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The Pioneer Anomaly & Other Breaking Physics News

Posted by kdawson on from the explaining-the-unseen dept.

David Harris, editor-in-chief at Symmetrymagazine.org (a joint publication of Fermilab and SLAC), sends us to his blog covering the American Physical Society meeting now going on in St. Louis. Among the breaking physics news relating to topics we have discussed in the past: results that explain about 1/3 of the Pioneer anomaly by differential heat flow in the spacecraft; an analysis of the Fermilab Tevatron's chances of spotting the Higgs "God particle"; and a hint that an Italian team has replicated their results from the year 2000 pointing to a detection of dark matter.

100 comments

  1. Sloppy editing by Harmonious+Botch · · Score: 4, Insightful

    We have three separate subjects crammed together in one article. So some of the briliant, insightful comments by my fellow shashdotters may get buried. How about three separate articles?
    Or is this a new trend? Are we going to see twenty subjects crammed into the one daily article tommorow?

    1. Re:Sloppy editing by Anonymous Coward · · Score: 4, Funny

      So some of the briliant, insightful comments by my fellow shashdotters may get buried.

      On the other hand, we may get somebody posting a fantastic Theory of Everything that shows that the other two-thirds of the reason why Pioneer is off-course is because it is being bombarded with Higgs particles while bumping into dark matter.

      But yes, I suppose that your prediction of stupid comments is also possible. It's 50/50 really.

    2. Re:Sloppy editing by eyrieowl · · Score: 1

      nonono....as every veteran slashdotter knows, all physics is the result of the electric universe.... particle physics ppffftt!

    3. Re:Sloppy editing by Anonymous Coward · · Score: 0

      It's just the CNNification of /.

    4. Re:Sloppy editing by An+ominous+Cow+art · · Score: 3, Funny

      Electric universe is stupid singularity evil. 4 Day Time Cube disproves 1 Day Electric Universe.

      Electric Universe is as evil as God singularity evil.

      I have $10,000.000 that I will wager that Cubicism transcends and disproves Electric Universism.

    5. Re:Sloppy editing by caramelcarrot · · Score: 1

      For the love of god, don't start that.

    6. Re:Sloppy editing by Anonymous Coward · · Score: 0

      I believe that robots are stealing my luggage. It is but a small step of scientific reasoning to see that they might also be altering the trajectories of spacecraft.

    7. Re:Sloppy editing by traveller.ct · · Score: 2, Funny

      IIRC, the answer to the Theory of Everything is 42, no?

      --
      For the lack of a better sig.
  2. Rumor/conjector by harris+s+newman · · Score: 1

    I read the article on Higgs, and it is entirely conjecture based on specified rumor after rumor. Is this TMZ.com?

    1. Re:Rumor/conjector by FooAtWFU · · Score: 3, Informative

      I read the article on Higgs, and it is entirely conjecture based on specified rumor after rumor. Is this TMZ.com? It's a summary of a physics conference. This is news of physicists describing to each other the state of the art and what they're busy conjecturing, considering, and hoping to prove. Perhaps you were looking for Nature?
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    2. Re:Rumor/conjector by yomegaman · · Score: 4, Informative

      The bump in the CDF two-tau decay channel went away with more data, which wasn't too surprising. I'm not sure how all that got so blown up in the science press, the original blog post that started it at Cosmic Variance surely didn't make any discovery claim. Having said that, the other half of the story, the rumored huge excess in the D0 three-b-quark channel, is still unresolved as they have not released any results for over a year. We'll probably see something within a few weeks I guess, I have heard that it is close to ready.

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    3. Re:Rumor/conjector by evil+agent · · Score: 4, Funny

      I know right? And what about that sensationalist headline: "Breaking Physics News"??? If they had actually broken physics, I probably would have heard it on the news...

      --
      End transmission.
    4. Re:Rumor/conjector by HiggsBison · · Score: 5, Funny

      I read the article on Higgs, and it is entirely conjecture based on specified rumor after rumor. Is this TMZ.com?

      Rumors? About me? *sigh* I'm always the last to hear of them.

      --
      My other car is a 1984 Nark Avenger.
    5. Re:Rumor/conjector by Orange+Crush · · Score: 1

      I really hope nobody manages to break physics ANY time soon. We all remember the mess it made the last time that happened.

    6. Re:Rumor/conjector by MichaelSmith · · Score: 1

      Yes I heard it made a lot of people very unhappy.

      --
      http://michaelsmith.id.au
    7. Re:Rumor/conjector by dintech · · Score: 2, Funny

      That's just the creationists. Everyone else is fine with it.

    8. Re:Rumor/conjector by WhiteDragon · · Score: 1

      Yes I heard it made a lot of people very unhappy. I also heard it has generally been regarded as a bad move.
      --
      Did you mount a military-grade, variable-focus MASER on an unlicensed artificial intelligence?
  3. You must be new here. by Valdrax · · Score: 4, Insightful

    So some of the briliant, insightful comments by my fellow shashdotters may get buried. When's the last time you've read the comments section on any science article on Slashdot, particularly over discoveries in physics?

    Insightful comments are *always* buried under senseless meme-tossing and political (or other off-topic) ranting.
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    1. Re:You must be new here. by McGiraf · · Score: 1, Insightful

      self fulfilling prophecy

    2. Re:You must be new here. by Anonymous Coward · · Score: 2, Funny

      buried under senseless meme-tossing

      In soviet russia, memes toss you!

    3. Re:You must be new here. by i.of.the.storm · · Score: 1

      (or other off-topic) ranting. like your post?
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    4. Re:You must be new here. by Anonymous Coward · · Score: 1, Funny

      In Korea, only old tossers use memes!

    5. Re:You must be new here. by PopeRatzo · · Score: 3, Insightful

      When's the last time you've read the comments section on any science article on Slashdot, particularly over discoveries in physics?
      Quite regularly thank you.

      I happen to believe Slashdot, even with minuscule expense of a subscription, is an excellent bargain.

      Except for the time I waste on whiners like you, Valdrax. As pointed out by McGiraf, do you really think you're going to improve the senseless meme-tossing by doing your own senseless meme-tossing?
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    6. Re:You must be new here. by techno-vampire · · Score: 1, Funny

      Think of a Beowolf cluster of old memes, naked and covered with hot grits!

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    7. Re:You must be new here. by Anonymous Coward · · Score: 0

      Leave the senseless meme-tossing guy ALONE!!!!!!!!!!!!

  4. Before LHC though? by stevedcc · · Score: 3, Interesting

    The article states that Fermilab can begin exploring to 160GeV in the summer. LHC is due to be switched on before that. From all I've read, LHC has a MUCH better chance of being sure of what it finds at around those energies. I think any article on this subject can't even pretend to be balanced without discussing LHC.

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    1. Re:Before LHC though? by yomegaman · · Score: 5, Informative

      The LHC will probably switch on this year, but it won't generate very much luminosity at first. Perhaps by the end of 2009 it will have made a couple of inverse femtobarns which would be enough, but it will be another year or so after that before the data are processed and analyzed. It takes quite a bit of time to understand and interpret the detector readout. The Tevatron does have a chance if the Higgs is around 160 GeV, but only with about one-in-a-thousand level statistical significance, and so far we are not seeing any excess of events there, but in fact somewhat fewer events than expected.

      --
      ...wearing a skin-tight topless leather jumpsuit, with cutaway buttocks and transparent crotch panel.
    2. Re:Before LHC though? by maxwell+demon · · Score: 1, Funny

      and so far we are not seeing any excess of events there, but in fact somewhat fewer events than expected.

      So you are seeing Anti-Higgs? :-)
      --
      The Tao of math: The numbers you can count are not the real numbers.
    3. Re:Before LHC though? by bockelboy · · Score: 4, Informative

      It's going to be a race, really, to see what happens first - the Tevatron squeaking out enough events to confirm detection, or the LHC operating smoothly enough to get all the calibration and background processes established, then finding the Higgs.

      It's going to be a close race. On one hand, the LHC will ramp up to have a huge advantage over the Tevatron. On the other hand, the Tevatron folks are at the top of their game.

  5. On the Pioneer anomaly by Anonymous Coward · · Score: 5, Informative

    I read a discussion somewhere that many spacecraft pick up a sizable electric charge and keep it (they are after all in a vacuum), and that electrostatic forces from the Sun and the solar wind are enough to account for course deviations. It's certainly true that gravity is not the only force operating out there.

    1. Re:On the Pioneer anomaly by barath_s · · Score: 5, Informative

      Right, radiation pressure, gas leaks, drag, electric charge are all suspects, as are changes in the way data was collected. http://en.wikipedia.org/wiki/Pioneer_anomaly The issue is that the current best guesses for these effects do not yet account for the anomaly.

    2. Re:On the Pioneer anomaly by Tablizer · · Score: 1

      It seems to me it would be fairly easy to test the anomaly. The craft merely has to transmit "dumb" radio beeps. Sputnik-like even. Have a capacitor that stores up power from a weak nuclear-decay source and beeps off every few minutes. Because of the limited functionality, it may weigh say 10 pounds, meaning its relatively cheap to launch. I'm not sure it even needs to be a directional antenna.

      --
      Table-ized A.I.
    3. Re:On the Pioneer anomaly by Anonymous Coward · · Score: 1, Insightful

      data were collected...

    4. Re:On the Pioneer anomaly by IdleTime · · Score: 1

      Now, what of we have failed to notice that gravity comes in two forms too, the weak and the strong gravitational force?

      The strong gravitational force is what we see the effect of on a daily basis, the weak is so weak it only is seen on large scale structures and the effect of it on Pioneer is the combined weak gravitational field from the inner solar system bodies working on the probe?

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    5. Re:On the Pioneer anomaly by Anonymous Coward · · Score: 0
      Uh, great, but we can see deep field views into the gigaparsecs, and we can get reasonable angle-luminosity measurements up to megaparsecs; in these views we see large scale structures called galaxies and galactic clusters (and even huge structures like the Great Wall), with little indication that the GR model of gravitation has two modes that would make a difference on the scale of a star (and orbiting material) vs space probe interaction.

      Where we have open questions is with respect to effects consistent with GR where we do not see the energy term ("dark matter" and "dark energy").

      Dark matter is invisible energy (avoiding confusing use of the word mass) whose effects are visible and measurable.

      The reasons for not seeing it range from observational error, problems with GR's model of gravitation, diffuse distribution (MACHO hypotheses), heavy neutrinos and other weakly-interacting energetic particles that do not participate in electromagnetic or strong force interactions, or combinations of some or all of these. Observational evidence increasingly favours the WIMPs (weakly interacting energetic particles), and WIMPs are subject to several positive searches and disproof experiments (that if they go in the unexpected direction would definitively preclude WIMP solutions) in the next year or so.

      (This would be exciting as there are several extensions of quantum theories and alternative gravitation models that are inconsistent with WIMPs; one or the other could be an answer to several dark matter problems; WIMPs as a single (or at least almost complete) source of missing GR energy are a better bet though).

      "Dark energy" is dark in the sense of the "dark ages": Its effects are readily visible at large scales (the metric expansion of spacetime is not generally controvserial) but almost nothing is known of its mechanism.

      Other than that, in the limit of large objects (bigger than a breadbox) and low particle energies (less relativistic mass than a breadbox, per particle), General Relativity is useful and accurate to the limits of present testability.

      If you can write down a self-consistent model of gravitation that is also consistent with astronomical observation and terrestrial experiment, great. Please consult the Alternative Science Respectability Checklist and publish publish publish!

      My suggestion for your first two sentences:

      We have failed to notice that gravity comes in two forms: the weak and the strong gravitational force. This paper characterizes these two forces, explains their conformance with regularly repeated experiment and observation, and sets out experimentally and observationally testable parameters which will conform to this two force model better than existing models of gravitation.


      Good luck! Writing down such a theory is hard work.

  6. Enough of the "God Particle" please by smolloy · · Score: 4, Insightful
    Who first used the name "The God Particle" for the Higgs? It certainly wasn't a high energy physicist!

    The Higgs field is supposedly responsible for mass generation -- and that's it. Nothing else. Maybe something about "spontaneous symmetry breaking...mumble... big bang.. mumble... inflationary expansion... mumble", but hardly anything "God-like".

    This nickname comes across as something dumb invented by the popular press in a half-assed attempt to communicate to regular folk how exciting the LHC is to us physicists.

    Maybe /. could lead the charge to kill this nickname?

    1. Re:Enough of the "God Particle" please by yomegaman · · Score: 5, Interesting

      I think it was Leon Lederman who coined it in his book. He is definitely a high-energy physicist, he was director of Fermilab for years and won a Nobel Prize for discovering the bottom quark. I agree with the sentiment, though, if I never heard it again it would be fine with me. I read the book some years ago but can't remember why he called it that.

      --
      ...wearing a skin-tight topless leather jumpsuit, with cutaway buttocks and transparent crotch panel.
    2. Re:Enough of the "God Particle" please by spun · · Score: 4, Informative

      Its from the book The God Particle: If the Universe Is the Answer, What Is the Question?. It's a joke, son, laugh.

      --
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    3. Re:Enough of the "God Particle" please by kfort · · Score: 2, Insightful

      Mass generation is as God-like as it gets.

    4. Re:Enough of the "God Particle" please by Plazmid · · Score: 1

      Dude, I think you fail to recognize what understanding mass means. Mass is just so fundamental. Just about everything has it.

    5. Re:Enough of the "God Particle" please by smolloy · · Score: 1
      That's why I said, "to communicate to regular folk how exciting the LHC is to us physicists"

      It *is* exciting. I just think that the nickname is dumb.

    6. Re:Enough of the "God Particle" please by smolloy · · Score: 1

      ...He is definitely a high-energy physicist, he was director of Fermilab for years and won a Nobel Prize for discovering the bottom quark....

      Ooops. Now I'm embarrassed. Got that pretty wrong, didn't I? :S

      I still think it's a crap nickname though.

    7. Re:Enough of the "God Particle" please by Anonymous Coward · · Score: 0

      Maybe /. could lead the charge to kill this nickname?

      Yes! This could be Slashdot's contribution to the world of physics. I suggest, "the CowboyNeal particle".
    8. Re:Enough of the "God Particle" please by turgid · · Score: 2, Insightful

      Unfortunately, "regular folk" who are interested in celebrity affairs, plasitc surgery and drug abuse ,pay for physics experiments.

      It's impossible to convince them how important such experiments are, so we need to patronise them.

      --
      Stick Men
    9. Re:Enough of the "God Particle" please by Sique · · Score: 1

      But hey - charm quark. What the heck a name is that?
      (Especially for a German like me... where quark means white cheese.)

      God particle is not much worse.

      --
      .sig: Sique *sigh*
    10. Re:Enough of the "God Particle" please by emm-tee · · Score: 3, Informative

      Maybe /. could lead the charge to kill this nickname That would be nice. It's correct name is the Higgs boson. http://en.wikipedia.org/wiki/Higgs_boson

      I'm amazed that currently no comment on this article contains the word "boson". I've heard it called the Higgs boson more times than I have the "god particle". Maybe it's just the media I choose to read/watch.
    11. Re:Enough of the "God Particle" please by SteelAngel · · Score: 3, Interesting

      The quarks are supposed to be named in pairs thusly:

      Up down

      Strange Charm

      Truth Beauty

      But somewhere in the 70's some particle group with little sense of wonder renamed Truth and Beauty to Top and Bottom, thus leaving Strange and Charm as sounding anachronistic.

    12. Re:Enough of the "God Particle" please by ceoyoyo · · Score: 1

      It actually isn't such a bad name, except for the unfortunate resonance with some silly people. At the time it was coined those people weren't as high profile, so it was more like "God doesn't play dice."

      The Higgs field is supposed to suffuse everything. We're constantly immersed in it, and it is responsible for both some of the fundamental properties of the basic constituents of the universe and its largest features. That is, it sticks its fingers in pretty much everything.

    13. Re:Enough of the "God Particle" please by smolloy · · Score: 1

      The Higgs field is supposed to suffuse everything. We're constantly immersed in it, and it is responsible for both some of the fundamental properties of the basic constituents of the universe and its largest features. That is, it sticks its fingers in pretty much everything Qui-Gon Jinn? Is that you?

      Actually, the fact that the Higgs field is universal makes it much like gravity or electromagnetism. Theoretically, these fields extend to infinity, and, especially in the case of gravity, have/had a very profound effect on the evolution of the Universe. Perhaps gravitons should be considered the "God Particle"?

    14. Re:Enough of the "God Particle" please by ceoyoyo · · Score: 1

      The Higgs field is supposed to be the same everywhere. Unvarying, and an intrinsic part of space itself. Gravity is associated with a very obvious and material cause.

    15. Re:Enough of the "God Particle" please by greyhueofdoubt · · Score: 1

      It was originally known not as the God particle but the "Oh my God" particle- As in "Oh my god, that single particle had the kinetic energy of a falling brick!"

      More here-
      https://www.fourmilab.ch/documents/OhMyGodParticle/

      -b

      --
      No offense, but I've stopped responding to AC's.
    16. Re:Enough of the "God Particle" please by smolloy · · Score: 2, Interesting
      I'm not sure about that. The Higgs boson is a consequence of waves in the Higgs field, which strongly suggests that it isn't unvarying.

      Of course, I'm not an expert on this, so I'm prepared to be wrong.

    17. Re:Enough of the "God Particle" please by Anonymous Coward · · Score: 0

      Conspire to have Britney Spears rear-end a pickup carrying plastic models of subatomic particles?

    18. Re:Enough of the "God Particle" please by Anonymous Coward · · Score: 0

      That is the name of a Ferengi bartender living on Deep space 9

    19. Re:Enough of the "God Particle" please by justthinkit · · Score: 1

      Anyone who can get Joe and Jane Public to pony up billions of dollars to create a particle that lasts for a billionth of a second is God in my books. Let God name his particle.

      --
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    20. Re:Enough of the "God Particle" please by Impy+the+Impiuos+Imp · · Score: 1

      > I suggest, "the CowboyNeal particle"

      That's not funny! >:(

      Oh wait.

      --
      (-1: Post disagrees with my already-settled worldview) is not a valid mod option.
    21. Re:Enough of the "God Particle" please by Muad'Dave · · Score: 1
      The name "Quark" came from the story Finnegan's Wake by James Joyce.


      From the wikipedia article:

      The phrase "Three quarks for Muster Mark" on page 383 of Finnegans Wake is the origin of the spelling given by physicist Murray Gell-Mann to quarks, a type of subatomic particle.[88] (In the novel, the phrase is sung by a chorus of seabirds, and probably means 'three cheers' or--judging from Joyce's notes--three jeers.)
      --
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    22. Re:Enough of the "God Particle" please by Luyseyal · · Score: 1

      No. That Fermilab article specifically says the "Oh My God" Particle was a "proton with an energy of 3.2±0.9×10^20 electron volts."

      -l

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    23. Re:Enough of the "God Particle" please by JamesP · · Score: 1

      Then if they discover a new pair of quarks it will be called VIM and EMACS then??

      --
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    24. Re:Enough of the "God Particle" please by Anonymous Coward · · Score: 0

      Its from the book

      "It's".

  7. Breaking Physics News by Anonymous Coward · · Score: 2, Funny

    hey baby, wanna see my large hardon collider? I'll make you see the God particle.

  8. Portal gun by Plazmid · · Score: 1

    Sweet! These breakthroughs bring us ever closer to a portal gun.

    1. Re:Portal gun by Anonymous Coward · · Score: 0

      Somehow I get the feeling that creating a portal pair where you fall forever would somehow violate the laws of conservation of energy.

    2. Re:Portal gun by Miseph · · Score: 1

      Er, no, not really. Falling forever does not violate conservation of energy in the slightest. Actually, every single piece of matter in the universe is in a constant state of falling, it's just a matter of whether or not it's falling into something else.

      --
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    3. Re:Portal gun by Anonymous Coward · · Score: 0

      Accelerating linearly forever, however, which is what the GP was really talking about, would be somewhat difficult to explain.

      Especially since you could trivially turn it into a permanent energy generator in a box (for example, a water wheel). Which you can't do.

    4. Re:Portal gun by Miseph · · Score: 1

      I think that tearing a hole in the space-time continuum to allow for infinite single-vector movement through a small area is quite a bit harder to explain then that gravity is a constant force. It just seems odd that you (and the GP) are taking issue with breaking that particular law of physics, but ignoring the non-trivial breakage of dimensional locality that allows it to be broken.

      --
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  9. Dark Matter... by Anonymous Coward · · Score: 1, Informative

    Is it so hard to see that they're just dealing with the (luminiferous) (a)ether?!?

    See Tesla [1][2], Lyne[1], Silvertooth[3] and many others.

    Oh, but aether has become a term that is a no-no.. so let's call it dark energy, dark matter, the zero point field, etc.

    Currently no university is teaching the real work of Maxwell, but rather the simplified (and lacking!) version by Heaviside.

    [1] http://netowne.com/technology/important/
    [2] http://www.bibliotecapleyades.net/tesla/occultether/occultether.htm
    [3] http://www.unusualresearch.com/silvertooth/silvertooth.htm

    1. Re:Dark Matter... by jmorris42 · · Score: 2, Insightful

      > Is it so hard to see that they're just dealing with the (luminiferous) (a)ether?!?

      Oh course. History doesn't repeat exactly but it does tend to rhyme. Is it any wonder that science falls prey to the same human failings since it IS just another human activity?

      --
      Democrat delenda est
    2. Re:Dark Matter... by Protonk · · Score: 1

      It is hard to see that because they AREN'T just dealing with the aether. This isn't some substrate at rest upon which the motions of the galaxy play out. I know it is comforting to take refuge in crackpot science, but there really isn't a zero speed reference frame. It doesn't exist. I'm sorry.

    3. Re:Dark Matter... by Tenebrousedge · · Score: 4, Informative

      I would post that sort of nonsense as an AC, too. For those that are unaware, the theory of a luminiferous aether posits that there exists some sort of medium in interstellar space which conducts light. It was completely superseded around the beginning of the last century, mostly by the theories of a man named Einstein. Which explain quite well our observations of the universe on a large scale. Dark matter is an entirely unrelated question related to the amount of matter in the universe. Dark energy, zero-point field...you're just throwing around terms. What we know about the forces in the universe is not exhaustive, but to invent a completely new one just to account for a minor anomaly is not good science. What you are doing here is the equivalent of fighting for the Flat Earth theory, and it disturbs me to see that modded informative here...

      --
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    4. Re:Dark Matter... by domanova · · Score: 1

      but it's written in green ink

      --
      Down with categorical imperatives
    5. Re:Dark Matter... by ceoyoyo · · Score: 2, Interesting

      The Higgs field and dark energy are about the closest things directly comparable to the aether in modern physics. Dark matter is very different: it clumps, so it isn't everywhere.

  10. Peer review by Plazmid · · Score: 1

    Ahem, has it been peer reviewed?

  11. Fermi and the Higgs by stox · · Score: 3, Interesting

    Sadly, 10% of Fermi's staff is being laid off, and the rest must take a mandatory week off of unpaid leave every two months due to the funding SNAFU at the DOE.

    --
    "To those who are overly cautious, everything is impossible. "
    1. Re:Fermi and the Higgs by barath_s · · Score: 1

      The funding fiasco [http://www.sciamdigital.com/index.cfm?fa=Products.ViewIssuePreview&ARTICLEID_CHAR=1D650F43-3048-8A5E-106FD610574B73C8] impacts more [http://www.hpcwire.com/hpc/2153825.html ] than just this slim chance to find the Higgs

    2. Re:Fermi and the Higgs by schmiddy · · Score: 1

      I was a little shocked to read the parent post, but he's absolutely right. See the story (from December) here: http://www.nytimes.com/2007/12/22/science/22fermi.html?_r=1&oref=slogin

      However, I'm not sure I'd characterize the cuts as a "funding SNAFU". According to the NYTimes article, the cuts were "to meet bottom-line spending targets demanded by Mr. Bush, Congress rolled back the planned increases for the Energy Department and other science agencies." If I were more cynical I'd say that money just got funneled into Iraq.

      And it's not just Fermilab.. many other important domestic science programs are being cut, including the NIH: http://www.the-scientist.com/news/home/53858/ which many have been complaining to Congress about, such as Harvard pres. Faust recently: http://harvardscience.harvard.edu/culture-society/articles/president-faust-testifies-increase-nih-funding

      Oh well. Long as we're busy fighting terrorists, who cares if we have a $1T/year deficit, a weakened dollar, one of the civilized world's worst public education systems, an expensive, inefficient healthcare system, AND are cutting out the roots from future scientific progress in the USA. God bless America.

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  12. Pioneer Anomaly by calidoscope · · Score: 2, Insightful

    I was a bit put off by the tone of TFA with respect to the Pioneer anomaly. While it is unlikely that the anomaly will disprove our models of gravity, it is an excellent example of a gap in our understanding of physics.

    --
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    1. Re:Pioneer Anomaly by Protonk · · Score: 2, Interesting

      Well, let's be fair. the Pioneer anomoly is just that, anomalous. We don't see the impact in other situations, we don't have a good explanation for it and it isn't very large. It is entirely possible that this could be the same sort of anomaly as the orbit of Mercury or the Michelsonâ"Morley experiment. It's possible, but it is also possible that it falls into the category of experimental error.

      Please understand that the pioneer anomaly isn't treated in the same way as we remember (historically) anomalous results. No one disowned the researchers or completely dismissed their research. BUUUUTTTT...most of the explanations result in changes to the underlying framework of gravity (or alternatively, EM radiation) that don't really make sense. As far as we can tell it is better explained as an anomaly.

      Hopefully we are wrong and we discover something really awesome out there!

    2. Re:Pioneer Anomaly by postbigbang · · Score: 1

      It's kind of like the Schwarzchild radius. Instead of slowing down and being forever entrapped by the immense gravitational point source of the black hole, it's like being entrapped in the immense graviational field of a sun.

      No, wait....

      --
      ---- Teach Peace. It's Cheaper Than War.
    3. Re:Pioneer Anomaly by Protonk · · Score: 1

      It's kind of like the Schwarzchild radius. Instead of slowing down and being forever entrapped by the immense gravitational point source of the black hole, it's like being entrapped in the immense graviational field of a sun.

      No, wait.... Or it's like the doppler effect, except it is really small and happens only over long distances but we don't see it too far away because.....

      no, wait.... :)
    4. Re:Pioneer Anomaly by Baron_Yam · · Score: 1

      My Newtonian physics is a little weak - does the effect of gravity within a sphere change as you travel from the center to the surface?

      I'm wondering whether the Pioneer Anomaly can be explained by the Oort cloud. /Hey, I may be ignorant, but I'm ASKING, right?

    5. Re:Pioneer Anomaly by Protonk · · Score: 1

      kind of. Imagine gravity as a vector field pointing toward the center of the celestial body (assuming here that the body is a point mass). So as you move from the center to the surface, the vector field appears to be less and less curved--you go from seeing things flow like they would into a funnel (where you are close to the source) to seeing a field that effectively looks like it is perpendicular to the surface. Again, this assumes that you have a point mass. but this is basically why you can do those simple physics problems (the arc of a ballistic projectile, etc) without assuming that gravity acts in a way different than right angles to the ground.

      As for being explained by the oort cloud, what do you mean?

      Also, it is totally cool to ask. I am not a physicist (I'm an economist) but I'll try my best to answer from what I know.

    6. Re:Pioneer Anomaly by Baron_Yam · · Score: 1

      I was thinking of the Oort cloud as the surface of a sphere - would there be a lessening of gravitational effect while inside the sphere (because some of the mass is still ahead of you) followed by an increase once you passed it?

      Or, does it all effectively balance out at the center of the sun as far as the math is concerned...

    7. Re:Pioneer Anomaly by ceoyoyo · · Score: 1

      The Oort cloud would have to have a lot of mass in it to have much effect, and you wouldn't see much effect until a good part of that mass was between you and the sun.

    8. Re:Pioneer Anomaly by Protonk · · Score: 2, Interesting

      Oh. Well that is an interesting problem. Keep in mind that the oort cloud isn't really as dense as we might think it would be. If we assume only regular matter (no dark matter), then the density of the oort cloud is fantastically low. It is higher than the density of space between the earth and Mars only because there isn't the tidal and graviational forces of a Jupiter like body to pull stuff out of it.

      Then, from a gravitational standpoint, we are looking at VERY small curvature imposed by the comets and such floating around. Moreover, it is probably not something that translates well into some net field. We can abstract it, think of the oort cloud as a uniform density object, but that abstraction doesn't hold well to the truth.

      If we WERE to abstract it, the well created by the oort cloud might just overcome that created by the sun at distances far away from the sun. But remember, that is a spherical cow evenly distributed with milk (har, har). The reason the oort cloud exists is because the comets and dust caught up in it are orbiting the sun. So we would have to imagine that the point where that influence wanes is very close to the edge of what we might call the oort cloud.

      Even IF that is the case, we would see the impact of such a well (again, keeping with our assuption of a uniformally distributed Oort cloud) on light coming into the solar system from outside it. Much like seeing like passing a star (gets 'lensed') is sort of like seeing light emanating from that star seeing light from outside the solar system would be like seeing light from inside the oort cloud. We would have been able to find this anomaly by looking at any infra-solar source than comparing it to light from outside the solar system.

      In the case of pioneer, we need to explain a slight red shift growing larger as pioneer gets further from earth. a red shift seen on BOTH probes but not from (as far as we can tell) any source other than those two probes. It's a pickle. :)

    9. Re:Pioneer Anomaly by Zelrak · · Score: 1
      To answer your orignial question, the gravity in a hollow sphere is zero everywhere inside it and as if it was all concentrated at the center if you are outside it.

      So the gravity of a sphere at some point in it is the same as if you had all the mass of radius less than the point concentrated at the center.

      Basically, as you travel outwards from the center of a sphere of matter the gravity increases.(Mass grows like r^3 so gravity grows like r)

      -----------

      Note: all this assumes that I remember my classical mechanics course, I don't feel like redoing those integrals this late at night.

    10. Re:Pioneer Anomaly by sturle · · Score: 2, Informative

      The plutonium source in Pioneer emits 2000W of heat. If only 64W of that heat is radiated asymmetrically away from Pioneer, that will explain the whole anomaly. This is perfectly understandable, and it is even very likely that the heat dissipates a little bit unevenly from Pioneer. You don't need to change the theory of gravity to explain this. Reference here: http://66.102.1.104/scholar?hl=en&lr=&q=cache:Yw3pMm306akJ:www.aanda.org/articles/aa/full/2007/07/aa5906-06/aa5906-06.right.html+

    11. Re:Pioneer Anomaly by jo42 · · Score: 1

      Frankly, I surprised that no one has offered up the possibility of an RFID tag attached to Pioneer by The Department Of Immature Civilizations Space Junk Tracking Division of The LGMs.

    12. Re:Pioneer Anomaly by HarvardAce · · Score: 1

      In other words, if you assume that the mass of the Oort cloud is distributed evenly across a sphere, it would have no gravitational impact on anything inside of the cloud. It won't "pull" something on the inside out toward it.

      --
      Note to self: Stop putting jokes in my insightful comments so I can get something other than +1 Funny!
  13. Something doesn't fit...like.... by 3seas · · Score: 2, Funny

    ....the god particle????

    Is god that small?

    1. Re:Something doesn't fit...like.... by Impy+the+Impiuos+Imp · · Score: 1

      > Is god that small?

      He does do petty things like torture people for ever and ever for taking a weiner in the butt.

      --
      (-1: Post disagrees with my already-settled worldview) is not a valid mod option.
    2. Re:Something doesn't fit...like.... by bar-agent · · Score: 1

      How many angels can dance on the head of a pin? A lot, right? And since God is all that and a bag of chips, he ought to do better than the angels. So that's why it is the "god particle."

      --
      i'd hit it so hard, if you pulled me out you'd be the king of britain [bash.org]
  14. Lighten up. by Valdrax · · Score: 0

    Except for the time I waste on whiners like you, Valdrax. As pointed out by McGiraf, do you really think you're going to improve the senseless meme-tossing by doing your own senseless meme-tossing? Lighten up. It's called irony. It's a form of subtle humor. One that apparently went right over your head and that of a few other posters.

    Your indignant geek rage does nothing to help either.
    --
    If it's for-profit but free, you're not the customer -- you're the product (e.g., the Slashdot Beta's "audience").
  15. but TFA says... by Anonymous Coward · · Score: 0
    "Unemployment for physics graduates is very low, and for physics PhDs is an all-time low of 2.5%"


    and


    "Hodapp presented a string of evidence that shows just how serious the dearth of physics undergraduates is"

    1. Re:but TFA says... by stox · · Score: 1

      It takes more than Physics PhD's to run a large accelerator.

      --
      "To those who are overly cautious, everything is impossible. "
  16. Space environment by sturle · · Score: 1

    As this old article shows, thermal radiation can easily explain all of the Pioneer anomaly. Trying to show this by making a thermal model of the spacecraft is an interesting approach, but how well will they be able to model how the harsh environment of space, with all kinds of rays and particles from the sun and elsewhere are continuously bombarding the spacecraft form all directions? Just a small discoloring or formation of chemical substances on the surface will greatly influence how the heat is dissipated, and anyone who have seen a spacecraft which has been out there for a few weeks know that will happen.

  17. Lorentz contraction by Cajun+Hell · · Score: 1

    Is god that small?
    No, god is that fast.
    --
    "Believe me!" -- Donald Trump
  18. Particle man? by Anonymous Coward · · Score: 0

    Is he a dot, or is he a speck? Nobody knows...