Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

New test for GR ?

  1. Mar 23, 2006 #1

    wolram

    User Avatar
    Gold Member

    http://www.physorg.com/news12054.html

    Scientists funded by the European Space Agency have measured the gravitational equivalent of a magnetic field for the first time in a laboratory. Under certain special conditions the effect is much larger than expected from general relativity and could help physicists to make a significant step towards the long-sought-after quantum theory of gravity.
     
  2. jcsd
  3. Mar 23, 2006 #2
    Hmmm interesting stuff. Especially the degree of difference between predictions and actual measurements. I can only hope that someone follows the requests of the scientists running the experiments and do some of their own to confirm/verify the findings.
     
  4. Mar 23, 2006 #3

    pervect

    User Avatar
    Staff Emeritus
    Science Advisor

    *IF* this experiment is confirmed, it will be revolutionary.

    However, I don't think it will be confirmed - there's no reason to expect a spinning superconductor to have a gravitomagnetic field. It reminds me a lot of the Podkletnov fiasco.
     
  5. Mar 23, 2006 #4

    wolram

    User Avatar
    Gold Member

    I doubt if any earth bound experiments will ever solve the mystery of gravity
    but what are these people messuring ?
     
  6. Mar 23, 2006 #5
    UHHHHHHHHHH? Isn't this gravitomagnetic field the one that was predicted by the "crackpot" Heim in his crazy theory that derives masses from first principles? I'm gonna have to take another look at it
     
  7. Mar 23, 2006 #6

    pervect

    User Avatar
    Staff Emeritus
    Science Advisor

    So they mount an acceleration sensor (probably a gravimeter) above a spinning superconductor disk, and they think that they are getting some DC signal out of the sensor when the disk spins, due to the gravitational field of the disk itself which is obviously very small. This signal is so small that they really only measure the AC signal produced when the disk accelerates.

    It will probably turn out to have some mundane explanation, for instance the signal that is powering their motor could be being picked up by their wiring (by induction if it's AC, by a ground loop if it's DC), so that there is an AC signal from the accelration sensors when the motor is running, but it's not due to gravitational effects, but stray coupling.
     
    Last edited: Mar 23, 2006
  8. Mar 23, 2006 #7
    That would be very disappointing, I would hope that they figured out the shielding and that they have separated the power planes. This would be very sad, 3 years down the drain because of some elementary error.
     
  9. Mar 23, 2006 #8
    lol, I was so excited to see language similar to what I used last week in this article. I was playing around over spring break and came up with these becuase I was wondering if there was an analogue to magnetism for gravity.

    [tex] \vec{F} = frequency field [/tex]

    [tex]m_c = mass current[/tex]

    [tex]F_f = Frequency force[/tex]

    [tex] \vec{\ F _f} = m_c \vec{\ L} \times \vec{F}[/tex]


    [tex]\Phi_F = \oint \vec{\ F} \cdot \vec{dA}[/tex]

    [tex]\oint \vec{\ F} \cdot \vec{ds} = \nu_0 m_c_e_n_c[/tex]

    [tex] \oint \vec{\ G} \cdot \vec{dl} = - \frac{d \Phi _F}{dt}[/tex]

    [tex] d\vec{\ F} = \frac{\nu _0}{4\pi} \frac{m_c \vec{\ ds} \times \vec{r}}{r^3}[/tex]
     
    Last edited: Mar 23, 2006
  10. Mar 24, 2006 #9

    Garth

    User Avatar
    Science Advisor
    Gold Member

    There is - it is called the gravitomagnetic or Lense-Thirring or frame-dragging effect and is being properly tested at this moment as the GP-B data is being analysed.

    Garth
     
  11. Mar 24, 2006 #10
    This could be the break through that follows on from Podkletnov's work.

    The way in which Podkletnov's work was reported was strange, but I beleive it to be genuine.
     
  12. Mar 24, 2006 #11

    ZapperZ

    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor

    I guess people still hasn't learned not to do physics via press conferences. What, no one paid any attention to one of the questions posted in the comments asking for peer-reviewed journals where this is published? It seems that they missed "announcing" where they have submitted such a thing.

    Zz.
     
  13. Mar 24, 2006 #12
    I agree: shame on physorg.com for not even providing the reference to where the work is published.

    It can be found on lanl archives here:
    http://lanl.arxiv.org/abs/gr-qc/0603033

    Apparently it was also submitted for pier review to Physica C.

    Creator
     
    Last edited: Mar 24, 2006
  14. Mar 24, 2006 #13
  15. Mar 24, 2006 #14
    nope, it was never replicated.
     
  16. Mar 24, 2006 #15
    Try it now clj4. I've corrected it.
    It's a Los Alamos preprint : http://lanl.arxiv.org/abs/gr-qc/0603033

    It's the same report..... physorg.com should have at least included it.

    Creator

    -- I suport publik edjucashon-- :smile:
     
    Last edited: Mar 24, 2006
  17. Mar 24, 2006 #16
    Yes, thank you, now we have two links to work with!!!
     
  18. Mar 24, 2006 #17

    ZapperZ

    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor

    Now that's strange. Why would something that they claim to be THAT revolutionary and important, is submitted to Physica C? This is not a knock on Physica C (I have published a paper there), but shouldn't something this important be sent to Nature or Science, or PRL even?

    And let's not forget, Podkletnov's first paper on the dubious gravitational shielding was published in Physica B.

    Zz.
     
  19. Mar 24, 2006 #18
    Most of de Matos' previous theoretics answering the Tate cooper pair mass anomaly (1989) has been published in Physica C,
    which is (as you know) appropriate for superconductors. I think his experimental follow up should therefore be given review there.

    As far as Nature or Science ...they probably wouldn't have touched it until it had been pier reviewed.

    I am, however, glad this topic has come up here in PF since it contains some physics not generally well known and which isn't usually even addressed in graduate physics.:approve:

    I believe I may have addressed some of these concepts and background once here on PF, but only briefly, possibly in relation to the GPB's niobium spheres which rely on the London moment for its axial readout.
    Maybe I'll put more details of this mass anomaly issue when I have some free time.

    Creator
     
  20. Mar 24, 2006 #19

    ZapperZ

    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor

    But PRL, Science, and Nature are also appropriate for superconductors also. I know, I've published in those. And this report transcends just superconductors since it claims to have affected gravitational field. Physica C isn't in the same caliber as those journals. It isn't even in the same caliber as PRA, PRB, etc. Just look at the citation index for that journal if you don't believe me.

    Er... come again?

    If this has been "peer-reviewed", you won't get it published in Nature and Science. They want something new and high-impact.

    Maybe because this is still (i) a research front area (ii) unproven (iii) unverified (iv) not widely accepted (v) is one of a number of theoretical hypothesis.

    Zz.
     
  21. Apr 3, 2006 #20

    pervect

    User Avatar
    Staff Emeritus
    Science Advisor

    I may be digging up an old thread here, but one reason I don't believe this result is that I was under the impression that a even a field-theoretic approach to gravity using spin-2 gravitons was bound to wind up with GR.

    See for instance

    http://xxx.lanl.gov/abs/astro-ph/0006423

    Thus I would not expect results that were 10^20 different from GR's results, most especially in weak-field results, from any quantum theory of gravity.

    However, I am not very familiar with the details of these field-theoretic arguments, just that they exist.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: New test for GR ?
  1. GR's Tests (Replies: 11)

Loading...