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Why Even Talk About Gravitons Even Existing?

  1. Feb 14, 2010 #1
    From what I have read out there, of the four fundamental forces that have been detected in our universe, gravity seems to be the weakest at the atomic level and smaller.

    I figure this is most likely true because at the atomic level and smaller - the weak and strong forces (those causing beta decay and gluons to hold quarks inside of protons and neutrons) are the forces that build matter at an atomic level.

    Gravity seems to only rear it's head when the mass of any object is that of an atomic mass or higher. The larger the mass of anything....the more gravity plays a role according to Einstein's general relativity principles.

    Therefore gravity is a force that needs to be separated from the other three major forces because it doesn't seem to appear or work at levels smaller than anything smaller than an atom.

    If this is all true....then why the need to even talk about mass-less particles like gravitons even existing in the first place? After all, Einsteins' Gen. Relativity Theory says gravity is nothing more than the physical bending or curving of the space-time fabric which anything that has mass on it does. Thus it's nothing more than a force that only shows up when masses are that of an atom or larger and not at the quantum level.
    Last edited: Feb 14, 2010
  2. jcsd
  3. Feb 15, 2010 #2


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    Gravitons are hypothesized because of the overwhelming success quantum field theory has enjoyed using bosons to model the behavior of the other three fundamental forces of nature [EM and the nuclear forces]. Detection of individual gravitons is, however, virtually impossible due to the extremely low cross section for the interaction of gravitons with matter. It has been estimated that a detector the size of Jupiter orbiting a neutron star, would only detect a graviton once every 10 years under ideal conditions. Gravitional waves, composed of many gravitons, are detectable. There is little doubt of the existence of gravitational waves. Hulse received the 1993 nobel prize for the indirect detection of gravitional waves.
  4. Feb 15, 2010 #3

    Negative, all quantum particles with mass in the Standard Model experience gravitation, which are smaller than a nucleus, the only requirement is mass.

    It is only that the gravitational interaction strength is several orders of magnitude weaker than the other forces at this scale, making it extremely difficult to detect.
    Last edited: Feb 15, 2010
  5. Feb 15, 2010 #4
    Mass in itself is a serious problem. It only manifests through inertia and gravitational effect.
    yet we are told that mass is bestowed by a Higgs field.
    So the Higgs is the source of inertia and gravitation ?

    The three amigos Haisch, Rueda and Puthoff produced a paper some years ago that implied that inertia had an electromagnetic source.
    I'm not pushing their barrow, but it seems much more likely than the Higgs hypothesis.
  6. Feb 16, 2010 #5
    The Higgs MECHANISM would be the source of mass, Higgs boson or no.

    EDIT: you said... "Thus it's nothing more than a force that only shows up when masses are that of an atom or larger and not at the quantum level. "

    Wow... light must feel REALLY silly following geodesics right into the throat of a Black Hole when it must be immune to gravity. In fact, all particles should. IN FACT, lets just tell all nuclear fusion in the universe to stop right now.
  7. Feb 16, 2010 #6

    Light doesn't cause gravity to occur because it is mass-less. A black hole (being extremely massive) causes the light to get sucked into it.....not sure what your example is trying to say. If anything it further strengthens my QUOTE....not weakens it.
  8. Feb 16, 2010 #7
    Light doesn't cause gravity? In other words, light doesn't contribute to warping spacetime through the SET? So what? You haven't adressed how light can be subject to gravitational forces and must fullow spacetime geodesics if gravity 'only shows up when masses are that of an atom or larger and not at the quantum level'. Before you riposte, how about answering the original question?

    EDIT: Do some research on 'scalar fields' for the mass issue.

    Edit2: While you're at it, "Why Even Talk About Gravitons Even Existing?" is just eggregious. Spelling errors are nothing, and grammar in a post means little, but have some respect for your topic headers. :rofl:
    Last edited: Feb 16, 2010
  9. Feb 16, 2010 #8
    In my opinion it seems a bit far-fetched to link gravity to the other three major fundamental forces considering the other three are all strong at the atomic and smaller levels while gravity usually only rears it's head at large mass levels. The other three forces use "force fields" of some kind to attract and repel things while gravity really doesn't use any type of "force field" but rather is just physically bending space-time as we know it.

    This explains why electromagnetism uses photons to carry its attracting and repelling powers, while the strong force uses gluons for it's attracting powers and the weak nuclear force uses W and Z bosons for it's functions.

    Gravity, on the other hand hand, shouldn't have it's own similar particles like the graviton just for the sake of fitting in with the other three quantum forces.
  10. Feb 16, 2010 #9
    Yes... hence the great divide between SR/GR and QM. Hence the need for Quantum Gravity. Gravitons are one possiblity and hardly the only accepted one. Oh, and since when has 'shouldn't' or 'should' played a role in what 'IS'?
  11. Feb 16, 2010 #10
    There is no "need" for quantum gravity. That's exactly the point I am trying to make. Why should there be a "NEED" for quantum gravity like you said above?

    If gravity has no effect at the quantum level (objects with extraordinary small masses).....why try to unite it with the other three fundamental quantum forces to begin with?

    It sounds to me like quantum physicists are chasing after a "boogey man" to me.
    Last edited: Feb 16, 2010
  12. Feb 16, 2010 #11
    Seriously dude....I really don't think you know what you're talking about. You got lost somewhere and now just seem bitter for no reason. Try sticking to the question I asked, why I posed the question and the information that lead me to ask this question. If you can't come up with an answer or participate constructively to the conversation.....just go somewhere else.
  13. Feb 16, 2010 #12


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    It might be a bit premature to dismiss gravitions. The Hulse study makes a very strong case for the existence of gravitational waves, and waves without a corresponding boson would be clearly ATM proposition. Direct detection of gravity waves [the purpose of LIGO] would be huge step forward. It would effectively end any controversy over the existence of gravitons and constrain their properties.
    Last edited: Feb 16, 2010
  14. Feb 16, 2010 #13
    Hi Chronos,

    Could you go over your statement again....."The Hulse study makes a very strong case for the existence of gravitational waves, and waves without a corresponding boson would be clearly ATM proposition."

    What is an ATM proposition mean?
  15. Feb 16, 2010 #14
    Well, either Chronos is in love with an Automatic Teller Machine and wan't to propose to it... or he means, "At The Moment".

    I.E. A placekeeper theory to make progress with while more complete and accurate theories are developed.
  16. Feb 17, 2010 #15


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    Apologies, ATM = against the mainstream.
  17. Feb 17, 2010 #16


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    ATM means "against the mainstream". Discussion of ATM propositions is strongly discouraged here at PF, for good reasons.
    NYSportsguy, gravity is equally weak on all scales. There are some therories that postulate it could be stronger at small distances, but there are no observations to confirm this.
    So there's no "threshold scale" where gratvity starts to apply, thus there's no reason to assume that there's no gravity at the "quantum level", as you put it.
  18. Feb 17, 2010 #17
    Ahhhh... that makes more sense. I still harbor a deep suspicion that you have major issues with Automatic Teller Machines. You love them don't you? *shhh shhh* no crying now... it's ok... Let it all out!

    EDIT: Ich: Don't bother. This isn't NYGuy's first whack-a-do thread. In fact, it isn't even his only ACTIVE whack-a-do thread. He just finished posting the newtonian formula for work out of nowhere in another thread. *cries*. Make the bad man stop.
  19. Feb 17, 2010 #18


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    Just trying to help him out, frame dragger. I hoped pointing out the ATM component of his argument would be instructive. It is easy to wander into the ATM mine field. I view this as an innocent transgression until followed by denial of observational evidence.
    Last edited: Feb 17, 2010
  20. Feb 18, 2010 #19
    Because when you apply straight general relativity to certain situations and ask what happens you get the answer "divide by zero" which is no real answer. Once you compress things past a certain point quantum effects start becoming important, and if you exclude quantum effects from things like black holes, you run into problems with things like the second law of themodynamics breaking down, which is a bad thing.

    Basically, if you assume that gravity does not have quantum effects, your theories start giving non-sense results (i.e. divide by zero, infinities, answers that don't make any sense).

    But it does.
  21. Feb 18, 2010 #20
    Here is a cool experiment that illustrates gravity having quantum effects


    Basically, you create a gravity potential well, trap neutrons in it, and then the neutrons behave the same why as they would in an EM potential well.

    Also gravity is weak. It's not non-existent. One of the cooler experiments you can do is the Cavendish experiment where you see gravitation effect of brick sized object.

    There is also the Mossbauer effect, which is a standard experiment that shows that yes, gravity does act on particles

    Last edited by a moderator: Apr 24, 2017
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