In general relativity, gravitation is attributed to the curvature of the space-time fabric. Orbital period decay of two gravitating bodies such as binary pulsar results in loss of orbital energy of the system. This lost energy is dissipated in the form of ripples in the space-time fabric. These ripples are known as the gravitational waves. Graviton is a hypothetical elementary particle that mediates the force of gravitation in the framework of quantum field theory. If it exists, the graviton is expected to be massless (because the gravitational force appears to have unlimited range) and must be a spin-2 boson. The spin follows from the fact that the source of gravitation is the stress–energy tensor, a second-order tensor (compared to 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. Seeing as the graviton is hypothetical, its discovery would unite quantum theory with gravity. This result suggests that, if a massless spin-2 particle is discovered, it must be the graviton.
The three other known forces of nature are mediated by elementary particles: electromagnetism by the photon, the strong interaction by the gluons, and the weak interaction by the W and Z bosons. The hypothesis is that the gravitational interaction is likewise mediated by an – as yet undiscovered – elementary particle, dubbed as the graviton. In the classical limit, the theory would reduce to general relativity and conform to Newton's law of gravitation in the weak-field limit.
I agree with mr. Robert J.Low - and we dont know if Gravitons does exist, and do remember matter curves space-time in this case it is not a force.
You have to change Your question.
Further to the responses of Robert Low and Kurt Wraae, it appears that spin 2 massless particles do not couple to the energy momentum tensor unless in the vacuum where the Ricci tensor vanishes. Massive gravitons will certainly be a part of the quantization of spacetime at or near the Planck length. GR is unlike the other 3 forces and effectively describes the "force" of gravity without particle exchange. GR is hidden and resides beautifully within QFT. Please see https://www.researchgate.net/publication/304325189_General_relativity_and_dark_energy_are_hidden_in_the_quantum_equation_of_curved_spacetime?ev=prf_pub for details.
Gravitons describe the gravitational interaction between two masses according to general relativity. While their shot noise is a quantum effect, and hasn't been observed, gravitational waves, in particular, and metric perturbations, more generally, are classical effects and they are described, within general relativity, as coherent superpositions of gravitons. Indeed, both the period variation of binary pulsars and the measurements by LIGO are consistent with and can only be explained by the properties of the metric tensor, as provided by general relativity. Similarly for comparing measurements of the Planck satellite with calculations.
When relativistic effects are relevant, the interaction of matter and spacetime, which is what's called gravity, is described by the invariant combination of the metric and the energy-momentum tensor of matter (and radiation) that can be eliminated from the gravitational action by field redefinitions-not just the mass, which is but the integral of the time-time component of the energy-momentum tensor.
There are courses available on the subject, e.g. here: http://ocw.mit.edu/courses/physics/8-962-general-relativity-spring-2006/readings/ so there's really no excuse not learning this material, which is, really, background knowledge in physics and hardly cutting edge.
Words don't matter-calculations do. So where are the ``alternative'' calculations, that are consistent with everything's that's known, and allow to calculate new effects and thus design experiments? That's what matters, not gossip. Nonsense isn't helpful. Gravitons, spinning particles, the Coriolis force are all known concepts and how to do calculations with them and design experiments is known-there's nothing new here. So statements about them can be checked, whether they make sense or not. For instance, the claim that there's any difference between a particle and a wavepacket is easily shown to be meaningless.
The Sun's a star-its properties depend on the matter it's made of-its equation of state. How, is known for decades.
“…All physics questions have to be asked and answered within some theoretical framework. I've assumed the framework of conventional physics, as generally accepted by the community…”
- such statements indeed seems as rather questionable, especially “as generally accepted by the community”. Any indeed new [and correct, of course] ideas – i.e. that are indeed the science, are always outside “the accepted by the community”.
Returning to the thread’s question:
“…I agree with mr. Robert J.Low - and we dont know if Gravitons does exist, and do remember matter curves space-time in this case it is not a force…”
- to claim that is necessary, first of all, to define – what are “space”, “time”, “spacetime”, “matter” and only after proper definitions of the notions above, to define/introduce - what is “spacetime curvature” and how “matter curves space-time”.
GR doesn’t contain any of corresponding definitions, when if somebody understands – what are the notions above then she/he understands also that the Matter’s spacetime is [5]4D Euclidian “empty container”- or [5]4D Euclidian spacetime, which is “absolute” in the sense that nothing in Matter, including “masses” and “reference frames” can transform anything in the spacetime – “to contract”, “to dilate”, “to curve”, etc.
Including – there cannot be some “spacetime curvature”, when the gravity is simply the fourth fundamental physical force; at that there is no reasons to suggest that this force differs from the three other in that the gravitational interactions aren’t quantized – with a large probability gravitons exist and are corresponding mediators of the gravity force.
That is another problem that usually in the gravity very large “gravitational charges” interact and so usually it is impossible to select single gravitons interactions. Correspondingly to detect such interactions is necessary to use extreamly small masses, and such possibility exists – when, for example, to study the impact of Earth gravity on photons.
Photons have both – inertial and gravitational – masses and change their energy/frequency at motion between points with different gravitational potentials; though the GR postultes that photons don’t change their enrgy in this case, this postulate is very probably a next GR’s non-adequacy to the reality.
A possible version of the experiment where the quantum nature of the gravity rathrer probably can be ovserved – see “The informational model - possible tests”, https://www.researchgate.net/publication/215526868_The_informational_model_-_possible_tests
http://arxiv.org/abs/0706.3979 ; DOI 10.5281/zenodo.34963; at least the section 2.1.2. “Monochromatic photon beam distortion”
Cheers
Article The informational model - possible tests
All these statements are simply wrong, so it's not surprising that the conclusions drawn from them are, also. That something is ``old'' says nothing about its content, so it doesn't make sense. And a simple exercise is to check that Maxwell's equations are covariant under global Lorentz transformations: they take the same form in any frame, related to any other by a global transformation, if the metric is flat. If a system is accelerating, it's not an inertial frame, so Lorentz transformations to another frame are local not global-and it's known how to write them, in this case, too, the mathematical framework is called general relativity. In that case one needs to take into account the spacetime metric and then Maxwell's equations are, also, shown to be covariant, to take the same form in any two frames, related by a local Lorentz transformation, using the curved metric.
The confusing statements caused by trying to discuss ``retardation effects'' are, simply, that-confusing. It is known how to do the calculations in ways that avoid such confusion.
Lorentz transformations are mathematical statements, they don't have anything to do with physics-that comes afterwards.
Dear Ravi,
your intriguing question overlap two things that must be considered in two different contexts. When one talks of gravitons one refers to quantum world. When instead one talks of gravitation force one refers to the macroscopic world. Of course there is a relation between the two worlds ... this relation is given justifying at the quantum level the meaning of mass. My quantum gravity theory gives a clear understanding of these phenomena. In particular it is possible to answer to your question:
'How the gravitons determine the gravitational force between two masses?'
Dear Thierry,
I appreciated your effort to give a mechanics-like interpretation ... but in the quantum world the classical mechanics does not work ...
All the best,
Agostino
No Thierry !
you have written:
'If you are able to think outside the frame of the original theory in GRT, QM, SRT, you may get progress. If you can't, you get stuck in a very limited world. The more such theories are further developed inside their own frame, the farther from reality and from coherence they get, because the crux of the problem is not understood.'
But you do not think outside the frame ... you use classical mechanics ...
One thing is by now well clear: the logic of the quantum world is noncommutative. Where is this logic in your formulation outside the frame ?
No Thierry ! You are wrong.
You pretend to justify quantum phenomena with classical mechanics ... and at the same time to state that quantum phenomena follow a noncommutative logic.
This is a contradiction !
NO THIERRY !
What you write:
'As long as the quantum phenomena are not explained with physics, of course they may be non commutative.
The problem is not caused by the quantum phenomena, it is caused by the theory.'
is non-sense. In fact, to say that quantum phenomena are explained with physics it means that you did not understand that nobody knows physics !!!
In other words we do not know what is the world (physics) ... We can only do mathematical models that try to encode world. Therefore to claim that we can explain world by world is a nonsense.
Instead we can explain world with mathematical models that give us a rational map to understand world.
Even if QM and QFT are incomplete theories, what can be well understood from both is that the logic of the quantum world must be noncommutative. To state now that this is not true, it means that a century of science is passed in vain. I cannot seriously consider this your approach ...
Instead is more scientific to say that QM and QFT must be completed ... In fact my quantum gravity theory just completes QM and QFT adding the dynamic geometric meaning that was lacking in that theories of the quantum world. In fact, my quantum gravity theory is not a statistical theory !
Sorry I must insist.
Thierry is wrong.
@ Thierry De Mees
you have written:
'... you play with words but don't come to the facts. Very unprofessional!'
But what are your facts ?
1) Classical mechanics are physical theories.
2) SRT, GRT and QM are un-physical theories.
3) The Lorentz invariance is wrong.
What you call facts are only non-sense. Any mathematical model can be called a physical theory whether well interprets world under suitable conditions. From this point of view classical mechanics. SRT. GRT and QM are worthy to be called physical theories.
Furthermore, you confused Lorentz invariance with Lorentz covariance. Moreover a nonlinear quantum propagator encoding a quantum reaction (in my quantum gravity theory) does not necessitate to be Lorentz invariant. Therefore your 'fact (3)' is another nonsense.
I must insist once more.
Thierry is wrong.
In general relativity, gravitation is attributed to the curvature of the space-time fabric. Orbital period decay of two gravitating bodies such as binary pulsar results in loss of orbital energy of the system. This lost energy is dissipated in the form of ripples in the space-time fabric. These ripples are known as the gravitational waves. Graviton is a hypothetical elementary particle that mediates the force of gravitation in the framework of quantum field theory. If it exists, the graviton is expected to be massless (because the gravitational force appears to have unlimited range) and must be a spin-2 boson. The spin follows from the fact that the source of gravitation is the stress–energy tensor, a second-order tensor (compared to 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. Seeing as the graviton is hypothetical, its discovery would unite quantum theory with gravity. This result suggests that, if a massless spin-2 particle is discovered, it must be the graviton.
The three other known forces of nature are mediated by elementary particles: electromagnetism by the photon, the strong interaction by the gluons, and the weak interaction by the W and Z bosons. The hypothesis is that the gravitational interaction is likewise mediated by an – as yet undiscovered – elementary particle, dubbed as the graviton. In the classical limit, the theory would reduce to general relativity and conform to Newton's law of gravitation in the weak-field limit.
Dear Ravi,
You can find answers about gravitons and gravitational force in the paper: The Graviton Field as the Source of Mass and Gravitational Force in the Modernized Le Sage’s Model. More information is in the second paper about the origin of electromagnetic force: The Charged Component of the Vacuum Field as the Source of Electric Force in the Modernized le Sage’s Model.
http://vixra.org/abs/1503.0126
Article The Graviton Field as the Source of Mass and Gravitational F...
Dear Sergey,
the revised Fatio-Le Sage's kinetic theory of gravity considered in your papers, cannot justify the graviton contribution as you claim. In fact graviton is a quantum particle that can be considered in a quantum world. Your considerations instead are only classical ones. In other words the situation is like the classical statistical mechanics that should pretend to characterize thermodynamic properties of bodies, by adopting statistical considerations on a set of classical particles only. It is well-known that such an approach is not enough ...
The relation between graviton and gravitation necessarily passes through quantum gravity as I proved.
All the best,
Agostino
Dear Agostino, I wish you success in your research. But there is a problem with quantum mechanics in which we have mathematical models for calculations and cannot see real interaction picture. And up to now it is not clear what the graviton in the quantum theory is. Also I do not agree when for graviton the Plank constant is used as a quantum of action. We can imagine that gravitons are particles of the lowest level of matter (see Infinite Hierarchical Nesting of Matter) and then the particles have another value of the Plank constant.
Dear Sergey,
you have written:
1) 'But there is a problem with quantum mechanics in which we have mathematical models for calculations and cannot see real interaction picture.'
Right ! But I do not use classical QM or QFT. In my quantum gravity the real interaction picture is encoded by nonlinear quantum propagators. These are geometric objects that allow us to give a real description of quantum world dynamics.
2) '... up to now it is not clear what the graviton in the quantum theory is.'
This is not true ! In fact in my quantum gravity it is well defined the quantum graviton field as well the quantum graviton particle.
3) '... I do not agree when for graviton the Plank constant is used as a quantum of action.'
Right ! In fact the Planck constant is not necessary to define quantum graviton field and quantum graviton particle.
Some experimental results can only be explained by saying gravity is a pushing force
@RAVI
Most people will say we don't know and they are being honest.
But synthesizing the whole picture, we now know that space-time has inherent energy,
If you are a proponent of GTR then effectively gravity would be an energy density gradient.
That means the most likely role of the graviton as a guage particle is to repel the substance of space time, thus producing the energy density gradient.
I am no Physician but in my knowledge SR and GRT are parts of classical physics and can't be integrated in Quantum Physics. Einstein was at the beginning of quantum physics.
Gravitons seam to be very new and are in my understanding parts of QM. HIGGS-Particles are also quite new and not yet clear enough.
So it will be clever to say each own meaning and try to learn if differences appear. Try to be scientific and not emotional - summer time is coming!
Dear Kumar, your question is a very clear and surprisingly "simple"!
Nor Great Newton and no genius Einstein and anybody not yet gave any definite answer to it. Meantime, we know long ago how to calculate the gravity enough exactly! Of course, many people saying different things, in different time. Now is accepted to say, for example, that the spacetime is curved that creates the gravity! But you can just ask them - excuse me, and where is the "spacetime" himself? Is it a kind of physical reality or, what? If yes, who has seen it? If no, then about what we have talking? Such situation tell us that we completely not understand about what we have talking!
So, I have gone in described way and I got something, that can be interested you ... if the enough patience.
Regards
http://www.scirp.org/Journal/PaperInformation.aspx?PaperID=64836
It's been explained. Cf. here: http://www.lesia.obspm.fr/perso/bruno-sicardy/ensei/cours/cours_G1/dynamics_planetary_rings.pdf for instance.
- Badges
- Science topic
- Similar topics
- Physical Sciences
- Particle Physics
- Elementary Particle Physics