Quantum gravity' could help unite quantum mechanics with general relativity at last

[Admin]

Researchers have measured the gravitational pull exhibited by the smallest mass yet, a breakthrough that could lead to a quantum theory of gravity at last.

Quantum gravity' could help unite quantum mechanics with general relativity at last : Read more

 

[Icepilot]

Much discussion about the "smallest mass" & "tiny particle", but no actual value for the mass?

 

[bibhutibhusanpatel@gmail.]

The Primciple can be applied to solve such problems on quantum gravity related to entanglement;thus,no new fact.

 

[danR]

entanglement has to do with coordinating particles in such a way that changing the properties of one particle instantly alters the properties of an entangled partner particle

I don't know how many times and how many ways this misapprehension of entanglement has been displayed in pop-science articles. It's probably the number one reason why the lay public keeps coming up with FTL comms schemes:

' See, Bob changes the spin on his electron from up to down and Alice at Alpha Centauri has her electron changed so Bob can send binary code and Alice can receive the binary code instantly and they can... '

 

[danR]

Much discussion about the "smallest mass" & "tiny particle", but no actual value for the mass?

430 micrograms. A lot of things were left out, including the actual means of measuring the gravitational force itself. It's like the stage was set, the extras brought in, the props placed, the lighting turned on and... where is the main actor? BBC article did the same thing.

Perhaps everything is drafted by ChatGPT nowadays.

 

[Unclear Engineer]

"Quantum gravity theory" seems to be on the same schedule for completion as "commercial fusion power".

We keep reading about "progress", but there have been no deliverables, and no schedules for deliverables.

 

[Dr.Matthé]

Researchers have measured the gravitational pull exhibited by the smallest mass yet, a breakthrough that could lead to a quantum theory of gravity at last.

Quantum gravity' could help unite quantum mechanics with general relativity at last : Read more

This is an impressive technical achievement, but the whole hype about quantum gravity is without scientific basis. 1. Quantum field theory meanwhile is well possible within curved spacetime 2. Divergencies in General Relativity do not exist as people forget that time dilation automatically stops them. And how could black holes that by definition are not time reversible, ever be a solution of time-independent GR?! 3. It is easy to argue that any possible quantum effect from gravity could never be measured (gravity is too weak, self-interacting and since there's no negative mass, there are no dipoles to produce individual 'gravitons')

 

[Zdepthcharge]

Pathetic.

Congratulations to the scientists who have managed to measure the effects of gravity at the smallest scale yet. Boo to the people bringing up the idiocy of quantum gravity. And boo to the writers of this article for continuing to perpetuate the myth that gravity is a force.

Gravity is not a force in the way that we think of forces. Unlike the particle/field forces, gravity is not transactional. In other words, there isn't a mitigating particle that controls how gravity operates. You can claim all you want that there is, but you can't prove it. The graviton is so elusive because it is simply a particle of the imagination. People may complain that I can't prove it doesn't exist, which is true, but I'm not trying to base arguments on it's non-existence.

Particle physicists could advance scientific inquiry by fifty years if they simply stopped basing ideas on the existence of something that has not been shown to exist. The continued attempts and whining are pathetic.

 

[Atlan0001]

There is no "singularity" to gravity physics, so there is no quantum physics' (EW) point-particle singularity to gravity! and the many varieties of quantum-complex singularities "to gravity"! Again: no 0-point singularity to gravity's fundamental "zooms" (to the infinite and infinitesimal) element of "self-similar fractal zooms (infinities) universe structure" short the representative gluon of the boundaries crossing strong binding (including nuclear) force's / Casimir effect force's base2 "set and reset."

 

[Torbjorn Larsson]

Unfortunately the experiment is not very convincing yet. They use a small mass and get 35 % of the modeled signal with lots of noise. It would be more convincing if they started at larger masses for both test and outside mass and run a series of experiments to see how the huge discrepancy scales.

The article makes the usual pop science, unsupportable claim that gravity can't be quantized and that the two descriptions can't be unified. But a straightforward effective quantum field theory has been developed long ago and is consistent with general relativity except on highest energy Planck scales (where both theories break down).
http://www.scholarpedia.org/article/Quantum_gravity_as_a_low_energy_effective_field_theory

The potential problem with these theories seem to lie elsewhere. They are both effective and so need observations to pin down parameters, instead of being independent on observation as some would like to see. (But that is an odd requirement on scientific theories.)

 

[Torbjorn Larsson]

The Primciple can be applied to solve such problems on quantum gravity related to entanglement;thus,no new fact.

The experiment constitutes a new fact, a new range of putative observation.

I don't know how many times and how many ways this misapprehension of entanglement has been displayed in pop-science articles.

I agree, but to be a bit fairer the author said that it was likely an oversimplification. But it is in fact an error since an observation merely reveals how the correlation should be interpreted, and the result has to be signaled to the distant location to do so - that is the meaning of non-local system.

No property changes state, instead a state is observed. And while observation may seem odd, we have to remember that special relativity has "special" effects such as time dilation and length shortening. There is a paper that show observation "wavefunction collapse" stochastic behavior can be seen simply as a third "special" effect, of wavefunctions having quantum spin under relativistic reference frames.
[Stuckey, W.M., Silberstein, M., McDevitt, T. et al. Answering Mermin’s challenge with conservation per no preferred reference frame. Sci Rep 10, 15771 (2020). https://doi.org/10.1038/s41598-020-72817-7 https://www.nature.com/articles/s41598-020-72817-7.pdf]

"Quantum gravity theory" seems to be on the same schedule for completion as "commercial fusion power".

This is science, so unlike fusion power there is no master plan that we can observe delay against. But see my comment that there is a reasonable theory, but that popular science claims doesn't go into that.

There is no "singularity" to gravity physics, so there is no quantum physics' (EW) point-particle singularity -- and the many varieties of complex singularities -- to it!

Yes, there is a quantum physics, there is no problem to quantize the general relativity Lagrangian same as the other particle fields. See my own response to the article for references.

And the gravitational particle is the graviton, the force exchanging quanta of the field, same as other quantum fields, it is not the singularities of the theory. A theoretical singularity only means the theory has lost validity there, nothing more.

 

[Torbjorn Larsson]

2. Divergencies in General Relativity do not exist as people forget that time dilation automatically stops them. And how could black holes that by definition are not time reversible, ever be a solution of time-independent GR?! 3. It is easy to argue that any possible quantum effect from gravity could never be measured (gravity is too weak, self-interacting and since there's no negative mass, there are no dipoles to produce individual 'gravitons')

As I pointed out in my own response to the article, both effective quantum gravity field theory and effective general relativity has theoretical singularities at Planck energies. And that is where the theories lose validity. So I doubt you can rely on general relativity to convince people that it displays no singularity - you can find them, for instance in the stationary Schwarschild's black hole solution you claim do not exist - or that it also imply that infinite time dilation exist and/or somehow "stops them". I think you are trying to make an improper hypothesis to make a satisfactory personal opinion (a "solution" just for you)?

Gravitons would be produced by quadrupoles, same as the gravitational waves we detect (at too low energies to reveal their putative quantum nature). Gravitons are merely the field quanta, so if you can quantize the field (and that has been done) you will have them without needing "negative mass". This is no different from the Higgs particle, which exist despite that the scalar field has no analog "Higgs charge" at all (and the same goes for the inflaton field, looks like -see BICEP/Keck observations: no "inflaton charge"). While *other* particles have gravitational "charge" (mass) the graviton is "non-charged" (zero invariant mass). They can be produced by the field without it having mass as such.

 

[Torbjorn Larsson]

And boo to the writers of this article for continuing to perpetuate the myth that gravity is a force.

Gravity is not a force in the way that we think of forces. Unlike the particle/field forces, gravity is not transactional. In other words, there isn't a mitigating particle that controls how gravity operates. You can claim all you want that there is, but you can't prove it.

Gravity is a force, whether or not you consider it a pre- or posteinsteinian field, simply by analogy. Even general relativity approximates it as a force at low energies (flat space). The term "transactional" suggests you have some non-scientific (specifically philosophic) opinion about gravity.

Gravitons exist in theory, first from Weinberg's famous spin proof showing their uniqueness and later from showing an effective quantum gravity theory (and even from spin theory math, see the link below). Physicists think they have to exist in reality as well, but it needs to be observed. Not in order to claim the force-hood of gravity though.

In theoretical physics, the Weinberg–Witten (WW) theorem, proved by Steven Weinberg and Edward Witten, states that massless particles (either composite or elementary) with spin j > 1/2 cannot carry a Lorentz-covariant current, while massless particles with spin j > 1 cannot carry a Lorentz-covariant stress-energy. The theorem is usually interpreted to mean that the graviton (j = 2) cannot be a composite particle in a relativistic quantum field theory.

During the 1980s, preon theories, technicolor and the like were very popular and some people speculated that gravity might be an emergent phenomenon or that gluons might be composite. Weinberg and Witten, on the other hand, developed a no-go theorem that excludes, under very general assumptions, the hypothetical composite and emergent theories.

https://en.wikipedia.org/wiki/Weinberg–Witten_theorem

 

[Atlan0001]

Since people were somehow completely off base and totally misreading my post #9, I went back and edited it in hopes of clarifying the breakout of what I actually said!

 

[Dr.Matthé]

Pathetic.

Congratulations to the scientists who have managed to measure the effects of gravity at the smallest scale yet. Boo to the people bringing up the idiocy of quantum gravity. And boo to the writers of this article for continuing to perpetuate the myth that gravity is a force.

Gravity is not a force in the way that we think of forces. Unlike the particle/field forces, gravity is not transactional. In other words, there isn't a mitigating particle that controls how gravity operates. You can claim all you want that there is, but you can't prove it. The graviton is so elusive because it is simply a particle of the imagination. People may complain that I can't prove it doesn't exist, which is true, but I'm not trying to base arguments on it's non-existence.

Particle physicists could advance scientific inquiry by fifty years if they simply stopped basing ideas on the existence of something that has not been shown to exist. The continued attempts and whining are pathetic.

Who's 'we'?
And you're not a scientist, are you?

 

[Dr.Matthé]

As I pointed out in my own response to the article, both effective quantum gravity field theory and effective general relativity has theoretical singularities at Planck energies. And that is where the theories lose validity. So I doubt you can rely on general relativity to convince people that it displays no singularity - you can find them, for instance in the stationary Schwarschild's black hole solution you claim do not exist - or that it also imply that infinite time dilation exist and/or somehow "stops them". I think you are trying to make an improper hypothesis to make a satisfactory personal opinion (a "solution" just for you)?

Gravitons would be produced by quadrupoles, same as the gravitational waves we detect (at too low energies to reveal their putative quantum nature). Gravitons are merely the field quanta, so if you can quantize the field (and that has been done) you will have them without needing "negative mass". This is no different from the Higgs particle, which exist despite that the scalar field has no analog "Higgs charge" at all (and the same goes for the inflaton field, looks like -see BICEP/Keck observations: no "inflaton charge"). While *other* particles have gravitational "charge" (mass) the graviton is "non-charged" (zero invariant mass). They can be produced by the field without it having mass as such.

Time dilation is proportional to the strength of gravity, and so gravity stops itself from becoming infinite.
And the Schwarzschild solution of the space-time around a mass with infinity density is purely hypothetical, it simply can't be achieved in reality.
And in order to get quantum gravity effects you need INDIVIDUAL gravitons, not a whole field of them which onlyngets you back to GR...

 

[Atlan0001]

Who's 'we'?
And you're not a scientist, are you?

What identifies a scientist from a pseudoscientist when both have graduated from the same academy into the same guild elite priesthood? What separates an academic with a degree on his or her wall from, say a carpenter and clock maker John Harrison with no such academic degree on his wall?

Careful! "Who's 'we'? And you're not a scientist are you?" really does qualify as a personal attack! You attacked the person, not the content of their posts! I'm a seventy-year widely read and studied close student of history and other sciences such as cosmological physics ("cosmology" being remote observations (Big Bang Horizon, Planck Horizon, expansion of the universe, probable duality -- closed systemic / open systemic -- regarding the speed of light, and so on) and outside any proofs on the spot at this date). Like the fictional Sherlock Holmes or the real John Harrison representing people almost as good, I have no university degrees in history, physics, or any other such "sciences," on my wall but I consider myself qualified to argue and advocate!

In my own career fields, military, information, and computers, i have certificates and awards, but no academic degrees. With what you ask, the way you ask, I suppose I qualify as a low life.
-------------------------

"Great spirits have always encountered violent opposition from mediocre minds...." -- Albert Einstein.

 

[Atlan0001]

This, besides the Heisenberg uncertainty principle among a few other odds and ends, applies whether macrocosmic or microcosmic!

Three-body problem - Wikipedia

en.wikipedia.org

 

[skynr13]

Much discussion about the "smallest mass" & "tiny particle", but no actual value for the mass?

You have my vote. 30 attonewtons is necessary to attract how massive a particle? Assuming all things are relevant, we suppose.

 

[Dr.Matthé]

Unfortunately the experiment is not very convincing yet. They use a small mass and get 35 % of the modeled signal with lots of noise. It would be more convincing if they started at larger masses for both test and outside mass and run a series of experiments to see how the huge discrepancy scales.

The article makes the usual pop science, unsupportable claim that gravity can't be quantized and that the two descriptions can't be unified. But a straightforward effective quantum field theory has been developed long ago and is consistent with general relativity except on highest energy Planck scales (where both theories break down).
http://www.scholarpedia.org/article/Quantum_gravity_as_a_low_energy_effective_field_theory

The potential problem with these theories seem to lie elsewhere. They are both effective and so need observations to pin down parameters, instead of being independent on observation as some would like to see. (But that is an odd requirement on scientific theories.)

Why would one need a quantum gravity theory when it seems there's no problem with quantum field theory in curved space-time? Black Holes perhaps? But how can a time-irreversible black hole ever be a solution of time-independent GR?

 

[Dr.Matthé]

This, besides the Heisenberg uncertainty principle among a few other odds and ends, applies whether macrocosmic or microcosmic!

Three-body problem - Wikipedia

en.wikipedia.org

The correct translation is indeterminacy principle (fuzziness is fine too). This is part of what causes all the misconceptions about QM. The classical point partical concept is another one.