Although dark matter is a central part of the standard cosmological model, it’s not without its issues. There continue to be nagging mysteries about the stuff, not the least of which is the fact that scientists have found no direct particle evidence of it. Despite numerous searches, we have yet to detect dark matter particles. So some astronomers favor an alternative, such as Modified Newtonian Dynamics (MoND) or modified gravity model. And a new study of galactic rotation seems to support them.
The idea of MoND was inspired by galactic rotation. Most of the visible matter in a galaxy is clustered in the middle, so you’d expect that stars closer to the center would have faster orbital speeds than stars farther away, similar to the planets of our solar system. We observe that stars in a galaxy all rotate at about the same speed. The rotation curve is essentially flat rather than dropping off. The dark matter solution is that galaxies are surrounded by a halo of invisible matter, but in 1983 Mordehai Milgrom argued that our gravitational model must be wrong.
At interstellar distances, the gravitational attraction between stars is essentially Newtonian. So rather than modifying general relativity, Milgrom proposed modifying Newton’s Universal Law of Gravity. He argued that rather than the force of attraction being a pure inverse square relation, gravity has a small remnant pull regardless of distance. This remnant is only about 10 trillionths of a gee, but it’s enough to explain galactic rotation curves.
Of course, just adding a small term to Newton’s gravity means that you also have to modify Einstein’s equations as well. So MoND has been generalized in various ways, such as AQUAL, which stands for A Quadradic Lagrangian. Both AQUAL and the standard LCDM model can explain observed galactic rotation curves, but there are some subtle differences.
This is where a recent study comes in. One difference between AQUAL and LCDM is in the rotation speeds of inner orbit stars vs outer orbit stars. For LCDM, both should be governed by the distribution of matter, so the curve should be smooth. AQUAL predicts a tiny kink in the curve due to the dynamics of the theory. It’s too small to measure in a single galaxy, but statistically, there should be a small shift between the inner and outer velocity distributions. So the author of this paper looked at high-resolution velocity curves of 152 galaxies as observed in the Spitzer Photometry and Accurate Rotation Curves (SPARC) database. He found a shift in agreement with AQUAL. The data seems to support modified gravity over standard dark matter cosmology.
The result is exciting, but it doesn’t conclusively overturn dark matter. Thye AQUAL model has its own issues, such as its disagreement with observed gravitational lensing by galaxies. But it is a win for the underdog theory, which has some astronomers cheering “Vive le MoND!”
Reference: “Distinguishing Dark Matter, Modified Gravity, and Modified Inertia with the Inner and Outer Parts of Galactic Rotation Curves” by Kyu-Hyun Chae, 12 December 2022, The Astrophysical Journal.
Adapted from an article originally published on Universe Today.
[Editor’s Note: SciTechDaily’s initial title of “Modified Gravity Emerges as Leading Explanation for Dark Matter Following New Galaxy Rotation Measurements” was replaced as it was not accurate.]
Congratulations. MOND has been emerging for several years, which is another way of saying it’s actually going nowhere while its scribes and acolytes dutifully rewrite PR headline history for this plucky little theory on a monthly basis. It’s all likely to save historically oppressed wormholes for Hollywood
The same way particle physicists and astrophysicists for years ignore a gigantic problem with their theories and math and expect everyone to just move on?
Nah bro you’re just indoctrinated. The 3 frontrunners will probably all contain pieces of the truth so to dismiss theories which fill these enormous gaps in the one you like is exactly how we ended up in this bulls*** situation to begin with.
I see nothing constructive in what you wrote there.
I understand you are trying to be sarcastic and ambiguous and kind of very non-concretely dismissive of something somewhere. The quantum gravity and dark matter effect model I like is one I’ve described elsewhere on this site as a static galactic wave (DM halo effect as a stationary ripple effect in core-generated gravity) with cold focus enhanced couplings including frame-drag spin amplification capable of creating the “X” pattern visibly crossing the cores of many spiral galaxies seen edge-on. It’s simple enough to follow for anyone who has mastered electromagnetics. If anyone is working on some loose details (seems unlikely at the moment) and they publish widely that would be quite a kick for me since it’s nothing at all like GR.
Come to think of it, since I may have suggested on occasion an effect of spin coupling enhancement aligning with galactic cluster rotation planes and rotation axes, maybe you are referring to a very recent study of an apparent tendency of local galaxies to be found sitting in roughly the same plane which concluded it was a coincidence. Definitely a result worth re-checking independently, in my opinion.
Studies have long claimed voids delineated by filamentary and sheet-like structures in the distribution of matter in the universe, so it’s not like a local sheet appearing to be temporary is going to decide if the dark matter effect is due to gravity not agreeing with the anti-quantizable expectations of so called experts.
> MOND has been emerging for several years, which is another way of saying it’s actually going nowhere while its scribes and acolytes dutifully rewrite PR headline history for this plucky little theory on a monthly basis.
Yet another way to say that is that cold dark matter continues to fail at parsimoniously explaining what we see, since that’s the only reason modified gravity still gets attention.
Let’s be honest for a change – no one is actually talking about modifying gravity. People are merely following a natural tribal imperative by engaging in the favorite pursuit of exotic physics dark matter gatekeeping, namely putting a lot of social engineering energy into discouraging anyone from treating gravity as a force and eliminating general relativity.
Yet another way of saying that is that cold dark matter continues to fail at parsimoniously explaining observations thus motivating into alternatives.
Determining the mass of a black hole, or even the location of the nearest black hole, especially seems to be sort of a crapshoot when it’s a system of holes at the galactic center, maybe this is relevant.
The most obvious problem right off the bat is an attitude that “dark matter” is a better placeholder for something that is possibly best largely downgraded to a “dark matter effect.” If I had to choose between “mirage matter” and “mirage matter effect” to describe something that looks conceivably wavy and out of place, I wouldn’t pretend “mirage matter” or “reflection matter” is a cool “placeholder.”
“Thye AQUAL model has its own issues, such as its disagreement with observed gravitational lensing by galaxies.”
That’s prime time MOND for you.
This headline REALLY overstates the strength of the new evidence. The study is interesting absolutely merits follow-up, but MOND absolutely HAS NOT overtaken WIMPs as the leading theory of dark matter. Sensational headlines are a plague on science journalism.
The AH-HA! MOMENT Redefined: Let’s fit the inexplicable to The Model! And call it EVEN.
AH-HA…!? HA-HA-HA-HA… HA!
Infinity fits nicely into a NUTSHELL:as:a thousand Angels can fit on the head of a pin…
Bless you, Pangloss.
Count Rückwärts Vum Zen
Duke of Earl D’Voltaire
QUOTH Saint John of Liverpool: “Science is a six-inch Ruler* by which we measure our Certainty and libidinal prowess.”
*[Napoleon Bonaparte comes to mind.]
Well… It’s off to Waterloo-oo! Warp Nine, Mister Worf. And be quick about it!
Happy News Year, Muppets!
A scitechdaily science writer reveals that MOND is the leading explanation for DM (even though it utterly fails to explain gravitational lensing).
Simply put, so-called “dark matter” is the misinterpretation of the stronger influence of radiant angular coherent (attract perpendicular to their length) lines of gravity force from all cosmic objects rotating in a cosmic sea of said gravity lines of force all radiating to the extremes of the universe than in non-rotating cosmic objects (if there are any). Think of a propeller in water, not rotating and rotating in one direction or the other; stationary-push-pull with no imaginary particles required. Videos of rotating wheel experiments since 2012, now uploaded to my non-economic Odysee dot com/@charlesgshaver video channel.
Rotation curves is just one evidence.
Galaxy gravitation lens is mentioned which cannot be explained by MOND.
What about large scale cosmological structures? DM is also needed.
Anyway, gravitation lenses show DM are even displaced from galaxies, not MOND can help, because it’s based on gravity only, not the dynamics.
So MoND explains well what we can’t (dark matter) see but is in conflict with what we do see (gravitational lensing)? That’s not helping.
Besides the obvious MOND issues, this article assumes stars revolve around the galaxy center like the planets revolve around the sun. Another explanation is the overall spiral arms revolve like that, but the individual stars have their independent motions as strong elliptical orbits coming close to the center and far back out to the arms.
Regarding Dark Matter itself, another possibility, from a view of String Theory, is that Dark Matter appears to us as an effect of string/anti-string annihilations. As you may know, quantum mechanics requires that strings must be formed as pairs in the quantum foam – a string and an anti-string – that immediately annihilate each other. Quantum mechanics also requires both the string and anti-string to be surrounded by “jitters” that reduce their monstrous vibrating energies. What if this jitter remains for a fraction of an instant after their string/anti-string annihilations? This temporary jitter would be seen by us as matter, via E=mc2, for that instant before it too returns to the foam. That’s why we never see it – the “mass” lasts only for that instant but is repeated over and over and over, all over. Specifics on this can be found by searching YouTube for “Dark Matter – A String Theory Way”
Too bad MoND can’t explain why a handful of galaxies rotate slower at the edges… While a galaxy that has less dark matter than would be typical does.
Dark matter simps fail to remember that the standard model has a similar degree of weakness. Also, variable Mass theory has almost exactly the same weakness, and explains all of the “omg 2 big 2 fast” and “2 complex 2 early” issues the standard model will literally *never* manage to explain.
When astrophysicists and particle physicists find stuff that makes 0 sense why is it their impulse to go “but no it’s just the next discovery that will explain it” as opposed to “maybe renormalization is bad”
“maybe renormalization is bad”
That’s a great observation, if I may say so. Thank you for pointing that problem out.
Seems Feynman was able to discredit any version of Gauss’s radiated gravity information carriers by supposing Planck-scale monopolar bosonic vacuum energy gravity carriers, not Planck-scale dipolar bosonic vacuum energy gravity carriers.
Why MOND and not Quantized Inertia?
How randomly chosen parameter is better than strong science?
Thank you, I mean I think that is exactly the right idea and it pinpoints the conceptual problem (beyond lensing) with MoND and all of its potential offshoots, all of which also have a related problem with thinking of gravity as being fundamentally a force.
I’ve never understood how a gravitational force (halo of DM) outside of objects orbiting around a central gravitational source could explain the faster than expected orbital velocity of the objects further from the center.. at the speeds we observe the outer objects should want to fly out of the galaxy and additional gravity outside of their orbit should only make that more likely.. the only simple explanation would be to factor in the additional mass of the inner stars and planets which would extend the strength of the central gravitational source.. that also explains the curved shape of the spiral arms..
Suppose gravity is a vector field expressing radiated gravitational information in the form of vector carriers, analogous to the virtual carriers of the electric field around a charged particle. Suppose further that the information radiated also ultra-slowly rolls (pitches) synchronously, covering only one full roll cycle before it reaches the periphery of the galaxy, as an intrinsic to unitary-spin (bosonic) gravity information carriers, allowing them to be their own antiparticles and net massless. An inflection formed by the ripple of the rolling field has a matter-trapping effect at the periphery of the galaxy. Mathematically speaking the roll effect is equivalent to multiplying Newton’s low energy gravity inverse square rule by a complex sinusoid where the real component expresses the radial component of gravity as if Newton’s gravity should be modified by a cosine function. That’s the simplest way to modify a flux rule applied to the mass of the galactic core in to explain a galactically peripheral mass effect.
Mea culpa, two small typos: “an” is not needed in “as an intrinsic to unitary spin” and “in” is not needed in “core in to explain a galactically peripheral mass effect.”
I could say a lot about spiral arms, there are many types of spirals and interestingly enough to me it’s easy to imagine a 3D toroid surrounding the core of a spiral galaxy and containing the arms on its surface, for many of the most undisturbed spirals. There are many aspects of a complex wavefunction seemingly evident in the most placid spiral galaxy forms. Possibly as if a ring region once existed which accumulated so much mass and became so stretched by energetic interlopers that two spiral arms formed simultaneously from the collapsing ring, as if there is a loss of galactic gravitational coherence. I don’t know about anyone else, but it makes spiral galaxies a lot more interesting to me to think of them as decohering complex wavelets.
Maybe the idea of a complex wavefunction applied to an ideal spiral galaxy is the motivation for so called “holographic” theories. AdS space is analogous to negative phases (core-based repulsive effect) of spatial quasi-static complex gravity waves and the ringlike matter-accumulative inflections of a galactic scaled complex field could be re-imagined as holographic boundaries. Maybe thought leaders wish to be unclear on this as a test, but it seems they are doing field theory in the dark with no concept of field unification.
My original idea for explaining spiral galaxies evolving from a symmetric ring galaxy has a central bar forming as another consequence of the ring accumulating too much material as the process is assisted by sitting in the core-generated concentric gravity inflection. As the ring gains mass, ring self-gravity causes ring constriction, which in turn constricts the core into an unstable proto-bar shape that eventually topples into the ring plane, at the same time destabilizing the ring into forming two arms.
An image search on multiring galaxies (flat galaxies with highlights suggesting wavelike periodicity), shell galaxies (ellipticals with wavelike periodicity), and galaxy morphology, is always something to consider revisiting from time to time.
There are apparently not too many examples of the first two notions as conditions need to settle down for extremely long times in a large region surrounding an unusually strong gravity source in the former case, and in the latter case highlighting of the wavelike nature of the gravity flow is very sensitive to positioning of one or more nearby bright galaxies since around the cores of ellipticals is matter inflated by too much post-collisional kinetic energy for even one clear innermost ring of stars to condense upon the innermost gravity roll wave inflection. That’s just my opinion for now.
As the author of the original article, I haven’t granted you permission to reprint this article, and I certainly didn’t grant you permission to lie in the headlines.
… and now!
Lagrange points, dripping faucet, the Albert’s things… Schrödinger equation and you are getting closer!
This dark matter vs MOND war of words is as unproductive as it is unedifying. It doesn’t have to be a binary choice thing. I have been looking at this generally and this paper specifically – a suggestion: Keep normal matter and gravity as is; keep dark matter but apply a MOND type approach only to dark matter. (There will be a consequential effect on normal matter – these are not independent gravitational systems). I think it might fit the data best of all?
If it’s in conflict with observed gravitational lensing, it’s not a leading candidate. I’m willing to keep an open mind, but dark matter is still the leading candidate even after this study. There’s no mention in the article of large scale cosmological structures and the galaxies that rotate as if they don’t contain dark matter. The title is still sensationalism.
Zwicky first theorized DM to explain coma cluster galactic motion in 1933. Ninety years later with still no clarity, It’s good scientific practice to keep looking for explanations and alternate theories while using the best available observation and data to confirm said theories.
Only layman have become religiously tied to the idea of DM as a halo of undetectable particles when after ninety years we have no direct evidence of such a form of DM. And we have thrown the bank at it (eg $$$CERN
DM is a placeholder, I’m with NGT and we should call DM Fred or Modified Gravity to avoid layman getting so hung up on the unproven prevalent idea DM particles and galactic halos.
The writer calls it “modified gravity” in the article, and someone claims the title is a “lie.” The psychological problem I keep seeing repeated is one of calling the DM effect a consequence of “modified gravity” while behaving as if one is doing science outreach while mainly just pretending to not be an unapologetic general relativity chauvinist cartoon character. Someone is insecurely trying to hide a theory behind a natural phenomenon called gravity, in other words. It’s a practically-untouchable modified gravity theory that is the topic, not modified gravity.
So, the article title, and the article both accomplish two goals:
(1) Priming people to constructively conflate real gravity effects with an iconic gravity theory apparently so esteemed that mentioning it by name, or giving it a hairy eyebrow while considering tossing it into an esteemed theory trash, should be considered unsafe for headline work, and …
(2) Prime people to constructively conflate massive real DM effects with a confirmation of said iconic gravity theory that should not be questioned or given the hairy eyebrow for simply being a perfect locator of invisible motherlodes of inexplicably dark particles buried in plain sight that conceivably may someday solve all of mankind’s problems providing clean water in every desert, controllable climate change mitigation and abundant cheap energy.
“… you also have to modify Einstein’s equations as well”
As if it’s a personal moral imperative. Otherwise, space and time are not welded together by light, gravity is a force, and all the invisible stuff is that way due to it being too small to see directly not that it is too big to naturally appreciate.
“At interstellar distances, the gravitational attraction between stars is essentially Newtonian.”
Fundamentally misleading. Actually, it’s low energies (low velocities), not significant distances, that supports a focus on Newton’s gravity theory vs. Einstein’s gravity theory.
“At interstellar distances, the gravitational attraction between stars is essentially Newtonian. So rather than modifying general relativity, Milgrom proposed modifying Newton’s Universal Law of Gravity. He argued that rather than the force of attraction being a pure inverse square relation, gravity has a small remnant pull regardless of distance.”
It starts out on a bad foot and just gets worse. A small residual pull maintained regardless of distance is the most anti-quantum concept I’ve ever been forced to think about, apart from GR itself. It’s like perpetual motion where the cosmic galaxy-embracing action figure battery is successfully hidden from the eye by pure distance with the unending vastness of the divine extragalactic realm it perpetually governs with such a wondrously generous and even hand
“rather than the force of attraction being a pure inverse square relation, gravity has a small remnant pull regardless of distance”
Saying that gravity follows a flux rule in 3D basically just creates intolerable cognitive dissonance in the mind of a general relativity acolyte.
If your model of gravity cannot be mapped completely into inverse square relations like light and electric fields, then it lacks single point-source flux intensity diminishing in Euclidean space, meaning it’s not flux-based thus gives no excuse for calling gravity a “force” even though most people feel very comfortable with suggesting gravity is a “force.”