Science topic

Quantum Gravity - Science topic

Explore the latest questions and answers in Quantum Gravity, and find Quantum Gravity experts.
Questions related to Quantum Gravity
  • asked a question related to Quantum Gravity
Question
59 answers
The introduction to the discussion is the 16:58 minute video of Sabine Hossenfelder. In my opinion Sabine Hossenfelder is one of the physicists who shows an outstanding insight in modern theoretical physics. Her videos at Youtube.com are well argued, founded and understandable for every theoretical physicist. So I hope that every RG member who wants to participate in the discussion about the Big-Bang hypothesis will try to communicate at the same level as Sabine Hossenfelder (I cross my fingers).
With kind regards, Sydney
Relevant answer
Answer
The discussion was mainly reduce to identifying the contradictions of the existing model, as well as the correspondence between this model and experimental data. That is, the discussion answers the question: "Is the existing cosmological hypothesis of the Big Bang correct?" Meanwhile the question was: "Did the Big Bang happen?". Or are theoretical possibility and a real event the same thing?
  • asked a question related to Quantum Gravity
Question
411 answers
One of the alleged difficulties of producing a so-called quantum gravity theory is due to the Heisenberg's uncertainty principle.
To probe ever tinier distances, we need ever greater energies. The problem is that if you concentrate too much mass/energy in a tiny space, the gravity of such a space becomes so huge that tiny black holes form, making the measurement impossible. Even though that assumes GR holds in the microscopic realm.
This is my question. How do we know that a high energy allocated to a tiny subatomic region of space would create a tiny black hole, since we don't have any proven UV-complete theory of quantum gravity to begin with?
How do scientists know that a high energy concentration in a tiny space would lead to a tiny black hole?
Here's a precise description of this issue:
  • asked a question related to Quantum Gravity
Question
6 answers
A rigid body with vertical proper length J rises along the Y direction in an inertial frame S(T,X,Y) with constant proper acceleration, therefore me may write the equation of hyperbolic motion of the body along the Y direction as:
1) J2 = Y2 - c2 T2
Using Born´s definition of rigidity, the proper length “J” must be invariant under Lorentz transformations between instant commoving inertial frames where the proper length (squared) J2 coincides with the line element (squared) along the Y direction: Y2 - c2 T2. It is straightforward to see that this is the case just for boosts along the Y direction. If the velocity of the body and its inertial commoving frames have an aditional constant component along the X direction, the line element is different, the vertical length J cannot be invariant in the inertial comoving frames and we get a violation of Born´s rigidity.
Relevant answer
Answer
And it is a pitty that the students fail to take into account simultaneity of relativity since it is a straighforward consequence of the two more basic priciples of SRT:
1) Constancy of speed of light.
2) Equivalence of inertial frames.
  • asked a question related to Quantum Gravity
Question
8 answers
Consider two particles A and B in translation with uniformly accelerated vertical motion in a frame S (X,Y,T) such that the segment AB with length L remains always parallel to the horizontal axis X (XA = 0, XB = L). If we assume that the acceleration vector (0, E) is constant and we take the height of both particles to be defined by the expressions YA = YB = 0.5 ET2, we have that the vertical distance between A and B in S is always (see fig. in PR - 2.pdf):
1) YB - YA = 0
If S moves with constant velocity (v, 0) with respect to another reference s(x,y,t) whose origin coincides with the origin of S at t = T = 0, inserting the Lorentz transformation for A (Y = y, T = g(t - vxA/c2), xA = vt) into YA= 0.5 ET2 and the Lorentz transformation for B (Y = y, T = g(t - vxB/c2), xB = vt + L/g) into YB= 0.5 ET2 we get that the vertical distance between A and B in s(x,y,t) is:
2) yB - yA = 0.5 E (L2v2/c4- 2Lvt/c2g)
which shows us that, at each instant of time "t" the distance yB - yA is different despite being always constant in S (eq.1). As we know that the classical definition of translational motion of two particles is only possible if the distance between them remains constant, we conclude that in s the two particles cannot be in translational motion despite being in translational motion in S.
More information in:
Relevant answer
Answer
Larissa, I might be wrong but I believe that you wanted to post in another quest on dark matter and dark energy.
  • asked a question related to Quantum Gravity
Question
12 answers
I worked for months on writing this paper, but it's been rejected twice. It gives an alternative explanation to the expansion of the universe and gives a hint to quantum gravity, but there is no mathematics to back this idea, although it only needs some basic knowledge to understand. I've also given testable perditions to prove my point. Should I make it public or keep sending it to journals?
I've attached abstract and Introduction of my paper.
Relevant answer
Answer
Dear Dr. Vishal Wagh
I feel its too early to give up, better to look into the comments of the reviewers, get them fixed, and keep sending the article out to journals until it is accepted for publication
  • asked a question related to Quantum Gravity
Question
44 answers
1) Can the existence of an aether be compatible with local Lorentz invariance?
2) Can classical rigid bodies in translation be studied in this framework?
By changing the synchronization condition of the clocks of inertial frames, the answer to 1) and 2) seems to be affirmative. This synchronization clearly violates global Lorentz symmetry but it preserves Lorenzt symmetry in the vecinity of each point of the flat spacetime.
Christian Corda showed in 2019 that this effect of clock synchronization is a necessary condition to explain the Mössbauer rotor experiment (Honorable Mention at the Gravity Research Foundation 2018).
---------------
We may consider the time of a clock placed at an arbitrary coordinate x to be t and the time of a clock placed at an arbitrary coordinate xP to be tP. Let the offset (t – tP) between the two clocks be:
1) (t – tP) = v (x - xP)/c2
where (t-tP) is the so-called Sagnac correction. If we call g to the Lorentz factor for v and we insert 1) into the time-like component of the Lorentz transformation T = g (t - vx/c2) we get:
2) T = g (tP - vxP/c2)
On the other hand, if we assume that the origins coincide x = X = 0 at time tP = 0 we may write down the space-like component of the Lorentz transformation as:
3) X = g(x - vtP)
Assuming that both clocks are placed at the same point x = xP , inserting x =xP , X = XP , T = TP into 2)3) yields:
4) XP = g (xP - vtP)
5) TP = g (tP - vxP/c2)
which is the local Lorentz transformation for an event happening at point P. On the other hand , if the distance between x and xP is different from 0 and xP is placed at the origin of coordinates, we may insert xP = 0 into 2)3) to get:
6) X = g (x - vtP)
7) T = g tP
which is a change of coordinates that it:
- Is compatible with GPS simultaneity.
- Is compatible with the Sagnac effect. This effect can be explained in a very straightfordward manner without the need of using GR or the Langevin coordinates.
- Is compatible with the existence of relativistic extended rigid bodies in translation using the classical definition of rigidity instead of the Born´s definition.
- Can be applied to solve the 2 problems of the preprint below.
- Is compatible with all experimenat corroborations of SR: aberration of light, Ives -Stilwell experiment, Hafele-Keating experiment, ...
Thus, we may conclude that, considering the synchronization condition 1):
a) We get Lorentz invariance at each point of flat space-time (eqs. 4-5) when we use a unique single clock.
b) The Lorentz invariance is broken out when we use two clocks to measure time intervals for long displacements (eqs. 6-7).
c) We need to consider the frame with respect to which we must define the velocity v of the synchronization condition (eq 1). This frame has v = 0 and it plays the role of an absolute preferred frame.
a)b)c) suggest that the Thomas precession is a local effect that cannot manifest for long displacements.
More information in:
Relevant answer
Answer
Cameron Rebigsol I understand your world view and Sir Isaac Newton would have agreed with you. Newton explained gravity and made the connection between the gravity on Earth (e.g. the falling apple) and the motion of the moon. He worked out that it would all be explained by an inverse square law of distance. Even Newton was a bit puzzled about how this "action at a distance" worked.
James Clerk Maxwell pointed out that this "action at a distance" was not a good explanation and felt that there had to be some mechanism through the medium to produce electromagnetism and gravity.
I agree with the viewpoint of Maxwell and I do take as my starting assumption that General Relativity is completely correct as there is sufficient evidence for this. Then the question of "action at a distance" is resolved because it is the state of the medium (i.e. spacetime) which is the underlying cause of the gravitational and electromagnetic forces.
Richard
  • asked a question related to Quantum Gravity
Question
5 answers
Please, see the attached file RPVM.pdf. Any comment will be wellcome.
More on this subject at:
Relevant answer
Answer
I think that an interesting point is that, using units with c = 1, the 4-velocity (dt,dx,0,0) is a 1-tensor that is the same for any offset of clocks of the inertial frame. Then we have that the 4-velocity (dt,dx,0,0) transforms the same for any synchronization, it satisfies the Einstein addition of velocities and consequently it also satisfies the principle of constancy of speed of light. On the other hand, as it behaves like a tensor under Lorentz transformations, the relativity principle holds for it an for all derived 1-tensors like velocity, acceleration and so on.
  • asked a question related to Quantum Gravity
Question
7 answers
You can find the wording in the attached file PR1-v3.pdf. Any comment will be wellcome.
More on this topic at:
Relevant answer
Answer
I think that an interesting point is that, using units with c = 1, the 4-velocity (dt,dx,0,0) is a 1-tensor that is the same for any offset of clocks of the inertial frame. Then we have that the 4-velocity (dt,dx,0,0) transforms the same for any synchronization, it satisfies the Einstein addition of velocities and consequently it also satisfies the principle of constancy of speed of light. On the other hand, as it behaves like a tensor under Lorentz transformations, the relativity principle holds for it an for all derived 1-tensors like velocity, acceleration and so on.
  • asked a question related to Quantum Gravity
Question
15 answers
If you have an object and you drop it from a high altitude (that is, its velocity is zero, then it accelerates.) and I lower it one second later at zero speed, that object will accelerate at 9.80 m/s per second.” DEAR WALTER LEWIN
Accordingly, what can be said about gravity? GET A ZERO M/S SPEED BALL DROPPED FROM A HEIGHT OF 100 METERS. So what can we take from here? From here we deduce:
Gravity is caused by acceleration. Gravity is equal to accelerated motion, and we can deduce it from here. Because the speed of the matter, the ball, has increased and decreased by one. and so gravity was formed. a=g thanks.
Relevant answer
Answer
When objects fall to the ground, gravity causes them to accelerate. ... Gravity causes an object to fall toward the ground at a faster and faster velocity the longer the object falls. In fact, its velocity increases by 9.8 m/s2, so by 1 second after an object starts falling, its velocity is 9.8 m/s
  • asked a question related to Quantum Gravity
Question
7 answers
There is a good book of C.Rovelli, "Quantum gravity", where this old issue is very well discussed. Namely, do we have treat the metric as characteristic of real space-time manifold or as pure gravity field which fills the big nothing. Let's assume that the second is true, the metric is a gravity field and consider any vacuum solution of Einstein equations. It must be a source for the metric in this case as well, there is no matter, therefore the simplest conclusion is that the vacuum field has it's own energy, at least locally, which we can call as a positive or negative.
So, as it seems, in this interpretation of the metric, it must be some kind of cosmological constant simply by definition of the what the field is. An another consequence is about the energy conservation. If we have a vacuum with some energy, how it was created and where from the energy did come? Again, the simplest explanation is that initially we had two vacuum states with different signs of the energies equal zero overall, which somehow have been splitted and separated.
Of course this is an issue about how the matter is arising, we can also speculate that the matter is first and the geometry is second and that there is no pure vacuum solutions without matter present. Of course, is it seems, the questions about the energy and entropy of the initial state will remain in this case as well.
Relevant answer
Answer
I suppose that the metric you are thinking about is the minimal length scale. Nowadays a lot of theorists are convinced that the minimal length scale is identical to the Planck length (ℓP = 1.616255(18)×10−35 m). But about 80 years ago theorists like Werner Heisenberg (and others) proposed that the metric must be ≈ 1 x10-15 m. Their reasoning was simple: the smallest wave length and the smallest “tangible” particles have the size of ≈ 1 x10-15 m. The Planck length shows an enormous empty gap of 1020 with the smallest particles so its proposed existence is fantasy.
The idea of a minimal length scale goes back to the ancient Greek philosophers who proposed the existence of a spatial dynamical unit that cannot be divided any more. The volume of our universe is tessellated by these spatial dynamical units. Their reasoning was simple: if the universe can reproduce all the observable phenomena in time and place the structure of the universe must have this spatial structure. The strange story about the race between a tortoise and Achilles was meant to show that only equal units can describe reality in a convincing way.
In your description of the discussion you use the term “spacetime”. That is a bit problematic in relation to the topic (the existence of a universal metric). Because spacetime – Einstein’s model that describes phenomenological reality – is what it is: a dynamical model. But the model doesn’t fill the whole universe because it only describes the observable phenomena and the mutual relations between these phenomena. In other words, spacetime cannot have a metric, like spontaneous deformable “rulers” have no metric. Thus a metric is part of Euclidean space and is termed discrete Euclidean space. Therefore Einstein’s spacetime is enveloped by Euclidean space.
Be aware that the proposed metric in quantum gravity is actually a proposed metric of Einstein’s spacetime. So don’t be surprised that all the research during more than 3 decades to find the metric of curved spacetime wasn’t successful (see https://www.youtube.com/watch?v=PRyo_ee2r0U).
There is a short article about the foundational problems in physics: https://iai.tv/articles/why-physics-has-made-no-progress-in-50-years-auid-1292. Anyway most theorists are unwilling to discuss the serious problems.
With kind regards, Sydney
  • asked a question related to Quantum Gravity
Question
26 answers
at large scale, do earth goes around sun or particles of the earth goes around the particles of the sun?
i am proposing new theory which says; the Gravitational force in between two objects depends on the most probable distance in between them.....
my dear unique scholars welcome to your valuable feedback, answers, comments....
thank you
Relevant answer
Answer
In chord space, chord interaction is manifested as spatial interaction, the basic way is: separation and combination.
  • asked a question related to Quantum Gravity
Question
28 answers
I would like to do work on quantum gravity. But general relativity is not complete. So if i want to do work on GRT. I am beginner for this course. GRT fails in few aspects. Any one suggest me research papers. Please send me your answers.
Relevant answer
Answer
Today I read a quote from Einstein (1934) that the properties of all the basic fields (universal “back ground” fields) represent the properties of space itself. I was a bit flabbergasted because it was Einstein in 1920 who stated that the theory of general relativity (gravitation) don’t exist in a universe without matter. A concept that was proved in 2011 by Eric Verlinde (emergent Newtonian gravity).
The consequence of an emergent force field is the absence of an “independent” field structure that is only dedicated to this force field. It means that gravity – no matter if it is GR or Newtonian gravity – is mediated by one of the existing universal “back ground” fields. In other words, at the moment matter is created in the universe there emerges a field we have termed “gravitation” and it is mediated by the Higgs field, the electric field or the magnetic field.
The exchange of energy between decreased scalars of the Higgs field and the local electric field is determined by Planck’s constant (the Higgs mechanism). But the magnetic field is a vector field and cannot exchange energy. A vector field only determines the direction of the transfer of energy. That is why the electric field and the magnetic field are corresponding fields. The electric field generates a local quantum and the local quantum creates a vector within the magnetic field and visa versa. The duration between the start of the increase of the local energy – the beginning of the flow of a fixed amount of energy – and the moment the quantum has the energy of Planck’s constant is termed “quantum time”. Thus quantum time is a constant.
But if the field of gravitation is mediated by one or two of these universal fields the “holy grail” of quantum gravity already exists. Because we know the properties of these universal fields.
If Einstein’s curved spacetime is mediated by the magnetic field GR is equal to Newtonian gravity but space isn’t curved at all (because the curvature of space represents nothing more than the magnitudes of the vectors).
If GR is mediated by the electric field curved space is not a real curvature but a resultant “curvature” because the electric field is a topological field with a discreet structure that is responsible for the creation of quanta, the fixed amounts of energy (Planck's constant).
The last possibility is the Higgs field. Unfortunately the Higgs field is nearly totally flat in the whole universe (vacuum space). Only rest mass itself forces scalars of the flat Higgs field to decrease their magnitude. Therefore it is impossible that space itself is curved like GR predicts.
The main law in physics – the law of conservation of energy – is restricted to the electric field if there exists no matter in the universe. The consequence is that all the vectors of the corresponding magnetic field in the universe are conserved too (a more fundamental conservation law than the conservation of momentum because momentum is directly related to detectable phenomena). So if matter is created in the universe a new situation is born. The decreased scalar(s) of the Higgs field doesn’t exchange vectors but at the same moment the force of gravitation emerges. The only sensible solution to this problem is that the force of gravitation is equal to the “lost” vectors of the magnetic field because the total amount of vectors in the universe is conserved. So at the end Newton was right although the vectors of the force of gravitation are influencing matter as a push force.
With kind regards, Sydney
  • asked a question related to Quantum Gravity
Question
10 answers
At Planck scale, the physical gluon acquires third degree of freedom in the form of scaler potential when the unphysical ghost particle effect disappears at Gribov horizon. Now, relativity demands Lorentz Fitzgerald contraction of Planck scale at light speed of gluon. But that would mean sudden demise of quantum theory. In order to unite relativity with quantum theory, the physical gluon speed instead reduces to zero in any inertial frame and accordingly exhibits mass gap property. For more details, please refer to my preprint http://dx.doi.org/10.13140/RG.2.2.25092.65926
Relevant answer
Answer
The Gribov horizon is the frontier in the space of fields, not in spacetime, where the Faddeev-Popov determinant changes sign. Which just means that a new change of variables is needed. This is just a completely routine technical point, that doesn’t affect perturbative calculations and can be avoided on the lattice. Thzt’s why bringing it up doesn’t help.
  • asked a question related to Quantum Gravity
Question
40 answers
A complete and provable theory on Quantum gravity has not been is achieved so far. Some approachs suggest that space-time is quantized at a very small scale. It is really quantized space-time? What's the scale? Can this scale be explored experimentally?
Relevant answer
Answer
The concept of the quantization of space itself is about 2500 years old (ancient Greek philosophers).
In physics the idea was investigated in the first half of the 20th century (e.g. by Werner Heisenberg). Although they used another term: the minimal length scale (the metric was about 1 x 10-15 m). Nowadays a lot of theorist have the opinion that the metric is near the Planck length (p ≈ 1,6 x 10-35 m). Unfortunately, the smallest detectable phenomena have a scale size of 0,5 x 10-15 m. So the question is why mother nature has created a gap of 10-20 m between the Planck length and the smallest configurations. In my opinion the metric is about 0,5 x 10-15 m. Moreover, the Planck length is derived with the help of the gravitational constant G and as long we don’t know the true nature of gravitation the existence of the Planck length is 100% speculative.
The scale size of “quantized space” is explored experimentally because we cannot “split” particles with a diameter of about 0,5 x 10-15 m in smaller constituents (asymptotic freedom). The smallest wave length of electromagnetic radiation is about 1 x 10-15 m.
Quantized space (another term is discrete space) is supposed to be the underlying structure of the basic quantum fields: Higgs field (scalar field), electric field (topological field), magnetic field (vector field) and the field of gravitation (probably a vector field too). In other words, we are aware of the existence of discrete space because the properties of the basic quantum fields represent the invariant and variable properties of the units of the structure of space itself.
There is a nice video about discrete space. I don’t agree with some details (discrete space isn’t curved and the metric of the Planck length is 100% speculative) but the lecture of prof Renate Loll gives a lot of information about some basic ideas (https://www.youtube.com/watch?v=PRyo_ee2r0U).
With kind regards, Sydney
  • asked a question related to Quantum Gravity
Question
3 answers
What is the symmetry group of the configuration space of scale factors of pseudo-Riemannian, symmetric metrics on a three-dimensional manifold?
Relevant answer
Answer
Definitely the perception of Riemannian on geometry is fascinated, but it is totally incorrect to apply it on universe. 1) his knowledge on universe was not adequate to write something on universe.
2) our universe with several hundred billions of galaxies can not be described by math, or mechanical perception.
regards
  • asked a question related to Quantum Gravity
Question
1 answer
Is it possible to formulate the Ricci-flow as the Euler-Lagrange equations of some system? What would be the corresponding action functional?
Relevant answer
Answer
  • asked a question related to Quantum Gravity
Question
10 answers
As stated in a robotics lesson, "the time variable t varies from 0 to 1, that is, 0 ≤ t ≤ 1". Therefore, this discussion’s logic states that 0 may be equal to 1 (division by 1 is accepted, so why isn't division by 0?) Since time is permanently united with space in physics, 0=1 in space-time too. This is consistent with a proposed future theory of physics called Quantum Gravity; where Quantum Mechanics is united with General Relativity, Einstein's theory of gravity. A possible path to attainment of quantum gravity is realizing that all objects and events on Earth and in space-time are just one thing - like 0 equalling 1, and like the objects in a computer image seeming to be a lot of separate objects but really just being one thing (strings of binary digits). A spacecraft sitting on its launchpad can be assigned t=0, and its destination t=1. Since 0=1, reaching the destination takes the same time as reaching the launchpad from the craft’s position on the launchpad (travel is instant). Robot motion can also be instant and not require interpolation, which is making the end of a robot arm move smoothly from A to B through a series of intermediate points. Of course, this is nonsense if viewed from CLASSICAL mechanics. We need a mindset immersed in QUANTUM mechanics which has been extended to macroscopic entanglement.
Relevant answer
Answer
Recalling my statement in the discussion that "all objects and events on Earth and in space-time are just one thing - ... like the objects in a computer image seeming to be a lot of separate objects but really just being one thing (strings of binary digits)".
If this is true, your consciousness and mine could exist forever since it isn't merely connected to the brain inside our heads at this moment. It's connected to all the space and time in the universe.
I also believe the universe has always existed and always will. So you and I not only could, but would, live infinitely long after the bodies we're in reach their expiry dates and infinitely long before conception.
Why has nobody returned after death to give us proof of this possibility? I think it may be that eternal life only exists as a result of what happens during this Earthly portion of our lifetime. Those who have "died" can never risk coming back to tell us about life after death because we'd then become complacent and would lose incentive to cause eternal life to come into existence. It'd be strict non-interference with civilization's progress ... if you like, obeying the Prime Directive which Star Trek brings to our attention.
I know these ideas go far beyond medical practice and physics as they're presently understood. But that doesn't automatically make the ideas wrong (look in history books - all sciences have often adopted changes).
  • asked a question related to Quantum Gravity
Question
9 answers
Quantum information theory suggests out of probabilistic information we only get definate information, if so then anything around is should also be definate due to the classical gravity iff quantum gravity influence quantum measurement.
Relevant answer
Answer
"Collapse of the wave function" is a strictly nonrelativistic phenomenology because of its inconsistency with relativity (simultaneous collapse in the whole space). It cannot therefore be relevant to quantum gravity by definition. A consistent relativistic quantum measurement theory is yet to be developed, but this is a totally different matter.
  • asked a question related to Quantum Gravity
Question
3 answers
I would like to know what you think of this theory
Relevant answer
Answer
The gravitational field is formed at the quantum mechanical level. They are connected, like a sheet of paper - tends to 0 across, and along - tends to infinity.
  • asked a question related to Quantum Gravity
Question
17 answers
I am stuck between Quantum mechanics and General relativity. The mind consuming scientific humor ranging from continuous and deterministic to probabilistic seems with no end. I would appreciate anyone for the words which can help me understand at least a bit, with relevance.
Thank you,
Regards,
Ayaz
Relevant answer
Answer
I suspect that the reason you struggle with quantum mechanics is because of quantum foundations, which are the most interesting and intractable problems in quantum mechanics. You can read an overview here.
Here is an overview of the difficulties in devising a theory of quantum gravity.
The most successful attempt at quantum gravity is superstring theory. Here is a good introduction.
If you have further questions, you can email me at jeffery_winkler@mail.com
  • asked a question related to Quantum Gravity
Question
4 answers
I think the chaos applies to all theory because chaos existed in classical physics itself so the chaos should exists in quantum and relativity
Relevant answer
Answer
No-because chaos is known as a property of classical systems; so it doesn't have anything to do with providing an obstacle for quantizing gravity, i.e. finding the quantum theory, whose classical limit is general relativity. The obstacle to that, rather, is finding the-qantum-degrees of freedom that can resolve the singularities, that appear in gravitational collapse.
  • asked a question related to Quantum Gravity
Question
12 answers
I wish, I could be agree with is paper or the book. As we know, the building block of universe is quantum mechanics remark. in addition we know atoms are very organized entity, and that should not be a theory. I call an atom intelligent element, and any intelligent element is following nature of that specific environment, which they are temperature, pressure. Therefore, an atom is made of very large number of Intelligent Quantum mechanics Constituent Elementary Particles.
Relevant answer
Dear Prof. Fardei,
To prove our YangMills Theory we need Vector Gauge Bosons so we need Higgs-Mallick field and Science.
S.K.Mallick,
for S.K.Mallick, S.Raychaudhury, S.Mallick and others
IAS & RHMHM School
  • asked a question related to Quantum Gravity
Question
21 answers
It is known that Higgs mechanism is right but the theory does not fully explain mass and gravitation (see for instance http://www.higgs-boson.org/).
In the meantime, there is a rather old paper by M. Consoli where he tries to make connection between Newtonian gravity and Higgs condensate (Url: http://cds.cern.ch/record/404050/files/9910372.pdf).
Another paper by Paul S. Wesson suggests a connection between scalar field 5D gravity and the Higgs field of particle physics. See http://arxiv.org/ftp/arxiv/papers/1003/1003.2476.pdf.
For more recent reference, see for example Dejan Stojkovic (http://arxiv.org/abs/1305.6960) who discusses implications of the Higgs discovery for gravity and cosmology. The abstract goes as follows: "The discovery of the Higgs boson is one of the greatest discoveries in this century. The standard model is finally complete. Apart from its significance in particle physics, this discovery has profound implications for gravity and cosmology in particular. Many perturbative quantum gravity interactions involving scalars are not suppressed by powers of Planck mass. Since gravity couples anything with mass to anything with mass, then Higgs must be strongly coupled to any other fundamental scalar in nature, even if the gauge couplings are absent in the original Lagrangian."
So do you think it is possible to explain gravitation from Higgs boson? If yes, then how? And are there experimental supports for it?
Relevant answer
Answer
Dr. Assam Mohanna
All what you said in your last comment is standard knowledge since the beginning of the past century. Most of Einstein’s discoveries have been confirmed by experimental observations. However, the experimental observations also have disclosed impasses that, although not disproving relativistic effects, demonstrate that some fundamental assumptions and postulations in the construction of the TR are groundless. In my mentioned article, these problems are discussed in profundity and amendments are suggested that, besides entailing the observed effects of the TR, appoint their exact physical origin.
Would be a pleasure to discuss with you specific points of my article or of your works.
  • asked a question related to Quantum Gravity
Question
1 answer
A metric at the most has 10 degrees of freedom. How do you show the same from the metric in Newmann-Penrose formalism?
Relevant answer
Answer
A metric doesn't have at most 10 degrees of freedom-it has exactly 10 degrees of freedom.Just that many of them are redundant, they're gauge artifacts.
The Newman-Penrose formalism doesn't change this, of course.
This is a homework problem, whose solution is known-it suffices to write down the metric in that formalism: http://www.phys.ufl.edu/courses/phz6607/fall08/AA_Newman-Penrose%20Formalism.pdf
  • asked a question related to Quantum Gravity
Question
6 answers
There is a plenty of examples of classical solutions to low-energy effective theories that were proved to have vanishing α'-corrections to all orders and hence be also perturbatively exact string solutions in the literature, see e.g.
Since in all the literature I'm familiar with, the proof of α'-exactness of leading-order solutions relied heavily on the fact that the corresponding spacetime metric admits a covariantly constant null Killing vector, I'm currious if this is always the case.
Is anyone aware of some paper which proves α'-exactness for leading-order solutions beyond those with spacetime backgrounds admitting a covariantly constant null Killing vector?
(I'm aware of the fact there are also different approaches in finding exact string solutions that do not relly on proving α'-exactness of leading-order solutions and hence may yield exact string backgrounds with no covariantly constant null Killing vectors but the present question is focused strictly on this approach.)
Relevant answer
Answer
Stam Nicolis So, your problem with my question lies in the terminology I used - correct? Specifically, is it the term "string solutions", by which I mean solutions of effective field equations for the background fields?
  • asked a question related to Quantum Gravity
Question
3 answers
I am aware that Prof Subramanian Chandrasekar did considerable work on eqilibrium configuration of bodies (including rotating) under gravitational potential. Has this / Could this been applied to the Strong Nuclear Force which is also attractive though of a different form (and scale) and the attractive EM force (possibly repulsion could be handled by symmetry ??) ? Could this have connections to Quantum Gravity / Solitons / Self-focusing under a combination of forces etc ?
Relevant answer
Answer
  • As far as my understanding goes quantum mechanics is nothing but Fourier Analysis plus some tricks to remove the infinities. As a result I think your (@Sundaram) main spirit is ok. However one needs to be careful about some names of subjects. There is a mess in the language used in Theoretical Phys today as clear from some discussions on the perceived connection of supergravity and positive mass theorem regarding the recent breakthrough prize. It is a challenge to write physics without misusing the word quantum or other high sounding words. Otherwise the problems you cited are on solutions of PDE's only. Essentially the present situation is due to lack of interdisciplinary studies. People who are experts on PDE are usually not much exposed to quantization and vice versa. So two representations of the reality are developing in parallel although one has serious problems with infinities.
  • asked a question related to Quantum Gravity
Question
126 answers
It is sometimes good to examine the progress in science, even for the most passionate topics such as quantum gravity
Relevant answer
Answer
Sergey
Im tired about this bla that the external world does not exist except of information about it.(ie. what you say about particles)
Information does not just generate itself spontaneously.
In any case you talk about philosophy, not about physics.
Maybe you can discuss what limits the information you can have, might be more productive.
Bell understood very well what is SR, and has written about it.
  • asked a question related to Quantum Gravity
Question
2 answers
This paper of mine cites evidence of Gravity in works in the He-2-4 Geometric Model.
It has taken me 20 years of chase of Truth to understand these things and Gravity was one of the most complex topics. Equally complex was understanding the Strong Force. The work on He-2-4 took 2010 to 2017 of constant thinking of the problem after I hit this mysterious nucleus using simple arguments of symmetry of 3 Fields: Electric, Magnetic and Space (Ether) Fields.
He-2-4 is the most abundant, most stable, most symmetry and mother nucleus to the rest of nuclei, except H. It also explains why Noble gases are stable and why some nuclei are Radioactive.
We find the tell tale signs of Gravity through the gradient of mass-density observed in the He-2-4 Geometric Model that enabled us to calculate its mass accurately in 2 different ways using the Energy Partition Theorem and Equivalence of Energy Principle. The model satisfies Quark and QCD models and uses the same QCD quanta unit which Yukawa derived. It also satisfies the Nature's CCP Packing, Thomas Problem of distributing charges, and Vector Equilibrium.
Relevant answer
Answer
Dear Sunil,
Your model of He-2-4 is very original. May be, it is too complicated. Nature is perfect in its simplicity. If you will have some free time, please look at the book "Electromagnetic Gravity. Part 1" in my profile. In my opinion alpha-particle contains two protons and two neutrons. I draw it - look at the picture, please.
Yours
Valeriy Pakulin
  • asked a question related to Quantum Gravity
Question
10 answers
Einstein tired to construct EM force as an aspect of geometry.
while i am constructing a theory of quantum gravity i tried so many ways. EM force as an aspect of geometry is one of them.
i am requesting to unique scholars to discuss about this.
Relevant answer
Answer
Dear shs hussainsha, thanks for your invitation.
My viewpoint on your question is:
Electromagnetic force doesn't exist. Gravitational force and electrostatic force exist and they don't have geometrical nature but physical nature.
  • asked a question related to Quantum Gravity
Question
6 answers
Greetings,
Completing Bachelors in Engineering this June'19, I thought I'd start with Masters/PhD in Gravitational Physics this fall but I received rejections from almost every graduate school I applied to. To where I received an offer from, I won't be able to pay off the tuition fees.
Of course I knew that to receive an offer, one needs to have some experience with the subject. With the engineering curriculum on one hand, I tried to manage my interests in gravity. From watching lecture videos by Frederic Schuller and Leonard Susskind to reading books by Sean Carrol and to even doing a summer research internship on black hole geometries, I tried to gain experience on the subject.
I wish to understand relativity from a mathematical point of view.
" A good course in more abstract algebra dealing with vector spaces, inner products/orthogonality, and that sort of thing is a must. To my knowledge this is normally taught in a second year linear algebra course and is typically kept out of first year courses. Obviously a course in differential equations is required and probably a course in partial differential equations is required as well.
The question is more about the mathematical aspect, I'd say having a course in analysis up to topological spaces is a huge plus. That way if you're curious about the more mathematical nature of manifolds, you could pick up a book like Lee and be off to the races. If you want to study anything at a level higher, say Wald, then a course in analysis including topological spaces is a must.
I'd also say a good course in classical differential geometry (2 and 3 dimensional things) is a good pre-req to build a geometrical idea of what is going on, albeit the methods used in those types of courses do not generalise. "
- Professor X
^I am looking for an opportunity to study all of this.
I would be grateful for any opportunity/guidance given.
Thanking you
PS: I really wanted to do Part III of the Mathematical Tripos from Cambridge University, but sadly my grades won't allow me to even apply :p
Relevant answer
Answer
There are two sides to your problem: the practical and the ambitional. You will have to look after both. Recognize the practical issues but don't let go of your ambition. You may have to get a temporary job just to live, but that does not mean you give up on your dreams.
Your problem is not unique and has been overcome by famous scientists. Faraday started working for a bookbinder and ended as a revered scientist. His personal drive got him through. Dirac got a first degree in electrical engineering and ended as a revered theorist. Einstein worked early on in a Patent office and ended as a revered theorist. Other examples can be found, such as Ramanujan. Now there's a great example of talent beating disadvantage. So you see, it's not the end of the world if there are practical difficulties in your way at this time in your life. If you keep your spirits high, focused on what really interests you, you may succeed. It may be very hard, but don't give up.
You should understand that training is not enough. You have to practice being creative. Some people on this forum will probably disagree with the following suggestion, but have a go at writing a paper on a novel topic and seeing the reaction. It may take time to find a problem that you can work on, and you may very well get rejection. But having a go will teach you more than doing a lecture course on analysis. Papers do not all have to be in quantum field theory or relativity. Go on the arXives and see what sort of topics are viable for you. Most likely, at this stage, it might be in the General Physics section. But at least you might start from there.
Good luck in your ambition. Never give up.
George Jaroszkiewicz
  • asked a question related to Quantum Gravity
Question
14 answers
The classical limit of loop quantum gravity is Einstein-Cartan theory (EC), not general relativity (GR). I would like to know whether the other main approach to quantum gravity - string theory - also has as its classical limit EC, with torsion and the spin-torsion field equation. Or is its classical limit GR or something else?
At the April APS meeting:
(a) I attended a presentation on a loop quantum gravity model of the origin of cosmic inflation. I asked the researcher what quantization contributes to the model, compared to just using classical EC (which causes inflation-like expansion). The presenter thought the classical limit of loop quantum gravity is GR.
(b) A researcher at a major university told me that the Hamiltonian and other mathematical properties of EC as so much superior to those of GR that they do all their theoretical research based on EC and not GR.
Is EC quietly displacing GR as the foundation of quantum gravity research, and do some of the researchers not recognize this is happening?
Relevant answer
Answer
Dear Stam,
The continuum limit may be unnecessary for someone like you who sees EC as a modest extension to GR that enables modeling exchange of intrinsi and orbital angumar momentum (and improse some other things like elminating some singularities from GR).
However, I believe 99% of the graviational researchers (maybe 99% of researchers ove age 40) dont' accept this point of view. For them, the derivation of translatonal holonomy from a single Kerr mass and the continuum limit of distributions of Kerr masses might, just might, ignite a flame insight, or at least respect.
As an example of the problem, in January 2019, I submitted a slightly edited version of " to Phys Rev D, after trying CQG And GRG journals in the past year or two. I have appended the vebatim referre report below, and my response. Every sentence of the review after the first one is unmitigated horsefeathers.I have been on this case for 30 years, and I know what passes for competence out there.
The editor's response was brief: he stands by the original review.
Planck wrote: “A new scientific truth [that alters the elements of a field] does not triumph by persuading its opponents and making them see the light, but rather because its opponents eventually die, and a new generation grows up that is familiar with it.”
--Max Planck, “Scientific Autobiography and Other Papers,” 1949, p 33-34.Quoted in “The Structure of Scientific Revolutions,” by Thomas Kuhn, 4th edition, 2012, p 150.
I would prefer that someone who sees the light like you would help to get this into the mainstream.
Referee report from Physical Review D (verbatim)
The aim of the manuscript is to derive Einstein-Cartan theory form General Relativity by showing that in some GR configurations involving a distribution of Kerr black holes, there exists torsion using the concept of "translational holonomy." It is not at all clear what "translational holonomy" is supposed to be. The usual holonomy that defines curvature (what the author calls rotational holonomy) has the structure that it does precisely because torsion cancels. Therefore, I do not see how one can "derive" torsion when none existed in the first place. Moreover, the configuration that the author uses to "prove" this is not a stationary configuration as the Kerr masses will feel an attractive force with respect to one another.
My rebuttal
The first sentence of the review correctly states the most important claim of the work.
1) “It is not at all clear what ‘translational holonomy’ is supposed to be.”
The concept of holonomy is defined in references [1] page 87 and [2] page 71.
Translations are not treated the same as rotations in spacetime gauge theory. The root issue is that the geometric structure group (symmetry group) of GR and EC is the semidirect product of the Lorentz group and translations (which has a fixed origin point), not the Poincaré group (which has no preferred origin point). See [3] page 128 for a rather abstract statement of this positon. Therefore we must modify the definition of holonomy for translations.
The definition and construction of translational holonomy is discussed in the manuscript in sections 3.1 and 3.2.
I have provided a brief intuitive description of translational holonomy in section 3 of this document.
2) “The usual holonomy that defines curvature has the structure that it does precisely because torsion cancels.”
This statement is false in Riemannian geometry and in RC. It is a denial that RC can exist.
I believe the referee has in mind the derivation of Riemannian curvature by constructing a piecewise almost–closed loop from four geodesic segments. In this construction, the “failure-to-close” vector is generally nonzero for finite loops. The quantity that vanishes is:
limit[t → 0] (failure-to-close vector)/t^2 = 0.
The manuscript uses only closed loops, in which the “failure-to-close” vector is by definition zero. It use no geodesics.
In RC, my derivations of rotational curvature from rotational holonomy and of translational curvature (affine torsion) from translational holonomy work fine. See manuscript section 3.2. “Definition of curvature in terms of holonomy.”
(manuscript equation 3) limit[t → 0] (rotational holonomy)/t2 = rotational curvature
(manuscript equation 4) limit[t → 0] (translational holonomy)/t2 = translational curvature = torsion
3) “I do not see how one can ‘derive’ torsion when none existed in the first place.”
The disruption of ordinary geometry (singularity?) inside each Kerr mass makes this possible, just as the core of a dislocation in a crystal enables torsion to exist around a dislocation, when there is none in the lattice outside the dislocation.
4) “The configuration that the author uses … is not a stationary configuration…”
This referee’s statement is true. However, non-stationarity does not invalidate the result, any more than the non-stationarity of cosmological solutions in GR, invalidate GR.
The manuscript (constraint m << r in Table 2 in section 5.1) states that the present computation is valid only if the distance between Kerr masses is sufficiently large.
Here is why non–stationarity does not invalidate the results in the manuscript.
a) My configuration of Kerr masses starts with zero relative velocity. Therefore a finite time interval will pass before the attraction causes the Kerr masses to get so close that the computation requires additional terms. Throughout this time interval, translational holonomy (before the continuum limit is taken) and torsion are present.
b) We can do the computation in an expanding universe, so the torsion appears before the configuration begins to contract. I did not do this computation because argument (a) is adequate, and because adding expansion would make a complicated computation more complex.
5) Definition of translational holonomy
This definition applies to structure groups that are inhomogeneous linear groups (groups that include translations).
5.1) Development of curves
“Development of a curve” is defined in section 3.1 of the manuscript. See also references [1] page 98 and [2] page 131.
The rationale for development of curves is to distinguish the influence of manifold geometry and acceleration of a curve.
5.2) Definition of translational holonomy in terms of development of curves
Section 3.2 of the manuscript contains a theoretical and procedural definition of translational holonomy in terms of development of curves into Euclidian space.
The basic idea is to develop a spacetime loop into a Euclidean space, and use the “failure-to-close” vector of the “almost–closed” loop in Euclidean space to define the torsion translation in spacetime.
6. References
1. Geometry of Manifolds, 1964, by Richard J. Bishop and Richard L. Crittenden, Academic Press. For physicists, I recommend [1], which is more geometrical and intuitive, over [2] which is more abstract.
2. Foundations of Differential Geometry, vol 1, 1963, by Shoshichi Kobayashi and Katsumi Nomizu, John Wiley and Sons.
3. Transformation groups in Differential Geometry, 1972, by Shoshichi Kobayashi, Springer Verlag.
  • asked a question related to Quantum Gravity
Question
8 answers
can anybody explain what is erik verlinde's emergent gravity in a layman words rather than giving links?
Relevant answer
Answer
Since entropy is an emergent property so it seems entropic gravity should not be able to describe gravity beyond certain scale
  • asked a question related to Quantum Gravity
Question
13 answers
The topological abroach on the space-time dimension and also the differential geometry of the transitor and also quantum gravity as the new approach in unifying all force of nature into one equation that really describe the vibrating string of the quantum mechanics...THIS THE APPROACH WHICH MIGHT CHANGE THE SCIENCE OF OUR CENTURY PEOPLE!!!
Relevant answer
Answer
Hello everyone,
You are right, but you are also partly wrong.
You can write an equation at all, as long as it is describable in two ways: time-dependent and time-independent, much like Heisenberg's equation.
Finally, and more simplistically, an equation can have several parts, separated from each other by the + operator. Thus, one can imagine an equation of all including the fundamental laws of dynamics, generalized gravitational and magnetic forces etc ...
Finally, a generalized equation must necessarily be tensor, as is the Einstein equation. Such an equation, when solved in some particular cases, would "shrink".
For example, imagine:
Equation of the whole = tensor Generalized electromagnetic interaction + tensor generalized gravitational interaction + tensor strong interaction etc ....
If we have to solve it in the case of the fall of an object, taking into account that its acceleration of terrestrial gravitation as well as a Newtonian space time, we would have first of all:
(free fall case) Equation of the whole = generalized gravitational interaction tensor
The fields of interactions and other elements are null, only the gravitational interaction is maintained. Then it was solved in a relativistic case. This gives :
(case freefall) Equation of all = Einstein's tensor
Finally, we ignore the limit speed of light, it has been solved in the context of Newtonian gravity:
(free fall case) = Poisson equation
Finally, we can write it in the more well known Newtonian form:
(free fall case) Equation of all = Newtonian gravitation
My explanation here only reflects an idea. It is by no means rigorously mathematical.
Finally, a theory with two temporal dimensions seems to me far too complex to interpret. If there are two "times", are they different from each other? Do you rely on the theory of double causality? Please, explain your theory.
Regards,
BAUDRIMONT Roman
  • asked a question related to Quantum Gravity
Question
2 answers
Relevant answer
Answer
I would be interested to know if this can be generalized beyond the local system, to a scope from probability density function, which also fits with Hamiltonian-Jacobi theory. I'm among a minority who are not convinced of photon energy loss in GR .
  • asked a question related to Quantum Gravity
Question
3 answers
On dark matter, dark energy and the Chinese Go model of cosmos evolution
Abstract
In addition to the known universal gravitation,electromagnetic interaction,strong interaction and weak interaction,there are three basic interactions in nature,and there are three kinds of mediated mesons,one of which forms dark matter together with neutrinos,and the other two kinds of mediated mesons forms dark energy together with photons,which are based on this basis,This paper describes the Chinese Go model of cosmos evolution。
Keywords
Special relativity;dark matter; dark energy; cosmos evolution; Chinese Go; general relativity;Supermassive black hole;Sight; gravitational wave;Cosmological constant
***************************************************************
8. Discussion
Anthropic Principle requires that the Medium quality black hole and the supermassive black hole explode in a way that does not release huge amounts of energy in the galaxy like a supernova explosion (stellar seed). The Chinese Go model of cosmos evolution requires that supermassive black holes cannot be universally born from the stellar mass black hole s and Medium quality black holes by the original way of annexing stellar matter, or just like the evolution of the origin of life,once a supermassive black hole is born in the original way in a galaxies with relatively few dark matter microphoton, it will spread to the universe through a process similar to the division and genetic variation of living cells. The universe is infinite. In a corner, through the violent collision between supermassive black holes, can or can not let a supermassive black hole core“cosmic egg”(a ascending generation transition shell, a Photino cavity, and a changesphoton cavity)appear big bang of metric tensor (analogous to inflationary theory of Alan Guth, numerical drastic change of Λ ), and so on.
Relevant answer
Answer
No. Black holes describe future singularities, cosmology describes past singularities.
Black hole metrics-like any metric-are written in some coordinate system and they don't have any physical significance themselves, anyway. As solutions to Einstein's equations, they can be changed by general coordinate transformations, that map one solution to another solution.
  • asked a question related to Quantum Gravity
Question
12 answers
From my research on Quantum Gravity, I have found out that there was many attempts to write the best theory by changing our interpretation of Quantum Physics. This change in interpretation has impact on our mathematics too, which is interpretation free.
In the history of physics, we had lots of interpretations those now we consider them wrong. In my view PMI is constructed on those kind of interpretations.
Is not the time to abandon interpretations of Quantum Physics for good?
Relevant answer
Answer
Theory needs reformulation when it is not able to interpret and explain the observed behavior of the objects that would be subjected to such theory.
For example the Rutherford atomic theory that was not able to interpret the spectrum emission of the atoms when they excited.
This may be a very simple view of the raised issue.
People changes the theoretical formations when they fail to interpret their observations using such formulations. On the other hand the strength of a theoretical is that can correctly interpret the observed behavior of the intended objects. As a human language formulation and due to limited time and space of the observations the theoretical formulations have their limitations in the application domain of time and space.
Best wishes
  • asked a question related to Quantum Gravity
Question
4 answers
In other words, if you project the ten-dimensional space of string theory onto a four-dimensional space-time, is the resulting space-time, which will have an uncertainty principle in the coordinates at the Planck scale, accurately represented by a spin foam?
Relevant answer
Answer
I don't enjoy the aggressive tone used by many contributors to blogs on RG. I believe that people who know me do not blame me to be arrogant; and I don't think that I am particularly stubborn. I actually only try to sometimes comment on questions. People who do not like my comments are not obliged to study them! I am retired, and I do not have to make a career, anymore. But sometimes I am still thinking about science, and I am interested in upholding intellectual honesty. (There are no benefits to be gained from kidding oneself into believing that certain problems are understood or, at least, promise to be understood, soon, when they are very poorly understood.)
  • asked a question related to Quantum Gravity
Question
8 answers
Couldn't you create a quantum theory of gravity simply by using the energy-momentum tensor of QED or the Standard Model or whatever in Einstein's field equations without specifically or explicitly "quantizing the gravity 'field'"? Surely this has been tried. If so, what turned out to be the problem with it? Could you provide me with references to the literature (primary or secondary--I tend to do better with the secondary literature)?
Relevant answer
Answer
Hi Stuart
Below please find a few contributions which may interest you:
Quantum gravity: a geometrical perspective - Ivano Tavernelli
Unified Classical and Quantum Mechanical’ Gravity - Partha Ghose
Curvature dependence of quantum gravity - Nicolai Christiansen, Kevin Falls, Jan M. Pawlowski, and Manuel Reichert
Testing Quantum Gravity Johan Hansson and Stephane Francois
The most interesting in reading many of the articles that appear in hep-inspire is that there are many researchers following the path of building and developing conventional quantum mechanics. There are many articles with titles and mention to old authors and researchers and proposals of historical relevance in the development of conventional quantum mechanics. It's like revisiting history from a new perspective. It's worth reading. The authors above, I do not know them, but they were selected by me because their works have points of contact with your inquiries. Good reading.
  • asked a question related to Quantum Gravity
Question
1 answer
Horava-Lifshitz gravity has proven to be a mathematically consistent framework for a quantum theory of gravity with several interesting applications, however, in the other hand, it has certain physical limitations (just like any other quantum gravity theory does). What are the perspectives of this theory?
Relevant answer
Answer
Currently, the scale invariant Horava-Lifshitz gravity is being realized as a dynamical Newton-Cartan geometry as well as a non-relativistic tensor calculus in the presence of the scale symmetry. The connection with the RG flow is interesting. A rigorous proof of its renormalizability is not done yet.
  • asked a question related to Quantum Gravity
Question
1 answer
What is meant by gravitational degrees of freedom?
Relevant answer
Answer
In general relativity, the physical states are described by isometry classes of solutions of Einstein’s field equations. The resulting space of the totality of these states on a 4-dimensional manifold is the space of gravitational degrees of freedom.
  • asked a question related to Quantum Gravity
Question
16 answers
"I thought about quantum mechanics a hundred times more than general relativity, but I still don't understand," Einstein said.
Perhaps the most difficult to understand is the wave-particle duality, which may be because the understanding of it is only in the form of mathematics.In fact, no one can actually verify the wave-particle duality, because the experiment can't verify a single photon.
Electrons orbiting the nucleus of the cycle and the volatility of the particles there are closely linked, we can think of chemical bonds between atoms and atomic are fluctuating, at a certain moment because electronic is only a position on the orbit, and from the time a constantly changing position, the this kind of change has the regularity.When two atoms of electrons near each other, two atoms repel each other, and when electrons in an atom near the nucleus of another atom when they will attract each other, so that can form regularity of volatility.
Inner surface cracks in the double-slit experiment of atom has been in a regular wave conditions, when the particle is trying to through the gap, when near the atom will be fluctuations in the perforated of atomic bomb, a reflection of photonic and electronic electromagnetic ejection in such a state of regular fluctuations, as the accumulation of time and the number of regular interference fringes are formed.The smaller the momentum of a particle is, the larger the Angle of the ejection is, the greater the spacing of the stripes, the longer the wavelength is.
Electronic counter near the double slit to observe, emitting a large number of photon hits the aperture inner surface of atoms, and makes the surface atomic wave interference, can be seen as inhibits such a state of regular wave, the particles will no longer through double slit by regular reflection and ejection, which in turn has emerged two bright stripe.
This is why increasing gap width will not cause interference and diffraction, because of the emitted particles and gap edge contact and collision probability becomes a matter of fact interference and diffraction and crack width, crack of fluctuations, particle momentum, launch position and the Angle of aperture.
Relevant answer
Answer
No there isn't. All this is understood and taught in physics courses, so it would be useful to actually study quantum mechanics, instead of trying to guess.
These lectures: http://www.feynmanlectures.caltech.edu/III_toc.html might be a good place to start.
  • asked a question related to Quantum Gravity
Question
164 answers
Hawking's Legacy
Black hole thermodynamics and the Zeroth Law [1,2].
(a) black hole temperature: TH = hc3/16π2GkM
The LHS is intensive but the RHS is not intensive; therefore a violation of thermodynamics [1,2].
(b) black hole entropy: S = πkc3A/2hG
The LHS is extensive but the RHS is neither intensive nor extensive; therefore a violation of thermodynamics [1,2].
(c) Black holes do not exist [1-3].
Hawking leaves nothing of value to science.
REFERENCES
[1] Robitaille, P.-M., Hawking Radiation: A Violation of the Zeroth Law of Thermodynamics, American Physical Society (ABSTRACT), March, 2018, http://meetings.aps.org/Meeting/NES18/Session/D01.3
[2] Robitaille, P.-M., Hawking Radiation: A Violation of the Zeroth Law of Thermodynamics, American Physical Society (SLIDE PRESENTATION), March, 2018, http://vixra.org/pdf/1803.0264v1.pdf
[3] Crothers, S.J., A Critical Analysis of LIGO's Recent Detection of Gravitational Waves Caused by Merging Black Holes, Hadronic Journal, n.3, Vol. 39, 2016, pp.271-302, http://vixra.org/pdf/1603.0127v5.pdf
Relevant answer
Answer
Well, to put it on a more concrete foundation, here's my view on his scientific achievement, not exhaustive, as I don't think I am entitled to judge on Hawking's scientific legacy.
His works on black hole theory are from about 50 years ago, and I would consider the singularity theorems he proved together with Roger Penrose quite the highlight of his scientific career. In a nutshell, what they say is that black hole creation takes place under very general conditions in space-time and is a necessary consequence of ART, and does not require very special, e.g. highly symmetric conditions.
With his work on Hawking radiation from teh mid-70s he applied semiclassical analysis to ART which paved the way to a more thorough treatment of quantum field theory on curved space/spacetime.
Although his scientific highlights might stem back from the 60s and 70s, I would nevertheless stress that his legacy surely comprises all that he did as an ambassador to science, as it seems. He surely was someone who gave inspiration to at least a complete generation of scientists many man years ago, his publicity starting to spread with the little booklet he wrote end of the 80s: "A Brief History of Time". I would never underestimate the importance of lighthouse figures like him with this regards, even though the hard-core scientific hightime had then already been past.
  • asked a question related to Quantum Gravity
Question
41 answers
In the Quantum Mechanics, the origination and essence of the spin angular momentum remain a mystery. Recently some viewpoints are in the violent competition.
The first viewpoint deems that the spin angular momentum is intrinsic, and is a quantum property without detailed classical analogy [Copenhagen interpretation]. Of course, not everyone accepts the idea.
The second viewpoint argues that the spin angular momentum is not intrinsic, and is merely the property of wave-field [F. J. Belinfante, “On the spin angular momentum of mesons”, Physica, 6 (7-12) (1939) 887--898. H. C. Ohanian, “What is spin?” Am. J. Phys., 54 (6) (1986) 500--505.], which is independent of the internal structure of particle.
The third viewpoint considers some suppressed precessional motions as the spin motions. In the complex octonion space, the precessional equilibrium equation infers the angular velocity of precession. The external electromagnetic strength may induce a new precessional motion, generating a new term of angular momentum, even if the orbital angular momentum is zero. This new term of angular momentum can be regarded as the spin angular momentum, and its angular velocity of precession is different from that of revolution. [“Spin Angular Momentum of Proton Spin Puzzle in Complex Octonion Spaces”, International Journal of Geometric Methods in Modern Physics, 14 (6) (2017) 1750102. “Two different types of precessional angular velocities in the complex-octonion space”, April, 2017]
Furthermore, there may be certain other viewpoints. Undeniably these different viewpoints violate the physical model of spin angular momentum. And these conundrums will intrigue and faze some scholars continually.
Relevant answer
Answer
Dear Zi-Hua Weng,
Unfortunately, I discovered your interesting question on the various explanations of particle spin only now. There is a long article "Stochastic Foundation of Quantum Mechanics and the Origin of Particle Spin" which I published together with a colleague in arXiv: 0912.3442. We explain in detail where the particle spin comes from and how this explanation leads to the non-relativistic Pauli-equation and further to the Dirac-equation. The upshot is that spin has definitely nothing to do with a rotation of the particle about its axis -- in agreement with the objections of H.A. Lorentz which he raised when Goudsmit and Uhlenbeck explained to him their idea of the electron as a rotating top.
Lothar
  • asked a question related to Quantum Gravity
Question
20 answers
i developed concept related to Gravitational waves in which quantization of Gravitational wave can be done similar to light waves or EM waves...
energy of Gravitational waves comes in discrete packets called g-quanta....
E = If
where, I = constant similar to plancks constant.
f= frequency chirp of Gravitational waves.
welcome for your valuable comments...
Relevant answer
Answer
The sources of gravity are quantized. So gravity is quantized. Theories don't seem to capture the physical reality. From Feynman the graviton is postulated to have a quadrupole moment but no dipole moment.
For a long time it was thought that a graviton could be produced by combining two electromagnetic dipoles. More recently the dipoles have been demonstrated with their interference pattern to be producing a curl free vector potential of kinetic energy which passes through shields and barriers and is detected in a Josephson Junction.
Gravity field is usually represented as potential energy. Moving of a Graviton implies kinetic energy which occurs in this question. Theories don't reconcile the difference. Maybe the Graviton does exist as a field component of localized stress energy like a set of quantum states which satisfy the requirement of potential energy.
  • asked a question related to Quantum Gravity
Question
29 answers
What is a theory of everything?
“A Theory of Everything is literally a theory of everything, including the force of gravity (which is not described by the standard model or a GUT), and anything else in our universe that our current theories cannot explain. One of the main ingredients in a "theory of everything" is Quantum gravity, the unification of gravity (general relativity) with quantum mechanics (quantum field theory). We do not yet have a successful theory of quantum gravity. A GUT is also a necessary ingredient of a theory of everything, but only if a GUT exists”. [1]
Solution the problems of GUT and a Theory of Everything:
It may be thought that these two problems are separate of each other, but both problems; GUT and the Theory of Everything has a common root. Therefore, the solution of each of them includes another solution as well.
A. The solution of GUT: if we describe the mechanism of the virtual photons production (electromagnetic force carrier) by charged particles, then we will see that electromagnetic repulsive force in a very short distance, turns to the attractive force, then the GUT problem can be solved. In this way we will reach to unify the electromagnetism and gravity that is the Theory of Everything. [2]
B. The solution of the Theory of Everything: to get understand the Theory of Everything, we must re-define fundamental particles. In CPH Theory, mass/energy and the amount of speed of fundamental particle must be constant and not turn into other particles. While in the Standard Model, fundamental particles have variable mass and speed, so they are not fundamental particles. To find fundamental particle we must reconsider and analyzed the interaction between photon and the graviton. In this way the GUT problem can be solved, too. [3]
Both of the above methods have been given in CPH Theory.
1 - Barak Shoshany's answer to What are the Grand Unified Theory and the Theory of Everything, and what is the difference between them?
2 - Hossein Javadi’s answer to What principle can potentially substitute 4 fundamental forces in physics? Is it the principle of least action?
3 - Hossein Javadi’s answer to Are massless Dirac fermions, as discussed in the literature of graphene, identical to Weyl fermions? If yes, from where does the name of massless Dirac fermions come?
Relevant answer
Answer
Dear Paul
Photon is the basic quantity of energy, it shows energy does not experience passing time. In the other word, time does not exist for energy or time is related to matter.
  • asked a question related to Quantum Gravity
Question
5 answers
Quantum gravity could be probed by entangled masses
Two separate groups in the UK; have proposed experiments that may for the first time reveal a link between the theories of quantum mechanics and general relativity.
In CPH theory, the graviton identity is changed and the information is transmitted by exchange color-charge (graviton with the new identity).
Connection between quantum gravity and entanglement
The Mechanism of Graviton Exchange between Bodies, Part II
e
Relevant answer
Answer
Interesting question. I want to learn more.
  • asked a question related to Quantum Gravity
Question
8 answers
Quantum gravity could be probed by entangled masses
I have described the relationship between quantum gravity and quantum entanglement, before. See:
Connection between quantum gravity and entanglement
Relevant answer
Answer
I will do my best.
  • asked a question related to Quantum Gravity
Question
19 answers
What is the possibility that I'll get a PhD job for research in String Theory and Particle Physics? I'm currently in my 3rd Year of Undergraduate Studies and have done research work in Photonics. Due to unavailability of faculty specialized in relativity, cosmology, particle physics etc., I chose to do research in Photonics. To manage my interests, I studied relativity, particle physics from online resources. What are the chances that I'll get a PhD job at institutes like Perimeter Institute of Theoretical Physics, Institute of Theoretical Physics, Stanford, Kavli IPMU etc.?
Relevant answer
Answer
Before you start investigating textbooks and study programs in fields of science, you should seriously contemplate whether you want to invest your life and talents in these areas.
The Standard Model of Particle Physics were completed in the mid-1970's. Try to explore which new, experimentally verified, ideas have emerged in the field of theoretical particle physics since then. Likewise, string theory was invented in the late 1960's and superstring theory during 1970's. Try to find out what these theories have contributed to observed physics.
The recent discovery of gravitational waves have opened new ways to explore cosmology and astro(particle) physics. This will hopefully lead to new insights and increased activity, both observationally and theoretically.
  • asked a question related to Quantum Gravity
Question
6 answers
I am investigating the thermodynamics of quantum gravity as part of my QG project. I want to find the quantisation energy of the intergalactic medium.
Relevant answer
Answer
@Andy Biddulph
The following paper might be helpul
  • asked a question related to Quantum Gravity
Question
9 answers
If on the way to quantum gravity there is some use in models simulating both the one-dimensional theory of relativity and quantum mechanics, why not consider the random walk model of a sailing boat along the surface of a torus. Could you share links on this topic?
Relevant answer
Answer
I can not write articles very much, but I fix all the details in the file of the book http://bayak.socionet.ru/files/principle.pdf
  • asked a question related to Quantum Gravity
Question
7 answers
Even though they say information is conserved, can information be biased at the first place?
Example:
Example 1:
Observer A and B saw a 10 *10 matrix. However, due to technique reason(for example, A was very short and B was tall enough) A could only say the last role, yet B was able to see all 10 rolls. Thus even the matrix was the same, A and B had different answers due to observation limits.
Example 2:
Observer A  and B saw a 10 character string 0101010101. However, A use the binary system reading and got 341, B use decimal reading thus got 101010101. Thus even the character string was the same,  A and B got different answers due to interpretation.
Example 3:
Observer A  and B was in a massive gravitational field near a black hole, yet non of them was aware of the situation. B was close to an object and observed it as a cube, A was far away from the field and the object and observed it as an "oval". Thus even the object was the same, A and B got different answers.
e.t.c.
That was, even though the observer agreed on the result/measurement, or agreed on the observation of the outcomes; can the information they preserved being biased towards each other?
Relevant answer
Answer
The statements aren't sharp enough for any conclusions to be drawn. The only quantities that are relevant in any observation, are those that are invariant under the transformations of interest-other quantities carry, by themselves, no information at all, in that sense. 
The examples aren't meaningful, since changing a mathematical representation, e.g. a base of counting, doesn't change the information content. 
The three examples lead to confusion, because they get known physics and mathematics wrong. 
  • asked a question related to Quantum Gravity
Question
29 answers
I have been working on a model of quantum gravity in which GR is formulated in the language of Quantum Mechanics .The latest version can be downloaded from the link below. Kindly peruse through to see if it meets the criteria of a  self consistent theory. 
Relevant answer
Answer
The statement that the description proposed has anything to do with quantum gravity is incorrect. The reason is that how a classical gravitational wave induces transitions between quantum states isn't under control. The transition amplitudes aren't ell-defined.
Insofar as the ``Nexus graviton'' is a solution of Einstein's equations, it is a classical background and doesn't imply anything about quantum effects.
  • asked a question related to Quantum Gravity
Question
212 answers
In order to start going into the topic, let us consider two alternatives. If we think that the photon dies out when absorbed then there is not much to talk about. However, if we consider the second alternative, lets us point out that in loosing its energy it becomes unobservable since our senses as well as all our apparatus need an energy transfer to achieve any detection.
So, if photons do survive after being absorbed they thus became ghost photons, i.e. invisible. Evidently this is problematic. But let us not dismiss so fast.
Let us make an imperfect analogy between a photon and a spring. If the spring vibrates it has an oscillatory energy. If it transfers its oscillatory energy to an external material it looses its energy, but the spring is still alive, it has not disappeared. Well, if you see the photon as an oscillator then the analogy makes some sense.
Let us address now a still more controversial issue. Let us suppose that if the spring is not stressed it has no strain mass. But if it is vibrating it has then just energy without having mass, and this analogically applies to the photon.
Well, let now consider the case of a stressed spring that is vibrating. It has then mass and energy. Again, analogically this applies to massive elementary particles.
Why should we appeal to very complicated models and theories? Is it really worthy?
Those interested in this viewpoint and willing to go deeper into this issue may read the paper: “Space, this great unknown”, available at: https://www.researchgate.net/publication/301585930_Space_this_great_unknown
Relevant answer
Answer
Dear Daniel.
How much credibility can we grant to theoretical physics?
It looks like you prefer to rely on the conventional theoretical physics, however the image that theorists are giving is not that much upright. Let me illustrate this.
In December 2015 an excess at 3.6 local sigmas was observed at 750 GeV in the difotonic channel (H → γγ), by pure chance, both in ATLAS and CMS (LCMF, Dec 15, 2015). This led to the publication of more than 600 theoretical articles in arXiv about the process (LCMF, Mar 22, 2016). Months later the excess disappeared (LCMF, 05 Aug 2016).
So, in a few months 600 theoretical articles were written justifying a fake event. What is therefore the credibility of mathematical issues in view that they can manage to justify an inexistent upshot?
Theorists should be more careful in “not throwing so many stones against the roof of their house”. Furthermore, “Publish or perish” may not be so wise after all and publishing compulsivity may have the opposite effect.
  • asked a question related to Quantum Gravity
Question
15 answers
What additional quantum number has the antiparticle that annihilate it? The sign of its Ricci scalar curvature in the non-Euclidean space-time?
Quantum gravity
Relevant answer
Answer
Dear Piero,
“…The vacuum is not actually, an empty entity like a container: the vacuum is not empty but it is more like a physical mean…”
“Physical vacuum”[or “Aether”], if it exists [and it exists with a great probability] isn’t the Matter’s spacetime. It  is a component of Matter, and, as the rest in Matter, exists and changes in the Matter’s [5]4D Euclidian spacetime, which is, in this sense, an “empty container”.
“…it has its own elasticity and other properties, and, moreover it has an implicit scale (see the attached paper) so that the classical self-similarity is a broken symmetry on small scale and the quantm behavir appears. So quantum mechanics come from the properties of vacuum...”
here I cannot make some rational comment, I was educated in experimental nuclear physics and we studied hydrodynamics on insufficient level for this case. However such claims as, for example, about the vacuum’s “own elasticity” seems can be as  some ad hoc suggestions, some guesses; which can be correct and can be not correct. Since nobody knows – what the physical vacuum is, indeed there is no other variants besides putting forward some suggestions, and testing them experimentally. So for some more convincing claims is necessary to wait corresponding experimental results.
Including “the classical self-similarity is a broken symmetry on small scale and the quantum behavior appears” isn’t, in certain sense [“ontologically”], correct. The quantum uncertainty appears because of that the absolutely fundamental notions/phenomena “a Change” and directly relating to Change “Time” are logically self-inconsistent, thus the states of  any/every changing material object/system of objects become be on some scale of changing uncertain – that was rigorously proven 2500 years ago by Zeno. However this principal uncertainty can be different in different dynamical systems, in the case of the system “Matter” it can be as some “broken symmetry”, but can have other realizations that can be introduced in physics in framework of some other approach also.
If the vacuum generates massive particles, how mass cannot be correlated to it?
that is again a non-evident assertion. For example in the informational model Matter’s spacetime is filled by an Aether that is dense lattice of primary fundamental logic elements, when particles appears if   some FLE is impacted with transmission to it some momentum. The result is creation of some closed-loop algorithm, that moves in the spacetime with the speed of light as a 4D helix, which has 3D projection as de Broglie wave, being at that some 4D gyroscope. The mass of a body is a measure of resistance of the body to change its motion; and in this case it is the resistance of the gyroscope to change its rotation rate vector’s direction and/or its absolute value. Again, the vacuum doesn’t “generate massive particles”, that make other particles, which have the energy value large enough at many types of interactions.
Cheers 
  • asked a question related to Quantum Gravity
Question
2 answers
https://en.wikipedia.org/wiki/Superfluidity: Superfluidity is the characteristic property of a fluid with zero viscosity which therefore flows without loss of kinetic energy. When stirred, a superfluid forms cellular vortices that continue to rotate indefinitely. Superfluidity occurs in two isotopes of helium (helium-3 and helium-4) when they are liquified by cooling to cryogenic temperatures. It is also a property of various other exotic states of matter theorized to exist in astrophysics, high-energy physics, and theories of quantum gravity The phenomenon is related to Bose–Einstein condensation, but neither is a specific type of the other: not all Bose-Einstein condensates can be regarded as superfluids, and not all superfluids are Bose–Einstein condensates
Relevant answer
Answer
Bose Einstein condensates held in an optical lattice have a superfluid regime, wherein the atoms are not localised to any particular well of the lattice. This can happen for compound bosons, that is particles for which the spins sum up to an integer. An example of these is lithium 7. Lithium 6 is a fermion and cannot do some of the same things because of the Fermi exclusion principle. Nevertheless, there are some aspects of degenerate fermion behaviour that can lead to them being considered as superfluids. Fermions are not my specialty, so I won't comment further.
  • asked a question related to Quantum Gravity
Question
8 answers
we will try to write matrices whose obeys to some algebra to describe the graviton. is that is possible? if your answer is no, why ? 
Relevant answer
Answer
"Can we write Dirac equation with replacing gamma matrices with others that we construct in the aim to describe graviton?"
Yes, it is possible (but not simple!). The Dirac algebra corresponds to spin-½. The Kemmer algebra corresponds to spin-1. The graviton (if it exists) would be a massless spin-2 particle. There is a general theory of “spin-s” field equations (see for example Corson’s book https://archive.org/details/IntroductionToTensorsSpinorsRelativisticWaveEquations.
investigated the spin 3/2 and spin-2 algebras.
  • asked a question related to Quantum Gravity
Question
6 answers
"Despite the great success of General Relativity in describing the physics of
the Solar System, there are still  puzzles left. When Albert Einstein introduced his theory of General Relativity in 1915 there were no measurements, which tested gravity on scales far beyond the distances of the Solar System.
As General Relativity was able to solve several problems like the gravitational bending of light or the precession of the perihelion of Mercury, it was quite natural to accept it as the standard theory for gravity.
But nowadays there is data from far more distant objects, like other galaxies or galaxy clusters. On these distance scales there arise several problems. For example the measurement of rotational velocities of stars or gas in galaxies differs very strongly from the expectation.
Thus, it is only possible to fit this behavior by invoking some unknown Dark Matter,
which interacts with the baryonic matter only via gravity or via the weak force, but not electromagnetically or strongly."
The conformal theory of gravitation seem to address to these issue in a more satisfactory way
Relevant answer
Answer
Equation of the gravitational field (12) is by no means stationary.
In the article two strict examples are given, they are in fact stationary. But one of them is a gravitational field.
Pay attention to section 6. Universe in new interpretation of general relativity theory and Fig. 6. Bubble growth on the basis of conservation laws. A new article describes the derivation of the field equation somewhat simpler. However, it has not yet been translated into English.
I spread the picture with a dynamic solution for the development of cosmic bubbles and the universe as a whole.
  • asked a question related to Quantum Gravity
Question
134 answers
It is said of general relativity that it has been experimentally proven.
But what about experiments involving black holes and the recent LIGO experiments - do they really uphold GTR?
Relevant answer
Answer
   To doubt about one theory, any theory, is always a healthy exercise and the GRT was one of the theories that was tried to modify several times. What is not so healthy is if the discussion transforms in a war between personal opinions without given enough information on where can be the fails and if there is one real alternative. I think that it would be very worthy if it would be possible to present these "weak" and "strong" points.
1. For more than one hundred years very good scientists were following the GRT and trying even to find a better theory. One of them was Einstein with the unified theories trying to unify electromagnetism with the gravitation (classical theories), for example Kaluza-Klein theory. This has failed.
2. More recently String theory or its generalization in M-theory found a mode of oscillation with coincides with the graviton. This is very appealling because unifies quantum mechanics and gravitation (with the possibility of introducing the gravitation in the context of the Standard Model) but it only works at very low energies.
3. With the simple Hilbert action and Einstein's motion equations this old theory of GRT follows to be the simplest and more accurate theory of gravitation for explaining the present phenomenology.
   There are several basic problems associated to gravitation
4. It is a very weak interaction (difficult to carry it to the lab) if we compare it with the other three interactions and the geometrical Riemann interpretation introduced by Einstein is not possible to be introduced within perturbation metheds (renormalization group).
   Perhaps what would be interesting is to know what are the concrete points of criticisms that can be put to GRT instead of transforming this fantastic achievement of physics as a personal attack to his creator.
  • asked a question related to Quantum Gravity
Question
6 answers
The group MG/r occurring in an equation indicates that action at a distance is being described. Newton realized that something unknown must be operating on a smaller scale, but had no tools to explore it. Einstein offered geometry of curvature which can be expressed locally. but G/c2 remained invariant in General Relativity as shown in the integration of functions.
Einstein offered a variable scalar light speed when gravity must be considered.
c/co = ( 1 - 2MG/rc2)
Suggesting
G/Go = ( 1 - 2MG/rc2)2
By applying equivalence principle for mechanical acceleration and making r very large
c/co = ( 1 + v2/c2)
which is just a case of invariant h Planck's constant, but results in G/c2 that decreases very slightly with increasing speed. Then one possibility of G is given,
G/Go = ( 1 + v2/c2)2
but this result is not in agreement with Vacuum Partition theory.
General relativity seems to be over constrained except in the low energy case.
Einstein's ( c/co = ( 1 - 2MG/rc2) ) is not exactly compatible with invariant (G/c2).
How Is Large Scale Gravity G Expressed In Local Properties Of Space?
Relevant answer
Answer
Hi,
Do they connect G to all free motions in space?  I did experiments of the kind ' falling leaf' indoors, with a thin papper. Found 4 types of motion. Could summarize them with
'I do' and some kind of gravity. First it was a harmonic oscillator ( the curved part of the d). Then in some cases it did entire laps, the o. Then it took a different direction in a fast straight motion, some cases, the I. If the person performing the experiment was sufficiently close it approached as1/r, and then bumbed outwards.
The I and the o, may need a little input of air layers, and the other 2 cases more often obtained.
Large scale if mostly space, is difficult to scale,  and geometric means will also be spatial.
But the local property before the bump, would be also gradient of density.
And before that, it created kinetic energy with small curved paths, into a harmonic oscillator.
Kind regards
  • asked a question related to Quantum Gravity
Question
7 answers
If matter is Abelian(inertia), then it will point to energy since energy and matter are equivalent through equation E=Mc2...Theory of Relativity. 
Relevant answer
Answer
 An abelian group is a group in which the law of composition is commutative; i.e. the group law satisfies for any in the group.
  • asked a question related to Quantum Gravity
Question
6 answers
Consider the Goldstone model of a complex scalar field ΦΦ. It has U(1)U(1) global symmetry, so if we apply the transformation Φ→eiαΦΦ→eiαΦ the Lagrangian is left invariant
Relevant answer
Answer
The (values of the) Casimir operators label distinct states-by construction. In the case at hand, the Casimir operator is the charge. So the states created, for instance,  by Φ are distinct from those created by Φ+ or ΦΦ+, since they have different charge-and that's expressed by the fact that only the last is invariant under U(1) transformations, which means it creates states of zero charge; the others create states of non-zero charge and, in fact, of opposite charge. 
In the case of spin, since total spin is one of the  Casimir operators (the other is the mass)  of the Lorentz group, states with the same value of both  are physically equivalent, with respect to Lorentz transformations, since these depend only on the two Casimirs. 
To distinguish spin up from spin down requires a specific kind of operator, e.g. a magnetic field. 
(The reason is that the representation for non-zero spin isn't one-dimensional, SU(2) has one generator that can be diagonalized, along with the Casimir and in the space where this generator is diagonal, it's possible to move from one state to the other by corresponding operators...)
It is possible to couple a particle, with non-zero spin, to a magnetic field, in a way consistent with Lorentz invariance, since the magnetic field transforms in such a way to lead to a Lorentz invariant interaction.  It's not useful to change the subject, however. 
  • asked a question related to Quantum Gravity
Question
38 answers
The metric tensor of general relativity reduces to the metric tensor of special relativity in the absence of gravity. Therefore, both possibilities may exists.
Relevant answer
Answer
A physical quantity is defined by the series of operations and calculations of which it is the result” - A S Eddington
Accepting that, we can say that the physical quantity we call “time” is defined as “that which is measured by a clock”.
Suppose we measure the time elapsed between an event A and an event B, by transporting a clock from A to B. In Newtonian physics it is assumed that the elapsed time will be independent of how the clock is transported from A to B (ie, independent the route taken by the clock - independent of the clock’s trajectory). In Einsteinian physics (Special or General Relativity - makes no conceptual difference) that assumption is not valid. The time elapsed is not merely a property of the pair of events A and B, it is a property of the chosen trajectory between A and B, and is calculable. It is the “proper time” of the trajectory. It is independent of the choice of coordinate system; it is an invariant.
  • asked a question related to Quantum Gravity
Question
6 answers
As we know the interactions of Higgs field gives mass to particles. Greater the interaction, greater will be the mass (or energy) possessed by particles. Any difference in energy or mass should naturally make differences to the gravitational interactions, although it will be very small as compared to other dominant forces at sub-atomic levels. 
Relevant answer
Answer
No-in this context gravitational effects are suppressed with respect to non-gravitational effects by powers of MHiggs/MPlanck~10-17 since MHiggs is about 100 GeV and MPlanck about 1019 GeV. The energy ratio would be 4th power of this, i.e. even smaller.
The fact that matter has mass (and energy) means that the RHS of Einstein's equations isn't strictly zero. But the deviation produces a curvature that can't be distinguished from flat spacetime.
That's why the finite mass of particles doesn't affect spacetime, unless it is expressed in ``very massive'' objects like planets or stars. 
Incidentally, while the Brout-Englert-Higgs mechanism describes the way leptons and the weak gauge bosons get their mass and how the quarks get some of their mass, gravity is, still, classical. So the fact that matter is massive affects the RHS of Einstein's equations, independently of the microscopic mechanism. 
  • asked a question related to Quantum Gravity
Question
4 answers
Effective-theories characterized by a coupling strength that is not dimensionless, include important examples in quantum-field theory , such as the four-Fermion theories, chiral-effective-theories in QCD, Nambu-Jona Lasinio(NJL)-type of models, Gravity..etc. Further, effective theories  have assumed increased significance , primarily due to the fact that Nature has revealed the basic-structure of matter in layers of energy-scales.  The primary reason, which excludes these effective theories from the domain of renormalization-programme ( and thereby, preventing meaningful comparison with experiments), is perhaps the non-applicability of power-series expansion in the coupling-strength of the conventional perturbation theory (CPT) to such cases.
    Recently, however, a radically different formulation of perturbation-theory has been  proposed and tested in the context of quantum-mechanics, which gets rid of the power-series-expansion in the coupling strength altogether, thereby extending its domain of application for arbitrary values of the coupling-strength (cf. https://arxiv.org/abs/1607.01510). Answer(s) to the above question  assume importance in this changed perspective.
Relevant answer
Answer
@Stam Nicolis
     I do not agree with your answer as it is contrary to established wisdom and settled issues in the theory of renormalization, as well as, being based on an incorrect appraisal of the quoted paper.
My response to your views, are given below:
``Liberation from a power series expansion'' would imply that the theory is free.”
 --Not at all !  The dependence on the coupling-strength can be incorporated entirely differently ( e.g. non-perturbatively) by  getting rid of the power-series expansion in the coupling-strength about the free-theory limit. This is the main result of the referred article
(hereinafter, referred as MFPT).
“The paper quoted doesn't describe anything of the kind-it attempts to formulate a perturbative expansion when the coupling constant is ``large''. “
   This is an amazing statement ! It leads me to believe that you have perhaps not looked closely enough at the contents of the paper. We have achieved very accurate results for the standard bench-mark systems,i.e. the anharmonic-oscillators and the double-well oscillator, covering the range of values of ‘g’ ( the coupling strength) from 0.1 to 200.0 by MFPT, yet without using the power-series expansion in ‘g’ (see, Table-I). I would urge you to carefully look at the contents of the paper again for details.
 “For quantum mechanics this statement is meaningful, because the coupling constant doesn't get renormalized.” 
   This again is an incorrect assertion. Renormalization of the ‘coupling-constant’ (as well as, the ’propagator’) cannot be avoided in any interacting theory (including quantum mechanics(QM)) due to the fact that these get ‘dressed’ due to interaction. The governing equations are the self-consistent Schwinger-Dyson equations (SDE) in QFT and analogous integral equations in quantum-mechanics. The only distinction in QM is perhaps the absence of ‘regularization’ (due to the absence of UV/IR divergences). Otherwise, the other two steps in the renormalization-programme, namely ‘subtraction’ and ‘definition’ (of the renormalized parameters at the subtraction point/scale) are mandatory. Hence, the renormalized coupling-strength is scale-dependent and the Renormalization Group Equations (RGE) are operational in full glory also in QM.( The literature is replete on these aspects. I’ve found the following papers especially helpful: Gupta and Rajeev, Phys.Rev.D,1993[hep-th/9305052]; “Renormalization without infinities-an elementary tutorial”-Arnold Neumaier-http://www.mat.univie.ac.at/~neum/; H.E.Camblong et al.,[arXiv:hep-th/0003255v2]).
    Returning to the main question, as emphasized in the explanation thereto, it concerns effective-theories characterised by a coupling strength that is not dimensionless.  The primary reason for exclusion of such theories from the purview of perturbative-renormalization, is the obvious fact that the power series expansion in the corresponding coupling strength is ab initio meaningless. In that context, the results in the quoted paper may perhaps be of some relevance in surmounting this primary obstacle as it altogether gets rid of power-series expansion in the coupling-strength, while presenting an alternative perturbative frame-work.
  • asked a question related to Quantum Gravity
Question
15 answers
Observational data indicates that the cosmological constant has a positive value, resulting in a de Sitter spacetime. In loop quantum gravity, the IR divergences in the Ponzano-Regge model can be made to disappear through q-deforming SU(2) to SUq(2). The classical limit of this Turaev-Viro model is GR with positive cosmological constant.
On the other hand, anti de Sitter spacetime has a number of (potentially) desirable properties as well, for example the AdS/CFT correspondence. This correspondence is used in Light Front holographic QCD and seems to offer some insights into confinement as well as meson and hadron spectroscopy (arxiv:1407.8131). AdS also admits a positive energy operator making it more suitable for a particle interpretation. There has been some work (mostly by Flato and Fronsdal) describing photons and leptons as composites of singleton representations that live in an AdS spacetime.
Would it be possible and sensible to describe spacetime as being anti de Sitter at very small scales and de Sitter at cosmological scales? Perhaps this would be possible through a bi-metric model?
To me it seems that such a model would offer the best of both worlds (LQG without IR divergences, agreement with cosmological observations, AdS/CFT, singleton representations). I am just not sure if such a model would be possible and if it even makes sense to think along these lines. I would very much value any comments people may have.
Thanks in advance!
Relevant answer
Answer
Dear Stefano,
Thank you for your comment. Like Martin pointed out, nature does behave differently at different scales. I want to know if it is reasonable to have a metric that is also scale dependent.
One of my interests is deformations of algebras as a means of generalizing symmetry. So for example, both SR and QR can be seen as deformations of Galilean relativity and classical mechanics respectively. Taking Minkowski spacetime with Poincare symmetry and deforming it give either dS or AdS. At this point the isometry group is rigid and cannot be deformed further. The mathematics does not tell you the value of the cosmological constant (just as it doesn't tell you the value of x or hbar).
Experiments suggest that at least on large scales the cosmological constant is positive. Loop quantum gravity seems to introduce a positive cosmological constant to rid the theory of IR (large scale) divergences. On the other hand many theories make use of the AdS/CFT correspondence and assume an AdS spacetime. This also gives some impressive results. There is interesting physics in the singleton representations of AdS (discovered by Dirac all the way back in 1963). 
My question is whether it is possible to reconcile these approaches. I think that if it is then it could lead to interesting new physics.
  • asked a question related to Quantum Gravity
Question
26 answers
Einstein described gravity as equivalent to curves in space and time, but physicists have long searched for a theory of gravitons, its putative quantum-scale source. Physicists have searched for a theory of quantum gravity for 80 years. Though gravitons are individually too weak to detect, most physicists believe the particles roam the quantum realm in droves, and that their behavior somehow collectively gives rise to the macroscopic force of gravity, just as light is a macroscopic effect of particles called photons. But every proposed theory of how gravity particles might behave faces the same problem: upon close inspection, it doesn’t make mathematical sense. Calculations of graviton interactions might seem to work at first, but when physicists attempt to make them more exact, they yield gibberish — an answer of “infinity.” “This is the disease of quantized gravity,” Stelle said.
With regard to the exchange particles concept in the quantum electrodynamics theory and the existence of graviton, we will present a new definition of graviton. To define graviton, let’s consider a photon that is falling in the gravitational field, and revert back to the behavior of a photon in the gravitational field. But when we define the graviton relative to the photon, it is necessary to explain the properties and behavior of photon in the gravitational field. The fields around a "ray of light" are electromagnetic waves, not static fields. The electromagnetic field generated by a photon is much stronger than the associated gravitational field. When a photon is falling in the gravitational field, it goes from a low layer to a higher layer density of gravitons.
We should assume that the graviton is not a solid sphere without any considerable effect. Graviton carries gravity force, so it is absorbable by other gravitons; in general; gravitons absorb each other and combine. This new view on graviton shows, identities of graviton changes, in fact it has mass with changeable spin
Relevant answer