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

Gravitational vs electromagnetic quantum trajectories

  1. Jun 2, 2004 #1
    Consider a hydrogen atom, with orbitals describing movement of an electron about a proton, together bound by the electromagnetic force. Next consider an equivalent "atom" made up of two massive neutral particles, where the gravitational force at a given separation is the same as the Coulomb force between the above proton and electron, and with a similar center of mass as hydrogen.

    Is the quantum interpretation for the trajectories of the latter case essentially the same as that of the hydrogen atom? How does the spectrum appear, and is it of gravitational radiation rather than electromagnetic? Otherwise, is the situation now correspondently classical?
  2. jcsd
  3. Jun 3, 2004 #2


    User Avatar

    Hint:Consider order of the ratio between strenght of Gravitational force and Coulomb force in nature and estimate the size of the gravitational potential "atom" you are thinking of..

  4. Jun 3, 2004 #3
    Remember that the masses of the neutral particles give the same mutual gravitational force over the same distances as the electromagnetic force between electron and proton in the hydrogen atom, and that the relative center of mass is similar in both cases.
  5. Jun 3, 2004 #4


    User Avatar

    Gravitational force between proton and electron is by HUGE order of magnitude smaller than Coulomb force between them over the same distance.
    Gravitational force between some two massive neutral particles ,like between two neutrons at Bohr radius separation,is still way way weaker than electromagnetic force between 2 elementar charges at the same separation.
    But regardless of that ,you may examine the model (just for the sake of theory) where
    2 point ,charge-neutral, stabile masses orbit each other. Set their gravitational force to be the same as Coloumb force between 2 elementar charges.Firstly you will notice there are some effects doing this ,like radious change due to changed mass etc.
    But even that isn't important.Now,I guess that your primary interest would be to know 1.wether trajectories are subjected to some degree to quantum interpretation of electron trajectories in hydrogen atom?
    2.if there is EM radiation?
    Answer1:No.The system is still described classicaly very well.
    Answer2:Potentatialy just weak gravity wave radiation can occur.Gradually, the system looses energy.

    There's significant difference between classical EM fields, quantum EM fields and associated QM fluctuations of EM field that occur on stage of theoreticaly flat -unperturbed spacetime ,and ,on the other side, "fluctuations" of the stage (spacetime) itself.The thing we don't fully understand yet.
    Even in classical physics clear example ,quite fundamental difference,is fact that in classical physics nothing can stop graviational wave while EM waves can be stopped by appropriate conductive shield.
  6. Jun 3, 2004 #5
    Let's assume that the neutral particle situation is classical. What if an isolated hydrogen atom is devoid of charge, having only gravity to cohere the electron and the proton - is that now classical?
  7. Jun 3, 2004 #6


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

  8. Jun 3, 2004 #7
    Beautiful! Why hasn't this more renown? The data requires more scrutiny, refinement, and replication, though. I might extrapolate the given experiment to a neutron star's radial gravitational resonances, perhaps measurable in a pulsar's E-M spectrum at 1.2 x 106m for the first ground transition. Thank you for gracing us with your presence, Hurkyl.
  9. Jun 3, 2004 #8
    I havn't really read anything you've said, but i'll just say this

    gravity is the weakest force, think about it, a small magnet can pick up a peice of metal against the gravity created by the whole planet.
  10. Jun 3, 2004 #9


    User Avatar
    Science Advisor
    Gold Member

    Is anyone else trying to duplicate their experiment? The data looks convincing to me.

    Do you know how the neutron detector might work?

  11. Jun 4, 2004 #10
    The "Booda experiment"

    Visualize two fields of hydrogen atoms, one whose spin axes oscillate by a strong magnetic field between poles parallel and antiparallel to the earth's gravitational field, and the others' spin axes oscillate by a magnetic field of equal magnitude between poles perpendicular and antiperpendicular to the earth's gravitational field. The difference between the frequency of precessing electrons radiating in the two situations may be evidence of quantum gravity.
  12. Jun 4, 2004 #11


    User Avatar

    If masses are comparable with m*masses of proton and electron than no.if just gravity holds them togather in atomic size orbit (in classicall physics generally elliptical) than rotational energy is low ,slow velocity-->long DeBroglie wavelenght.
    However,remember what I told you about simulating same magnitudes Coulomb force of hydrogen atom at same atom radius sizes by gravity interaction between 2 particles. Take the same ratio Mp/Me ,assume circular orbit, and calculate rest mass of Mp in eV.Now the problem of quantizating the orbit decreases:you will see that quantum problem shifts to HE "nuclus" question wether or not neutral particle of such a huge rest mass can exist.Which would open road to difficult questions such as relation between quantum gravity and strong nuclear force etc,etc.

Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Similar Discussions: Gravitational vs electromagnetic quantum trajectories
  1. Quantum trajectories (Replies: 3)