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wolram
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am i correct in thinking that the graviton is out of favor, along with
other "things", that could explain gravity?
other "things", that could explain gravity?
wolram said:am i correct in thinking that the graviton is out of favor, along with
other "things", that could explain gravity?
Haelfix said:... its oft argued that 'who needs background independance if your theory outputs gravitons' (the thing that makes the geometry in the first place). So what if its perturbative?
Since physics is about predicting things, and we more or less know what geometries are interesting already, if String theory could output the full particle spectrum for each background, then you're really done. Thats the big 'if'!...
Haelfix said:Note, I was saying what is often argued, not what I may or may not think of the situation.
The thing is, even in General relativity, all manifolds can be taken to have a locally smooth chart.. Its hard to think of curvature entering any perturbative theory of gravitons, unless its at least 2nd order effects or higher. Now, the principle contribution to quantum curvature is precisely what belongs to the manifold itself, degenerate geometries would intuitively be small perturbations of that.
Hence, its hard to see how a perturbative theory of gravitons (string theory) will be able to feel the effects of background independance until very high orders (or probably all orders of perturbation theory).
wolram said:am i correct in thinking that the graviton is out of favor, along with
other "things", that could explain gravity?
marcus said:there are some interesting points here which we might get into
Haelfix---Stevo said:...Its hard to think of curvature entering any perturbative theory of gravitons, unless its at least 2nd order effects or higher. Now, the principle contribution to quantum curvature is precisely what belongs to the manifold itself, degenerate geometries would intuitively be small perturbations of that.
Hence, its hard to see how a perturbative theory of gravitons (string theory) will be able to feel the effects of background independance until very high orders (or probably all orders of perturbation theory).
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...Is Haelfix saying that because manifolds are locally smooth, curvature will have negigible effect on the dynamics of the strings, and so background independence - while nice from a mathematical point of view - may not be strictly necessary?
marcus said:hope its going well
Stevo said:Yeah, it's almost done. I've had to revise my plan a little, basically to keep within the word limit and to keep it more in line with the course content. It's more about the ontology of spacetime described in quantum gravity,...
A graviton is a hypothetical particle that is believed to carry the force of gravity. It is out of favor because there is currently no experimental evidence to support its existence.
The lack of evidence for gravitons does not significantly impact our understanding of gravity. The theory of general relativity, which describes gravity as the curvature of spacetime, has been successfully tested and used to make accurate predictions without the need for gravitons.
Yes, there are ongoing experiments and research related to gravitons. Some scientists are attempting to detect gravitons using high-energy particle colliders, while others are studying the effects of gravity on the smallest scales, such as in quantum mechanics.
It is possible that gravitons could be discovered in the future. As technology advances and our understanding of gravity deepens, new experiments and theories may provide evidence for their existence.
The concept of gravitons is a part of the larger field of particle physics, which studies the fundamental particles and forces that make up our universe. Gravitons are often studied in relation to other particles, such as the Higgs boson, in an effort to create a unified theory of all the fundamental forces.