal
    Heres the real proof. Wile E. Coyote never fell until a split second after looked down and saw the canyon floor. Because he fell after he saw the canyon floor the Speed of Gravity is slower than the Speed of Light.
  • If you read the article, they imply--numerous times--that the issue with SCO is solely if you are using their libc on Linux in order to run legacy SCO applications. That should not be able to impact Linux in any real way, unless I am grossly misunderstanding something.
  • The military loves Iridium and will not let it die until we start hearing about the system they are producing to exceed its capabilities.

    The blurb about OS/Comet doesn't really say anything, because Iridium doesn't have the capital to replace something that is a huge part of their infrastructural investment (it'd be like replacing the linux kernel and tcp/ip on your computer without changing any other files and doing it while the machine is running and, oh yeah, you have to write it yourself and nobody else has ever done anything remotely resembling it, including all the ancient, legacied bugs).

    The big story would have been if Iridium had told Harris to take a hike, because then we'd get to wonder where Iridium got the "fuck you" money.

  • Ok, this is what i think (Score:4, Insightful)

    by FS1 ( 636716 ) on Thursday January 16, 2003 @10:55PM (#5099590)
    I have seen alot of people here who say that gravity can't travel faster than the speed of light and usually back their response up with relativity. But mind you, relativity is still theory not law. Say for example gravity could travel faster than light, we will say that gravity waves travel at 2x the speed of light. Now say we have a way to measure the effect of gravity waves and not of gravity itself, just going to Heisenberg's uncertainty principle to say we can't measure the intensity of gravity waves unless we change their position. Because we would have to use light or energy or something that goes slower than light to measure the speed of the effects, that renders the results of any such attempt to send information or energy this way useless.

    Now getting back to what someone asked earlier, what would happen if the sun were to be removed, would the earth spin off or stay in place for 8 minutes. To answer you question i use will use einstien's theory of gravity. He equated space to a 2-d surface, like a trampoline, gravity would warp that surface and create indentions. Ok say i put a bowling ball (sun) on the trampoline, and put a baseball (earth) in orbit of it. Now lets say i pick up the bowling ball quickly (almost instaneously), the baseball does just go off in a straight line, right?. What if i did it slowly?

    Now saying that, you all know that you just simply can't move a mass such as the sun faster than the speed of light, heck you can't even make an bowling ball go faster than the speed of light, but the problem is relativity doesn't quite work for very large or very small objects. My theory is that gravity can move faster than the speed of light but the mass that generates it can't so you could never use it to create any paradox that was suggested.

    • You made a typo in your post.

      I believe what you meant to say was "My entire understanding of physics comes from half-remembered articles in Scientific American that I didn't really understand."

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