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Space Science

Mystery Force Affecting Probes 296

Posted by michael
from the VGER-awakening? dept.
imipak writes: "The BBC reports that after exchaustive investigations, NASA scientists have run out of possible explanations for the mysterious tiny course deflections experienced by the Pioneer and Voyager spacecraft as they head out of the solar system towards the heliopause. Could it be that there's something wrong with our theory of gravity? (Well, yes, we already know that...) or could it be Oort Cloud objects? The tenth planet? Informed comment, please!"
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Mystery Force Affecting Probes

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  • by Anonymous Coward
    Hmm. I kind of see what you're saying. An object B appears to move away from an object A, assuming they're both bound to space and move with it
    I don't like saying that objects are "bound to space" or "move with it", or that "space moves". That's too much like pretending that space is an actual physical rubber sheet, which it isn't. Rather, simply say that the space between A and B expands, so the distance between them increases (not "appears to", actually does).
    Thus, to an observer on A, B is receding according to his (physical) measurement system. An object B in orbit around A would not be moving toward A by definition (well, by approximation to a circular orbit). The points are bound via gravity to each other, and we assume they're not bound to space as it expands (or they'd move with it).
    In a gravitationally bound system, space doesn't expand, so B doesn't move away from A. (By "gravitationally bound" I don't mean "bodies bound to space" or anything like that, I just mean the kind of "bound state" you see in ordinary Newtonian gravity. In Newtonian gravity it means that the whole system has negative total energy -- i.e. it requires the input of energy to separate the particles to infinity, so it's a stably bound configuration. Of course, in general relativity there is no such concept as "gravitational potential energy" so the idea of "bound system" requires more care to define.)
  • by Anonymous Coward on Tuesday May 15, 2001 @02:53PM (#220988)
    So, let me get this straight. NASA has given up trying to explain this, they have no idea. So for informed comments, now we turn to ...

    Slashdot Readers

    Hurrah! Please explain it for me, guys. I have a friend at NASA who would really like to know.

  • Thanks for the input from your experience. I agree, the problem is seperating good spending from abusive spending. However, I do take issue with your suggestion to ditch the Nat'l Endowment for the Arts. Ever since Gingrich, it's been horribly underfunded. Think of the NEA as the artist's version of the NSF.

    -Paul
  • by Paul Komarek (794) <komarek.paul@gmail.com> on Tuesday May 15, 2001 @11:44PM (#220990) Homepage
    As someone considering NASA after their Ph.D., I find your comment offensive and ill-informed. Government wages for scientists at NASA are decent, easily enough for comfortable living. But there is also job security, an above-average vacation policy (for the USA), and exposure to a wonderful variety of people and technologies.

    Not to mention that some people might actually like helping their country, despite the fact that folks like you diss all public servants as "also-rans". Because US taxpayers have a screwed-up sense of what public servants deserve, there are some fairly draconian policies in place in various government institutions:
    * All cups of coffee must be accounted for, and paid for individually
    * No Christmas parties, even if financed by
    discretionary money
    * Spouses not allowed to ride in government
    vehicles, even when travelling together
    Obviously, I don't like your attitude. That said, it's quite possible you were making a joke -- an inappropriate joke, in my opinion. How would you like it if your company couldn't hold a Christmas party, despite a year of record performance?

    Your comment is certainly not "informed". Consider the following data, all found via Google at
    http://www.hq.nasa.gov/office/HR-Education/workfor ce/endofy99.html [nasa.gov]:
    * 74% of NASA's workforce have a Bachelor's
    degree or higher.
    * 34% have a Master's or higher
    * 10% have a Doctorate
    For an agency with 17,000 employees, that's not bad. How does your company stack up, Mr. Fancy Pants? Here's some more info:
    * Average salary across all NASA's scientific
    and engineering employees: $79,000
    * Average salary across all NASA's employees,
    regardless of job: $69,000
    * Average salary of scientist or engineer at
    NASA's headquarters: $103,000
    * Average for same at Ames Research Center:
    $86,000
    * At all of NASA's centers, scientists and
    engineers have higer average earnings than
    professional administrators -- music to my
    ears!
    Remember that these are averages, not maximum salaries. Also, consider that NASA has 17,000 employees, though I don't know how many are scientists or engineers. Given that 35% percent have an advanced degree, this is likely to be a large number. At any rate, these numbers are just fine, if you're not a mercenary.

    It is very interesting to look at the top ten reasons people remain federal employees. You can see this list here [reinventing.com].

    -Paul Komarek
  • Physics should be about particles, their properties and their interactions, the only physical stuff there is. Everything else is either abstract or voodoo.
    Damn right! I blame it all on those damn micro-scopes and instraments. Why, when I was young we used to do physics by using our God-given eyes, and consulting the Aristotle when we weren't sure.

    Okay, more seriously, what the hell are you talking about? It's all abstract voodoo. Have you seen an electron? No, you can't. Electrons and all your beloved particles are invisible. You can see the effects of them, I suppose. But are you really sure it's not fairies doing the real work? Are you really sure it's not God, setting up little games for us to figure out? I mean, if He plants bones in the ground to test our faith, it doesn't seem far fetched that He'd come up with other little games. Or maybe it's multidimensional strings?

    You've never seen an atom, not to mention an electron... and certainly not quarks. All that makes you think that they exist is some model, which apparently has been consistent in predicting a wide range of experiments. It's a nice enough model that you have been able to internalize its metaphors, even with only indirect evidence.

    But it's just a model made up of a bunch of equations and notions and assumptions. It isn't magic. It isn't Truth. And that model is not somehow endowed with some status that makes it somehow more The True Model than any other mathematical model. Atom theory predicts things good. Newton's theories predict things good. Aristotle was a idiot, and he didn't predict crap, but that's an aside.

    So far, no model has predicted and explained everything. Maybe no such model exists, or maybe it does. Maybe many such models exist. You want underlying causes, but you won't get them, ever (unless maybe God is proven to exist). You can only get models. One after another, which by some really long chain of deduction end up in something you can directly sense. Or, at least, you think you can sense, because this all might just be a dream in the mind of Shiva.

    It's just turtles, all the way down.

  • This troll also goes by Nemesis [google.com] on the sci.physics.relativity newsgroup. He's a popular killfile item. He really likes to call people "prevaricating little lapdogs." This means he knows how to use a thesaurus and possibly a dictionary as well. He seems only capable of ad hominem attacks.

    Math does not create physics.

    Ack! He doesn't seem to be able to tell difference between a map and the actual road.

    from the Simpsons' Episode: $pringfield (or, How I Learned to Stop Worrying and Love Legalized Gambling):
    Mr. Burns - "Quick, Smithers! We'll take the Spruce Goose. Hop in."
    Waylon Smithers - "But that's just a model."
    Mr. Burns, cocking a revolver - "I said, 'Hop in.'"

    On the actual subject of the article: That is simply fascinating. I would like to see them add an experiment to the proposed Pluto probe to study this phenomenon further. Pluto-Kuiper Express [nasa.gov]

  • Though I'm on the fence about the probability, there is, I suppose, the possibility of intelligent influence as well. Since NASA has no explanation, it might very well be worth considering that an extraterrestrial entity could be responsible.


    After all, what better way to make contact than to cause an unexplainable error? We'd be sure to notice it!

    --

  • Math doesn't create physics, and nobody (sane) believes that it does. I do believe you're a troll, of course, but you do tap into some common frustration with the intangibility of modern (non-newtonian) physics.

    The field of particle physics that you extol would not exist but for mathematical models.

    If "mathematical what-if scenarios" are junk, how do you come up with a falsifiable hypothesis predicting the existense or behaviour of such-and-such subatomic particle? How do you design the experiment to falsify the hypothesis?

    Math isn't physics. Math is a tool for modeling. You're a tool for trolling. You may have a legitimate beef with news media who report abstract theory as sensational fact, but I deride the legitimacy of your beef against physicists.

    -Isaac

  • The acceleration is described as towards the Sun, not opposed to the motion of the spacecraft. Assuming those to directions are not so close together that they can't be distinguished, that would pretty much rule out drag.

    I think the science instruments would also have detected a change in the velocity of the surrounding medium. It's precisely to detect the heliopause that they are being run.
  • ...and consequently, SlashDot is as good a venue as any to look for explanations.

    Perhaps the stars really are embedded in a crystal sphere, and the perturbations are the gravitic effects of the sphere beginning to manifest. Watch for a sudden end to transmissions and soon afterwards the mother of all cracks in the sky... (-:

    ``But seriously, folks''

    NASA don't know how our own sun works [electric-universe.de], so how can they be expected to predict behaviour even further away from the sun? How is it that a (ghasp) lone scientist with no resources can bullseye planetary magnetic fields before the fact [icr.org], but NASA (besides many other large and well-equipped organisations) are several orders of magnitude wide of the mark?
  • Clearly, this is due to the Springfield Effect [flat-earth.org]. They have simply passed through new, undiscovered Springfield locations.

    Mr. Teapot [flat-earth.org] can answer all your questions.

  • There is a cult within the spacetime physics community led by a small but influential cadre of nerd physicists and mathematicians whose credo is "physics is math" and who think they are free to create physics simply by manipulating spacetime equations using what-if scenarios.

    LOL! That reminds me of Logopolis episode of Dr. Who. This was where the Doctor and the Master visited this city where these people run "block transfer computations" which control reality.

  • As someone considering NASA after their Ph.D., I find your comment offensive and ill-informed.

    Perhaps your University's graduate program should offer a course on emoticons and their meaning.

    -
  • As the article states, both Pioneer 11 and Pioneer 10, on opposite sides of the Solar System, are experiencing the same effect, which rules out local gravitational effects.

    Oddly enough, it also seems that this deviation is not evident in the orbits of the planets.

    Me? I just think that they've been slowed by local debris--though I'd like to believe in a gravitational constant.

    -W-

    "Is it all journey, or is there landfall?"

  • A few comments above we have, "So, let me get this straight. NASA has given up trying to explain this, they have no idea. So for informed comments, now we turn to ... Slashdot Readers Hurrah! Please explain it for me, guys. I have a friend at NASA who would really like to know.

    I thought it was funny (so did several moderators).

    And now we get this obvious troll, and it is moderated as insightful.

    Not so funny anymore.

    Steve M

  • by SteveM (11242)

    Its funny (or sad) not flamebait!

    Well it sure ain't funny. It may be a sad attempt at humor.

    But I'm going with flamebait.

    Steve M

  • Regarding the link to www.superstringtheory.com, I would like to point out that the standard string theory models include gravity with exactly the same behavior as in general relativity. (at least until you go up to absurdly high energies) While you have many choices for the matter content of the theory and the nature of the gauge forces (like electromagnetism and the strong and weak nuclear forces), general relativity pops out whether you want it or not.

    This property is generally seen as a desirable property of the theory. In fact the only really good argument in favor of string theory is that it is the only known quantum mechanical theory which produces the observed behavior of gravity and is not known to have internal inconsistencies.

  • Sorry but I don't think the instrumentation on these probes really is advanced enough to gather what is needed to make an accurate or informed decision.

    How so?

    To start with, the main data of interest (probe positions and trajectories) doesn't require additional instruments to measure. They're looking at the timing and doppler-shifting of the probes' radio signals, and getting a very good estimate of their positions and velocities.

    The record of the probes' trajectories over long periods of time is what suggests the effect and places limits on how it acts.

    Secondly, there isn't anything *out* there to look at. At least a few of these probes have micrometeorite detectors and dust analyzers and radiation analyzers. That covers just about everything you'll run into. What extra instrumentation do you propose to add?

    What kinds of instruments do you think would give us a better idea of what's going on than we already have?
  • Now, I can't remember the specifics, but the general equations we use when utilizing relativistic motion are actually still only approximations -- it's just that the third, fourth, etc. order terms of the equation are so small that you can ignore them.

    The thing is - what happens over large distances? Well, the smaller terms will start to become very important. I've got to wonder if they forgot that the equations they'll typically use ARE approximations which are simplified for ease of use in calculations?


    If I understand correctly, the approximations only cause problems in very extreme situations (sharply curved space, very high matter or energy densities, very oddly configured space, etc.). At the probes' location, space is so flat you could treat it with Newtonian mechanics and have a great deal of trouble finding discrepencies with observations.

    Thus, I doubt that equation approximations are the cause of the problem in this case.

    On the other hand, if I recall correctly there has been interesting speculation about the full versions of the equations allowing negative mass to be generated under some conditions. I'd have to study my relativity book a lot more thoroughly to tell if that's even remotely sane, though.
  • for instance if it were wrong, then (since we have a fairly good grasp of the distances involved, we would simply miscalculate the mass of a planet. And believe it or not we could probably go for quite some time convinced that jupiter was heavier or lighter than it was without finding a condradiction.

    If we were only looking at the orbits of the planets about the sun, this would most certainly be correct. However, we've also observed the orbits of the moons of the various gas giants about their primaries, and measured with fanatical precision the paths of the probes we've sent to and past the gas giants. If the mass values for the gas giants were off, this would have very substantial effects on the orbits of their moons and on the trajectories of probes that have visited.

    Good thought, though.
  • If they're slowing as they get very far from the Sun, that seems to imply that the force of gravity is not dropping of quite as fast as 1/r^2.

    The problem is, as the article points out, we would have seen the effects of this on the orbits of the planets if this was the case.

    I'm personally wondering about drift in the probes' radio sources throwing off the doppler measurements, but if this was happening they should have caught it already (you can directly measure the probes' positions by measuring the round-trip signal times to them at a few different imes during the year).
  • by RAruler (11862)
    Informed comment, please!

    Bullshit, informed? how do you know it's not a bunch of flying winged monkeys. Theories are only slightly better than guesses. Besides, Slashdot isn't exactly the best place to go for people knowledagable in the physics of bodies moving through uncharted portions of space. If you really want informed opinions, try and berate the people at NASA and JPL. Slashdot is more of a jack-of-all-trades thing, theres probably someone with the background similar to Stephen Hawking on here. But the only thing they can offer you is, their opinions and theories. Again, not necessarily better than my theory of tiny space going simians.

    ---
  • But how well do we know what shape the galaxies have? If this effect were a result of "warped space-time" would it be large enough to detect in the images of galaxies? We know with a good degree of accuracy where the probe started, how fast it was moving, how much it weights, etc. So it is quite likely that we can make a more exact projection of where the probe should be than of how a galaxy should be shaped.

    Just consider, we don't even know, really, how much "dark matter" there is in either our own galaxy, or in any of the nearby galaxies. But that could profoundly effect the shape of the galaxies. Those who argue that we know that the universe is flat on the order of a mega-parsec (or whatever) actually don't have that much evidence. Just how flat are they asserting it is? And on what fractal scale? (Consider: "How long is a coastline on a fractal scale?" to be the appropriate analogy.) Certainly is must be lumpy near each star or other massive body. The assertion of flatness then is either the assertion that a) that doesn't matter, or b) but it lumps the other way too, so it evens out. Normally we say that is isn't lumpy enough to make any difference, except when we do something like use gravitational lensing. But how exact is our knowledge?

    Even things that are straigtforward projections from well known physical laws tend to be scoffed at if they are unfamiliar. Consider the early days of black holes. But they had been predicted in the 1800's (well, not their more peculiar features, but a star that was too heavy for light to escape from). If anybody had run a straightforward calculation (post Einstein) they would have come up with black holes. And they did, but the idea was so strange that nobody would believe it, and it was considered a purely theoretical curiosity. Perhaps there is another "theoretical curiosity" that will explain this. But it's likely to require being willing to accept that the universe isn't a simple as we like to think of it as being.

    Caution: Now approaching the (technological) singularity.
  • Ok. But if it's stellar gas, then there's no reason to assume that it's uniformly distributed. Perhaps then the spaceship is acting as an air plane hitting an air pocket, and getting slightly refracted? (After all, it wouldn't take much.)

    Caution: Now approaching the (technological) singularity.
  • One of the big open questions of the day is: What is the shape of the universe?

    Bent. Or was that time? I'll have to re-read Dr. Streetmentioner's work again.

    --
  • Perhaps we should be careful. It may be Thread, which inhabits the Oort cloud around the Rukbat system, and very nearly destroyed the colonists on P.E.R.N.

    --
  • by nyet (19118) on Tuesday May 15, 2001 @03:36PM (#221035) Homepage
    I am extremely offended at your attitude. My father spent the last years of his life _skeptically_ examining all the evidence gathered throughout the THIRTY years the pioneer probes were operational.

    The fact that you can sit in your armchair and question his objectivity, wonder, and *passion* for the mysteries of life makes me physically ill.

    Any failing of science is OUR fault. OUR faliere to educate. OUR faliure to recognize our biases. OUR faliures to drag concieted shits like you out of the dark ages.
  • by nyet (19118) on Tuesday May 15, 2001 @03:22PM (#221036) Homepage
    My (recently deceased) dad is on that paper.. he believed that it was most probably (b) (outgassing of some sort, possibly a malfunction/weakness common to both pioneer probes). No real evidence of that of course, and a "mysterious" force is more publishable ;) Still it is very spooky.

    (g) and (h) were (in his opinion) the least likely.

    Note that the paper was actually first released in April, and just revised today.
  • by KFury (19522) on Tuesday May 15, 2001 @03:48PM (#221038) Homepage
    Could it be that there's just more mass in the solar system than we think? Wait, hear me out. I'm not talking about Planet X or a bloated G, I'm talking about ambient stellar gas.

    Here's the deal: On the Earth, the gravitatinal forces acting on you at the surface all sum out to equal to the forces that would be exerted by a point source with the Earth's mass and a distance r, the diameter of the Earth. Though that ocean to your left and that continent to your right pull you in opposite directions, and the ground under your feet is pulling harder than the ground in China (um, unless you're in China, in which case, 'hi'), but it all sums out exactly right to a point mass at radius r.

    Now, take that example and pose it to the solar system. Forget about the forc of solar wind blowing, and realize that all that wind has mass, and exists everywhere. It's pretty thin, but it's a lot thicker than the four hydrogen atoms per cubic meter in deep interstellar space. All that stuff, wispy as it is, has mass, and even though most of it is so godawful far away, the net gravitational effect of all of it is as if there were an additional point source inside the sun, with the mass of all the stray gasses and particles inside the huge sphere that has the sun as the center and the space probe on the outer surface.

    What makes the math even more wonky is that, assuming a roughly even distribution of gas as inversely proportional (or inverse square, or even constant, doesn't matter in this case as long as it's uniform by uniform radius) to the distance form the sun, then the farther out the probe goes, the more mass there is behind it, and the farther back the point source goes.

    If the density were uniform (it's not) then the effect of this force would actually increase as the probe got further away. As it is, it may be a constant force. For conceptualization's sake, if you had a well to the center of the earth and went to the bottom (forget magma, use the moon if it makes you feel better) you'd be weightless. Go halfway up, and you'd have a force of one-half g. Go to the surface and you are being pulled with a stronger force than you were when you were closer to the center.

    Anyhow, HTML's bad for math, but I just wanted to get the idea out there. I don't have enough info on particulate density over the scope of the solar system and beyond to make any educated numbers anyhow. Hopefully someone out there does.

    Kevin Fox
    --
  • Gravity is many orders of magnitude less powerful than the other fundamental forces, but at least in our experience gravity is also the only force that is always attractive. It is also one of the forces that has a measurable impact at distances beyond a few angstroms.

    If you charge up a baloon with static electricity you can see just how strong the other major fundamental forces are. The number of electrons you're moving around is tiny, but it's enough to overwhelm every single proton, neutron and electron being pulled by gravity. The fact that gravity has a measureable impact isn't anything spooky, it's just the sum of a lot of very weak interactions with no opposing interactions.

  • by SEWilco (27983) on Tuesday May 15, 2001 @03:10PM (#221044) Journal
    As the article says, four probes in different directions are showing this behavior so this is probably not due to an unknown planet.

    The interstellar medium (interstellar gas & dust) is much less dense than normal around our solar system due to the Scorpius-Centaurus Association superbubble [uchicago.edu] and the Geminga supernova bubble [lanl.gov]. Perhaps we're seeing a slight increase in the ISM density -- of course these researchers should know all about this, so it's still a puzzle...

  • so what you're saying is "bill gates sucks"?
  • A hundred years ago, an unexplained force seemed to be affecting the orbit of Mercury, causing a wobble in its orbit that should not have existed in a Newtonian framework. Then in 1915, Albert Einstein developed the theory of General Relativity, describing the complex curvatures of our universe that could explain Mercury's path around the Sun.

    You know... a lot of these problems occur when you take an approximation instead of the real thing.

    Eg. Newton's laws are a 1st order approximation to the real thing.

    Relativity gets closer.

    Now, I can't remember the specifics, but the general equations we use when utilizing relativistic motion are actually still only approximations -- it's just that the third, fourth, etc. order terms of the equation are so small that you can ignore them.

    The thing is - what happens over large distances? Well, the smaller terms will start to become very important. I've got to wonder if they forgot that the equations they'll typically use ARE approximations which are simplified for ease of use in calculations?

    Simon
  • by Mike Van Pelt (32582) on Tuesday May 15, 2001 @02:59PM (#221049)
    If they're slowing as they get very far from the Sun, that seems to imply that the force of gravity is not dropping of quite as fast as 1/r^2. If the strength of gravity is higher than inverse square and great distances, perhaps that effect would explain the "missing mass" problem? There isn't really any missing mass. This effect makes it look like the galaxies are more massive than they really are.
  • by Mignon (34109) <satan@programmer.net> on Tuesday May 15, 2001 @03:58PM (#221052)
    I have found a truly marvelous explanation, which this input field is too small to contain.

    --Fermat

  • by slickwillie (34689) on Tuesday May 15, 2001 @06:01PM (#221053)
    I'm sure it's cognitive gravity. You know, like when Wile E. Coyote runs off the cliff, but he doesn't fall until he looks down and realizes he not standing on solid ground anymore. I think those NASA guys stopped looking at those spacecraft, and they stopped moving until someone looked again.
  • by coyote-san (38515) on Tuesday May 15, 2001 @05:52PM (#221054)
    The only problem with this analogy is that the precession of Mercury's perihelion occured in the area of the highest graviational field within 4 light years. This is where you would expect to find simplier theories to break down.

    In contrast, the probes are in areas with a relatively small gravitational field. While the field is smaller than anything this side of Pluto's orbit, it's not that much smaller. (The contribution from the sun is lower, but the contribution from the entire Milky Way, and our gravitationally bound galactic cluster, is just as large.) A breakdown in the existing theory just doesn't make sense here - and even if it does break down, where does the energy come from?

    As for the issue of the space of the universe... get a grip. :-) The shape of galaxies - and interactions of galaxies in clusters and super-clusters, shows that the universe is "flat" on the scale of many millions of light years. If you equate that to the size of the earth, then 1 meter represents about 1 LY, and the helipause will easily fit within a postage stamp. Or maybe the period at the end of this line. Something definitely "flat" by any reasonable definition.
  • by thogard (43403) on Tuesday May 15, 2001 @05:04PM (#221059) Homepage
    An early theory of gravity said it pushed in all directions at the same time but things with mass blocked it slightly. The attraction force is simply the delta of pushes from two sides not being equal. This was thrown out because things in space would slow down over time. However...
    it appears that things do slow down over time. The deep space probes are not the only ones showing this. The gps sats are doing it and this is one of the problmes that gravity probe B is suppoed to help solve. I guess it means we have a wrong view of what keeps up stuck on this world.
  • NASA scientists have run out of explanations, but we're going to figure it out. Right here on Slashdot.
  • by devphil (51341) on Tuesday May 15, 2001 @02:55PM (#221065) Homepage


    It's Protector Brennan, making slight alternations to make certain that the probes don't eventually travel to planets with possibly-hostile alien species, thereby alerting them to the existence of humans.

  • Voyager is more advanced than anything that NASA has produced lately.

    Based on what criteria?

    Well, there's that hologram doctor... and the hot babe with the retractible ass ticklers in her arms... and its micro-wormhole generating technology that lets it communicate far further distances than simple subspace...
  • The probles don't *need* to be sophisticated. It's sufficient to use the doppler effect of the radio signals from the spacecraft to determine the speed of the craft, and the position can be determined by simple position in the sky. Distance can be determinedby delay between send and receive, which can be measured.
  • Another likely source of the accelerartion is neutrons (and other particles) from the radioactive power source that the probes carry. This effect is much larger than relativistic effects and is probably much larger than any new physics effects. The decay of these power sources over long periods is not well known, and hence their effect on perturbing the trajectory is not well known.

    Huh? the RTGs' radioactive heat source is completely enclosed, the particles it generates do not have enough energy to penetrate the shielding and give up their momentum to the enclosure. Therefore, no net momentum change caused by the decay products, other than the known-to-be-miniscule contribution of individual neutrinos.

    Not that it matters anyway, since the decays would happen equally likely in all directions, so even if the particles were released the net effect would be zero.

    More ACBS...

  • Since i first heard from this effect i thought it might be some magnetic braking effect (all metals would be affected by this when they pass through changing (not spatially uniform) magnetic fields, like that of the sun e.g.). The idea is pretty simple, it would also explain why artificial probes are affected, but not planets, asteroids, etc., since the probes are made of metal. Maybe it's just a hint, that the changes in magnetic fields out there are (for some reason) stronger than we think.

    But then something that obvious would probably have been looked into. It would be much easier to make a wild guess, if there was a list of effects already looked into and dismissed. (The paper is apparently slashdotted).
  • You think THAT'S funny, you should follow his link. He's even better at being a crackpot than Alex Chiu [alexchiu.com].

    Then again, crackpottery is relative, as MOBE2001 demonstrates by calling every other spacetime physicist one.
    --

  • There's another page somewhere which discusses crackpot theories... however, that page is written by MOBE2001, a crackpot himself (though he calls everyone else one), who loves to troll Slashdot with his "theory".
    --
  • You can't decry one model of the Universe until you have another one that explains experimental findings better. MOBE didn't do any experiments, he just mangled the definitions of physics terms. The burden of proof is on you, I mean MOBE.

    Looks like he's got multiple Slashdot accounts, too.
    --
  • I have the answer, but just as I was about to come public with it a little gray lawyer came to me and told me that it was the Intellectual Property of an Alien Race. Any attempt to reveal it would be met with litigation of galactic proportions.

    Sorry guys, but the strong arm tactics of The Orion Grays and their Intellectual Property Laws have somewhat forced me into silence.

    I'll give you a hint though...

    ...it has something to do with ò[NO CARRIER]

    "Everything you know is wrong. (And stupid.)"
  • And wasn't it Niven who asserted that humans didn't discover FTL because they did all their experiments in a gravity well and so didn't realise that the laws of physics were slightly different outside the solar system .... so they had to buy the technology from the Outsiders. He he he.

    Peter
  • by selectspec (74651) on Tuesday May 15, 2001 @03:31PM (#221083)
    New Physics Theory Highlights:

    Due to the fact that the size of the anomalous acceleration is of order cH, whereH is the Hubble
    constant (see Eq. (56)), the Pioneer results have stimulated a number of new physics suggestions.
    For example, Rosales and S anchez-Gomez [136] propose that aP is due to a local curvature in
    light geodesics in the expanding spacetime universe. They argue that the Pioneer eect represents
    a new cosmological Foucault experiment, since the solar system coordinates are not true inertial
    coordinates with respect to the expansion of the universe. Therefore, the Pioneers are mimicking
    the role that the rotating Earth plays in Foucault's experiment. Therefore, in this picture the
    eect is not a \true physical eect" and a coordinate transformation to the co-moving cosmological
    coordinate frame would entirely remove the Pioneer eect.
    From a similar viewpoint, Guruprasad [137] nds accommodation for the constant term while
    trying to explain the annual term as a tidal eect on the physical structure of the spacecraft
    itself. In particular, he suggests that the deformations of the physical structure of the spacecraft
    (due to external factors such as the eective solar and galactic tidal forces) combined with the
    spin of the spacecraft are directly responsible for the detected annual anomaly. Moreover, he
    proposes a hypothesis of the planetary Hubble's ow and suggests that Pioneer's anomaly does
    not contradict the existing planetary data, but supports his new theory of relativistically elastic
    space-time.
    stvang [138] further exploits the fact that the gravitational eld of the solar system is
    not static with respect to the cosmic expansion. He does note, however, that in order to be
    acceptable, any non-standard explanation of the eect should follow from a general theoretical
    framework. Even so, stvang still presents quite a radical model. This model advocates the use
    of an expanded PPN-framework that includes a direct eect on local scales due to the cosmic
    space-time expansion.
    Belayev [139] considers a Kaluza-Klein model in 5 dimensions with a time-varying scale factor
    for the compactied fth dimension. His comprehensive analysis led to the conclusion that a
    variation of the physical constants on a cosmic time scale is responsible for the appearance of the
    anomalous acceleration observed in the Pioneer 10/11 tracking data.
    Modanese [140] considers the eect of a scale-dependent cosmological term in the gravitational
    action. It turns out that, even in the case of a static spherically-symmetric source, the external
    solution of his modied gravitational eld equations contains a non-Schwartzschild-like component
    that depends on the size of the test particles. He argues that this additional term may be relevant
    to the observed anomaly.
    A proposal to modify the theory of gravity in order to provide an explanation of the Pioneer
    anomaly has also appeared. Capozzielo et al. [141] discuss the possibility of determining the
    stability and characteristic geometrical and kinematical properties of galaxies strictly based on a
    minimal action whose value is on the order of the Plank constant.

    Due to the fact that the size of the anomalous acceleration is of order cH, whereH is the Hubble
    constant (see Eq. (56)), the Pioneer results have stimulated a number of new physics suggestions.
    For example, Rosales and S anchez-Gomez [136] propose that aP is due to a local curvature in
    light geodesics in the expanding spacetime universe. They argue that the Pioneer eect represents
    a new cosmological Foucault experiment, since the solar system coordinates are not true inertial
    coordinates with respect to the expansion of the universe. Therefore, the Pioneers are mimicking
    the role that the rotating Earth plays in Foucault's experiment. Therefore, in this picture the
    eect is not a \true physical eect" and a coordinate transformation to the co-moving cosmological
    coordinate frame would entirely remove the Pioneer eect.
    From a similar viewpoint, Guruprasad [137] nds accommodation for the constant term while
    trying to explain the annual term as a tidal eect on the physical structure of the spacecraft
    itself. In particular, he suggests that the deformations of the physical structure of the spacecraft
    (due to external factors such as the eective solar and galactic tidal forces) combined with the
    spin of the spacecraft are directly responsible for the detected annual anomaly. Moreover, he
    proposes a hypothesis of the planetary Hubble's ow and suggests that Pioneer's anomaly does
    not contradict the existing planetary data, but supports his new theory of relativistically elastic
    space-time.
    stvang [138] further exploits the fact that the gravitational eld of the solar system is
    not static with respect to the cosmic expansion. He does note, however, that in order to be
    acceptable, any non-standard explanation of the eect should follow from a general theoretical
    framework. Even so, stvang still presents quite a radical model. This model advocates the use
    of an expanded PPN-framework that includes a direct eect on local scales due to the cosmic
    space-time expansion.
    Belayev [139] considers a Kaluza-Klein model in 5 dimensions with a time-varying scale factor
    for the compactied fth dimension. His comprehensive analysis led to the conclusion that a
    variation of the physical constants on a cosmic time scale is responsible for the appearance of the
    anomalous acceleration observed in the Pioneer 10/11 tracking data.
    Modanese [140] considers the eect of a scale-dependent cosmological term in the gravitational
    action. It turns out that, even in the case of a static spherically-symmetric source, the external
    solution of his modied gravitational eld equations contains a non-Schwartzschild-like component
    that depends on the size of the test particles. He argues that this additional term may be relevant
    to the observed anomaly.
    A proposal to modify the theory of gravity in order to provide an explanation of the Pioneer
    anomaly has also appeared. Capozzielo et al. [141] discuss the possibility of determining the
    stability and characteristic geometrical and kinematical properties of galaxies strictly based on a
    minimal action whose value is on the order of the Plank constant.
  • by selectspec (74651) on Tuesday May 15, 2001 @03:35PM (#221084)
    Bill Gates dark life force is clearly sucking the energy out of these scientific projects. We must remember that these spacecraft have been an endevour of science and that the scientific process has often been linked as an inspiration for Open Source. Need to paint a picture people? Of course, the Gates-Effect doesnt bother the planets. I'm still trying to figure out the Intel angle, but I suspect they might be involved too.
  • I don't know if this original, but I worked out from first principles that gravity is caused by "shade" from gravitons.

    In other words, all objects in the universe emit gravitons, and these exert a force on objects that they weakly itneract with. When you have two objects near each other, they shade each other from the cosmic background graviton flux. As a result, instead of each object having the same force on them from all directions, they now have less force on them from the shaded direction. So the two objects fall towards each other. The force is, coincidentally, proportional to inverse square of distance.

    However, a small correction factor is required. The thinning effect of a nearby object is not proportional to the amount of matter in it exactly, because the object shades itself from gravitions. Therefore the correct formula is an integral of an inverse exponential with respect to how deeply the gravitons have passed through the material.

    The effect of "self-shading" from gravitons implies that the force law must be corrected so that the gravitional force is smaller than the inverse square of distance for smaller distances. Conversely, as you get further away, the correction is positive relative to the inverse square law.

    This theory also helps to explain so-called missing dark matter, and of course it explains the expansion of the universe. It also has strong implications for black holes and the big bang, because it implies that the force of gravity is bounded by the total mass of the universe multiplied by a weak interaction factor. It explains lots of other strange things too.

    Could someone pass this on the NASA please?

  • though science destroys wonder by replacing it with understanding

    Naah. Sounds like you simply lost your ability to let your imagination run free.

  • My proposition: as the gravity drops down as the probes go out of Solar system, the time goes faster, relative to our position near the Sun. That causes us to detect a bit higher radio signal, which looks just like the probe had slowed down. Pretty simple Einstein, eh?

    Well, this was probably the first possibilities they thought of. Anyhow, the phenomenom doesn't have to be caused by a "force".

  • The problem with NASA's calculations is that they all involve objects in space that are either drifting or in some sort of orbit,etc -- but they haven't taken into account other space craft that would be wizzing by along the way. In fact, if one of our little probes were to pass close enough to a large transport, it may well get slingshotted not just out of it's course path, but to places completely unfathomed by our dear NASA engineers.
  • I was visited by a little green man last night who promised to tell me all the secrets of the universe for a buck and a quarter. I told him all I had was two bits, to which he replied that he'd only be able to tell me why our space probes aren't sticking to their projected paths. I took note of his advice, but can't say that I believed much of what he told me. I was just about to shred the notes that I took, lest they be discovered in my posession and I be taken for a lunatic, possibly even a danger to our society as we know it. I will have to weigh further what to do with this transcripts, .... damn, I spilled coffee all over them! ..nevermind.
  • by polymath69 (94161) <dr@slashdot.mailnull@com> on Tuesday May 15, 2001 @06:28PM (#221102) Homepage
    OK; having read the comments, and then the article, this occurs to me, and doesn't seem to have been mentioned or proposed.

    All these craft are still within the heliopause and will be so for a long time. They're moving outward faster than the solar wind, which means they're flying into it. The vacuum of space is only mostly a vacuum, remember, so the combined impacts of many little atoms will add up over time. The Pioneer craft, in particular, have been out there 20+ years, so the culmulative effects have had time to add up, and these would tend to slow the crafts over time. This effect is not negligible, or solar sails wouldn't work.

    Also, as probably a lesser effect, there's all the virtual particles that are springing up in front of the craft and getting run into before they can meet their natural antipartners. These also will register as mass impacts and tend to slow the vehicles.

    The first cause in particular will only get worse when the first craft hits the heliopause. At that point, it will no longer be plowing along with, but faster, than our Sun's wind, but head on into new solar winds. I wonder how much more difficult this makes it to come up with enough energy for eventual real interstellar travel.

    Just a late night thought or two... but it doesn't seem unreasonable.

    --

  • Let us spread this failing of science everywhere, so that we can regain our childhood sense of wonder and expose the necessary failing of science.
    A failure to explain a phenomenon isn't a failure of science. It's the opposite. It's what every scientist dreams of. Finding a disagreement between observed reality and theory is what the most exciting science is about.

    I'm not sure what planet you're on because you seem to be trying to write an anti-science diatribe and yet much of what you say is no different from the view of a scientist.

    --

  • Sounds close.

    My guess was to resolve two questions with this deviated course observation.

    1. What is causing the course deviation?
    2. Where is all the unaccounted dark matter [netlabs.net] in the universe?

    If the course deviations get large enough they could point to the missing matter (assuming it is distributed inhomogeneously), if that is in fact, the cause of it all.

    Far from being an amateur astronomer, I'm still aspiring to achieve full-fledged diletante status.

  • How is it that a (ghasp) lone scientist with no resources can bullseye planetary magnetic fields before the fact, but NASA (besides many other large and well-equipped organisations) are several orders of magnitude wide of the mark?

    You can ignore these links they are creationist psuedo science.

  • Pardon my doofyness but a certain piece of obviousness is just begging to be laid out. Theories are like lossy data compression: You never get a perfect rendition. In fact, if "reality" could be said to contain an infinite amount of information everywhere (I mean, what sets the resolution of a definition, some mythical objective reality or simple satisfaction? How many words are enough?) then any theory made about it must always be infinitely deranged. So mysteries, while easily ignored-to-forgetting from the comfort of your livingroom/office/customary-groove (in fact one might say that an act of intentional ignorance is the bedrock underlying any useful theory. Ignoring the irrelavent.), should be considered the norm to a degree proportional to your elsewhereness.
  • Funny, they didn't include my first thought on what might be causing it: (i) our understanding of the heleopause is incorrect.

    It may be that the heleosheath is not a hard boundary, but rather has a mix of both solar winds and interstellar gasses for a much wider region than is presently thought. In other words, it could be that there is no true heleopause at all. If that was the case, our little space probes could have been heading "upwind" against largely stagnant gasses for some time now, slowing them.

    Of course I have absolutely no evidence for this, but it is a missing hypothesis.

  • <sigh> Brings back memories of sitting up all night at a terminal cluster reading Usenet...
  • by Argylengineotis (118734) on Tuesday May 15, 2001 @03:10PM (#221121)
    There is no reason to suppose gravity gradients are even across large distances (>20 A.U.) If you pour over your references, you'll see that at no point, from the General Theory on up, does any theorist take into account the possibility that between strong influences (astral bodies), spacetime must be smooth. in fact, it is perfectly reasonable to suppose that there are variations large enough to account for these variances in trajectory. The universe is not beholden to your 'rubber sheets and marbles' analogy for gravity.
  • That's Right.

    All your gravitational forces are belong to us!

  • by efuseekay (138418) on Tuesday May 15, 2001 @03:15PM (#221135)
    (1) What you described is called "vacuum energy", and is actually one of the suspects. However, current physics has a problem : the predicted vacuum energy is 10^(120) (that's 1 followed by 120 zeroes) larger than the actual measured vacuum energy (called the cosmological constant by some people). With respect to the Pioneer 10 acceleration, the predicted VE will be too big, the measured VE will be too small.

    (2) Not likely. Small things can theoretical deflect the probe. However you run into two showstoppers (i) things are too small to make any difference (ii) the things will deflect the probe, averaged out, in an "isotropic" way (what this means is that, on average, there will be no net deflection).

    (3) Possible. But this uneven distribution will be detected long before. It's discussed in the paper that I listed in another post here. The punchline is that such things will also cost deflection of the planets, and we don't see that.

    Hope this helps.
  • by efuseekay (138418) on Tuesday May 15, 2001 @03:00PM (#221136)
    Check out the JPL final paper [lanl.gov] on this.

    Possibles are :
    (a) Heat Ejection (b) Gas Leak (c) Clock Drift (d) Anomalous objects (pretty dead, despite BBC giving prominence) (e) modifications to gravity (f) solar radiation pressure (g) systematics of observations (h) antenna radiation pressure

    Let the armchair speculation begin. (But remember to read the paper to check your answers!) Have Fun!

  • Screw what's affecting space probes that NASA can't figure out, how about some informed comments on a cure for cancer? Clearly there's a slashdotter somewhere just waiting to spill out the answer to that if you just ask.
  • The measurements are not being made via the instruments on the probes, but rather from measuring the dopper shift of signals from the probes.



    -----------------------------

  • Maybe all their calculations were in feet and inches, and all their measurements are in centimeters.

  • by rmcgehee (142010) on Tuesday May 15, 2001 @03:09PM (#221143) Homepage
    A hundred years ago, an unexplained force seemed to be affecting the orbit of Mercury, causing a wobble in its orbit that should not have existed in a Newtonian framework. Then in 1915, Albert Einstein developed the theory of General Relativity, describing the complex curvatures of our universe that could explain Mercury's path around the Sun.

    While this news report is very likely just a measurement error, we must be reminded that the last time we discovered an error in a celestial body's trajectory we reinvented the notion of the universe.

    One of the big open questions of the day is: What is the shape of the universe? Euclidean, hyperbolic, a torus--we aren't sure. It is thought that each of these geometries would profoundly affect an object moving across the universe in a different way. These NASA probes could in a sense be the moving laboratory that we need to understand what exactly our universe looks like.

    Robert

    http://wso.williams.edu/~rmcgehee [williams.edu]

  • I don't think the instrumentation on these probes really is advanced enough

    Voyager is more advanced than anything that NASA has produced lately. Pathfinder was a joke, not to talk about the failures that followed. It is doubtful whether with "faster, better, cheaper" Goldin in power, NASA would manage to build another Voyager, let alone a more advanced probe. I'm happy that they keep listening to it at all.

    But if we get something decent built in the next decades, we might as well send a probe to 550 AU and use the sun as a gravitational lens for SETI. Talk about alien TV stations ..

    --

  • While this news report is very likely just a measurement error, we must be reminded that the last time we discovered an error in a celestial body's trajectory we reinvented the notion of the universe.

    I understand measurement error has been pretty much ruled out as well as another planet.

    By the way, this news report first appeared in The Economist over a year ago.

    Not the first time it has happened either. The Economist was the first non-technical journal to talk about the Internet in a general context, abck in 1991-1992.

  • This Bible prophecy [philologos.org] site reported the same thing in 1998. They referenced a Washington Times report. This Space.com story [space.com] reported the same thing in November last year.

    Well, I guess the final JPL report is newsworthy.

    Note: I don't frequent the online Bible sites, but I knew I had heard this years ago and the referenced site turned up near the top of my Google search!
  • This article may or may not be the one that prompted this thread, but read to the bottom http://news.bbc.co.uk/hi/english/sci/tech/newsid_4 60000/460095.stm and you find "Earlier this year, scientists were puzzled by what was described as a mysterious force acting on the probe. It led to speculation that there was something wrong in our understanding of the force of gravity. Eventually the effect was tracked down to the probe itself, which was unexpectedly pushing itself in one particular direction."
  • Though I'm on the fence about the probability, there is, I suppose, the possibility of intelligent influence as well. Since NASA has no explanation, it might very well be worth considering that an extraterrestrial entity could be responsible.

    I have always been of the opinion that if alien life can't find a better way to communicate than anal probing -- and now maybe monkeying ever so slightly with the course of our abandoned spacecraft -- then they are not worth talking to. Worth bombing, maybe.

    Damn aliens.
  • by TeknoHog (164938) on Tuesday May 15, 2001 @04:32PM (#221158) Homepage Journal
    For a photon, it was proved long ago that its energy = h * its frequency and momentum = h / its wavelength (h = Planck's constant). Some people (Louis de Broglie was one of the first, IIRC) asked: what if we could use those same relations for all particles including material?

    And that was one of the most important creative leaps that led to quantum mechanics that gave us electronics, computing, and hence Slashdot. Almost as if my miracle, the equations worked! After some eighty years, we still don't admit that particles are waves, but it is one heck of a model. In principle, physics is not about what is real, it is about models of the nature. (Insert your favourite definition of reality from the Matrix here.) Physics does a lot of things purely systematically, but new theories like wave mechanics require those what-if ideas that may seem stupid at the first glance. The validity of a model can usually be tested by experiment, and if it fails then we can be certain that the idea was 'stupid' indeed. We can only let Nature judge which models are better.

    I agree that ultimately physics should be about particles - or rather whatever the fundamental objects turn out to be (strings? a very elegant _model_ but maybe nothing more). The problem is, before we get there, we want to be able to model the larger scales as well. We can quite safely model the largest scale of the universe without worrying about the underlying forces between individual particles. Maybe that model (i.e. General Relativity for now) isn't absolutely accurate, but it's better than having to wait for a theory of everything - which BTW may never come up.

    --

  • by proxima (165692) on Tuesday May 15, 2001 @04:14PM (#221159)
    For each of the other 3 forces (weak, strong, electromagnetic), we have discovered a "carrier" particle for that force.

    The strong force is carried by particles called "gluons" while the weak force is carried by "weak bosons". The electromagnetic force is carried by "photons". These have been detected in particle accelerators. Scientists have a name for the carrier particle of gravity - "graviton", but it has never been detected - yet.

    The strong and weak force have a relatively (no pun intended) limited range. The strong force has a range of only about 1x10^-15 meters. On the other hand, gravity and the electromagnetic force have infinite ranges. Perhaps we're wrong about the gravity force, considering we don't even have a carrier particle. Maybe its strength isn't an inverse squared relationship for infinitely long distances - or it's simply an approximation.

    Too bad I don't know nearly enough about experiments testing the gravitational constant and how well we've applied it to extrasolar objects.

  • I read it - and I agree that you should post a link if you're sincere that it's all been solved.
  • by Sodium Attack (194559) on Tuesday May 15, 2001 @02:57PM (#221177)
    Informed comment? On slashdot? Methinks you're looking in the wrong place.

    You'll see lots of speculation by people who have no idea what they're talking about, but at least that won't get modded up. You'll also see lots of speculation by people who have a very slight idea of what they're talking about, and even though that speculation is little better, it will get modded up by other people who have a slight idea of what they're talking about, because it sounds plausible.

    Maybe a legitimate space scientist or two will post with something that might actually be useful. Maybe--possibly--that will get modded up. More likely it won't, because it will be over most people's heads, or because he came too late to the conversation (say, two days from now) when no one's going to use mod points on the story.

    Assuming your characterization of the BBC story is accurate (/.ed, can't get to it right now), and assuming that the BBC story itself is accurate--both of which are nontrivial assumptions--why wouldn't the quoted "NASA scientists" be the informed comment you're looking for? Is anyone here going to give you a better answer than the "we don't know" you got from the NASA scientists?

    (Don't mind my ranting, I'm just in an anti-/. mood today.)

  • by agentZ (210674) on Tuesday May 15, 2001 @05:07PM (#221184)
    Or they could put the recording on Napster and wait until the RIAA tries to sue them.
  • "Aye, ye know...it's all due to them damn metric system. Dammit, we used the english system again"
    -Daniel S. Goldin, Head of NASA, two weeks later
  • Voyager is more advanced than anything that NASA has produced lately.

    Based on what criteria? The processing power of its computer? The sophistication, compactness and sensitivity of its instruments? The Voyagers were marvels of 1970s technology, but current probes can definitely do more for less.

    The difference between Voyager and current proposals is that Voyager cost billions of dollars, while most probes nowadays come in at under $400 million. Voyager had about a dozen instuments, most probes now have at most five or six. Voyager was exploring areas of the solar system that we had never been to before, so everything was new, and major discoveries were dropping into our laps. Mars still has surprises in store, but they are more subtle than volcanos on Io, or braided rings around Saturn.

    There is one last superprobe still to go; Cassini [nasa.gov] is the biggest probe ever launched, with a dozen instruments. It also cost over three billion dollars. We will not see its like again.

  • This obviously proves that the Creationists were right all along. Our projections weren't perfect, therefore the Universe was created 6000 years ago.
  • Sorry but I don't think the instrumentation on these probes really is advanced enough to gather what is needed to make an accurate or informed decision.

    I would not mind seeing a mission equiped so they could determine what really is out there. In other words, ditch the hardware needed for planetary observations, use the slingshot effects of gravity and get a probe out there pronto.

    It would probably be a better use to understand what goes on out there than visit the disney planet.
  • It's the Russian COSMOSPHERES! The Russians have had CONTROL OVER GRAVITY since 1965! Even if the NA$A scientists have been kept in the dark by their FA$CI$T MA$TER$, the Russians are sending a clear signal that they have SPACE-BASED GRAVITY WEAPONS that they will turn on the UNITED $TATE$ at the SLIGHTEST PROVOCATION.

    This IMPORANT INFORMATION should be DISSEMINATED etc etc...

    With apologies to Robert McElwaine, and everyone else.

    OK,
    - B
    --

  • Well, yes, but I'm not above showing my age, or my 01d sk001 cred. ;)

    And besides, McElwaine is still out there, just with a smaller readership.

    OK,
    - B
    --

  • by the real jeezus (246969) on Tuesday May 15, 2001 @02:54PM (#221207)
    Jedi:"You will alter your course."
    Probe:[ continues course ]
    Jedi:(under breath) "Oops."
    [ Jedi waves hand in front of probe ]
    Jedi:"You will alter your course."
    [ back on earth... ]
    BBC News:"Mystery force tugs distant probes" [bbc.co.uk]


    Ewige Blumenkraft!
  • > Maybe a legitimate space scientist or two will
    > post with something that might actually be useful.

    Curiously enough, that was exactly what I was hoping . Now that I've finally lain the karma-whore ghost, I'm reading at -1, and, well, it's embarrassing to admit but I've been laughing my arse off.
    --

  • IIRC, some ground-breaking automated surveys going on at present are producing three dimensional maps of our local galactic environment (the SMC and LMC, local group etc), and that they're finding 'stuff' (objects, phenomena) that weren't previously known. Could any such things produce a systematic error in the observations that set currently accepted values for physical constants?
    --
  • I believe this has already been taken into account.

    As an example of the sort of phenomena which can add up to a noticeable effect over long periods of time, check out the results from NEAR Shoemaker probve to Eros (you rmemeber, probe that orbited & finally landed on asteroid Eros.) ON eof severla unexpected results is that there are disproportionately fewer small impact craters than would be expected, given the number (density) of larger ones. One possible explanation for this is is that small (c. 1cm diameter) orbiting rocks may be preferentially expelled from the inner solar system, due to the fact that as they spin, the side that has just moved from sunlit to dark side re-radiates some of the energy it's absorbed from the sun. This leads (in some obscure but very clever theory which I can't find a link for right this moment) to these objects drifting slowly away from the sun. This doesn't affect larger objects because their ratio of surface area to volume is different...
    --

  • by imipak (254310) on Tuesday May 15, 2001 @03:43PM (#221213) Journal
    Right. Thans for the link.

    Sod's law suggests that it's 99% likely to be one of (a|b|c|d|g|h). However, astronomers and physicists are generally rather good at methodically excluding likely explanations, starting with the least unlikely, until all that's left, however unlikely,..

    We know that, at some level, the standard model is inconsistent - quantum physics and relativity are mutually incompatible. One tantalising observation for which there's no generally accepted explanation is that gravity is many, many orders of magnitude less powerful than the other fundamental forces.

    I'd love ot believe that this phenomena, which has been bobbing around for a few years now, is a pointer to some Theory of Everything. But, after 25 years in space, the tiniest force acting on the probes which is not accounted for, can stack up to an observable difference of position from prediction.
    --

  • Why would an intelligent species want to slow down our probes, but not stop them, or capture them?

    About the only theroy I've got is maybe there is a dark "brown dwarf" star companion of Sol orbiting out there. Could that explain it?

    Don't know, but I suspect that small mass pseudo-stars like Brown Dwarfs will be found to be among the most common objects in the universe (as it's known that the sim, low mass, long lived Red Dwarf stars are by FAR the most common stars).

    A brown dwarf in the Oort Cloud may be dark enough to be obscured by the comet-like matter there, yet have enough influence to affect the outer solar system (like sending the odd new comet towards the Sun every now and then).

    But then, I'm only a curious amateur in Astronomy ;)
  • The coolest thing about Astronomy, is that we "KNOW" very little. What we have are mostly very brilliantly reasoned "guesses" that presumably get more accurate as more minds refine and build on the therories pioneered by Copernicus, Galileo, and Newton.

    Just in my own lifetime, the picture of our Solar System has changed drastically, with the information the Pioneers and the Voyagers returned and still return (Pioneer 10 was launched close to the very day I was born!)

    In fact, with the recent confirmation of the existance of other solar systems with planets, our theroies on what is "normal" for solar systems are already in question...

    Is there any doubt that those four little spacecraft, of our WHOLE space program, delivered the MOST bang for the buck? And that we should be sending more advanced versions of them out?
  • I find a particular comment in the BBC article somewhat curious... It claims that the orbits of the planets in our own solar system do not seem to exhibit any effects comparable to that of the four probes in question:
    "It would be apparent in the orbits of the planets around the Sun - which it is not".

    Now, someone please correct me if I have this wrong, but don't estimates of the physical properties' of planets *derive* from the behavior of those planets under the assumptions of our best current understanding of gravity?

    So, how can we claim that the planets do not seem affected by this "mystery force"? If we use the orbital radius and centripetal acceleration of a planet to calculate its mass, we can't then use that calculated mass to "prove" that the THEORY of gravitational attraction as we know it applies perfectly.

  • You're modding me down because the truth hurts. Your favorites gurus are either frauds or crackpots and you can't stand it. Trying to stop this stuff from coming oput is like the music industry trying to stop people from copying music. It can't be done.

    Thanks to the moderators who modded me up.
  • Why do we assume that an "apparent anomalous acceleration is acting on Pioneer 10 and 11"?

    Perhaps this observed acceleration is actually us "decelerating". Could our close proximity to a large source of gravitation (the sun) lead to such an observation?

    We need to, er, Think Different(TM) about stuff like this.

  • It's those damn elves again...

    1. Deflect space probe courses.
    2. Profit.


    God bless those Albino Ninjas...
  • "Do not all charms fly At the mere touch of cold philosophy."
    - John Keats

    I have many times had this aesthetic argument with math and physics students. It took a long time, but we eventually came to the following consensus on the aesthetics of science:

    Scientific fact, in and of itself, is as completely devoid of artistic interest, as any fact is. The mere cold fact of the way in which paint was arranged on a piece of canvas to create the Mona Lisa is devoid of aesthetic value. Only a human interpretation of the meaning of this arrangement of paints can yield aesthetic worth. Therefore, for example, while the theory of relativity is, in and of itself, without merit as art, by an interpretation of its implications to humanity, it can gain meaning. The exciting thing about it is that we DON'T understand it completely. We can make all manner of wild romantic ponderings on its meaning with regard to light-speed travel and all sorts of fantasies. It's only because we don't understand it that we can make these ponderings, however. If we had a complete and thorough "scientific" knowledge of its (or "the theory of everything"'s) meaning and nature, light-speed travel or time travel, for that matter, would be either 1) recognised as impossible or 2) as matter-of-fact as travel at greater than the speed of sound.

    The only reason science is interesting is because it entails mystery (if it didn't, there would be nothing more to investigate) and uncovers new topics for us to consider in wonder. Unfortunately, while it does this, it disproves the things that we used to wonder at (like a 6,000-year-old earth and Thor weilding his thunderbolts from the clouds). The end result is that the only things that we have to wonder at any more are so incredibly abstruse that only scientists can explore them. The common man used to be able, as the above poster noted, to look up into the stars and wonder even what they might be. Unfortunately, these wonders within the reach of the common man have already been explained. The worm holes, dark matter and Uncertainty which remain the wonders of today are somewhat beyond his grasp.

    I think this is all summed up in a quote from David Hume:

    The anatomist is useful to the painter"

    The scientist investigating the human body and the artist who depicts it work hand in hand to create the final product. This is perhaps a consensus to be made between scientific and artistic aesthetics.

Somebody ought to cross ball point pens with coat hangers so that the pens will multiply instead of disappear.

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