It might well be; its equation of state isn't known. It's only known that it interacts gravitationally with ordinary matter, so its equation of state can't be deduced from that. However we know that we couldn't ``touch'' dark matter, since it doesn't have electromagnetic interactions with ordinary matter.
If dark matter has a gravitational effect, then it can't be a superfluid. Both superfluid and superconducting matter are (or could well be) weightless :
Preprint Does the superfluid part of a supersolid, superfluid, or sup...
Preprint EUREKA ------Is there a substance that weighs nothing here on earth?
(And I would question whether dark matter exists at all).
“Is dark matter a superfluid?”
- that looks as rather vague question, since it isn’t defined what is “superfluid”. If that relates to standard “superfluid” physical effect that occurs in ultracold matter, when a corresponding liquid flows “without friction” i.e. atoms in a liquid don’t interact in the liquid and with environment with dissipation energy, then the dark matter indeed is similar in this case; however, unlike atoms in any liquid, dark matter particles interact with each other and environment by only extremely weak Gravity Force,
- and so particles in some concrete dark matter systems, that are formed by some large enough masses – say, galaxies, where dark matter particles compose galaxies haloes, practically don’t interact mutually, while all material structures in galaxies, i.e. stars, molecular clouds, etc., are practically completely transparent [in orders by magnitude more transparent than that is at neutrinos propagations in this case].
So dark matter particles move along their individual orbits around the centers of masses, in the haloes move well below “event horizons” of galaxies’ SMBHs; though if a dark matter particle hits into the central compact object in a SMBH, it practically for sure is absorbed. So dark matter particles compositions really are some swarms, while calling that “fluids” looks as superfluous, or even misleading.
More about what can be dark matter particles, etc., see the Shevchenko-Tokarevsky’s initial cosmological model in
https://www.researchgate.net/publication/354418793_The_Informational_Conception_and_the_Base_of_Physicssection “Cosmology”.
SS posts on page 1 in https://www.researchgate.net/post/Can_dark_matter_be_due_to_quantum_gravity/2 are relevant to this thread question.
Cheers
As of now I understand the dark matter particles are hypothetical subatomic particle axion-like, with masses of order eV, thermalizes and condenses to form a superfluid phase in galaxies. They Bose-Einstein condense into a superfluid phase in the central regions of galaxy helos and superfluid dark matter( i think this is a strong confusion of cold dark matter or hot dark matter) which made of weakly interacting particles fills empty space(displaces by ordinary matter), an exotic quantum state of matter that has zero viscosity.But still its look like impossible , unseen gravity, low temperature and quantum are really emerged, possibilities of superfluid phases forming naturally in extreme conditions of space.
Though in the SS post above the tread question is clarified rather in detail, from the post after it looks as worthwhile to clarify some points again. So
“…As of now I understand the dark matter particles are hypothetical subatomic particle axion-like, with masses of order eV, thermalizes and condenses to form a superfluid phase in galaxies…”
- any hypothetical subatomic particle can really be created, if not completely mystically, only at interactions of other particles, and so has some energy; if particles have extremely small masses – of order eV, as that, say, would be so called “axions”, these particles even having ~eV energies have so large speeds that are much more than escape velocities even from galaxies, where escape velocities are ~ few km/s,
- and so such particles by no means can compose some stable systems, say, observable galaxies haloes; etc.
Including since dark matter particles interact with everything, including mutually, only by extremely weak Gravity Force, these particles cannot be thermalized at all.
Including so to that
“…. They Bose-Einstein condense into a superfluid phase in the central regions of galaxy helos and superfluid dark matter( i think this is a strong confusion of cold dark matter or hot dark matter) which made of weakly interacting particles fills empty space(displaces by ordinary matter), an exotic quantum state of matter that has zero viscosity…”
- despite that any Bose-Einstein condense really is impossible, nonetheless, because of the Gravity is extremely weak Force, the dark matter particles move along their, independent on anything, besides “host gravity field” own orbits around the center of mass of, say, a galaxy;
- so their permanent state is a “swarm” – that has, of course, just “zero viscosity”; and, again, dark matter is just “cold matter”, which, though, becomes be "heated" at perigees and "cooled" at apogees of particle orbits; but application of the term “temperature” in this case looks as quite useless.
“…..But still its look like impossible , unseen gravity, low temperature and quantum are really emerged, possibilities of superfluid phases forming naturally in extreme conditions of space...”
- that is really so, and for at least a few reasons. First of all for exclusively by Gravity Force interacting particles the conditions of space aren’t extreme; again – the term “superfluid phases” really has no physical sense – in contrast to the case when it is applied to really interesting physical effects in concrete quantum liquids,
- while really dark matter particles [see the link to the SS&VT cosmological model in the SS post above] with a well non-zero probability are Planck mass particles, i.e. have masses that in ~1019 times larger than nucleons’ masses, and so, despite that rather probably dark matter mass in Matter really is in ~ 20 times larger than mass of the visible matter, the dark matter particles density in the space is in ~1018 times lesser than baryons density, i.e. ~ a few DM particles in a cube with million m size; what, again, excludes any mutual DM particles interactions.
The dark matter particles with a rather non-zero probability can compose some quantum systems, however only inside the black holes’ extremely compact and dense central objects.
More see the SS post above and links in the post.
Cheers
Lensing is one consequence of gravitational interactions, whose non-relativistic approximation is given by Newton's law.
Dark matter interacts with ordinary matter gravitationally through its energy-momentum tensor, just like any other form of matter. The gravitational interaction doesn't depend on any other features beyond the energy-momentum tensor and that of a perfect fluid seems to do the job. A superfluid is a special case of a perfect fluid, but the measurements aren't sensitive to the particular properties of a superfluid.
it is quite disputable since one should see ordinary masses oscillating then...
you can understand why...
Dear Stefano: Dark matter interacts with ordinary matter through the Lagrangian LXoXodm=−λ0f2o Φ where Φ is the trace of Φαβ (the energy-momentum tensor of the gravitational field in MGR), f0 is the magnitude of a spin-1 vector describing ordinary matter and λ0 is a coupling constant. Near the Earth Φ = 1.42×10−39m−2 but if f0 is unity, λ0 is ~c3/16πG so the interaction is ~1.13 × 10−5. However, since attempts to detect dark matter near or in the Earth have not yet been confirmed, it is more likely that λ0f2o is not large. See Article Modified general relativity and dark matter
p14. Dark matter can be a spin-1 vector or a pair of spin-1/2 spinors; a spin-0 axion does not describe dark matter because it does not belong to the metric as a line element vector field, which exists in all Lorentzian metrics.
Dear Gary
Gary Nash ,
although it may interact, it does it in a very different way than ordinary matter and since DM is like a bosonic aggregate, attraction of ordinary matter to it would mean that this mass would oscillate around the center of mass of the DM.
I think DM consists of axion-like particles with mass of order eV and strong self-interactions. Its not like a antimatter, anti matter has an opposite charge and cannot interact with matter, while dark matter interacts with matter through gravitational forces. DM does not interact with electromagnetic force, cannot absorb, reflect, emit light, that's why it cannot be detected by EM(electromagnetic) Radiation. There is a couple of problematic query with superfluid Dark Matter like (1) how axian like phonon caries the superfluid energy (2) can it overcome many of the theoretical problems with the particle clouds, why mediation occurs, what scale it is achieved,(3) is this a cosmological superfluid droplets (4) unstable formation of stationary self bound structures which can minimise the energy , from condensed matter physics and theoretical physics point of view remain to be solved.
Ashish Thakur,
a lot of searches for axions or the alike have been done up to now but all have failed. See my last book (Born: A universe V, in my profile).
In my first book I found that up to 90 % of the mass universe could be due to neutrinos. They will look like DM.
Really rational and scientifically clear proposal of what “dark matter” can be - see in the SS posts on page 1, while after the posts rather vague posts appeared, as, say,
“…>
it is quite disputable since one should see ordinary masses oscillating then...
you can understand why...….”
- what looks as rather questionable claim. Really in this case there is no some physical reasons for some “ordinary masses oscillating”, DM particles are fundamentally cold, i.e. have rather small speeds, and are distributed in space too smoothly and chaotically, so really cannot to make, say, a star in a galaxy be “oscillating”.
And to
“…a lot of searches for axions or the alike have been done up to now but all have failed. See my last book (Born: A universe V, in my profile).
In my first book I found that up to 90 % of the mass universe could be due to neutrinos. They will look like DM.…..”
- again, the assumption that some really light particles, i.e. real neutrinos and/or too questionable at all “axions”, which – if that relates to DM – constitute mass in Matter that in well more than a dozen of times is larger than mass of visible matter,
- were created as just cold matter or for/by some mystic reason were cooled up to few km/s speeds, looks as too questionable. If some creation of DM particles really happened, then it could be quite reasonable that these particles really had at creations speeds much more km/s – and, since practically don’t interact with visible matter and mutually – so have large speeds till now,
- and so these particles principally could not compose some, again, seems really observable, stable systems. Though yeah, this hypothesis is rather popular in main stream physics, and, say, in May in top journals a couple of papers were published, where the authors write about the highly technological experimental installations that are intended for detection of ultralight particles [including axions] that would be dark matter particles; and these papers were pointed in phys.org articles https://phys.org/news/2023-05-laws-physics-symmetric.html and
https://phys.org/news/2023-05-world-sensitive-model-independent-dark.html
After in the articles reDzennn comments appeared [practically that is above here] as, say, ~ 20-th comment in the first link, in the article’s comment string more 80 full stop comments appeared in a couple of days; what was/is evident spam, since some people didn’t like the reDzennn comments…
Cheers
Ashish Thakur, I have proved that DM cannot be a spin-0 particle and therefore axions with that spin are not dark matter particles . If you digest Article Modified general relativity and dark matter
you will learn that it must be a spin-1 or its equivalent, a pair of spin-1/2 particles like massive neutrinos. The reason for the spin-1 (pair of spin-1/2) nature of dark matter is because the line element unit covector field is a natural part of any Lorentzian metric. That leads to a solution of the Einstein equation for ordinary matter-free spacetime Gαβ + Φαβ = 0 from which the modified Newtonian force lawFr = −GMm/r2−| b | mc2/r+a0mc2/2 appears from the extended Schwarzschild solution to Gαβ + Φαβ = 0. You can see that the dark matter force is the second term and the dark energy force is the third. You can see in the article how MGR beautifully describes dark matter without any DM profiles as compared to GR with a DM profile (GR cannot account for DM without an additional profile to describe the missing mass). For example, the total perihelion advance of Mercury from GR, dark matter and the quadrupole moment of the Sun is calculated in MGR to be 43.01 arc sec/century without any DM profile. That result compares very well with the measured value of 43.0115±0.0085 arc seconds per century.
Dear Gary,
Gary Nash
let's consider this simple scenario that a massive particle begins to be attracted by some dark matter. That means that given a hypothetical center of mass COM of the DM cluster, the massive particle begins to change its speed in reference to it.
Since the DM does not interact electrically with it means that the mass can cross it without finding any resistance. Once the mass has passed the COM, it will get decelerated and gain potential energy till it will stop and come back. This gets in a never ending oscillation at variance with a one time collision and scattering occurring with ordinary matter.
what about the one calculated with GR only?
Dear Stefano. Relative to your question, the quadrupole moment of the Sun generates a contribution of 2.8361 × 10−10 to the advance of Mercury/orbit in both GR and MGR. But GR cannot explain the DM result of 3.4341 × 10−11 to the advance/orbit. Adding the GR, quadrupole and DM contributions gives the result as stated according to the details on p.24 of the paper/century of orbits.
Your explanation of the oscillations of the interaction of DM and ordinary matter cannot be quite that simple because there is an interaction between DM and OM as I showed you; it is small but non-zero. Some experimental evidence of exactly what value λ0 can have will some day be available.
Its high level miscommunication about dark matters existence, gravitational lansing, rotation etc.. We will get everything clear whether dark matter really affects the orbits of a planet or not?
Dear Gary,
Theories from the Bose Einstien about self interacting(dark matter interacts with normal matter) is one side but another side rotation velocity, existence are less known even some says this is a neutrino/ higgs boson/cloud...
Dear Ashish: the interactions with ordinary matter and dark matter, and self interactions of dark matter were investigated in "MGR and dark matter" as well as modelling galactic rotation curves and several other topics. There seems to be no point of further participation in this thread because: words are cheap, but mathematics is expensive.
What is the experimental evidence that Dark Matter exists? Can we trust that the experimental evidence (if there is any) is not just fiction, for funding purposes? Grants &c.
Dear Gary Stephens,
As of now I understand there are couple of theory/ theoretical calculations/models/postulates/ technical definitions in favor of dark matter existence. 1884 to 1980 there are few observations suggested for the support evidence of existence, observations are likely to noted are hypothesis, astronomy observations, galaxy rotation curves, velocity dispersion, gravitational lensing of background objects by galaxy clusters,cosmic background radiation theory, structure formation by 3D-Map, bullet cluster etc. Bose-Einstein, Lambda-CDM model of cosmology are few of them rules. Experimental work carried out in laboratory and analysis report which approves in appropriate evidence of dark matter existence experimentally is not available much or not seen.
Ashish
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