Handy andy Posted June 21, 2017 Posted June 21, 2017 Could gravity be caused by virtual particles or virtual waves stretching space. https://profmattstrassler.com/articles-and-posts/particle-physics-basics/virtual-particles-what-are-they/ The above thought provoking link was kindly posted by Strange, would any one like to discuss the concept of gravity being caused by a virtual field or virtual particle, as opposed to a theoretical graviton that might not exist. When visualizing the graviton or how such a concept could work, to give the appearance of stretched space. I came up with the amusing idea off all space being full of gravitons which vibrate(spin) around atoms and are boiled off to be replaced with lower energy gravitons, effectively like vibrating sand, or like aerated water they are less buoyant, things will sink into it due to gravity. As was pointed out by Imatfaal I have no clue what a boson with spin 2 would look like, so the above visualisation may not apply to a graviton. I do however have a clear picture of a liquid full of waves off all shapes induced by vibrations and movements of real particles, (stable waves) and I can see how this would give the appearance of stretched space and gravity. Would any one care to discuss or add to this idea.
swansont Posted June 21, 2017 Posted June 21, 2017 Would any one care to discuss or add to this idea. You first. How is this testable? What evidence exists that supports this idea? Do you have a mathematical model? Anything that adheres to the guidelines?
Strange Posted June 21, 2017 Posted June 21, 2017 The above thought provoking link was kindly posted by Strange, would any one like to discuss the concept of gravity being caused by a virtual field or virtual particle, as opposed to a theoretical graviton that might not exist. If it is mediated by virtual particles, then that (virtual) particle would be the graviton. And, as far as I know, the field would still be space-time.
Mordred Posted June 21, 2017 Posted June 21, 2017 If it is mediated by virtual particles, then that (virtual) particle would be the graviton. And, as far as I know, the field would still be space-time. Correct, even if the graviton were discovered nothing would change in GR. Unless the graviton has unpredicted characteristics which is more unlikely now that we detected GW waves. (matched spin 2 statistics)
Handy andy Posted June 21, 2017 Author Posted June 21, 2017 Correct, even if the graviton were discovered nothing would change in GR. Unless the graviton has unpredicted characteristics which is more unlikely now that we detected GW waves. (matched spin 2 statistics) Is the graviton considered to be a virtual particle/field? How big can a virtual particle be? Can multiple atom sized virtual fields be lumped together and represented as one planet sized gravitational field as in GR perhaps? . Does a graviton moving away from a mass have increased energy (take up more space), compared with gravitons moving towards a mass? You first. How is this testable? What evidence exists that supports this idea? Do you have a mathematical model? Anything that adheres to the guidelines? I am trying to restrict myself to asking questions as suggested by Imatfaal, I think I am with in the guidelines in so doing, and restricting my line of questioning as suggested. I may have mistakenly posted in the speculations forum, instead of the physics forum, but since I generally wind up here, I thought this the best place to start. Regards a mathematical model I suspect the graviton may already cover this idea, but am seeking some clarification. ------------------------------------------------------------------------------------------------------------------- @ All What a graviton looks and moves like, and how it transmits the gravitational force is interesting to me. Does any one have any thoughts to add on the ideas above.
DrP Posted June 21, 2017 Posted June 21, 2017 How would anyone know? No-one has ever detected one... they are speculation and we do not even know they exist for certain. As for thoughts and ideas... that is way above my head with where we currently are in science. I would wait for the gravity wave people and the LHC lot to do more research and see what they come up with.... whether or not they will find something out in our lifetime though is uncertain.
swansont Posted June 21, 2017 Posted June 21, 2017 I am trying to restrict myself to asking questions This claim holds no water. Phrasing your post as questions does not shield you from the guidelines. "Could gravity be caused by virtual particles or virtual waves stretching space. " is a question, but it's also an assertion. You are explicitly excluding the graviton, and yet have no proposal of what virtual particle would take its place. "I came up with the amusing idea off all space being full of gravitons which vibrate(spin) around atoms and are boiled off to be replaced with lower energy gravitons, effectively like vibrating sand, or like aerated water they are less buoyant, things will sink into it due to gravity." is an assertion, not a question. If you're going to ask questions, then ask questions. But stop making assertions unless you are prepared to back them up.
Strange Posted June 21, 2017 Posted June 21, 2017 Is the graviton considered to be a virtual particle/field? Like all bosons, when it acts as a mediator of the force then it is a virtual particle. You could also have a "real" graviton (which is probably unstable and very short-lived). I assume the guys at the LHC are looking for signals that could be a graviton. But as we don't know what mass it might have, we don't know if it is feasible to find it (if it exists). How big can a virtual particle be? I don't think that question means anything. Virtual particles don't, as far as I know, have a size. And "real" particles have (or are modelled as) zero size. (The fundamental ones, anyway.) Can multiple atom sized virtual fields be lumped together and represented as one planet sized gravitational field as in GR perhaps? . Again, not sure if that make much sense. However, because gravitons are bosons (not fermions) any number of them can occupy the same space. Fields extend through all of space. And, arguably, so do particles until they are localised by interacting with something.
StringJunky Posted June 21, 2017 Posted June 21, 2017 (edited) Are gravitons visualised as tiny perturbations/excitations in the spacetime field as a means to try to quantise it? Edited June 21, 2017 by StringJunky
Strange Posted June 21, 2017 Posted June 21, 2017 Are gravitons visualised as tiny perturbations/excitations in the spacetime field as a means to try to quantise it? Or, perhaps, as quantizations of the excitations of the field (which would be caused by the presence of mass-energy.
StringJunky Posted June 21, 2017 Posted June 21, 2017 Or, perhaps, as quantizations of the excitations of the field (which would be caused by the presence of mass-energy. Right. Cheers.
Strange Posted June 21, 2017 Posted June 21, 2017 Right. Cheers. Don't thank me until someone who knows what they are talking about answers!
Mordred Posted June 21, 2017 Posted June 21, 2017 (edited) Your answers have been accurate thus far. Individual VP are not observable or measurable. So size has no meaning. I like to call them perturbations to distinquish from excitations. However that also has little meaning. Once you have a quantum of excitation/energy you are no longer dealing with a VP but a real particle. Theoretically the graviton should be the heaviest boson on the mass/energy relation via the full energy/momentum version of e=mc^2. Though the invariant mass via the last equation will be zero. Edited June 21, 2017 by Mordred
Handy andy Posted June 21, 2017 Author Posted June 21, 2017 (edited) Would those quantizations of the excitations of the field have different energy levels and directions of movement. ? Do Gravitons flow towards and away from masses, as has been mentioned in popular physics books.? Would this type of flow be regarded as a type of entropy in line with the 2nd law of thermodynamics.? "Once you have a quantum of excitation/energy you are no longer dealing with a VP but a real particle." How far can a virtual particle field extend due to a real particle or boson? Edit Is Quantum foam a more likely means of the cause of gravity https://en.wikipedia.org/wiki/Quantum_foam instead of graviton. ? Would quantum foam have a higher energy level nearer to a mass and again would this tend to flow as described above? Edit I was looking for anything on gravitational entropy theories and this popped up https://en.wikipedia.org/wiki/Entropic_gravity amongst other items I found related to the search. Does entropic gravity have any mileage as a theory based on virtual particles ? Edited June 21, 2017 by Handy andy
StringJunky Posted June 21, 2017 Posted June 21, 2017 Don't thank me until someone who knows what they are talking about answers! I know you aren't conversant in the this field but I appreciated the other angle you presented.
Mordred Posted June 21, 2017 Posted June 21, 2017 (edited) Well you definetely have a string of related questions lol. As to the first, all excitations that are definable as a particle must be under confinement. The confinement would be a quanta or greater in amplitude wirhin a coulomb wavelength as your boundary confinement. VP as far as I know hasn't got any meaningful confinement as we cannot measure a VP. Regardless of having a perfect detector or not, this will always be the case as it requires a quanta of action to influence a detector. Spin foam is rather tricky to describe accurately. However think of the term degrees of freedom. Ie every interaction is an additional degree of freedom. Now model each degree of freedom under a seperate geometry. Usually only require 2d ie Hilbert space. Then interconnect each geometry under a 4d geometry (embedded). So quantum foam can represent either just spacetime or the graviton as the effective degrees of freedom should match. However spin foam as it models interactions within spacetime under SU(2) which covers. SO(1.3) Lorentz/Poincare group. In a sense it is a GUT modelling approach via symmetries. Well here is a simplified example lecture. (not the greatest of articles but does describe the above) https://www.google.ca/url?sa=t&source=web&rct=j&url=http://www.icra.it/MG/mg12/talks_plenary/Freidel.pdf&ved=0ahUKEwjJkv2m4s_UAhWL6YMKHQKzB0YQFghDMAc&usg=AFQjCNE_2UFsPHqvSlnCcQW8ROVi4sYO9w I would have to review gravitational entropy to be of any use there. I hadn't studied that field in ages. I should add to better understand quantum field theory. Propogators are in essence your permutations of the field described as virtual particles. Operators are when the particles are real ie field excitations. Here is an article on Graviton propogators. Ie vector gauge boson (VP). https://www.google.ca/url?sa=t&source=web&rct=j&url=http://www.icra.it/MG/mg12/talks_plenary/Freidel.pdf&ved=0ahUKEwjJkv2m4s_UAhWL6YMKHQKzB0YQFghDMAc&usg=AFQjCNE_2UFsPHqvSlnCcQW8ROVi4sYO9w The rules for the above takes cobsiderable time to understand. The distinctions between propogators vs operators are part of the S-matrix. Which defines your Feynman diagrams. Operstors are external lines with propogators being the internal squiggly lines. The Graviton as a vector gauge boson would be internal. Edited June 21, 2017 by Mordred
MigL Posted June 21, 2017 Posted June 21, 2017 Just to be clear... ( or at least, as I understand things ) You are better off considering the interaction as due to a field, which in the case of gravity, would be space-time geometry. This is a 'classical' view, however. And it so happens that when you quantize a field ( any field ! ), quantum field theory dictates the existence of mediator bosons, or excitations of this quantum field. Certain properties of the field ,then, dictate the properties of this mediator boson ( spin and mass/energy ), which has been named the graviton. Now, although we haven't been able to quantize the gravitational field yet, we can do an end run around the problem, and look for particles with that spin and mass/energy; and, if they are found, it would be confirmation that gravity CAN be quantized. Although I'm not sure if the LHC can achieve the kind of energies that would manifest gravitons. I assume they'd be pretty heavy. 2
Mordred Posted June 21, 2017 Posted June 21, 2017 (edited) Excellent summary of quantum field theory in general. You also accurately described the problem with detection. It is predicted to be the "heaviest boson ". Under SU(2) spin foam in this case this corresponds to your Pauli matrixes. All standard model particles fall under the Gell-Mann matrixes which has 8 generator matrixes.(Google eightfold Wayen) As opposed to the 3 generator matrixes (Pauli). Just an aside on those articles. Edited June 22, 2017 by Mordred
imatfaal Posted June 22, 2017 Posted June 22, 2017 On the detection side - gravitons have a very low cross section of interaction with matter; they make neutrinos look interactive; they are also stable so there is no possibility of detecting specific and characteristic decay cascades. Really difficult to spot them. About 30 orders of magnitude harder to spot than photons at the energy of the LHC - this is bearing in mind that LHC detects real particles - not virtuals. and they are massless
MigL Posted June 22, 2017 Posted June 22, 2017 Sorry, I tend to use mass/energy for eV ( probably GeV for gravitons ) even though they are massless. ( they would have to be or gravity wouldn't have infinite range ) I was never any good at remembering proper terminology.
dimreepr Posted June 22, 2017 Posted June 22, 2017 At the risk of displaying my density; what's the difference between the higgs boson and the graviton boson?
swansont Posted June 22, 2017 Posted June 22, 2017 At the risk of displaying my density; what's the difference between the higgs boson and the graviton boson? How they interact, for one. I don't know what a graviton interaction looks like in a Feynman diagram, but they would be different. Gravitons would be spin-2, while the Higgs is spin-0. Gravitons will be massless, since the interaction has an infinite range.
Mordred Posted June 22, 2017 Posted June 22, 2017 (edited) How they interact, for one. I don't know what a graviton interaction looks like in a Feynman diagram, but they would be different. Gravitons would be spin-2, while the Higgs is spin-0. Gravitons will be massless, since the interaction has an infinite range. An internal wavy sinusiodal line denoting it is its own antiparticle. Length will vary on the spacetime aspects. On representation essentially identical to photon. Edited June 22, 2017 by Mordred
Handy andy Posted June 22, 2017 Author Posted June 22, 2017 (edited) Well you definetely have a string of related questions lol. As to the first, all excitations that are definable as a particle must be under confinement. The confinement would be a quanta or greater in amplitude wirhin a coulomb wavelength as your boundary confinement. VP as far as I know hasn't got any meaningful confinement as we cannot measure a VP. Regardless of having a perfect detector or not, this will always be the case as it requires a quanta of action to influence a detector. Spin foam is rather tricky to describe accurately. However think of the term degrees of freedom. Ie every interaction is an additional degree of freedom. Now model each degree of freedom under a seperate geometry. Usually only require 2d ie Hilbert space. Then interconnect each geometry under a 4d geometry (embedded). So quantum foam can represent either just spacetime or the graviton as the effective degrees of freedom should match. However spin foam as it models interactions within spacetime under SU(2) which covers. SO(1.3) Lorentz/Poincare group. In a sense it is a GUT modelling approach via symmetries. Well here is a simplified example lecture. (not the greatest of articles but does describe the above) https://www.google.ca/url?sa=t&source=web&rct=j&url=http://www.icra.it/MG/mg12/talks_plenary/Freidel.pdf&ved=0ahUKEwjJkv2m4s_UAhWL6YMKHQKzB0YQFghDMAc&usg=AFQjCNE_2UFsPHqvSlnCcQW8ROVi4sYO9w I would have to review gravitational entropy to be of any use there. I hadn't studied that field in ages. I should add to better understand quantum field theory. Propogators are in essence your permutations of the field described as virtual particles. Operators are when the particles are real ie field excitations. Here is an article on Graviton propogators. Ie vector gauge boson (VP). https://www.google.ca/url?sa=t&source=web&rct=j&url=http://www.icra.it/MG/mg12/talks_plenary/Freidel.pdf&ved=0ahUKEwjJkv2m4s_UAhWL6YMKHQKzB0YQFghDMAc&usg=AFQjCNE_2UFsPHqvSlnCcQW8ROVi4sYO9w The rules for the above takes cobsiderable time to understand. The distinctions between propogators vs operators are part of the S-matrix. Which defines your Feynman diagrams. Operstors are external lines with propogators being the internal squiggly lines. The Graviton as a vector gauge boson would be internal. Thanks for the answers (the links you posted are identical is there something else you meant to post). I can see how it takes a considerable time to understand, I will be reading the link several times following down every term, which I am not familiar with, of which there are many. You stated above " So quantum foam can represent either just spacetime or the graviton" are you saying that the graviton and quantum foam are one and the same thing or just very similar concepts, modelled with different bounderies.? Can both quantum foam and gravitons being virtual particles not having meaningful dimensions or detectable mass, exist at the plank length but equally be described as having a infinite range. Can both could be viewed as excitations of a single field or multiple excitations of minute interlinked fields extending to infinity giving the appearance of one field.? I understand that GR represents space time as a smooth substance which once you zoom in it is not. I understand there is a lot of work going on with various theories, some of which are more valid than others, all of which seem to be lumped parameter. Which route do you think most represents the real world and what is actually happening to give the appearance of stretched space.? Does the concept of Gravitational entropy explain the movement of miniscule virtual particles, quantum foam or gravitons? . An internal wavy sinusiodal line denoting it is its own antiparticle. Length will vary on the spacetime aspects. On representation essentially identical to photon. Is the graviton just a mathematical construct, A photon is a single packet of energy or field is it not?. I tend to view it as a pipe spinning through space, is this wrong? Excellent summary of quantum field theory in general. You also accurately described the problem with detection. It is predicted to be the "heaviest boson ". Under SU(2) spin foam in this case this corresponds to your Pauli matrixes. All standard model particles fall under the Gell-Mann matrixes which has 8 generator matrixes.(Google eightfold Wayen) As opposed to the 3 generator matrixes (Pauli). Just an aside on those articles. On the detection side - gravitons have a very low cross section of interaction with matter; they make neutrinos look interactive; they are also stable so there is no possibility of detecting specific and characteristic decay cascades. Really difficult to spot them. About 30 orders of magnitude harder to spot than photons at the energy of the LHC - this is bearing in mind that LHC detects real particles - not virtuals. and they are massless I am easily confused how can a graviton be the "heaviest boson", and massless.? Thanks all for the answers, Edited June 22, 2017 by Handy andy
Mordred Posted June 22, 2017 Posted June 22, 2017 (edited) Spin foam is a different approach to model spacetime. Which invariably can also be used to model the graviton. The approach on Spinfoam arises from looking at the quantum number wavefunctions such as spin etc. When looking at total mass you have the rest mass+ inertia mass. E=mc^2 is just the rest or invariant mass. However inertia also adds to the mass total. Due to be relativistic ie c, and the effective degrees of freedom ie spin 2. The graviton will be heavy. As mentioned before the way to visualize any particle is simply an excitation. Particles do not have corpuscular (solid like) structure. An excitation is a field dynamic. And no what I posted I meant to say, I usually prefer to add supportive material so no one has to take my word on any topic. Edited June 22, 2017 by Mordred
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