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. M

    How do Gravitons escape from a Black Hole?

    1 : Am I right in thinking gravitons are the mediators of the gravitational force, just as photons are the mediators of the electrostatic force? If this is correct, then presumably the gravitational force between A and B can only be manifest (detected) in circumstances where gravitons can...
  2. S

    String Gravitons yield GR. NOT

    This paper does a lot of testing of different kinds, and concludes that the string theorists assertion that the graviton reproduces the physics of GR in flat spacetime is a myth.
  3. G

    Do Gravitons Play a Role in Simulated Gravity on a Rotating Spacestation?

    If a spacestation were rotating to simulate 1g Earth conditions, would gravitons be involved? Is this a gravity well like the rubber sheet analogy. How does the equivalence principle play into all this. Please keep the answer in laymans terms if at all possible. I want some hopes of...
  4. G

    Gravity, Gravitons, and Geodesics.

    Hi, Hopefully someone can explain this to me in laymans terms... If I am understanding what I am reading correctly, gravity the result of the shape of space-time? I don't understand why this is considered a force at all if it is the result of the shape of space-time. Where does the...
  5. C

    Gravitons, Gravity and The Beginning

    A new / revised theory <snip> At first there was ‘nothing’. It was empty and had no bounds. One could not identify coordinates of space, nor time. Then the ‘nothing’ started to quiver. The quivers were in every direction but still there were no coordinates for direction or distance...
  6. F

    How do gravitons behave in relation to general relativity?

    It must be wrong to think of gravitons like air molecules that have the free space to move in any direction, because if a wave of gravitons could move side to side, they could effectively ‘miss’ attracting some small particles. So they must behave like a complete solid wall of particles. But...
  7. K

    Dark energy could be gravitons

    Dark energy could be the energy of a huge number of gravitons. As photons traveling from one galaxy to another redshift they could emit gravitons that adds to the dark energy total and so keep the density of dark energy constant.Also if the gravitons carry the colour force , like gluons, then...
  8. K

    Gravitons and force of gravity

    Would a graviton emitted by a proton lose energy as it climbs through the gravitational field of the proton - would other gravitons inhibit its progress?If the graviton is absorbed by another proton then would it get the energy back as it falls in the gravitational field of this second...
  9. K

    Photons are made from gravitons

    If a spin 1 photon is made from spin 2 gravitons then when the gravitons initially formed the photon, they must have reduced their angular momentum. They could do this by splitting into two spin 1 particles, one of which helps form a photon, while the other moves off into space as a free...
  10. K

    Graviton Energy: Min. Amount & Universe Total

    What is the minimum amount of energy that a graviton is expected to have? And how much energy are all the gravitons in the universe expected to have in total?
  11. H

    What is the Renormalization Group Flow of Gravitons in String Theory?

    I can't seem to get an answer on sps, so maybe someone here knows. Typically in Quantum gravity, people deal with the truncated graviton series (since its not renormalizable) following Wilson's ideas. Its usually cut off at 1 loop. It still gives a value, and people take it fairly...
  12. F

    How can gravitons pass so effortlessly through a solid?

    I realize gravitons are only a theory, but what do the theorists have to say about gravitons traveling easily through huge amounts of solid?
  13. S

    Gravitons in the 5th Dimension

    Can someone please explain to me or direct me to a website about the theory that there are 4 spatial dimensions, and that gravitons exist in the 4th one. I am now aware of this theory, and that this could explain why gravity is so weak. I find this really interesting, and would appreciate any...
  14. K

    What are the properties of gravitons?

    Four Forces and "Gravitons" Hello. Well, we were watching an old video, presumably from the 80s or so in physics class, and it stated: There are 4 basic forces in the universe: ElectroMagnetic, Gravity, Weak and Strong. Now, EM and Gravity make sense to me that they exist, but weak and...
  15. Orion1

    Exploring the Possibilities of Quantum Gravitons and Their Decay Products

    Given that the Standard Model states that only three families exist, and given that gravitons can exist with mass, why could it not be implied that there are also three graviton types?: g^0_e - electro-graviton g^0_\mu - mu-graviton g^0_\tau - tau-graviton Given that no primordial...
  16. wolram

    If gravity begets gravity, do gravitons emit gravitons?

    if gravity begets gravity, do gravitons emit gravitons?
  17. X

    The Graviton: A Missing Link in Understanding Gravity?

    Upon trying to understand gravity force, I run into to the BIG G problem, which is, what does the unit and magnitude of G stand for. As I asked others this question and did my own research I found out I am not the only one who have asked these questions, as matter of fact there is countless of...
  18. X

    Deriving 'G' from E=mc^2 and Gravitons

    What does the unit and magnitude of constant 'G' mean, and what is its relation with graviton? ANY OPINION? Here is how i see it: E=mc^2 c^2=E/m where E=W=Fr (r stands for radius or distance or ‘s’) therefore c^2= Fr/m therefore c^2= c^2----when forces interact the forces hold true...
  19. C

    Theory of Gravitons: Exploring the Origin of Time and Space

    [SOLVED] Theory of Gravitons I have tried to picture the beginning. At first there was only an endless void with no bounds. There were no coordinates in this void, no time. Then the void started to quiver. The quivers were in every direction but there were no coordinates for direction...
  20. T

    Are gravitons a certainty like electrons in reality?

    OK we know beyond doubt that electrons exist in reality, even if no-one really knows what they actually are. Can we claim the same certainty that gravitons exist in reality or not? Thanks for the info.
  21. Ivan Seeking

    Why do we use gravitons without a corresponding theory?

    I hear many models for particle interactions described that use gravitons, virtual particles, and that reference many concepts that I thought were highly controversial; but these models don't seem to be treated as such. Mainly though the question of gravitons is what attracted me. If we...
  22. N

    Gravitons & Photons: How Many Interactions?

    For the purposes of this question, assume there are gravitons and they are the carrier of the gravitational force. I could use one of the other forces and leave out gravitons, but it's easier for me to envision this question using a very low strength force. Q1) -- For gravity to deflect the...
  23. M

    What is the behavior of gravitons

    i think i asked a question here a long time ago and nobody fully answered it so here goes: what is the behavior of gravitons. i know they are virtual particles and cannot be observed, but is there a way to manipulate them such as we can with charged particles? also, have we any...
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