As per quantum field theory each field has its own quantum. Examples electron, photon, phonon etc. After evidence of gravity waves its quantum graviton also exists. Is there any evidence or any thought experiments?
Dear Rasbindu,
In the "Standard Model" of particles, each of the 4 fundamental forces is mediated by bosons (obeying Bose-Einstein statistics). These bosons are :
- For the electro-magnetic force (or interaction) : the photon
- For the weak interaction : the 3 bosons W+, W - and Z0
- For the strong interaction : the 8 gluons
- For gravitation : the graviton
Thus a total of 13 bosons, but only for 12 of them their existence has been experimentally confirmed. The existence of the graviton is not confirmed (yet ?). The recent detection of gravitational waves by LIGO could bring some indirect information about the hypothesized graviton (mass ?...). But, for the present we have no confirmation of its existence.
The problem is also that the performant theory for gravitation is Einstein's GR (General Relativity) which has nothing to do with the "Standard Model". In GR, there are no particles, no interaction or force, no mediating bosons. Gravitational phenomena are due to curvature of space-time. GR is said to be "background independent" while the "Standard Model" is "background dependent".
Therefore the present efforts to conciliate both theories in a most fundamental theory of quantum gravity. See : Strings Theory, Loop Quantum Gravity, etc.
I suggest you to check the following link in Wikipedia where yo will find additional comments and good references.
https://en.wikipedia.org/wiki/Graviton
It is difficult to know (the details of) how theoretical predictions of black hole Physics are tested by a recent observation of gravitational waves (by LIGO experiment) emitted when a binary black hole system collapsed and became a single black hole. Eventually the signal is coming from a source which is 1.3 billion light years away.
Following remarks made by Prof. Stephen Hawking in a TV interview on (16th Feb 2016) may be of your interest. I have collected these information from the web page of Discovery channel.
Dear Rasbindu!
In my opinion the "Graviton" is a theoretically concept.
We don't know the fundamental and common properties of all particles. Can it be right to invent particles to explain observations and phenomena of the objective reality? This primary theoretical solutions are determining developments and evaluations of experiments, moreover the thougts of the scientists in particular like Hawkins.
Regards!
Hans
Dear Ales Kralj,
Thanks for your answer. Is the measurements of radiation pressure not direct proof of force exerted by photons? Classically this is well explained.
One thing are gravitation waves and another very different gravitons which assumed to have a quantum theory for the gravitational, as QED for electrodynamics. Let us try to show a simple analogy for seeing the difficulties involved.
If you put one electron and a proton at 1m of distance, their gravitational force is around 10^(-67) N while its electromagnetic attraction will be 10^(-28) N, that is to say, the electromagnetic is 39 times order of magnitude higher than their gravitational. Now suppose that you have photons and gravitons in between. As particles with zero rest mass their energy is given by E=h nu and momentum P=h/ lambda. Could you imagine the frequency and wavelength of those gravitons?
Philadelphia, PA
Dear Mehta,
The oscillation of a charge produces electromagnetic radiation, and the concept of gravitational radiation is analogous: accelerating masses emit gravitational radiation, though in most cases, and with small masses, this is negligible. It takes the acceleration of gigantic masses to produce detectable gravitational radiation.
The hypothesis of gravitons does not really belong to the standard model of particle physics --which does not include gravity. Instead it belongs to proposals to extend the standard model to include gravitation. These proposals are much more speculative than the standard model. While gravitational waves were strongly and confidently predicted as a large-scale implication of Einstein's theory of general relativity, the concept of the graviton, as the supposed carrier of the gravitational force, is much more problematic, since this concerns extremely small scale phenomena, at or near the Planck length, and falls into the domain of proposals for theories of quantum gravity. Gravitational waves are an implication of GR, gravitons not.
In any case, if one follows the proposals for gravitons (Freeman Dyson, e.g., has expressed strong doubts that they could ever be detected), then they would arise as the quantum of the gravitational field in correspondence with gravitational waves. But see Dyson's doubts:
https://publications.ias.edu/sites/default/files/poincare2012.pdf
There is also a video by Dyson presenting this paper and available on line.
https://www.youtube.com/watch?v=l-FSFtoeagc
Incredible! A man of 90 years.
H.G. Callaway
Also, see:
If black holes are out of contact in light waves and gravitational waves, how could two of them pull on each other in LIGO's close binary system? - ResearchGate. Available from: https://www.researchgate.net/post/If_black_holes_are_out_of_contact_in_light_waves_and_gravitational_waves_how_could_two_of_them_pull_on_each_other_in_LIGOs_close_binary_system [accessed Mar 16, 2016].
A few remarks about the role of gravitons in GEM.
In the framework of the gravito-electromagnetic (GEM) description of gravitation, the “gravitational field” is introduced as the medium that plays an intermediary role in the gravitational interaction between (whether or not moving) masses. It is, just as the electromagnetic field (EM), defined by two three-dimensional intertwined vector fields: the “g-field” Eg and the “g-induction” Bg. And it is mathematically described by a set of four partial differential equations, the “GEM-equations” (or the “Maxwell-Heaviside equations”) that are formal analogue to, and play the same role as Maxwell’s equations in the case of an EM field: the GEM equations describe how Eg and Bg vary in space due to their sources - the masses and the mass flows - and how they are intertwined.
It can be shown that the existence of gravitational waves is embedded in the GEM equations and that a gravitational wave can deliver energy to a body on which it falls. By analogy with the role and the nature of the photon in EM, in the framework of GEM it is assumed that the energy in a gravitational wave travels through space in concentrated bundles, called “gravitons”. It follows that an oscillating electrically charged point mass is an emitter of both photons and gravitons. Comparing their energies in the case they are emitted by a proton, leads to the conclusion that the ratio of the energy of a photon to that of a graviton should be of the order of magnitude of 1036.
Let us still remark that in GEM gravitons are not associated with gravitational interactions between material objects. According to GEM, gravitational interactions are the effect of the tendency of a material object to accelerate in order to become blind for the gravitational fields generated by other objects. The action of the gravitational field on a point mass is described by the “force law of GEM”, a law analog to Lorentz force law in EM.
Here is a follow up that i'm pretty sure is naive, but here goes. I never liked the idea of gravitons until i had this thought. As the universe expands the cosmic background radiation loses energy. If you believe in energy conservation, this energy has to go somewhere. Maybe into the increase in gravitational potential energy as the universe expands? If so, since photons are quantum particles, they have to lose energy by a quantum process. Could that process not involve gravitons?
Well, E = hf, so you are saying no energy is lost when f is less? Are more photons then being somehow created?
“Graviton is it a concept or reality?
- there is no any evidence that isn’t so; and “…Gravity is thought as a property of space and not as force...” isn’t, of course, an argument – the Matter’s 3D space hasn’t any properties besides the property to be empty and so to be the 3D component of 4D “empty container” – 4D Matter’s spacetime. This spacetime is so “absolute” and cannot be “curved”, etc. as that the GR claims.
Thus the gravity very probably is a “usual” force, moreover – it seems something as is rather similar to the EM force. For example – if two bodies having masses m1 and m2 are on some spatial distance and these bodies are electrically charged by charges q1 and q2 so, that the gravitational attraction is equal to the electrical repulsing, such system will be in a balance independently on – what is the distance between bodies and at any spatial speed of the system.
So since the quantum nature of the EM force is well known, is seems quite natural to suggest that the gravity force is quantized as well.
At that indeed it “…force between the two electrically charged masses that is modelled with "virtual" photon exchange that has no direct observational proof of photons being actually exchanged…”. – in contrast to the events when “usual”, i.e. “non-virtual” photons interact with charges, say, at photo effect.
Such situation rather possibly occurs because of in the reality there are two types of photons - “usual photons” that live and move in the 3D space as some singled out particles and “circular photons” that are non-virtual and constantly are radiated by charges as some components of electrostatic field – see https://www.researchgate.net/publication/273777630_The_Informational_Conception_and_Basic_Physics)
In this case it is rather probable that gravitational mass is a “gravitational charge” that radiate constantly “circular gravitons”.
That is a next problem - there exist or not “usual gravitons” as analogs of “usual photons”, and how they move in the space and interact with matter.
In physics now there is no experimental data that could indicate on the gravitons’ existence, first of all – because of that this force is extremely small. But just by this reason in this case it is possible to detect possible “circulating gravitons” (an so indirectly - “circular photons”) when particles with low enough masses move in a gravistatic field. Such particles are known and widely used in practice, namely – photons.
Though the GR claims that photons are “massless” and don’t interact with the gravity, that is a next wrong GR claim, in the reality they change their energy/frequency at motion in gravity fields. If a time/ distance when photons interact with, say, Earth’s gravity is small enough, then after this distance an monochromatic photons’ beam will obtain some random spectrum’s distortion, what can be detected yet now – see https://www.researchgate.net/publication/215526868_The_informational_model_-_possible_tests ), the section 2.1.2. “Monochromatic photon beam distortion”.
Such experiment can be made at using any installation that were made aimed at detection of the “gravitational waves”, it is enough to use arms with 300-400 m length, and besides, to build additional vertical arm, e.g. in a hole; thus all seems would be cost no more 50-100 $millions…
Cheers
Article The informational model - possible tests
Article The Informational Conception and Basic Physics
Graviton is a forced concept. There's a place for it in the standard model, so it must exist.
In my work I show how quantum gravity doesn't need at all the existence of gravitons. We need quantum space and its dynamics.
I am sure that the free place in the standard model will be occupied by the quantum of space. Not by the graviton.
Article A superfluid Theory of Everything? [outdated version]
Probably you can lead back the gravity on the electromagnetic force like one of the great scientists of the past tried. But it seems there is no place for reality in the theoretically described world by physics.
There is a possibility.
Electromagnetic force acts between different charged matter/bodys/objects/masses. In my opinion is the question how must be the state or quality of the matter resp. mass to have or to show gravity. This means, matter shows not automatically gravity like the theories implies. Or has someone measured the gravitational force between neutrons or other particles? The gravitational constant is obvious depending on the material. ...
OK, is conservation of energy real or not? Doesn't the gravitational potential energy increase due to a photon moving away from a gravitating body as is the case with a massive body? I know this is Newtonian, but Newton gravity is the weak field version of general relativity. But then, E =mc2.
It has long been known that Einstein’s General Relativity has wave-like solutions (perturbations of a curved space - like ripples on a pond − that travel with the speed of light). The experimental verification of this prediction is a great achievement but it tells us nothing we didn’t already expect. The underlying theory is strictly classical − it tells us nothing at all about quantum theory or whether “gravitons” exist.
I'm not sure gravity waves have to travel at the speed of light. I have come up with a wave solution of the field equations where the speed is not determined. However, i'm not sure if it is physical or not\, but at least it satisfied the field equations.
In the framework of iSpace (integer Space) theory it is possible to calculate the exact symbolic (and hence infinite precision or predicted) value of over 50 constants of nature by using the somewhat rarely seen concept of a changed distance definition, a very small "magic" prime number (6961) and the Golden-Ratio to determine e, h, KJ, alpha, me, R and many more (please see my RG papers for details) and - most important - G and alpha-G, both of which are based on the Quantum of Gravitation and the following *extremely* simple relation of Newtonian gravitational constant G to Fg (please see also the work of John A. Macken who is also on RG and initially derived the crucial relation Fg/FE=FE/FP the iSpace Fg is based on). So long story short, the value (mantissa) of (iSpace) Fg is basically based on 3/c^4 (!). The resulting gravitational force quantum Fg is about 3.71*10^-46N (but calculable with arbitrary precision).
Why should this be physically correct - and not just some numerological number?
Well, that is easy to see following my NEW extremely simple and easy to verify relation of Fg to G, with a0 is Bohr radius, re is classical electron radius, me the electron mass and alpha the fine structure constant and Pi3 = 3 (hexagonal iSpace Pi3 circular number):
G = Fg * (a0 * re / me^2)
Fg = G * (alpha * me / re)^2
but also (from iSpace theory)
Fg = 1/2 * (2*Pi3*1/(299792458*1000)^4 [Volt Ampere Second Meter^-1] or [Newton]
Welcome to the wonderful and seemingly crazy (simple) theory of iSpace (geometry)!
https://www.researchgate.net/profile/Christian_Wolf20
https://www.researchgate.net/profile/John_Macken
Conference Paper iSpace - Exact Symbolic Equations for Important Physical Con...
Conference Paper iSpace - Deriving G from α, e, R∞, μ0 and Quantum of Gravita...
We have not evidence about gravitational waves, statistics with sample N=1 is not statistics.
Besides that there exist many experimental gray zones, see linked article for a first review.
Additionally I agree with Francis Redfern above, since speed of the alleged 'gravitational waves' depends on the choice of reference frame, see work of S. Crothers here for math details:
http://vixra.org/abs/1603.0127
(Unfortunately no formal journal accepts such works for publishing)
Data A first critical review of event GW150914 observed by LIGO d...
“…I have come up with a wave solution of the field equations where the speed is not determined…”
Paul Gerber, who correctly estimated the Mercury perihelion shift in 1902 (his result Einstein repeated in 1916 by using GR), in his calculations used the free parameter – the speed of gravity interaction propagation in the 3D space, VG, and obtained that to obtain the consistent with the experiment value, for this speed is necessary to be VG =305 000 km/s…
Cheers
Sergey, i don't know if my solution is physically real. Although it satisfies the field equations, it is a longitudinal wave and that gives me some heartburn. Maybe what i've found is a coordinate wave, but i'm not to the point yet where i can check that out. Also, the results of linear approximation to GR implies gravitational waves travel at the speed of light. I really think i should leave these questions to someone more versed than myself. :-) After all, the "add your answer" box says i should identify myself as an expert on GR. Well, i'm not!
What is "concept" and what is "reality"? IMHO, the former is synonymous with "theory" and the latter with "experimental fact". Gravitational waves were a concept till very recently. Gravitons surely remain a concept.
UNIFICATION of GRAVITATION and ELECTROMAGNETISM
I unified at Quantum level, Electromagnetism and Gravitation with Ferent equation for the energy of a photon:
E = h × f + a × f
Ferent equation for photon – graviton interaction:
E = h × f + a × f - a × ν
where - a × ν is the negative energy of the graviton
ν is the frequency of the graviton
“I am the first who understood and explained Gravitation with high speed gravitons v = 1.001762 × 10^17 m/s, with Negative Momentum, Negative Mass and Negative Energy” Adrian Ferent
https://www.researchgate.net/publication/299135595_Ferent_Gravitation_theory
Article Ferent Gravitation theory
Dear Eric,
It is with much trepidation i attach this derivation of a longitudinal gravitational wave. I'm sure there is some problem with it. For example, it may only be a coordinate wave. But, you asked for it, so here it is.
Planck’s constant h is a universal constant associated with exchange of energy between electromagnetic radiation and matter (ie, charged particles). This experimental observation (black body spectrum and photo-electric effect) led Einstein to propose that an electromagnetic wave can be conceived of as a stream of particles called “photons”. That concept is now a well-established foundation stone of quantum theory. By analogy, it may be that gravitational radiation also exchanges energy with matter in discrete units E = hGν. If that is so, is there any reason to jump to the conclusion that hG = h?
“… Planck’s constant h is a universal constant associated with exchange of energy between electromagnetic radiation and matter…”
- the Planck constant, h (seems more precisely – h-bar), is one of utmost fundamental constants in Matter (with Planck length and Planck time) that is equal to elementary unities of the [physical] action and the angular momentum. Just therefore it is the unity not only for the EM radiation; when any other force – weak, strong - act in a concrete system, then any change in the system’s energy state or angular momentum are aliquot to the h-bar. There is no any prerequisites to claim that the gravity force is some exclusion; besides, of course, if somebody believes that the gravity force doesn’t exist and material bodies' motion is determined by the “spacetime curvature”…
Cheers
Experiments to test Ferent Gravitation theory!
In the double slit experiment the interacting observer is an instrument, detector…
My experiment is: if you replace the detector with a piece of metal the wave will collapse into a particle because of my theory photon – graviton interaction:
Ferent equation for photon – graviton interaction:
E = h × f + a × f - a × ν
where - a × ν is the negative energy of the graviton
ν is the frequency of the graviton
Here we know the frequency of the photon f and the frequency of the graviton f. With different metals we have different frequencies of the graviton ν.
A lot of experiments can be done, and will result a lot of data!
Ferent gravitation theory explains the double slit experiment!
https://www.researchgate.net/publication/299135595_Ferent_Gravitation_theory
You can read on my theory:
Decoherence explained by my theory
The electromagnetic wave is the superposition of 3 sinusoids; this means the electromagnetic wave will be collapsed by the presence of an electric field, of a magnetic field, of a gravitational field, by another electromagnetic wave…
In my electromagnetic theory, gravity does collapse quantum superpositions, gravity bends light because light has 3 sinusoids, has a gravitational sinusoid!
In Maxwell electromagnetic theory, gravity does not collapse quantum superpositions, gravity does not bend light, because light has only 2 sinusoids!
So decoherence is due to the gravitational field, for example to the gravitational waves generated by the observer in the double-slit experiment.
Article Ferent Gravitation theory
Sergey ~
Thank you for your response. Your reminding me that intrinsic angular momentum is in integral multiples of hbar = h/2π (or hbar/3 in the case of quarks) removed my doubts; the intrinsic angular momentum of gravitons (if they exist) should then be 2hbar, thus confirming the universality of Planck’s constant.
Dear Eric,
Are you speaking about the twistor eigenvalues for their fields in the space
SU(2,2)/[SU(2,1)xU(1)]
The main problem, from my humble point of view, is that the energy given by such quantums must be so small that it cannot give information of the the interaction. Over all if you compare it with the rest of interactions as electromagnetic which shares also to have one boson of rest mass zero (long range interaction). Taking metrics with 8 real numbers or 4 complex ones is a beautiful form to increase the possibilities to implement more symmetries as the conformal one and therefore to obtain Weyl spinors as physical representations.
In any case, this was one of the candidates to quantum gravity formalism by itself, but very far of the rest of interactions which were so well quantized within gauge theories.
“…The main problem, from my humble point of view, is that the energy given by such quantums must be so small that it cannot give information of the interaction..."
- that isn’t so (of course not relating to the “twistor eigenvalues”). A possible gravitons’ interactions with extremely small gravitational masses with rather large probability are observable – see the experiment
when such masses, i.e. photons [that have evidently inertial and gravitational masses] interact with Earth gravity field,
suggested yet in 2007 (see the link in the SS post on 2-th page here (the section 2.1.2. “Monochromatic photon beam distortion”.)
When in this case, if one understands the importance of such experiment, seems necessary 50-100 $millions that ere necessary to make it, are rather reasonable and acceptable cost; especially comparing with [having be made and be making] experiments aimed at the GR testing…
Cheers
Sergey,
Photons have no inertia, their state of motion cannot be accelerated at all.
Daniel,
“…Photons have no inertia, their state of motion cannot be accelerated at all…”
-? “Inertia is the resistance of any physical object to any change in its state of motion (this includes changes to its speed, direction or state of rest). It is the tendency of objects to keep moving in a straight line at constant velocity.” https://en.wikipedia.org/wiki/Inertia
- to change “a straight line motion” of any photon is necessary to act on the photon by some force, and, for example photons are reflected from a mirror just as a billiard balls are reflected from a billiard table board. And if, say, among of billiards balls there is one ball, which is made 50/50 from matter and antimatter, then a mud balance will be in the balance if on the mud balance’s bowls are an usual ball and the 50/50 ball; and any billiard player will not distinguish these balls at a game. If the 50/50 mix annihilate and transforms into photons, again a mud balance will be in the balance and the billiard player will not distinguish the balls.
So – see again the SS post on 4 page, pages in this thread are so short…
Cheers
Dear Sergey,
The rest mass of the photon is zero, isn't? Then if you use Lorentz transformations, you will go to obtain always zero, isn't? Where is then the mass obtained for the photon. The wikipedia didn't refers to rest mass particles as the photon.
Daniel ~
A photon has no rest mass (it’s never at rest!) but it has energy and momentum and therefore an effective mass (relativistic mass) can be defined. The momentum p, energy E and rest mass m of a particle are related through E2/c2 – p2 = m2c2. For a photon (m = 0) this gives E = |p|c. The “effective” mass is m′ where E = m′c2 and |p| = m′c.
The Lorentz transformation acts on momentum p and energy E.
Dear Daniel,
the physical values/ notions that characterize material objects (particles, bodies, etc.; further- particles), i.e., - “rest mass”, “inertial mass” and “gravitational mass ” are quite different notions.
Inertial mass characterize the value of some impact (force, momentum) that is necessary to change a particle’ motion (change the speed and/or the direction); the gravitational mass is the charge of the gravity force. Both masses are fundamental in Matter.
The “rest mass” is neither first nor the second, it is only a consequence from that in Matter there are two types of particles – “T-particles” and “S-particles”, which are created by two principally different momentums at [other] particles interactions: T-particles are created by momentums that are directed along 1D t-axis (so all T-particles are fermions; neutrinos have rest masses since they are fermions ), X-particles are created by purely 3D spatially directed momentums, and so they are bosons (here only fundamental particles - seems only forces mediators, at least for EM and G forces; say, mesons are T-bosons).
All particles move in the [5]4D Matter’s spacetime with identical by absolute value 4D speeds “c” [vector] having momentums P=mc, and energy E=mc2 where m is the inertial mass.
T-particles at 3D spatial rest move in the time only having 1D P0=m0ct and just m0 is called the “rest mass”, but they can move (and seems all always move), after obtaining a spatial (what is practically always in macrophysics) momentum 3D PX, in the 3D space also; and so, since the t-axis is orthogonal to any spatial direction, the value P0 cannot be changed, thus total 4D momentum P=P0+PX=mc, where m is the “relativistic [again inertial] mass” as that Pythagoras prescribed.
X-particles move evidently in the 3D space only so have always 3D spatial speed always be equal to c, having 3D P=hnucX/c2 and E=hnu. Nonetheless X-particles have the inertial mass m= hnu/c2; and havn't the "rest mass" only since they cannot be at a spatial rest.
Moreover, any particle is a 4D "wave" and for any particle is true that P=hnuc/c2 and E=hnu, simply for X-particles this fact is more observable.
As well as all particles are charged by a gravitational masses, which in the statics are equal/ equivalent to the inertial masses.
More see https://www.researchgate.net/publication/273777630_The_Informational_Conception_and_Basic_Physics
Cheers
Article The Informational Conception and Basic Physics
Graviton seems to be more concept and less reality. However, more research required to come to the final conclusion.
Dear Eric,
I don't know what the effective mass is. The mass is defined by (as you know very well)
m=gamma. mo
where gamma is (1-v2/c2)-1/2. Where v is the relative velocity with respect to one inertial observer and mo its rest mass. Thus independently of other subtleties, if mo is zero it means that it mass be zero for other inertial observer that you want or in other words, the mass of the photon is always zero for every observer.
Dear Daniel ~
As you correctly point out, an "effective mass" m can't be obtained from the formula m = gamma.m0 when m0 = 0. But the formula doesn't tell us m is zero, it says only that m is undetermined (m = 0/0 because gamma is infinite when v = c). But an "effective" m can be defined in an alternative way. Because a photon has energy E (=hf) and m can be defined from E = mc2, it is legitimate to say "the mass of a photon for any observer" is not zero, it is m = E/c2 = hf/c2.
I don't claim that this m is a particularly useful concept, only that it can be defined, that's all I was pointing out.
The terminology is all a bit illogical anyway. Why do physicists say the "rest mass" of a photon is zero? That doesn't make sense because a photon is never "at rest" with respect to any observer! i suppose it doesn't matter what people "call" things, so long as they know what's meant (-;
The formula E=mc^2 doesn't apply to the photon which has rest mass zero. I am not going to enter in the indeterminacy which could make very difficult the discussion. But it is well accept that the photon is without mass. Notice that the mass measures the opposition of the change of motion for one body and for the photon this is non sense.
Dear Eric,
Sorry, I forgot to answer one of your questions.
Rest mass zero means that the photon cannot exist at rest, i.e. its energy in such state is zero or its momentum.
Dear Sergey,
I am very sorry but I cannot answer you because I do not understand what you want to say. Is original the classification of S and T particles? What is that?
Dear Daniel ~
”The formula E = mc2 doesn't apply to the photon…”
Please pay more attention to what I said. It does apply!
The formula E = m0c2 refers to a particle at rest. That formula, obviously, cannot be applied to a photon! For a particle moving relative to an observer, the observed energy is E = mc2 where m not the rest mass m0, it is is the “effective mass” (ie., "relativistic mass" or "observed mass"). That is the definition of “effective mass”. A photon has energy. Therefore its effective mass is E/c2.
SR reveals that mass and energy are the same thing. (The factor c2 is a conversion factor between the units in which physicists express energies and masses, just as c converts between measurements of lengths and times. We could choose the units so that c = 1. This is often done…)
Dear Charles ~
I'm not "advocating" anything!
"Relativistic mass" (which I've been calling "effective" mass) is well-known terminology encountered in all elementary textbooks on Relativity. It's not my invention! I'm just pointing out that it can be applied to photons; I'm not saying that I think any of this is a good idea or that it implies anything!
Understanding physical concepts and playing with words (or formulae) are not the same thing, as you know full well... (-;
Charles, the gamma factor has to do with motion, not gravitation. However, the fact that it doesn't might be a good argument against gravitational mass being gamma times rest mass. Maybe philosophically it makes more sense to tie gamma to relativistic momentum, which is gamma times Newtonian momentum.
Dear Eric,
Let me to go to your definition of effectiv mass and accept it ( I must say that I never found it even teaching these things for a long time). If mass is given by
m= hf/c^2
there are at leat two problems:
1. Experimentally the mass is measured (even what could be called in dynamic situations as your formula suggests) and there is a limit
m
The issue of "mass" is different for fermions (matter particles) and bosons (field carriers in the usual terminology). For fermions we shall acknowledge that they have kinematic characteristics which are independant of any observer (like their proper time). It is represented by a spinor, which is a geometric quantity. As a vector, it does not depend on the frame in which it is measured, but its measure depends on the frame. With a metric this vector has a length which is a scalar which can be related to the mass. So the mass is defined as a constant scalar, but the definition is somewhat conventional. For instance the sign of the mass of an antiparticle is arbitrary.
For boson the problem is different. We know for sure that bosons show kinematic properties (they transfer momentum) and interact with charged particles (the Compton effect). The mass of a boson is linked to its momentum, but actually this is the momentum which has a physical meaning. One can associate a spinor to a boson, and the same computation as for fermion leads to a scalar, which can represent the mass, and is null for a boson moving at the speed of light. So the mass of the photon and a graviton is null, but not so for the other bosons (actually we know little about the strong and weak fields).
If we keep the same representation for the graviton as for the other bosons, a graviton should act through a momentum, that is by its inertia, and trough a gravitational charge, which is the mass. This leads to a more complicated picture, in which gravitation is involved two folds. I have my view on this subject (bosons as discontinuities of a field), which leads to a satisfying picture, but of course it is speculative for gravitons. However, because they have never been observed, it is good to have some theories on the subject, even speculative.
Charles and Daniel ~
I have said nothing that goes beyond what is implicit in standard conventional Relativity. I see nothing controversial in the statement that a photon has an "effective mass". It's synonymous with the statement that it has energy.
So I am taken aback by your reactions!
Much of the the nomenclature of physics is baggage that has come to us from the way the subject developed historically.
Physical units of length and time can be chosen so that the “speed of light in a vacuum” is unity (as is frequently done to simplify typography, and is done routinely by astronomers whenever they refer to “light years”…).
"Energy" and "mass" are then seen to be simply different words for the same thing. It then follows that we could throw out the word “mass” and refer only to “energy-momentum” − a property of a system consisting of a particle and an observer, satisfying E2 − p2 = 0 for a photon and E2 − p2 = E02 for a particle with a “rest energy” E0 (the energy associated with an "particle-observer system" for which p = 0).
Charles, the energy tensor for dust is rest density times the outer product of the 4 velocity vector with itself. That's where the gamma squared comes from. The moving dust gets one gamma from its speed and another from length contraction, which is why there is a gamma squared. Since energy contributes to gravity, maybe this is what you are referring to, but i don't see any reason to differentiate between gravitational and inertial mass. Perhaps i'm misunderstanding you.
Dear Eric,
The problem is only one: the kinetic energy has no rest mass by definition and the photons are only kinetic particles (no dynamical particles involving forces from the relativistic point of view). But if you want to compatibilize this macroscopic aspects with the ones of quantum field theory (QFT), where the mass appears as constant for every particle, and there is an additional field (Higgs field) to the one of QFT following a certain gauge symmetry (which provides the conservation of sources).
Introducing the coupling term of the above fields in the action, depending of the value of such value it is possible to find the dressed masses of the particles of the fields. Thus we have the mass as a quantum number associated to an irreducible representation of the Poincare group composed with the unitary ones due to the gauge interaction.
On the other hand there is another form of mass, called the same as you have made: effective mass, but this is due to the motion of the electrons in bands of energy in a solid. In such a case even it can takes negative values in half of the Brillouin Zone. Obviously this aspect is absolutly out of our discussion.
Dear Daniel,
“…Is original the classification of S and T particles? What is that?”
- the classification of all particles (bodies, etc.) in Matter as “T-particles” and “S-particles” indeed exists till now only in the informational physical model, the link – see 2-th SS post on already 5-th page. The pages in this thread are rather short…
And this classification is utmost universal in Matter – every particle is T- or S- particle. At that it seems the number of S-particles is very small – evidently those are photons and gravitons, which evidently (for the gravitons – very probably) move in the 3D space of the absolute 4D spacetime only with the standard speed of light.
Both are mediators of corresponding forces – EM and gravity. Now we cannot exclude that mediators of the strong and weak forces aren’t S-particles.
Why that is so? – that is how the informational structure “Matter” is [logically] organized, where to make essentially complex systems of particles, i.e., bodies, stars, etc. is necessary mainly to use the T-particles, when to unite all objects in Matter seems is necessary to use some long range and universal interactions, when the propagations’ speeds of these interactions in the space should be maximal – i.e. be equal to the speed of light. Why in the space only? – that has the reasonable explanation: since all interactions of all material objects happen in the space and the “true time” only, independently on the objects’ 4D spacetime coordinates; and, since all material objects always are in one “true time” moment – so, in fact, in the space only.
As to the notion “rest mass” (and other “masses”, though) – again, these notions (and variables in physics) characterize (for humans) the same indeed fundamental value/ notion – the inertia. Which, in turn, with a rather great probability is the consequence of that all /every particles are some “4D gyroscopes”, when an impact on a particle results in a change of the gyroscope’s rotation rate and (the rate is pseudo – but, nonetheless, a vector) a change of the rate’s orientation. Just therefore, for example, if a force acts on a fast body, it becomes be accelerated not in the force’s direction – as that happens if somebody acts on usual 3D gyroscope.
Thus again – all/ every particle is something “inertial” – or all/every particle has an inertial mass; (and a gravitational mass also). Including photons’ masses are equal to E=hnu/c2 and at interactions with the substance photons by no principal means differ from any, including “T-” particles. Though at interaction with photons of an electrostatic field (which seems differ from “usual” photons), when photons, which move in the 3D space only and so have S-directed 3D momentum, this momentum is divided on two +/- [coordinate] time directed momentums and the pair of T-particles – electron + positron appears.
Again – more see the post and the link on 5-th page.
Cheers
To all,
My answer has been downvoted by 2 people, and supported by one. I winder what that means...
I tried to stay on the topic. The dicussion was about the concept of mass, and I noticed that certainly it is not the same for fermions and bosons. I recalled some basic concepts about spinors, using the common vocabulary. I introduced some ideas, that I said are speculative, but could be useful about such an unknown subject as the graviton. So I tried to be "scientifically correct", but it does not matter. Perhaps my post lacked the necessary references to the great priests.
I am a bloody French intellectual, so I feel compelled to draw some general conclusions about a simple fact (but quite frequent on this site). For a long time the criterium of scientifically proven has been the peer review. Is there a safer mean for a corporation to keep its power than to submit the publication of ideas to a board appointed by the corporation and, to be on the profitable side of things (we are all corruptible), to have in this process the support of 3 multinationals which profit outrageously by this process ? But I see that now our academics have moved to the modern ways. A scientific idea is deemed correct by the number of "likes" or "dislikes". I am not sure that this is a progress towards democracy (there is an interesting article about the subject in the latest issue of the Economist). I am not sure that this contributes to the progress of sciences. This is still anonymous (one cannot be perfect, and habits of anonymity are long to discard) but this is a progress of sort. So I will not complain.
Dear Daniel ~
“…photons are only kinetic particles (no dynamical particles involving forces from the relativistic point of view)”
That is where we disagree! All particles are “only kinetic” when they travel freely, not acted on by forces. All particles are “dynamical” when they interact. Photons are no exception. When radiation interacts with matter the matter experiences “radiation pressure”. In terms of “photons” that is the result of interactions between photons and charged particles (typically, electrons), in which energy and momentum are exchanged. That is “dynamics”. The fact that a photon has no (so-called) “rest mass” is virtually irrelevant in this context.
The point of my previous remarks (which seems to continue to elude you…) is that “energy” and “mass” are, according to Relativity (Special and General), merely interchangeable words that denote the same physical concept.
Thanks Thierry,
I will not dwell on the downvote, and trying to stay on the topic (graviton). It seems relevant to come back to the concept of boson, force carriers, since the graviton is the boson associated to the gravitational field. The full (speculative) theory is exposed in my book (Maths in Physics) but, as it comes at the end and is somewhat technical, I will try to summarize the idea.
The starting points are the classic theory of fields and the gauge theory. A field is assumed to exist everywhere (in order to remove the idea of action at a distance) and propagate in the vacuum (by interacting with itself). The phenomenon of propagation is itself intriguing, and not really addressed in the litterature. For instance as a physical entity a field should, in the relativist universe, occupy a definite area of space time, which leads to assign a proper time, the phase (similar to the proper time of a particle), to a field, different from the time of an observer, who can see only a part of the field (different for each observer). Anyway the field should propagates (in the vacuum) as 3 dimensional hypersurfaces, from where we have lines of propagations (normal to the hypersurfaces and parametrized by the phase). In classic and gauge theories fields are represented by differentiable maps, but one cannot exclude the existence of discontinuities. We know the phenomenon for fluids (shock waves). But in the case of fields discontinuities can happen only along lines (and not 2 dimensional surfaces as for fluids). This can be proven but requires some strong mathematics. As a result a discontinuity in the derivative of the potential (in gauge theories) manifest itself as a particle, moving along a line (at the same speed as the field) which can be endowed with the attributes of a particle. This is a boson, which interacts with particles in a kinematic way, and with charged particles, the usual way. Better, such a boson can enter a lagrangian as a particle, without the troubles linked to the potential, which are one of the motivations for the introduction of the Higgs boson in the Standard Model. Actually this picture provides a clear link between classic field theory and QTF : to continuous fields you add discontinuities, and they can appear in the same lagrangian. So classic field theory works well when one can neglect the discontinuities (in continuous processes) but must be accounted for in discontinuous processes (which the real area of QTF). The theory works pretty well, and can even explain the Plank's law. And this is a way to have some hint at what could be the graviton...
Dear Eric,
Trying to summarize I have avoided words that it seems to be necessary. The photon is ONLY a kinetic particle, i.e. you cannot catch one and store it in your pocket.
I didn't try to jump your question or remark:
The point of my previous remarks (which seems to continue to elude you…) is that “energy” and “mass” are, according to Relativity (Special and General), merely interchangeable words that denote the same physical concept.
I thought that it was just a form to speak,assuming natural units where c=1. This is a form to simplify the expressions but obviously
Joules are different than Kilograms
or
Joules are different than Kelvins
Although the energies, in certain circumstances, can be related by constants as the square of the velocity of the light or the Boltzmann constant.
P.S. Frankly speaking, I do not understand how we are now in this level of discussion when I know that you know very well all of that.
jean claude,
“….A scientific idea is deemed correct by the number of "likes" or "dislikes". I am not sure that this is a progress towards democracy…”
- it seems no necessity to take too much attention on “likes” and “dislikes” here – that are nothing more then some methods of manipulations if in some society some not too small and discipline group appears, including in the science now. In this case any number of these “marks” has no relation to the science. Including in the RG; the members of such group simply always vote “down” on any opinions of any human, if this human doesn’t belong to this group, – and thoroughly vote “up” on posts if authors belong to the group.
This technique is especially applied when the outer human posts indeed some worthwhile ideas; then this group apply “down” marks obligatorily, practically on every post, hoping that if somebody else meets some downvoted post, (s)he will read the post with a prejudice or even will pass by.
Besides, if posts of the “outer” human have small number of “ups”, they make the inference that this human doesn’t belong to some other not too small group and act more and more impudently.
Nothing more – only a politic…
Cheers
In the page1 devoted to this question, I have tried to give one idea of the electromagnetic and gravitational forces between an electron and a proton. The gravitational is actually too small respect to the electromagnetic and it is difficult to imagine (at least for me one boson as the graviton in such scale) and almost impossible to be measured (thus it will be just a concept and no a reality).
But let us go to a system where we can imagine the gravitational field to play a more important role. Let us study ,very broadly, the system Sun-Earth where the Sun emits photons and there is gravitational dipolar interaction Sun-Earth which acts as an antenna of gravitational waves. The maximum emitted gravitational power is around 300 w, while the Sun emits as photons a power around 3. 10^(26) w, i.e. 24 orders of magnitude higher.
To detect a photon here in the Earth is not even a simple task because it needs to have an special instrumentation for doing it. What could happen for the graviton? I think that it would be impossible and only if we assume a system with very strong gravitational field we could think in such possibility.
Recently it was published a paper
prl116,061102 (2016)
as a LIGO-VIRGO collaboration, which claims to have found a gravitational wave from binary black hole systems with initial masses
36 M ⊙ and 29 M ⊙
collabting to one black hole of mass
62 M ⊙
and therefore with one energy emitted as gravitational waves, given by
3.0 M ⊙ c^ 2
Even assuming these interpretations and huge amount of gravitational mass transformed in gravitational radiation ( three times the one of the Sun), we will very far of having measured a graviton,
Rasbindu,
I will attempt to prove that gravitons and virtual photon messenger particles do not exist. Instead all particles, fields and forces are fundamentally associated with waves in spacetime. I will do this by showing that the gravitational force is closely related to the electromagnetic force. The connection is inconsistent with the properties of gravitons and virtual photons.
This comparison of forces could use either Planck charge qp or elementary charge e = α 1/2qp ≈ qp/11.7 where α is the fine structure constant. Planck charge is actually the more fundamental unit of charge. It is derived from the permittivity of space εo and has a coupling constant of 1 to a photon. The magnitude of the electrostatic force between two particles with Planck charge will be expressed with the symbol FE and the gravitational force between the particles will be designated Fg. With two electrons (charge e) the ratio of these two forces is Fg/Fe≈ 2.4 x 10-43. However, if we assumed the electron’s mass but Planck charge, then the ratio is Fg/FE ≈ 1.75 x 10-45.
This enormous difference in force magnitudes makes gravitons and virtual photons seem plausible carriers of force because no simple connection between these forces seems possible. However, a fundamental connection has been found. Furthermore, this connection implies that both of these forces scale with a particle’s reduced Compton wavelength λc = ħ/mc. For example, an electron has λc ≈ 3.86 x 10-13 m. To see the connection, it is necessary to specify the separation distance r not in meters but in the number N of reduced wavelengths N =r /λc = rmc/ħ. Using this designation, the equation connecting N, Fgand FE is:
Fg /FEN = FEN /Fp where Fp = Planck force = c4/G
If the separation is equal to λc, then N = 1 and the equation is Fg/FE=FE/Fp. Also at this fundamental separation distance (r = λc), the square relationship between the forces becomes obvious. (Fg/Fp) = (FE/Fp)2. The point is that gravitons and virtual photons cannot explain 1) the importance of λc, 2) the importance of Planck force or 3) the square relationship between the gravitational force and the electromagnetic force. The linked paper below explains these and other relationships in more detail.
Chapter Spacetime Based Foundation of Quantum Mechanics and General Relativity
Dear Daniel ~
“I do not understand how we are now in this level of discussion when I know that you know very well all of that.”
Yes, we both understand the same physics, but have different habitual ways of conceptualizing its implications. Your way is congenial to me and my way is congenial to you. That will not change. Our argument has illustrated that there can be very different ways of interpreting experimental data and the implications of theory. Appreciating the internal logic of very different viewpoints is instructive and illuminating. It’s not always a matter of “right” versus “wrong”.
The units in which physical laws are expressed are freely chosen by physicists, not imposed by the nature of the physical world. They relate to the practical business of measurement. Measurement is what we do, not what "Nature" or “physical reality” does.
“Joules are different than Kilograms or Joules are different than Kelvins.”
They are different because they have been defined for convenience in very different experimental situations.
There are fundamental constants in Nature. Some of them (such as the fine structure constant) are dimensionless . They are pure numbers revealed to us by Nature and we just have to accept them as mysteries until a superior theory comes along to explain them. Some of them are not dimensionless but experiment has revealed that they are, so far as we know, but with a considerable degree of confidence, invariants (eg., c and h; G possibly…). That means something; it is telling us something important about the nature of physical reality. What the invariance of c is telling me is that the underlying physical reality is simpler than measurement procedures (and the concomitant definitions of units that physicists employ) have led us to believe. That is rather more significant than just “a form to simplify the expressions.”
Dear Daniel ,
Your statement that " photon is a kinetic particle and you cannot catch it and store it in your pocket' requires some discussion. There are a large number of experimental evidences that showed that photons can be trapped in disordered dielectrics or in Mie spheres. Does not this contradicts your statement?
Thierry ~
"The speed of a wave is given by the square root of the quotient energy-density / mass-density of the rope or the water, or.../ There is absolutely no reason why it would be different for gravity."
In the case of gravity (or electromagnetism) what is playing the role of "the rope or the water..."?
As per the present outcomes are concerned, I think that Graviton seems to be more concept and less reality. However, more research required to come to the final conclusion.
Graviton is presently a concept which, if observed, would complement the standard model of particle physics as a description of reality. But even then, this does not mean that the graviton will become part of reality. And surely not of physical reality (perhaps a little bit more of your reality ..... or of mine ..... or of their's ....).
Dear Eric,
In physics there are questions of discussion, as if the if the graviton could be find any time as a physical particle, but there are statements that every student of Physics needs to know and accept as conventions. It is true that the constants allow to relate the physical magnitudes in simple form or even in very different units. For instance, if you have h=1 and c=1, you can give wave-length in meters and obtain joules for a photon. But this is not at all true in general and only corresponds to the photons in vacuum.
The problem is that energy in physics has very different aspects and sometimes even not possible to transform one in the other. For example, the second principle of thermodynamics prevents to transform all the thermal energy using a thermoelectric material in electric one, even if the Seebeck coefficient were perfect: the thermal coductive very low and very high electric conductivity. Then, even if the Boltzmann constant were k=1, Planck constant h=1 and velocity of light c=1, could tell you how many Kelvin degrees corresponds to one electron volt. NOBODY!
Behind this security in the results, even without knowing the details, is the knowledge of the concepts in Physics which are absolutly necessary for understanding on what are we speaking on. It you tell me that you know the mass (kgs) of the electric field of an electron at 1 cm of distance; frankly, I think that you are living in other world ( perhaps better than the mine) of the physics that I use and have to teach ( trying to do it the best than I know).
Eric, I am not sure to convince you with these words, but don't worry there are many physicist in the World to discuss on this issue much much clever and important than me, and surely you have there collegues to speak about this question personally. From my side perhaps I cannot do it better.
Dear Rasbindu,
There are a large number of experimental evidences that showed that photons can be trapped in disordered dielectrics or in Mie spheres.
What do you mean by trapped? I do not know any dielectric material which have photons at rest, which on the other hand is impossible. Please tell me only one.
The materials that I know, which could be closed to this idea, are the photonic crystals where the photons are tranmitted instead electrons within nanoestructures which simulate semiconductors, etc...but always they are in motion an at the same velocity which numerically depends of the refractive index. But always in motion and never at rest!
The Mie sphere even than use the concept of photon, in all that I know, this is a model very old for calculating with classical electrodynamics the absortion of the electromagnetic waves for small metallic particles with polarons or polaritons.
It is true that nowadays there devices as the quantum dots, that can be designed to work in quantum confinement regime where a band gap can be created and the states depend strongly of the radius of the particle, which in any case must be smaller than twice the exciton Bohr radius. In these materials the photons are absorved by the states and as in a laser, they are again recovered. But this is a quantum process as it happens in one ordinary atom and never means a photon at rest! There are more example of materials as quantum wires, luminiscence, etc... but without contradicting my idea that the photon at rest is with zero mass, which is well known and accepted out of my humble opinion.
Dear Daniel ~
“…could tell you how many Kelvin degrees corresponds to one electron volt. NOBODY!”
The kinetic energy density at a given number of degrees Kelvin is not an exotic concept it’s standard thermodynamics. The units can be chosen to be ergs. Converting electron volts to ergs is also straightforward. (I‘m not going to waste time looking up numbers and doing the calculation.)
Whether you define c to be 299792458 “meters per second” or 1 “light year per year” is irrelevant.
I’ve been discussing the equivalence of mass and energy, which is hardly a debatable issue.
Let’s call a truce (-;
Eric: You ask “In the case of gravity (or electromagnetism) what is playing the role of "the rope or the water..."?” I will restate this question as “What is the medium which propagates gravitational waves?” Some physicists will say that there is no medium – gravitons propagate in waves of probability through the empty void of spacetime. However, among physicists involved in the detection of gravitational waves, it is well known that gravitational waves encounter the impedance of spacetime Zs = c3/G ≈ 4 x 1035 kg/s. To gravitational waves, spacetime appears to be a very stiff elastic medium which can propagate waves. For example, the gravitational waves recently detected had a measured dimensionless strain amplitude of ΔL/L = 10-21. This minute distortion of spacetime had intensity of about .02 w/m2 at 250 Hz. If this intensity was a 250 Hz sound wave, it would have been 103 dB which is a very loud noise about equivalent to a drum at a rock concert. Yet, the tremendously large impedance of spacetime made 20 mw/m2 only distort spacetime by 1 part in 1021.
I have taken gravitational wave equations and extracted the implied structure of spacetime. The vacuum fluctuations (quantum foam) is characterized as the vacuum having waves which modulate the distance between points by Planck length and modulate the rate of time such that perfect clocks in flat spacetime can differ by Planck time. These waves are primarily at Planck frequency (∿ 1042 Hz). They are undetectable to us because they lack quantized spin. However, they give spacetime its properties such as c, G, ħ, εo and Zs. If these waves all possessed spin, then they would have energy density about 10120 times larger than the “critical” energy density of the universe. Gravitational waves are carrying angular momentum, therefore they can experience some of the energy density of spacetime. However, there is a frequency mismatch which makes the energy density encountered by gravitational waves frequency dependent. The “interactive energy density (Ui)” of spacetime is:
Ui = k ω2c2/G and the “interactive density of spacetime” is ρi = kω2/G. These terms are explained in the attached paper. I will be writing a paper which specifically addresses the connection between gravitational waves and vacuum fluctuations.
Article Energetic Spacetime: the New Aether
Dear John,
I am very sorry to tell you that your work is wrong and it is a pity because I saw that you have made quite a lot of work.
Space-time is not at all an elastic material and it is well known that the accustic waves cannot propagate within it. The reason is very simple and fundamental the phonons are not transversal propagated as the photons, there are no one Poynting vector for the gravitational waves of the General Relativity.
Daniel: You say “Space-time is not at all an elastic material and it is well known that the acoustic waves cannot propagate within it.” My statement was that to gravitational waves, “spacetime appears to be a very stiff elastic medium which can propagate waves.” I can give numerous references that support this wording and concept. For example, the most authoritative recent book on gravitational wave detection is titled “Advanced Gravitational Wave Detectors” by D. G. Blair, E. J. Howell, L. Ju and C. Zhao. In Chapter 3 it says, “Gravitational waves propagate in a very stiff elastic medium as explained in chapter 1. Spacetime has a characteristic impedance – c3/G.”
I agree with you that “Space-time is not an elastic material” and cannot propagate acoustic waves. However, you have apparently gotten confused between a physically observable acoustic material which has quantized spin and the model of the spacetime medium containing Planck length/time waves which are unobservable because they lack spin and because of their undetectable small amplitude. These waves form the background “noise” of the universe. They make it impossible to make length measurements more accurate than Planck length or time measurements more accurate than Planck time. Ultimately, they are responsible for the uncertainty principle.
Dear John,
If you allow me an advice, don't waste your time writing papers without having a given aim where you cannot summarize what are the discovered made in it. That is to say, trying to solve problems and no write a salad of different things which are well known but only seeing from another point of view.
Some points to remark:
1. The impedance of the vacuum depends only of two electromagnetic constants (377 Ohms). No relation with photons and less constants of gravitation.
2. Einstein's equations are equivalent to a wave equation, by themselves without relation with quantum fundamental state of the Universe (i.e. your vacuum). The field of these waves are the metric of the space-time, no related with photons or electromagnetism.
3. The spin is out of the gravitational waves and only could enter in the graviton (boson of spin 2 because it is associated to the energy-momentum second order tensor. And less with their dynamics.
4. One thing is to have the gravitational waves directly associated to the Einstein's equations and another very different to produce them. Their production is due to accelerated motion of high masses as can be with black holes colliding. The power produced in such a case is something parallel to the Larmor equation in electrodynamics.
5. There are many problems related with gravitation nowadays, that could interest to editors or which could be appreciated by referees of reviews, and I think that is a pity that you do not concentrate on them instead of making this kind of salads.
I hope that I could help you with my sincere opinion, which obviously can be wrong, but with the best intentions.
Dear Daniel,
Photons are resonantly trapped in the mediums I have stated. Localization of light is a very well known phenomena and a large number of papers are available on this topic. It is shown that the resonantly trapped photons can be recovered under controlled conditions. But, what you said is also true. In such medium the trapped photons are never at rest . At the same time they are confined in the material. So, it can be said that they are stored.
Dear Rasbindu,
Perhaps it would be interesting that you could choose some references, I understand that some of them are enough if were well selected, where a photon is trapped and can survive at constant velocity without being never at rest. Thank you!
And what would be even more fantastic is if you could summarize how this is possible to get physically, given your opinion about this interesting behaviour (at leat for me).
I suppose that this is far of "devices" as the Mie sphere has you mentioned previously in your post.
Frankly speaking I think that you are confussing the conservation of the electron-photon in confinement regimen of nanosized devices, with the conservation of one photon as stable particle as we could have for one of them emitten in one far star that we catch here in the Earth. These are very different situations for the photons. In the first case, given that you hava a many-body configuration and the photon is a boson, then they tried to be joint and it is difficult to say that you have trapped "one" photon, as I have tried to say for explaining the non possibility of having a photon at rest. At least I do not know it and I would be very happy to learn about this possibility.
Daniel; I appreciate the sincere advice you gave in your last comment. Some of your points I will adopt. However, I believe that my main contribution is to show that a single logical model of the universe brings together quantum mechanics and general relativity. For example, the impedance of free space (Zo ≈ 377 Ω) converts to the impedance of spacetime (Zs = c3/G) when I use my proposed charge conversion constant η to change the units of coulomb to a distortion of spacetime. Also this constant converts the Coulomb force constant (1/4πεo) to c4/G (Planck force). The implication of Zo converting to Zs is that photons experience the same impedance as gravitational waves. I claim that this is a profound new insight. It implies that photons are quantized waves that propagate in the medium of spacetime. This is covered in my paper: Energetic Spacetime: The New Aether. Also the equations that I have developed which show previously unknown relationships between the gravitational force and the electrostatic force resulted from insights obtained by mixing the properties of spacetime and quantum mechanics.
Once again, I appreciate your advice and the time you spent writing this advice
Dear Daniel,
I would like first to clarify that purpose of the discussion is to throw light on the confusion about some aspects of duality of nature of light. As you stated first that photons cannot be stored in pockets. I like perhaps many others have observed that in certain sense , light that is photons can be stopped, stored and retrieve in a few materials. I have not disputed the prevailing idea that rest mass of a photon is zero. At the same time photons as photons can survive in some materials and certain typical conditions and remain there till you release them-in some sort of a cage. Following are few references in support of this.
1.D.Maxwell and others, storage and control of optical photons using Rydberg polaritrons, Phys. Rev.Lett.,110,103001(2013)
2.Yi Yin and others, Catch and release of microwave photon states, Ibid, 110,107001,(2013).
3.R.Patel and R.V.Mehta, Experimental demonstration of magnetic carriage for transport of light trapped in magnetizable Mie spheres, Advance Optical Materials, 1,703 (2013) and references therein.
There are some general semi technical articles on this like
4. Robert Kunzig, Trapping light, Discover magazine, April 2001
5. Sajeev John, Localization of light, Physics Today,32,May, 1991
6. Killugudi Jayaraman , Scientists trap light in nano-soup, Chemistry World, 27 December,2007
We have developed a model based on Mie scattering [7] as well as tried to explain the storage and release using effective potential effect[3]. A summary is given here for your quick reference.
According to Mie theory scattered intensity depends on two intensity functions
i1(2) = │ S1(2)( mMNS, α,θ ) │2 (1)
Here, suffix 1, 2 represent the two orthogonal states of linear polarization respectively,perpendicular and parallel to the scattering plane defined by the direction of propagation and the direction of applied magnetic field. α ( = πd/λ , d is diameter) is the size parameter and θ is the scattering angle. mMMS ( = ms / mf ) is the relative refractive index of the scatterer (ms) with respect to that of surrounding ferrofluids (mf).The scattering coefficients S1(2)( mMNS, α,θ )
in turn depend on Mie coefficients an , bn and partial derivatives of Legendre polynomials πn ( cosθ) and τn (cosθ). Detailed expressions are given in Ref. [1].
The Mie coefficients depend on the size parameter α and m MMS. It is known that refractive index of a ferrofluids is a function of applied field. Using Langevin theory of paramagnetism it has been shown that[22,23]
mf = m∞ L(ξ)m0 (2)
Here, m∞ is the saturation value of refractive index, m0 is the refractive index at zero field and Langevin function L (ξ ) = (cothξ – 1/ξ ), with ξ = μH/kT ,where μ is the magnetic moment of nanomagnetic particles, H is the applied magnetic field , k is Boltzmann constant and T is the absolute temperature. Accordingly, mMMS will also depend on the applied field. Mie calculations have shown that as the particle size increases, scattering in the forward directionincreases and sharp fluctuations in intensities (ripples) are observed. The ripples are due to resonances and lead to a number of nonlinear optical effects like glare spots, lasing in micro drops, and stimulated Raman scattering etc.[24,25]. It was also predicted that a very high resonance field gradient near the surface of the sphere may be useful for trapping of light[24].
The origin and physical interpretation of this phenomenon is explained on the ‘effective dielectric potential well’. Such a resonant state is referred as ‘quasi bound state’ [24,25]. The energy enters and exits the well by tunneling through a centrifugal barrier. The top and bottom of the well decides the upper and lower bound of the resonance level. The widths of the resonance which are inversely proportional to the decay time of the quasi bound state are determined by the rate at which energy tunnel through the outer barrier of the well. The lower levels have longer life time and hence narrower width since; it has to pass through a longer barrier. The shape of the potential well depends upon size, shape and refractive index of the scatterers,[24-29]. Quality factor Q (λ/dλ) can be > 108. Light trapping observed in the present case is attributed to MDR. The novelty of the present technique is that MDR can be tuned by applying static magnetic field of moderate magnitude and a small electromagnet is required for this purpose. Moreover resonance is sustained as long as field is present. This characteristic along with the long life time facilitates transport of light. Once the light is trapped in a MMS, it may remain within it depending on life time of the resonant state.During this time there may be continuous losses due to total internal reflections[24]. This losses being continuous it will increase with time. If, Nt is the number of wave packets trapped during the exposure time and NL is the number of packets that are lost during this time, then total number available at an instant will be ( Nt– NL). Once the incident light is shut off Nt will remain constant while NL will increases with time. Consequently after time T the available number will be only (Nt – TNL). Obviously, it will take a longer time T to transport the magnetic carriage to a larger distance. If, Nt > TNL then and then only flash will be appears. In other words, larger the exposure time (Nt) longer will be the transport distance.
Kindly refer the original paper for the above cited references.
I also would like to state here that I am not expert in field theory. And I and my colleagues have tried to explain the observed unusual phenomenon on available models. I shall be happy to receive your opinion on the observed localized photonic states.
Dear Rasbindu,
Thank you very much for your references and explanation. It is clear that we have not understand each other with the word to catch a photon in the pocket, related with the discussion of the rest mass of the photon,
Your first reference is for polaritons (not polaritrons), i.e. quasiparticles formed by strong electromagnetic waves (even no photons are necessary) with magnetic or electric dipoles.
The second is about microwave photon states. This is no a photon at rest as the lasers haven't them too or an excited electron in one state of an atom. Third is light in a classical electromagnetic model as the Mie one.
I am afraid that we were in big misunderstanding as I thought. The photons can form different kind of quasiparticles in solid state as excitons, i.e. bound states of electron-hole. Or their interference exciton-polariton, etc... but in any case the photon never states as particle at rest!
Perhaps it would be a good idea to open a new question about these quasiparticles related with the nanotechnology and which have the photon as component. But in any case this question if very far of our discussion.
It seems that the discussion is now rather far away form the thread’s question; and so the SS post on 3-rd page on https://www.researchgate.net/post/What_theories_explain_the_mechanical_inertia_of_an_object_by_the_actions_of_gravity_from_the_rest_of_the_Universe2
seems as would be fairly relevant here also.
With quite natural addition: the gravity force is, of course, some usual force in Matter – something like the EM force; and so it is quite natural to expect that in this force all interactions are quantized; including it would be quite natural, if there would exist “free gravitons” – as some analogues of free
[not the "virtually free", as that is claimed in the QED in the electrostatic (though the electrostatic field is rather probably composed from a “circular photons”, which differ from "usual", but are just real) ]
- “real usual” photons.
Cheers
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