Russian scientists find flaws in popular theories of gravity

October 27, 2017
Credit: CC0 Public Domain

Using a model of black holes, scientists from the Ural Federal university (UrFU, Yekaterinburg) determined that a popular theory of gravity that seemed to work perfectly at the cosmological level (a subclass of Horndeski theory) does not apply in the real world. They have published their results in Classical and Quantum Gravity.

Modern physics has accumulated a lot of prerequisites for the revision of , including the of the universe, the presence of dark matter, and the impossibility of renormalizing . All the fundamental interactions known to science have been described in quantum language except for gravitation. These small inconsistencies indicate that the theory of relativity is not the final theory of gravitation, but an approximation (a similar story occurred with Newton's theory). Theoretical physicists constantly propose extended theories of gravity, and these models need to be compared with observations.

One of the simplest versions of such an extended theory appears under the assumption that the gravitational constant (a fundamental physical quantity that is the same in time and at all points in the universe) is not a constant, but a field that can vary in time and space. Scientists cannot measure this slowly changing field with accuracy, and only therefore perceive it as a constant. This theory posits gravity with a scalar field (given only one number at each point). This is how the first and simplest theory of gravity with a scalar field, the Brans-Dicke theory, was formulated. This and similar theories are considered to be among the most promising ways of expanding General Relativity.

In her work, Daria Tretyakova, PhD from UrFU, together with her colleague from the University of Tokyo, explored one of these theories—the so-called Horndeski theory. The Horndeski framework gives the most general theory of gravity with a scalar field, without instabilities, and containing "healthy" physics—that is, without any unusual parameters of matter, for example, negative or imaginary mass.

At the cosmological level, a subclass of Horndeski models, which are symmetric with respect to the shift of the scalar field in space and time, have helped scientists describe the accelerated expansion of the universe without resorting to additional theories. These models were chosen for rigorous and comprehensive testing. The authors of the paper considered the Horndeski models at the astrophysical scale—the scale of individual objects of the universe—and determined that black holes (as real objects) turn out to be unstable in the models which previously successfully proved themselves in cosmology.

Consequently, these models are not suitable for describing the real , because black holes are currently believed to exist in space as stable objects. However, the scientists have proposed a way to construct Horndeski models that ensure stability. The paper is a step toward a new theory of gravity that fulfills the requirements of . Now, the authors are planning to subject the newly proposed models to standard tests to check their adequacy at the cosmological and astrophysical scale.

Explore further: Violations of energy conservation in the early universe may explain dark energy

More information: Daria A Tretyakova et al, Stable black holes in shift-symmetric Horndeski theories, Classical and Quantum Gravity (2017). DOI: 10.1088/1361-6382/aa8057

Related Stories

Cosmologists a step closer to understanding quantum gravity

January 23, 2017

Cosmologists trying to understand how to unite the two pillars of modern science – quantum physics and gravity – have found a new way to make robust predictions about the effect of quantum fluctuations on primordial density ...

Hints of extra dimensions in gravitational waves?

June 28, 2017

Researchers from the Max Planck Institute for Gravitational Physics (Albert Einstein Institute/AEI) in Potsdam found that hidden dimensions – as predicted by string theory – could influence gravitational waves. In a recently ...

Recommended for you

Single-photon detector can count to four

December 15, 2017

Engineers have shown that a widely used method of detecting single photons can also count the presence of at least four photons at a time. The researchers say this discovery will unlock new capabilities in physics labs working ...

Complete design of a silicon quantum computer chip unveiled

December 15, 2017

Research teams all over the world are exploring different ways to design a working computing chip that can integrate quantum interactions. Now, UNSW engineers believe they have cracked the problem, reimagining the silicon ...

A shoe-box-sized chemical detector

December 15, 2017

A chemical sensor prototype developed at the University of Michigan will be able to detect "single-fingerprint quantities" of substances from a distance of more than 100 feet away, and its developers are working to shrink ...

Real-time observation of collective quantum modes

December 15, 2017

A cylindrical rod is rotationally symmetric - after any arbitrary rotation around its axis it always looks the same. If an increasingly large force is applied to it in the longitudinal direction, however, it will eventually ...

39 comments

Adjust slider to filter visible comments by rank

Display comments: newest first

nikola_milovic_378
Oct 27, 2017
This comment has been removed by a moderator.
nikola_milovic_378
Oct 27, 2017
This comment has been removed by a moderator.
baudrunner
3.1 / 5 (7) Oct 27, 2017
@nikola_milovic_378

..that is a lot of nonsense. The Universe has a history. Scientists are fairly clear on the emergence and the order of the distribution of matter. The Universe has undergone, and undergoes, generational changes. This particular part of the cosmos bears little similarity to the newest parts of it, at its periphery, where space/time and matter are continually created in this ever expanding Universe.

Your notions aren't completely ununderstandable, but face it, Aether Theory is BUNK.
nikola_milovic_378
Oct 27, 2017
This comment has been removed by a moderator.
nikola_milovic_378
Oct 27, 2017
This comment has been removed by a moderator.
Hyperfuzzy
1 / 5 (4) Oct 27, 2017
Closer and closer to truth. By the way QM is a crutch, a broken crutch, juz say'n
TheGhostofOtto1923
3.6 / 5 (7) Oct 27, 2017
Russians come up with all sorts of theories. This is one of my favorites

"The New Chronology is a pseudohistorical theory which argues that the conventional chronology of Middle Eastern and European history is fundamentally flawed, and that events attributed to the civilizations of the Roman Empire, Ancient Greece and Ancient Egypt actually occurred during the Middle Ages, more than a thousand years later. The central concepts of the New Chronology are derived from the ideas of Russian scholar Nikolai Morozov (1854–1946)..."
https://en.wikipe...Fomenko)

-Its actually really fascinating, but it may be another indication of the extreme measures they will go to to compensate for their lack of self-confidence.

Russians never invented anything you see. Even communism was invented by germans which must bother them enormously.
Chris_Reeve
1 / 5 (5) Oct 27, 2017
For more information on chronological revisions, see my controversy cards:

The Phantom Time Hypothesis
https://plus.goog...tG3BxD1F

Heinsohn's Chronology
https://plus.goog...UrMbPFxH

The Debate Over Phantom Centuries Using Eclipse Data
https://plus.goog...U8mSM4hK

It's definitely worth knowing the basics of these claims. I'm still not sure what to make of all of it myself, but it's very fascinating!
Spaced out Engineer
3.4 / 5 (5) Oct 27, 2017
Hyperfuzzy, how is QM a crutch when you clutch to a name like that. It was a drunkards random walk. Now whether the direction should be open or closed, or if low dimensiality unfolds as he walks is a whole other ball game.
The symmetry may say not discriminating may buy us something, but that is guessing me are lucky with the epistemic tiling. Everybody can be right with variant origins of distinguishing.
Spaced out Engineer
4 / 5 (4) Oct 27, 2017
Me=*we
Da Schneib
5 / 5 (6) Oct 27, 2017
QM is a mathematical investigation of de Broglie's and Dirac's theories of quantum behavior of matter and EM energy. @Hyperfuzzy suggests we should not investigate these. It's like evangelical "Christians" claiming we shouldn't investigate Darwin because jebus didn't say so.

Follow the evidence. Sorry if your magic book about the super magic daddy in the sky by the drunken stone age sheep herders didn't pan out. Get over it.
NoStrings
1 / 5 (3) Oct 28, 2017
Popular theories of gravity find flaws in Russian scientists.

Just like TheGhostofOtto1923 pointed. Provincial selfdeluded bunch they are.

Whydening Gyre
5 / 5 (2) Oct 28, 2017
FTA;
One of the simplest versions of such an extended theory appears under the assumption that the gravitational constant (a fundamental physical quantity that is the same in time and at all points in the universe) is not a constant, but a field that can vary in time and space.

Well.... yaah... The gravitational constant that that we see is only in our visible context. The rest of the universe is waiting...

Whydening Gyre
5 / 5 (3) Oct 28, 2017
Me=*we

I am you and you are me and we are all together.... (Beatles)
RZ49
3.5 / 5 (4) Oct 28, 2017
About one of the "simplest version":
phys.org/news/2016-11-theory-gravity-dark.html
Reg Mundy
1 / 5 (9) Oct 28, 2017
Unbelievable! Yet another dubious theory given scientific credence, to be investigated at vast taxpayer expense.
Why not consider that the entire universe is expanding, everything in it is expanding including light (wavelength increase) and matter. It is the expansion of matter which gives us TIME, which is only meaningful when related to states of matter. The expansion of matter gives the effect we call GRAVITY.
Do the maths, and you don't need Dark Matter, Dark Energy, Gravitinos, etc., etc. , and you can dismiss this article, string theory, branes, and so on....
Captain Stumpy
5 / 5 (8) Oct 28, 2017
@reg the pseudoscience trolling idiot
The expansion of matter gives the effect we call GRAVITY
unbelievable that you would continue to argue this point as it's a false claim of pseudoscience

and again: you're wrong

it can be tested and we've shown, repeatedly, that you're wrong about that one
see: https://phys.org/...ong.html

Do the maths, and you don't need Dark Matter, Dark Energy, Gravitinos, etc.,
and again - see the above link

you have yet to provide any evidence whatsoever for any of your claims

your best argument to date is to "buy your book" - except every scientist who did said it was a waste of money and wrong, with no evidence or viable arguments at all

yet another epic reg fail
rrwillsj
2 / 5 (8) Oct 28, 2017
There is a simple test for quackery, bunco pseudo-science and stuporstitious frauds.

Real Science produces real machinery.

When the cranks can produce their anti-gravity vehicle, hand me the keys, and wave as I fly away in it?

I'm calling steershit on all of them. They certainly have massively failed to earn the designation of 'bulls'!
mackita
5 / 5 (6) Oct 28, 2017
The Horndeski framework gives the most general theory of gravity with a scalar field, without instabilities, and containing "healthy" physics—that is, without any unusual parameters of matter, for example, negative or imaginary mass.
New gravitational wave detection with optical counterpart rules out some dark matter alternatives. This does not affect all types of modified gravity, but it does affect Bekenstein's TeVeS and Moffat's Scalar-Vector-Tensor theory. And of course also 2nd order scalar-tensor Horndeski theory.
howhot3
4.5 / 5 (4) Oct 28, 2017
I think @Chris_Reeve had the understatement of the week;
It's definitely worth knowing the basics of these claims. I'm still not sure what to make of all of it myself, but it's very fascinating!

I'm tempted to say; "Spoken like a real Russian", but everytime I read a quantum gravity paper, that is usually how I feel. Haha. I still like Erik Verlinde theories on non-existence of dark matter. Verlinde suggests gravity as a product of quantum interactions and that dark matter is an effect of the expansion of the universe. See the phys.org stories. https://phys.org/...ity.html

howhot3
5 / 5 (3) Oct 28, 2017
@Ghost says
Russians never invented anything you see. Even communism was invented by germans which must bother them enormously.
He he he. Lol lol. Good one @Ghost
Da Schneib
5 / 5 (5) Oct 28, 2017
Hmmmm, black holes do not require singularities. Just sayin'.
TheGhostofOtto1923
3 / 5 (2) Oct 29, 2017
Perhaps I was being a bit [insert appropriate word] when I claimed that russkiys never invented anything. So let's find out...
https://www.rbth....ld_15164

Yeah ok so they invented yoghurt. Big deal.

No wait

"it is in Bulgaria that yoghurt is believed to have been born"

-So. Another unfounded claim by a people desperate to be relevant. Next they'll be claiming they invented the helicopter.
SlartiBartfast
5 / 5 (5) Oct 29, 2017
https://en.wikipe...ventions

Boy, that was tough to find.
torbjorn_b_g_larsson
5 / 5 (4) Oct 29, 2017
One one hand it is nice that fringe scientists subject their one-wonder ideas (not "theory" I think, since what I know GR is the only well tested description of gravity) to tests, such as that the ones mentioned by RZ and howhot has not. On the other it is slightly embarrassing when they take the expected failure as a reason to complicate their ideas even more.

[tbctd]
torbjorn_b_g_larsson
5 / 5 (3) Oct 29, 2017
[ctd]

Also, describing observations as "prerequisites" or "the impossibility of renormalizing gravity" are not scientific facts or problems. To quote Wikipedia: "However, in an effective field theory, "renormalizability" is, strictly speaking, a misnomer. ... Nonrenormalizable interactions in effective field theories rapidly become weaker as the energy scale becomes much smaller than the cutoff."

Gravity has a perfectly fine effective field theory in generic path integral formulations of standard particle theory [c.f. physicist and Nobel Laurate Frank Wilczek on today's core theory], same as the other particles. They all, as expected from "effective" theories, crap out at higher energies. Notably in that sense gravity field theory goes last, so is in that sense the best of them. It needs better PR. Or more Wilczek. ;-)
nikola_milovic_378
Oct 29, 2017
This comment has been removed by a moderator.
nikola_milovic_378
Oct 29, 2017
This comment has been removed by a moderator.
rrwillsj
4.2 / 5 (5) Oct 29, 2017
Sorry, n_m_3 but your delusions of a great magical faerie pulling the strings of us little puppets has been discredited.

I was conversing with the deity about this all too common delusion among monkeys. That the deity is capable of caring about the ephemeral insignificant. god pokes fun at me for being a materialist atheist. I poke fun right back about god being a 13+ billion year old infant. Just a baby!

Sorry, nope, no change from that sardonic newbie. The deity just don't care to interfere. Isn't that the point of Free Will?
OrangeHorse
1 / 5 (1) Oct 29, 2017
What is up with all these new theories on gravity?

I get this feeling that Einstein's General Relativity theory will not be around in another 10-15 years.
nikola_milovic_378
Oct 29, 2017
This comment has been removed by a moderator.
TheGhostofOtto1923
5 / 5 (1) Oct 30, 2017
https://en.wikipe...ventions

Boy, that was tough to find.
Barts list says Russians invented the laser and tv. That was easy to laugh at.

But garbage is not really funny is it bart? No it is tragic.
There is time for your mind to die and replace it with your consciousness, which has been destroyed by Free Will, and awareness is the power to recognize TRUE GUESTS IN THE UNIVERSE AND INTO YOU!
Addiction is also not something to laugh at haha.
rrwillsj
3.7 / 5 (3) Oct 30, 2017
n_m_3, I'd guess the biggest difference of opinion between us? Is you are chanting to your Great Magic Faerie in the sky to strike me down with the thundermug of divine wrath.

I, on the other hand, realize that you are already brain-dead and violence from me would be redundant.
Steelwolf
not rated yet Oct 30, 2017
Russians did invent a lot of things, many of them before Americans. Remember Sputnik?
Whydening Gyre
5 / 5 (2) Oct 30, 2017
Russians did invent a lot of things, many of them before Americans. Remember Sputnik?

Wasn't an "invention". Was an adaptation of previously developed ballistic missile technology. It was their captured German rocket scientists vs ours (captured German rocket scientists)
Meanwhile... Chinese invented rocketry quite a while ago, wasn't it...:-)?
howhot3
5 / 5 (1) Oct 30, 2017
One one hand it is nice that fringe scientists subject their one-wonder ideas (not "theory" I think, since what I know GR is the only well tested description of gravity) to tests, such as that the ones mentioned by RZ and howhot has not. On the other it is slightly embarrassing when they take the expected failure as a reason to complicate their ideas even more.


I doubt it. From another posting by @shavera which I agree with;

"The standard model doesn't really inform anything about dark matter one way or the other right now. GR is why we think there's dark matter. GR is remarkably accurate across a lot of experiments. So how do you explain GR being so right so often, but not in this case"
"we know the standard model is incomplete... it seems pretty reasonable to guess that our next correction of the SM will allow us to know more about that unknown mass/energy."
https://phys.org/...tic.html

Maybe you have a closed mind?

nikola_milovic_378
Oct 31, 2017
This comment has been removed by a moderator.
nikola_milovic_378
Oct 31, 2017
This comment has been removed by a moderator.
tgmeloche
not rated yet Nov 21, 2017
The thought of space-time geometry (GR) to explain how gravity works in nature originated over 100 years ago. Today's observational and experimental data sets confirm the idea that general relativity can now be kicked to the curb in the same way as in Galileo's time the idea that the Earth was at the center of the Universe. Fear of change and vested interests are at work as academics' hold dearly their faith in general relativity (GR) as the answer to how gravity works despite nature's disagreement with the evidence … history repeats. Clearly academia strives for clarity and truth and even Albert Einstein had his doubts about space –time geometry as the complete answer to how gravity works in the natural world.
21st century innovation to how the force of gravity transfers is found in the google links below.
The principles of atomic gravity are tools used to unify and advance academic research in all the natural sciences.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.