What is Gravitons: Definition and 173 Discussions

In theories of quantum gravity, the graviton is the hypothetical quantum of gravity, an elementary particle that mediates the force of gravity. There is no complete quantum field theory of gravitons due to an outstanding mathematical problem with renormalization in general relativity. In string theory, believed to be a consistent theory of quantum gravity, the graviton is a massless state of a fundamental string.
If it exists, the graviton is expected to be massless because the gravitational force is very long range and appears to propagate at the speed of light. The graviton must be a spin-2 boson because the source of gravitation is the stress–energy tensor, a second-order tensor (compared with electromagnetism's spin-1 photon, the source of which is the four-current, a first-order tensor). Additionally, it can be shown that any massless spin-2 field would give rise to a force indistinguishable from gravitation, because a massless spin-2 field would couple to the stress–energy tensor in the same way that gravitational interactions do. This result suggests that, if a massless spin-2 particle is discovered, it must be the graviton.

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  1. B

    Gravitons are still theoretical, of course, but I'm not quite sure how

    Gravitons are still theoretical, of course, but I'm not quite sure how they're supposed to fit into the current picture. If gravity is, in basic terms, caused by the curvature of spacetime around objects with mass, then what role would the theoretical graviton be playing? What comes first, the...
  2. M

    Understanding Gravitons: A Key to Quantum Gravity?

    Hello, I am about as far from a physicist as physically possible, but I am fascinated by the theory, so I've re-enrolled in some intro physics classes next semester. (I'm a Poli Sci/Pre-Law Undergrad). I've been reading a bit about the subject for some time now, and I'm a little confused...
  3. S

    Do gravitons spiral around a monopole?

    I'm a sci-fi writer and would like some help, if you would please. My story is simple: monopoles arising in spin-ice can be charged with enough magnetricity to deflect spin 2 gravitons, freeing manking from the tyranny of a lone world, and propelling us into a vast new tyranny. I heard...
  4. E

    What is the rationale behind gravitons?

    Can someone explain the rationale behind gravitons to me? My background is computational physics, and as such i may be biased towards physics that is actually computable, such as LQG and regge calc. I have some clue what this is all about, but i have some questions: Is there any reason...
  5. K

    Gravitons & Warping: Reconciling Extra Dimensions?

    i`m having trouble reconciling gravitons and the warping of space. Do the gravitons enter and leave the extra dimensions causing a fluctuation of the extra dimensions entering and leaving our visible dimensions?
  6. M

    Do Gravitons Attract Other Gravitons?

    As the title suggests, I'm wondering if gravitons feel the pull of other gravitons. And secondly, if a singularity emits gravitons, how do the gravitons get out of the event horizon to pull in other matter?
  7. K

    If they are real, what exactly do gravitons do?

    If they are real, what exactly do gravitons do? I mean are they absorbed by other particles resulting in an attraction like photons and warp space-time in the process or do they just warp space-time which causes the attraction? If it's the latter how do the gravitons get "used up?"
  8. D

    Could Weak Gravity Be Explained by Long-Wavelength Gravitons from Unruh Effect?

    An interesting property of the Unruh effect is that the very existence of particles depends on a frame. Unruh particles exist in the accelerating frame but not in an inertial frame. I think exactly the same is applicable to the gravitons for obvious reasons. So inertial pseudo-forces can be...
  9. wolram

    Gravitons: Clumping & Gravity Anomalies w/No Mass

    The only thing i think i know about gravity is it is an attractive pseudo force, so when one imagines gravity as gravitons, why do they not clump together and cause gravity anomalies (gravity with no mass)?
  10. F

    Are gravitons consistent with black holes emitting them?

    If gravitons exist, how can black holes emit them? It cannot be like Hawking radiation, which increases as the black hole gets smaller. The gravitational field grows larger as black holes grow larger. Also, would not the energy of the graviton decrease to zero (and its wavelength increase to...
  11. A

    Gravitons corresponding to flat spacetime.

    Is it possible to define gravitons corresponding to flat spacetime? If so, how? Flat spacetme has zero curvature. How does one mathematically describe gravitons for flat spacetime?
  12. L

    Exploring Quantum Gravity: Conservation Theory & Gravitons

    If quantum gravity exists, then gravitons are responsible; however, it seems to me as if a body of matter would need to be consuming energy/mass (as the sun does) to create gravitons, because of the Conservation Theory. Have I overlooked something? Almost certainly, but I cannot find it. Any...
  13. D

    How do gravitons cause gravitational attraction?

    I can picture gravity as the warping of spacetime as postulated by GR but I have not heard a descriptive explanation of how a graviton might cause an attraction between two masses, or even if it is a cause in quantum theory. So okay, you have a closed string or a massless particle with a spin of...
  14. J

    Gravitons and Photon interaction

    howya - for those who hold to a theory of gravitons being the operative mechanism of gravity (as opposed to GR), i have a small question: since light is affected by gravity, particularly as it passes a very massive body and curves around it, and graviton theory would indicate that a near...
  15. J

    Can Gravitons Escape From a Black Hole if Light Cannot?

    Assume we all accept that gravitational influence moves at the speed of light, just as EM radiation does. Light cannot escape from a black hole because the escape velocity from a BH exceeds the speed of light. If gravitons are a proposed particle-interaction based solution to explain gravity...
  16. H

    Gravitons Phasing Across Branes: Dark Matter Explained?

    "phasing" ? gravitons hey everyone, I am new here and I am wondering if anyone knows whether or not someone already came up with the idea i had a year or two ago, or perhaps if someone knows its impossible and doesn't work. - after reading somewhere that its theorized that gravitons can "phase"...
  17. M

    Are Gravitons the Key to Understanding Gravity?

    According to particle physics, there is a certain particle called a graviton which is the messenger particle of gravity but it so happens that Einstein's theory of general relativity says that mass affects the space time fabric which is responsible for gravitational force. So it is like the...
  18. Q

    Gravitons vs Relativity: Einstein or Particle Exchange?

    does the idea of how gravity works through gravitons contradict einsteins general relativity? the idea of a particle exchange (gravitons) does don't seem to agree with space-time fabric. can they agree or is only one right? if so which do you think?
  19. S

    Gravitons or Warped Space-Time?

    *Please read the thread before you vote in the poll! Disclaimer: I am not advocating a fraudulent theory, I am presenting original evidence and logic (detailing the contradictions in quantized gravity) both of which are certainly open for debate. Gravitation In classical mechanics, the...
  20. T

    Layman's question about gravitons

    Hello all. I have a quick question regarding gravity and I was wondering if someone could explain it to me in laymans terms, since I do not possesses the mathematical background to understand higher physics. According to Einstein, if gravity is simply the "fabric" of spacetime -- akin to a...
  21. K

    Detect gravitons at an accelerator

    my project is about the search for the graviton, i know we are using particle accelerators to try to find out about them however we cannot detect them still, but we can prove they exist, i am having trouble explaining what is actually being done to detect them in any kind of detail. and the...
  22. K

    Gravitons and infinite regress.

    Can anyone tell me what is wrong with the follow observation (if anything)? (1) The graviton (putatively) mediates the force of gravity. The phenomenology of masses moving toward each other is due to an exchange of gravitons. Call these gravitons G1. (2) The G1 are themselves, as massless...
  23. A

    What fallacies exist in arguments against gravitons?

    I just read this: http://www.americanchronicle.com/articles/50304 I'm just wondering what those who are more knowledgeable about this stuff think of it. My guess is the arguments are invalid otherwise people wouldn't bother studying string theory... Do gravitons interact with...
  24. M

    If gravitons exist, does that mean spacetime is not curved by mass?

    Or is there some way that they co-exist?
  25. S

    Where does the energy come from that produces gravitons?

    Where does the energy come from that produces gravitons? I understand it has to do with quantum field theory but that is all i know.
  26. E

    Does string theory gravitons have 4D GR as its low energy limit?

    Lisa Randall said "string theory reproduces GR in 10 dimensions" Does string theory gravitons have 4D GR as its low energy limit? I know that its lowest mode vibrations corresponds to a massless spin-2 particle, the graviton. I know GR in 4D can be extended with susy. Does it reproduce...
  27. L

    Gravitons and gravity vs curvature of space-time.

    Hey, I've been a little confused on the concept of gravitons. I know that they are the messenger particle of the gravitational force, but I thought that gravity was a result of the warping of the fabric of spacetime. If a large star warps spacetime, therefore attracting things around it, then...
  28. B

    Gravitons and gravity in a asteroid-planet interaction

    Let me start by saying I know nothing and just come seeking knowledge. I hear that a graviton has never been discovered, only theorized. True? If so, I was thinking of how we might find one. When planets get nailed by asteroids isn't the energy from the momentum of the asteroid getting...
  29. K

    Gravity is made of gravitons ?

    gravity is made of gravitons ?? the question is is gravity made of 'gravitons' i mean a particle adquire mass and gravity since it 'absorbs' a graviton.. and space time is Euclidean until it is surrounded by gravitons, then why could not construct a kind of field to polarize or avoid gravitons...
  30. I

    Gravitons and extra dimensions

    are there any introductory books on the theory behind gravitons and extra dimensions and also the experimental tests that could be done?
  31. N

    Gravitons and Photons: Engineer's Questions

    I'm an engineer, not a physicist, so you'll forgive my pre-uni knowledge of all things physics. I was discussing electromagnetic fields with someone, we got into it, photons being messenger particles, then onto gravitation and gravitons and so on. I got slightly confused by a few things...
  32. E

    Can you get gravitons to behave like photons in laser?

    Is it possible to create gravitons the way photons are created, with electrons falling from quantized systems, or create graviton analogies to photon-lasers?
  33. C

    Is it possible that gravitons also orbit nucleons like electrons do?

    Is it possible that gravitons also orbit nucleons like electrons do? I know this is speculative grounds, but are there any scientific principles that come to mind that could fallsify this question?
  34. B

    Gravitons & spacetime-curvature-geometry

    i have a question about gravitons and spacetime-curvature theories of gravity, are gravitons supposed to curve spacetime, or do gravitons dispense with the idea of spacetime curvature, and travel through flat minkowski spacetime, much as photons do? what would be the difference...
  35. E

    Can Gravitons Escape Black Holes?

    It is my understanding that gravitons are the elementary particles thought to transmist gravity. They must be massless and therefore travel at the speed of light. With this in mind, how can black holes gravitationally effect other bodies as the gravitons emitted by the black hole would not be...
  36. A

    My gravitons move out at the speed of light

    1.From the I see gravity is the only force that requires no energy. Because when I fall gravity is pulling me down. This is between the Earth and me. Yet neither of us give any energy. I actually lose energy while I accelerate due to air. Yet I still gain energy. Why? Were does this energy...
  37. C

    Why does gravity need gravitons?

    Why does gravity need gravitons? Gravity is the curvature in spacetime and it is itself required to create a gravitational field. Does it mean that a body creates gravitons around the spacetime which is curved? Or does it mean that the spacetime is made up of gravitons? If gravitons do really...
  38. H

    Gravity - Integrating General Relativity with Gravitons

    Gravity - Integrating General Relativity with "Gravitons" Every time I read about the hunt for gravitons I never see an explanation of how they will actually produce their effect. Maybe "integrating" is not the best word, but how will gravitons, if proven to exist, lead to the warping of...
  39. Dale

    Gravitons from a circular orbit

    When a charged particle accelerates it produces photons and loses energy which is part of the reason why an electron cannot "orbit" a nucleus. I would think that an accelerating mass would likewise produce gravitons and lose energy so that all orbits would eventually decay. Is this correct...
  40. S

    What is a graviton and why is it considered a boson?

    hey all, I'm pretty new to physics. all I know is what I was taught at secondary school, which wasn't much to be honest.. sorry if this is a stupid question or in the wrong place or whatever, feel free to move/delete it if it is.. so what I'm wondering about is gravitons. I know as good as...
  41. P

    Do Gravitons Exist? | Physics Forums

    First of all, I’m not well versed in Calculus or other tools required to fully grasp the latest understandings of QM or Relativity, so please take my question with a grain of salt. My question is simple. Do Gravitons exist? My intuition impels me to think of Graviton and Gravity in terms...
  42. P

    Are gravitons virtual or real.

    Maybe this thread should not be here. Are gravitons virtual or real. I've read that they are bosons, but... Also, are they expected to have momentum, virtual or otherwise? Thanks
  43. M

    Can EM fields exhibit the same energy-momentum tensor as gravitational waves?

    I don't know if my question belongs to this forum but I get some troubles within my approach; what would you think of a theory predicting that some EM fields can exhibit the same (type of) energy-momentum tensor (emt) than the emt associated with some gravitational waves or fields ? Such...
  44. B

    Can gravitons travel in a vacuum?

    I'm a complete newbie at physics so bear with me.. The minute a spaceship is out of the Earth's atmosphere and into the vacuum, the gravitational pull let's go and the spaceship is free. So what I'm asking is, how can the sun attract the Earth into its pull? Can gravitons travel in a...
  45. N

    Exploring the Role of Gravitons in Quantum Physics: Do They Possess Gravity?

    hi i'm in a dielema. i don't know if it is the right place to post the thread. if every particle is destined by the universe to have some gravitionrl force then does graviton itself have gravity. there is no point of it not having if it is a particle as treaded by quantum physics nabodit
  46. N

    Do Massless Particles Like Gravitons Interact With the Higgs Field?

    hi i'm in a dielema. i don't know if it is the right place to post the thread. if every particle is destined by the universe to have some gravitionrl force then does graviton itself have gravity. there is no point of it not having if it is a particle as treaded by quantum physics nabodit...
  47. M

    Can particles and geometry coexist in gravitational theory?

    I am doing some research this summer with a professor and we are learning GR. For the first time I am thinking about gravity actually in terms of geometry and started to ask my professor questions. He is a VERY smart man but I didn't get exactly what I was looking for with one question. I asked...
  48. wolram

    Gravitons and quantum gravity

    http://arxiv.org/PS_cache/hep-th/pdf/0506/0506189.pdf Title: Gravitons as super-strong interacting particles, and low-energy quantum gravity Authors: Michael A. Ivanov Comments: 38 pages, 9 figures, Latex. Will be published in 2005 It is shown by the author that if gravitons are...
  49. H

    Gravitons supposedley transfers gravity between two particles

    gravitons supposedley "transfers" gravity between two particles i know that gravitons supposedley "transfers" gravity between two particles, but can anyone tell me how gravitons work, and why they "transfer" gravity?
  50. D

    What Do We Know About Gravitons and Their Role in Understanding Gravity?

    Hi I freely admit that I am new to this forum site and pretty new to physics in general, however I am eager to learn. I know extremely little about Quantom mechanics. I won't ask you to explain it all now, I simply request that somone explain to me what is known about Gravitons, why do we no...
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