Are Dark Matter Concentrations on Earth Seasonal?

[ohwilleke]

[Gauge bosons always move with the speed of light.]

Not true. W and Z bosons are massive gauge bosons. Massless gauge bosons always move with the speed of light, but not all gauge bosons are massless. Massive gauge bosons do not move at the speed of light.

 

[ohwilleke]

At the limit of no energy and no frequency, photons convert to static electromagnetic fields. Which have no energy, but affect matter a lot.
If universe were charged, negative or positive, how would electrostatic repulsion affect expansion of universe?

At the limit of no energy and no frequency, photons don't exist. Anything that matters at all has either matter or energy or both. Photons with no energy would by definition be incapable of affecting anything.

 

[Stavros Kiri]

Not true. W and Z bosons are massive gauge bosons. Massless gauge bosons always move with the speed of light, but not all gauge bosons are massless. Massive gauge bosons do not move at the speed of light.

You're right of course. But here is what I was referring to (not including the W and Z bosons):

But in Elementary Particle Physics, [at least] two particles (sets of particles) are known to be massless (in the relativistic sense though): the two gauge bosons, i.e. photons and gluons. Gravitons would be as well, but they haven't been discovered yet. [All these three mentioned [sets of] particles are force carriers (for EM, strong and gravitational forces, respectively). You might hear of them also as field particles.]

Also regarding:

At the limit of no energy and no frequency, photons don't exist. Anything that matters at all has either matter or energy or both. Photons with no energy would by definition be incapable of affecting anything.

But at that limit also electrostatics emerge (no photons - you're right), so partially in a sense he is right too.

 

[ohwilleke]

Without photons there are no electrostatics.

 

[Stavros Kiri]

Without photons there are no electrostatics.

Coulomb's law requires no photons! ...
[I think what you stated is a common misconception in fundamental physics. Here is why:]
Only accelerating charges or time-varying fields produce EM waves, thus ... when quantized, ... Photons. Static E or B fields produce no photons, (nor EM waves), unless charges move or fields vary in time ... . Other than that they are just static fields ... as dictated by Coulomb's law etc.
(QED and Feynman diagrams would have no choice but to agree with that as well.)

 

[Drakkith]

Without photons there are no electrostatics.

Coulomb's law requires no photons! ...
[I think what you stated is a common misconception in fundamental physics. Here is why:]
Only accelerating charges or time-varying fields produce EM waves, thus ... when quantized, ... Photons. Static E or B fields produce no photons, (nor EM waves), unless charges move or fields vary in time ... . Other than that they are just static fields ... as dictated by Coulomb's law etc.
(QED and Feynman diagrams would have no choice but to agree with that as well.)

QED does model electrostatic interactions using virtual photons though, and Feynman diagrams incorporate both real and virtual particles if I remember correctly.

 

[ohwilleke]

(QED and Feynman diagrams would have no choice but to agree with that as well.)

A field is just photons. If there is nothing to transmit electromagnetic interactions, there is no electromagnetism. Coulomb's law absolutely requires photons in QED.

 

[Stavros Kiri]

Coulomb's law absolutely requires photons in QED.

Do you see any from a static charge? Where are they? What frequency? Virtual perhaps but ... long story ...

 

[mfb]

Photons have to be possible to have static fields in QFT, even if there are no photons flying around.

 

[bluecap]

Everything with energy interacts with gravity. It doesn't even need mass.

And everything has energy, something without energy cannot have any impact on the world and we can simply assume it is not there.
This would violate special relativity, unless "near speed" means the speed of light. But massless particles would not clump together like dark matter does.
I'm not a dark matter expert, but as far as I can see, all the phase space for their assumed WIMP mass and cross section has been ruled out by orders of magnitude since that publication was published, mainly by PICO-60, PandaX-II and CDMS-lite. Here is a recent study.

What if there were dark matter that interacts only with photons and concentrated in the sun and it doesn't interact with any other particles.. does it mean this dark matter species doesn't interact with the weak force but only gravity and with photons.. what are these called then and isn't there any paper that mentions this?

 

[Drakkith]

What if there were dark matter that interacts only with photons and concentrated in the sun and it doesn't interact with any other particles.. does it mean this dark matter species doesn't interact with the weak force but only gravity and with photons.. what are these called then and isn't there any paper that mentions this?

Please stick to real science and avoid speculation such as this. We can't hope to answer every "what if..." scenario that people come up with.

 

[bluecap]

Please stick to real science and avoid speculation such as this. We can't hope to answer every "what if..." scenario that people come up with.

I mean why does dark matter obey the weak interaction.. does it really interact with the weak force? Why not just gravity?

 

[Drakkith]

I mean why does dark matter obey the weak interaction..

As far as we know, it doesn't. It only interacts via gravity.

 

[mfb]

We know it doesn’t interact with photons, otherwise we would see it.
For particles that interact only via gravity it is unclear how they could have been produced in the right amount in the early universe.

 

[bluecap]

We know it doesn’t interact with photons, otherwise we would see it.
For particles that interact only via gravity it is unclear how they could have been produced in the right amount in the early universe.

I thought WIMP interacts via the weak force.. i thought anything that comes from Supersymmetry should interact at least the weak force.. but if it only interacts via gravity.. how come experiments reported WIMP null results when they can't be detected except by gravity?

 

[mfb]

I thought WIMP interacts via the weak force..

By definition, yes (WI in WIMP). That doesn’t mean dark matter has to consist of WIMPs.

i thought anything that comes from Supersymmetry should interact at least the weak force.. but if it only interacts via gravity.. how come experiments reported WIMP null results when they can't be detected except by gravity?

Additional particles don’t have to participate in the weak interaction, it is just likely.
Null results of detectors looking for weak interactions are perfectly consistent with particles with no weak interaction.

 

[ohwilleke]

By definition, yes (WI in WIMP). That doesn’t mean dark matter has to consist of WIMPs.
Additional particles don’t have to participate in the weak interaction, it is just likely.
Null results of detectors looking for weak interactions are perfectly consistent with particles with no weak interaction.

Particles with no weak, strong or EM interactions are not only perfectly consistent with the non-detection of dark matter in direct detection experiments and the non-detection of DM at the LHC. They are also consistent with the absence of any compelling DM annihilation signature. So, while non-detection of DM in those channels is parameter bounding for DM theories, it certainly doesn't rule out DM that is "sterile" (i.e. that only interacts via gravity) or DM that only interacts with other DM in addition to gravity.

The trouble is that the amount of correlation between inferred DM distributions and baryonic matter distributions is too tight to be explained by gravity alone and the shape of the DM distributions aren't what we would theoretically predict if DM was truly sterile or only interacted with other DM. So, truly sterile DM or DM that only interacts with other DM isn't enough to explain the phenomenology.

This leaves you looking for a fifth force that predominantly governs DM-ordinary matter interactions (and possibly also DM to DM interactions), such as the paper described below, in a dark matter particle theory.

Dark matter and neutrinos provide the two most compelling pieces of evidence for new physics beyond the Standard Model of Particle Physics but they are often treated as two different sectors. The aim of this paper is to determine whether there are viable particle physics frameworks in which dark matter can be coupled to active neutrinos. We use a simplified model approach to determine all possible renormalizable scenarios where there is such a coupling, and study their astrophysical and cosmological signatures. We find that dark matter-neutrino interactions have an impact on structure formation and lead to indirect detection signatures when the coupling between dark matter and neutrinos is sufficiently large. This can be used to exclude a large fraction of the parameter space. In most cases, dark matter masses up to a few MeV and mediator masses up to a few GeV are ruled out. The exclusion region can be further extended when dark matter is coupled to a spin-1 mediator or when the dark matter particle and the mediator are degenerate in mass if the mediator is a spin-0 or spin-1/2 particle.

Andres Olivares-Del Campo, et al., "Dark matter-neutrino interactions through the lens of their cosmological implications" (November 14 2017).

 

[bluecap]

Particles with no weak, strong or EM interactions are not only perfectly consistent with the non-detection of dark matter in direct detection experiments and the non-detection of DM at the LHC. They are also consistent with the absence of any compelling DM annihilation signature. So, while non-detection of DM in those channels is parameter bounding for DM theories, it certainly doesn't rule out DM that is "sterile" (i.e. that only interacts via gravity) or DM that only interacts with other DM in addition to gravity.

The trouble is that the amount of correlation between inferred DM distributions and baryonic matter distributions is too tight to be explained by gravity alone and the shape of the DM distributions aren't what we would theoretically predict if DM was truly sterile or only interacted with other DM. So, truly sterile DM or DM that only interacts with other DM isn't enough to explain the phenomenology.

May I know what this "correlation" you were referring to that indicates the amount of correlation between inferred DM distributions and baryonic matter distributions is too tight to be explained by gravity alone? Some references directly about it perhaps? Thank you

This leaves you looking for a fifth force that predominantly governs DM-ordinary matter interactions (and possibly also DM to DM interactions), such as the paper described below, in a dark matter particle theory.
Andres Olivares-Del Campo, et al., "Dark matter-neutrino interactions through the lens of their cosmological implications" (November 14 2017).

 

[Arman777]

Particles with no weak, strong or EM interactions are not only perfectly consistent with the non-detection of dark matter in direct detection experiments and the non-detection of DM at the LHC. They are also consistent with the absence of any compelling DM annihilation signature. So, while non-detection of DM in those channels is parameter bounding for DM theories, it certainly doesn't rule out DM that is "sterile" (i.e. that only interacts via gravity) or DM that only interacts with other DM in addition to gravity.

The trouble is that the amount of correlation between inferred DM distributions and baryonic matter distributions is too tight to be explained by gravity alone and the shape of the DM distributions aren't what we would theoretically predict if DM was truly sterile or only interacted with other DM. So, truly sterile DM or DM that only interacts with other DM isn't enough to explain the phenomenology.

This leaves you looking for a fifth force that predominantly governs DM-ordinary matter interactions (and possibly also DM to DM interactions), such as the paper described below, in a dark matter particle theory.
Andres Olivares-Del Campo, et al., "Dark matter-neutrino interactions through the lens of their cosmological implications" (November 14 2017).

It says it solves some problems for CDM also it can simulate on large scales.

But in general it doesn't seem to me a perfect candidate to understand the general description of CDM. As ohwilleke pointed out we need a new model and maybe even a new force.

 

[ohwilleke]

Some references directly about it perhaps? Thank you

Some references can be found in thIs post. I don't specifically mention it there but collisionless bosonic dark matter models also don't work.

 

[bluecap]

Particles with no weak, strong or EM interactions are not only perfectly consistent with the non-detection of dark matter in direct detection experiments and the non-detection of DM at the LHC. They are also consistent with the absence of any compelling DM annihilation signature. So, while non-detection of DM in those channels is parameter bounding for DM theories, it certainly doesn't rule out DM that is "sterile" (i.e. that only interacts via gravity) or DM that only interacts with other DM in addition to gravity.

The trouble is that the amount of correlation between inferred DM distributions and baryonic matter distributions is too tight to be explained by gravity alone and the shape of the DM distributions aren't what we would theoretically predict if DM was truly sterile or only interacted with other DM. So, truly sterile DM or DM that only interacts with other DM isn't enough to explain the phenomenology.

This leaves you looking for a fifth force that predominantly governs DM-ordinary matter interactions (and possibly also DM to DM interactions), such as the paper described below, in a dark matter particle theory.
Andres Olivares-Del Campo, et al., "Dark matter-neutrino interactions through the lens of their cosmological implications" (November 14 2017).

Just for sake of understanding of your "fifth force that predominantly governs DM-ordinary matter interactions (and possibly also DM to DM interactions)", supposed you had a dark matter jacket that somehow got binded to your body and the dark matter jacket weights 50 lbs and you weight 100 lbs.. what would happen if you put yourself in a weighting scale. Would it register 150 pounds or 100 pounds? I know the dark matter jacket won't affect the weighing scale directly and it won't be pull down because the Earth won't attract it.. so I guess it can just cause a drag in your body when you run.. can this drag be measured? In cosmological setting.. what are the results of attempts to measure this drag?

 

[Drakkith]

I know the dark matter jacket won't affect the weighing scale directly and it won't be pull down because the Earth won't attract it..

It would certainly be attracted to the Earth, as dark matter interacts gravitationally with normal matter. If you could somehow attach this jacket to yourself you would find that you weighed more. There would be no drag though, as that requires an EM interaction, which dark matter doesn't have.

 

[bluecap]

It would certainly be attracted to the Earth, as dark matter interacts gravitationally with normal matter. If you could somehow attach this jacket to yourself you would find that you weighed more. There would be no drag though, as that requires an EM interaction, which dark matter doesn't have.

Hmm... don't they make weighing scale in the labs that can measure the dark matter flux by coupling using the fifth force with dark matter moving all around.. it should register different readings.. shouldn't it?

 

[bluecap]

There are two known particles (gravitons and gluons) and one hypothetical one (gravitons) that have no mass, but all of them have energy, and gravity interacts with anything that has mass or energy or both. All Standard Model particles with mass interact via the weak force. All quarks and gluons interact via the strong force. All quarks, charged leptons and massive weak force bosons emit and absorb photons as part of the electro-magnetic force. All Standard Model particles interact via gravity as does the hypothetical graviton.

If something had no mass and also had no energy, it could not have interactions and could not do work because energy is defined as the capacity to do work. Physics is defined so that only things with observable effects are considered. Something that has no interactions and cannot do work can't have any observable effects, ergo, they don't exist.

Are there dark matter candidates which don't contain mass but only pure energy (which can still interact with gravity)?

If a particle has no mass (like photons) it moves at the speed of light... but photons have energy... I mean.. if dark matter contains no mass but only energy.. should it move at speed of light too?

 

[ohwilleke]

Are there dark matter candidates which don't contain mass but only pure energy (which can still interact with gravity)?

If a particle has no mass (like photons) it moves at the speed of light... but photons have energy... I mean.. if dark matter contains no mass but only energy.. should it move at speed of light too?

A massless particle moves at the speed of light which is inconsistent with dark matter which has sub-relativistic speeds (i.e. it is 'warm" or "cold" dark matter, not "hot" dark matter) if it exists in the form of a particle, although massless particles could, in principle be confined in a massive composite particle (e.g. a "glueball"). For the same reason, ordinary neutrinos cannot be dark matter because they are too "hot" which is to say that their average velocity is too large.

 

[bluecap]

A massless particle moves at the speed of light which is inconsistent with dark matter which has sub-relativistic speeds (i.e. it is 'warm" or "cold" dark matter, not "hot" dark matter) if it exists in the form of a particle, although massless particles could, in principle be confined in a massive composite particle (e.g. a "glueball"). For the same reason, ordinary neutrinos cannot be dark matter because they are too "hot" which is to say that their average velocity is too large.

what dark matter candidates are like glueball where the massless dark matter particles could be confined in the massive composite particle as you described?

 

[mfb]

Hmm... don't they make weighing scale in the labs that can measure the dark matter flux by coupling using the fifth force with dark matter moving all around.. it should register different readings.. shouldn't it?

I have no idea what you are talking about, but the answer is no. Nothing that would fit to your description is done.

 

[bluecap]

Hard to say since no dark matter has ever been detected directly and the density in our solar system is very low even by the standards of dark matter. As I recall, the general estimate is that in the entire solar system there is enough dark matter to make up the mass equivalent of a modest sized asteroid.

That are the constraints data on the general estimate of dark enough volume in the entire solar system besides that it has mass equivalent of a modest sized asteroid.. like could it have 10 times the volume of a modest size asteroid and still consistent with the data?

What is the maximum volume or threshold (compared to this reference modest size asteroid) when they can already affect the orbits of the planets?

 

[mfb]

That are the constraints data on the general estimate of dark enough volume in the entire solar system besides that it has mass equivalent of a modest sized asteroid

Can you rephrase this question?

like could it have 10 times the volume of a modest size asteroid and still consistent with the data?

Dark matter doesn't have a volume. If you multiply the volume of the solar system (defined by the outermost planet, the Kuiper belt, the transition to the interstellar medium or whatever you like) and multiply it by the local dark matter density you get this asteroid-scale mass value.

To calculate the influence of dark matter on an orbit, only dark matter closer to the Sun is relevant, so the volume is fixed by the object you consider.

 

[bluecap]

Can you rephrase this question?

typo, the "t" should be "w" or "what".

I meant, local dark matter density can vary between between regions in the cosmos, correct? So how many multiples increase in the local dark matter density of our solar system before it can change the gravitational properties of our solar system?

And if dark matter in our solar system is only asteroid-scale mass value.. how come it is said there are more dark matter than matter in the universe.. maybe you mean there are more dark matter in the outer region of galaxies and they are all crowding there?

ohwilleke mentioned about fifth force that predominantly governed DM-ordinary matter interactions (and possibly also DM to DM interactions)? So why is this not accepted as solution?

Dark matter doesn't have a volume. If you multiply the volume of the solar system (defined by the outermost planet, the Kuiper belt, the transition to the interstellar medium or whatever you like) and multiply it by the local dark matter density you get this asteroid-scale mass value.

To calculate the influence of dark matter on an orbit, only dark matter closer to the Sun is relevant, so the volume is fixed by the object you consider.

 

[phinds]

And if dark matter in our solar system is only asteroid-scale mass value.. how come it is said there are more dark matter than matter in the universe

Uh ... because there IS?

maybe you mean there are more dark matter in the outer region of galaxies and they are all crowding there?

Yes, the distribution of dark matter is not based on solar systems, it is spread somewhat evenly throughout the galaxy and the total volume of the galaxy makes the volume of our solar system approximately zero, thus the low absolute amount of DM in our solar system.

What's also true is that apparently the density of DM in our solar system IS anomalously low compared to the galaxy as a whole but I don't recall by what factor.

ohwilleke mentioned about fifth force that predominantly governed DM-ordinary matter interactions (and possibly also DM to DM interactions)? So why is this not accepted as solution?

What "5th force"?

 

[bluecap]

Uh ... because there IS? Yes, the distribution of dark matter is not based on solar systems, it is spread somewhat evenly throughout the galaxy and the total volume of the galaxy makes the volume of our solar system approximately zero, thus the low absolute amount of DM in our solar system.

What's also true is that apparently the density of DM in our solar system IS anomalously low compared to the galaxy as a whole but I don't recall by what factor.

How do we know that the density of DM in our solar system is anomalously low? If there is an increased of 100 times or say the dark matter from other part of the galaxy travels to ours because they can become dynamic due to some 5th force complexities or interactions.. can we measure it?

What "5th force"?

you missed ohwilleke post #52 where he shared:

"This leaves you looking for a fifth force that predominantly governs DM-ordinary matter interactions (and possibly also DM to DM interactions), such as the paper described below, in a dark matter particle theory.

Andres Olivares-Del Campo, et al., "Dark matter-neutrino interactions through the lens of their cosmological implications" (November 14 2017)."

 

[phinds]

How do we know that the density of DM in our solar system is anomalously low?

Good question. I don't recall. I just recall reading somewhere here on PF that that is the case.

If there is an increased of 100 times or say the dark matter from other part of the galaxy travels to ours because they can become dynamic due to some 5th force complexities or interactions.. can we measure it?

As far as I am aware that kind of change in the DM density just doesn't happen.

you missed ohwilleke post #52

Oh, yeah. I forgot about that because I considered it speculative (I could be wrong)

 

[mfb]

I meant, local dark matter density can vary between between regions in the cosmos, correct?

It does.

So how many multiples increase in the local dark matter density of our solar system before it can change the gravitational properties of our solar system?

Many orders of magnitude. Sure, people searched for it, but without expecting and without finding any effect.

how come it is said there are more dark matter than matter in the universe

Our solar system is not a typical place in our galaxy - it is a lot of mass in a small volume. Take a cubic light year containing our solar system and you get 1/4 Jupiter mass as dark matter. Take 5000 cubic light years and you get the mass of the solar system.

How do we know that the density of DM in our solar system is anomalously low?

It is not.

ohwilleke mentioned about fifth force that predominantly governed DM-ordinary matter interactions (and possibly also DM to DM interactions)? So why is this not accepted as solution?

There is absolutely no indication of any fifth interaction, why do you keep bringing this up?

 

[phinds]

It is not.

Hm ... I was SURE that I had read here on PF that it is, and that that was backed up by published information (although I have no recollection of the provenance of same). I'll poke around and see if I can find something. Perhaps I misunderstood.

EDIT: well, I'm coming up w/ nothing. Senior moment maybe.

2nd EDIT: I did find a pop-sci article that does at least support my recollection of having read about lower than expected DM in the solar system:

https://www.forbes.com/sites/alexkn...detect-dark-matter-near-the-sun/#1920ca287e0e

a quote from it:

Because of the high confidence level of these findings, this should clear up a recent controversy over the amount of dark matter in the solar system after a paper last year seemed to indicate that there was far less dark matter in the solar system than expected.