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.
I understand inflation is thought to predict primordial gravitational waves although their strength is undetermined by the theory with some models of inflation predicting them to be strong and others so weak they can never be detected.
However , this paper claims that if we detect a background...
Hi,
what effect do gravitons have on electrons. I know with photons the electrons absorb the photons and leave the atom. Would gravitons have the same effect?
if matter and anti-matter meet, they annihilate each other. Gravitons are anti-photons and photons are anti-gravitons. They MUST meet in immesurable quantities in our universe. Yet gravity exists, and light exists in our known universe. This denies the annihilation necessity. And annihilation...
Are there any limits to how fast forces can exert influence... or are they all instantaneous?
How fast are the forces of a collision?
I think frame dragging, with gravity, shows that at least gravity is not instantaneous, because if it is instantaneous, then how would it produce drag - it...
https://physics.stackexchange.com/questions/273918/is-there-a-possibility-for-discovery-of-anti-graviton-i-e-the-graviton-antipar
How can a graviton have an anti particle even though they are essentially the same thing? Same thing with the photon. Any help would be great
[Mentor Note: The PSE...
Hi! Isn't gravity just a smaller object moving toward the lower energy state created by a larger object (time slows down the closer you are to a massive object)? Why do we need a force carrying particle for gravity?
The spin-foam approach to quantum gravity is part of the class of approaches, that also include loop quantum gravity and a variety of other methods, that sets out to quantize space-time rather than the gravitational force itself.
But, according to a new paper, it turns out that "the continuum...
1) What is the relationship between gravitons and the curvature of space-time?
2) As gravitons move at speed c, the curvature of space-time is not instantaneous either, so how the curvature sets in or disappears gradually (for theoretical example if mass disappears suddenly upon collision of...
As per the summary I don't understand why physicists talk as if gravitons are inevitable, when gravity is just curved spacetime? Why would curved spacetime have a particle?
Specifically, how would graviton-graviton interactions increase the gravitational binding of matter?
I visualize that the beam of spacetime between two stars is very ordered, in that streams of gravitons from each star flow in very nearly anti-parallel paths. Will these gravitons interact?
Light...
We know about the Higg's field and boson, so what if gravity is the same.
There has long been a dispute as to weather gravity is a field or a particle.
Why can't it be like the Higg's boson.
Einstein's theory describes gravity as a curvature of spacetime. As such, everything is affected by it. This includes light, which has no mass, as was made clear for the first time during the famous 1919 solar eclipse. In the standard model, the cause of gravity is supposed to be gravitons...
If the metric ##g_{\mu\nu}## is dimensionless and gravitons are quantum excitations of the metric does that mean that gravitons themselves are dimensionless?
I say this as locally the metric is just the flat metric ##\eta_{\mu\nu}=\hbox{diag}(-1,1,1,1)## with the dimensions in the co-ordinates...
W and Z bosons, gluons, and photons are all gauge bosons that have been found. Since the graviton can be connnected to atoms and mass in certain ways, I think that CERN may eventually prove the graviton(if real) through smashing atoms that, supposedly, have a graviton orbiting them. Could...
A central feature of classical GR that it is background independent and operates via a curvature in space-time. As I understand it, this is not true of the other Standard Model forces which are consistent with special relativity and operate in Minkowski space, in which forces are transmitted via...
I wonder why electromagnetic waves don't escape from a black hole while gravitational waves (obviously) do.
What is the difference between the two kind of waves?
And between gravitons and photons?
thank you for your attention
So quantum states collapse when observed, ie they are interacted with, if one had an uncharged massive particle, in a true vacuum (yes, this assumption is egregious, not your usual "ignore air resistance"), and the state of the aforementioned particle collapsed, would that imply gravitons did...
See my previous post! https://www.physicsforums.com/threads/do-gravitons-have-frequency-like-photons.957146/
Let's say we had some aliens that had the ability to emit/interact with gravitons with frequency roughly in the range corresponding to human hearing (20Hz-20KHz), and that they had an...
<Moderator's note: Several threads merged and moved to cosmology.>
So I’m wondering about gravity. I was under the impression that gravity was created due to the curvature of 4d spacetime and whatnot. Can someone explain to me what gravitons are in relation to that? Are the gravitons making...
Gravity waves are very weakly absorbed.
The gravity wave detectors have so far detected 3 events of gravity wave emission: 2 from black hole pairs and 1 from neutron star pair.
The absorption is weak but the detectors are very sensitive.
How much energy did the gravity wave detectors actually...
Something I've been thinking about lately. If so, how'd we detect high frequency gravitons? I have Bachelors in physics so you may get a little technical ;)
Are gravitons postulated to be excitations of gravitational waves? If so, and since gravitational waves have been unambiguously observed, then gravitons must exist, no?
If not, then what is the postulated relationship between gravitational waves and gravitons? Are both deemed/postulated to...
If what we perceive as the force of gravity is really just the effect of curvature of spacetime, why do theorists
hypothesize the graviton as the force carrier for gravity? I thought that GR does away with the notion that gravity is a "force." So, is gravity a force or is it merely an effect?
I understand, for example, the photon for electromagnetic force, but I don't see the need for graviton. From my understanding of general relativity, gravity is caused by the warping of space-time. If I am right, why do we need a force carrier particle for a feature of space?
From what I can...
Hi everyone, today, I have a question about quantum gravity, good to begin with. I used Newton's formula to calculate gravity for nêutron , the result exceeded Planck's radius, the question is: could it be that gravity is not necessarily connected to the mass of a particle, nor with graviton...
In trying to understand the relationship between Higgs particles and gravitons, I would like to pose a question on hypothetical question:
What would happen if you increase the Higgs field around a planet? It seems it would mean its mass increases, which would mean its gravitation increases...
I'm not very conversant in the subject. But it is my impression that the acceleration of the expansion of the observable universe has generated a theory that there might be a new particle (field?) call the inflaton. On the other hand, I thought I'd heard that scientists were trying to find...
since gravity under GR has unlimited range the graviton must be massless. since the graviton is massless, the higgs field does not couple to the graviton. If the higgs field did couple to gravitons, it would cause gravitons to have mass, contradicting observation.
but the higgs field carries...
Is a sea of massive gravitons what ripples when galaxy clusters collide?
Accepted at APS Physical Review D:
https://journals.aps.org/prd/accepted/8b07dQ8dFbd1051b06704364802ee6ba42eea6f5e
Precursor:
Bigravitons as dark matter and gravitational waves
We consider the possibility that the...
This is a somewhat weird question, but here it goes:
What would happen if there were only gravitons? Would some other kind of particle appear in the Universe sooner or later? Would there be any chance for mass to appear in such a Universe (assuming that the graviton is a massless particle)...
Hi Everyone, my first post here.
I'm really confused by the comments around the recent LIGO gravitational waves discovery and how it connects to Einsteins gravitational model. My understanding is that he said a body warped spacetime around it forming a gravitational well into which other bodies...
Now that we have confirmed the existence of gravitational waves, have the odds of discovering a force carrying particle changed? With my limited knowledge it kind of seems like if gravity is caused by the warping of space-time, which was confirmed by gravitational waves, would mean that there is...
In QFT, an ultraviolet cutoff is imposed to avoid singularities. One physical reason for why this works may be that there actually is an ultraviolet cutoff from spacetime being quantized. Since in GR spacetime is responsible for the force of gravity, and gravitons are the hypothesized quanta of...
There is theory that masses like charges are transfering force gague bosons.
According to charges they transfering the boson called photon between the charges and responsible for the electromagnetic force. Photones qualities are that it doesn't have mass and behave like a particlee and also as a...
If a mass bends space-time somehow and then I nudge it, the bend changes. This distortion of space-time bend is supposedly expanding at the speed of light and could be called a "gravity wave" that carries energy. Why is this wave not the distortion that creates a "graviton" like EM and photons?
Past the event horizon of a black hole, gravity is so immense that even light can't escape. Wouldn't this cause the the gravitons, which travel the speed of light, to be trapped, making a singularity?
So, I'm still a bit new to the realm of physics but I was discussing theorized particles with my professor the other day and came to the conclusion, if gravitons do exist, could anti-gravitons be an explanation for why the universe is expanding? I was reading around and came across a similar...
planet Earth and the sun. in GR, gravity is not a force but simply a manifestation of spacetime curvature. the sun curves spacetime and the Earth is simply traveling through geodesic motion through curved spacetime.
in string theory, the sun and Earth exchange virtual gravitons through a...
"General relativity predicts that disturbances in the gravitational field propagate as gravitational waves, and that low-amplitude gravitational waves travel at the speed of light." It seems high energy waves may travel slower, but certainly not faster.
So, a large star whilst going supernova...
Hi everyone. Am trying to find out how many gravitons are in a quark, or in a proton. Anyone here know, or can point to a reference that might have the answer? Thanks!
Gravitons are hypothetical, I know. But, unlike other force carriers, gravity is simple ruled out by gravitational field theory. If gravitons are real, why can't we detect them?
In a theory like string theory or supergravity, gravity is described by gravitons on (usually) Minkowski background.
But I don't see how this works in terms of the expansion of the Universe. For example, two galaxies far apart can be moving away from each other at more than the speed of light...