Dark matter ....

[julius2]

Studying this is a complete waster of time. The theory is that much of the universe is made up of "dark matter".

What is more important is to see this as "time". It is a bit complicated and relies on an element of belief.

But I am just trying to saving our scientists (and people on this planet), from wasting their time.

 

[iNow]

1 hour ago, julius2 said:

relies on an element of belief.

That’s insufficient rigor given the rules of this subforum. Other people’s time is not yours to save 

[Phi for All]

1 hour ago, julius2 said:

Studying this is a complete waster of time. The theory is that much of the universe is made up of "dark matter".

Seems like a complete waste of two seconds. It's actually a bit deeper than that.

1 hour ago, julius2 said:

What is more important is to see this as "time". It is a bit complicated and relies on an element of belief.

Please focus on this bit about seeing dark matter as time. Also, please do so without this element of belief, unless this belief is supportable. I believe in photosynthesis because I trust the explanation and have loads of evidence in support. If your belief is base on faith or wishful thinking, it's not science.

1 hour ago, julius2 said:

But I am just trying to saving our scientists (and people on this planet), from wasting their time.

I'm so grateful science doesn't work this way! Imagine if everyone who didn't understand an explanation could get everybody else to drop it too, claiming they're just wasting their time. We'd never progress at all. Thanks to all the tireless researchers who don't think rigor is a waste!

 

[julius2]

25 minutes ago, Phi for All said:

Seems like a complete waste of two seconds. It's actually a bit deeper than that.

Please focus on this bit about seeing dark matter as time. Also, please do so without this element of belief, unless this belief is supportable. I believe in photosynthesis because I trust the explanation and have loads of evidence in support. If your belief is base on faith or wishful thinking, it's not science.

I'm so grateful science doesn't work this way! Imagine if everyone who didn't understand an explanation could get everybody else to drop it too, claiming they're just wasting their time. We'd never progress at all. Thanks to all the tireless researchers who don't think rigor is a waste!

 

Ok. I guess one cannot comment about dark matter idea unless they have some idea of what the concept is and the rigour that has gone in to it.

I obtained my information about dark matter from reading some books and also a magazine. According to the magazine and I quote "indicate that 85% of all matter consists of a mysterious form of "dark matter", so-named because it does not interact directly with light".

Honestly I truly respect the rigour scientists of the world have gone in to to try and discover about where we came from and where we are going.

[exchemist]

37 minutes ago, julius2 said:

Ok. I guess one cannot comment about dark matter idea unless they have some idea of what the concept is and the rigour that has gone in to it.

I obtained my information about dark matter from reading some books and also a magazine. According to the magazine and I quote "indicate that 85% of all matter consists of a mysterious form of "dark matter", so-named because it does not interact directly with light".

Honestly I truly respect the rigour scientists of the world have gone in to to try and discover about where we came from and where we are going.

OK, I'm not an astronomer either, so the little I have learned about Dark Matter also comes from magazine articles and the internet. I can summarise what I have learned as follows:

- Dark Matter is a just a placeholder label, for something we can't yet explain,

- the evidence for it is that the observed rotation rates of galaxies do not fit with the estimates of mass one gets by adding up the visible stars they contain,

- there is something going on that seems to cause them to have extra gravitation, presumably extra mass, but which is invisible and transparent to EM radiation. 

- so the simplest explanation would seem to be that there are forms of matter out there which do not interact with EM radiation, but do exert gravitational attraction.

(There are some further cosmological arguments to do with General Relativity and the cosmos but I have not followed those.)  

Is your understanding the same or different? 

 

[swansont]

3 hours ago, julius2 said:

Studying this is a complete waster of time. The theory is that much of the universe is made up of "dark matter".

What is more important is to see this as "time". It is a bit complicated and relies on an element of belief.

But I am just trying to saving our scientists (and people on this planet), from wasting their time.

 

Do you have a model and/or evidence for this?

[Phi for All]

3 hours ago, julius2 said:

Ok. I guess one cannot comment about dark matter idea unless they have some idea of what the concept is and the rigour that has gone in to it.

Yes. You should have given us enough in the OP to make comments and start a discussion. So far, I know you want us to see dark matter as time, and this involves believing in something. Nothing since has explained or persuaded anything about the topic.

3 hours ago, julius2 said:

I obtained my information about dark matter from reading some books and also a magazine. According to the magazine and I quote "indicate that 85% of all matter consists of a mysterious form of "dark matter", so-named because it does not interact directly with light".

OK. Always make sure your sources aren't pushing some popular POV just to get attention. "We call it dark because it doesn't interact with light" sounds like a pop-sci treatment. exchemist used a more accurate phrase regarding the interaction:  DM is invisible and transparent to EM radiation.

Quote

Honestly I truly respect the rigour scientists of the world have gone in to to try and discover about where we came from and where we are going.

Great!

Um, you still haven't given us any speculation, other than it's complicated and it may involve believing that DM is time. What are you talking about?

[julius2]

3 hours ago, exchemist said:

OK, I'm not an astronomer either, so the little I have learned about Dark Matter also comes from magazine articles and the internet. I can summarise what I have learned as follows:

- Dark Matter is a just a placeholder label, for something we can't yet explain,

- the evidence for it is that the observed rotation rates of galaxies do not fit with the estimates of mass one gets by adding up the visible stars they contain,

- there is something going on that seems to cause them to have extra gravitation, presumably extra mass, but which is invisible and transparent to EM radiation. 

- so the simplest explanation would seem to be that there are forms of matter out there which do not interact with EM radiation, but do exert gravitational attraction.

(There are some further cosmological arguments to do with General Relativity and the cosmos but I have not followed those.)  

Is your understanding the same or different? 

 

Yes. Your comments are very helpful.

So DM is a placeholder label. This roughly reconciles with my own theories. In other words my "time" concept is not explainable within the current context of physics. But I am happy to explore DM more as I only have speculation for my idea.

So DM looks at a MISMATCH in mass estimates for the universe?

 

Maybe you could elaborate more about the observed rotation rates (of galaxies?). I am okay with some maths but not super complicated maths.

[exchemist]

1 hour ago, julius2 said:

Yes. Your comments are very helpful.

So DM is a placeholder label. This roughly reconciles with my own theories. In other words my "time" concept is not explainable within the current context of physics. But I am happy to explore DM more as I only have speculation for my idea.

So DM looks at a MISMATCH in mass estimates for the universe?

 

Maybe you could elaborate more about the observed rotation rates (of galaxies?). I am okay with some maths but not super complicated maths.

It is explained here: https://en.wikipedia.org/wiki/Galaxy_rotation_curve

There is an animation which helps. The left hand galaxy rotates as would be expected on the basis of the mass calculated from the visible stars, while the right is closer to what is actually found. The difference is that in the right hand case extra, invisible, mass is distributed throughout the galaxy from the centre out to the edge. 

So that's the problem, or one of them. What else could account for the anomalous rotation pattern? There is a hypothesis that perhaps the law of gravitation works somehow differently at very long range from what we see in our own solar system. That is what the article refers to as "Modified Newtonian Dynamics", or MOND. But not many people seem to like that idea very much, as it makes some predictions which are not borne out by observation. The particle physicists on the other hand, struggle to imagine what kind of hitherto undetected particle, or particles, could make up the extra matter with gravitational mass needed to account for the astronomical observations.  

So we are in a quandary. The hunt is on for mystery particles, while people also struggle to refine MOND in an attempt to overcome some of its shortcomings, i.e. things it predicts we should see but which we don't.   

Edited July 30 by exchemist

[swansont]

!

Moderator Note

You are free to ask questions about dark matter, but if you have no model to present, then please refrain from mentioning your “theory” 

 

[julius2]

24 minutes ago, swansont said:

!

Moderator Note

You are free to ask questions about dark matter, but if you have no model to present, then please refrain from mentioning your “theory” 

 

The aim of my posts is to "stitch together" the "right theory". It is a difficult topic however. So the model so to speak would be the overall combination of my posts.

Hopefully small breakthroughs occur along the way which satisfy the rules of the forum?

[swansont]

49 minutes ago, julius2 said:

The aim of my posts is to "stitch together" the "right theory". It is a difficult topic however. So the model so to speak would be the overall combination of my posts.

Hopefully small breakthroughs occur along the way which satisfy the rules of the forum?

Thus far there is zero content that complies with the speculations rules regarding a new idea, so there’s nothing to stitch together

[Phi for All]

3 hours ago, julius2 said:

So DM is a placeholder label. This roughly reconciles with my own theories.

You have multiple theories?!

What does "placeholder label" mean to you, and what does it reconcile? I've heard it explained as an unknown like x, but we do know something about it. It has mass that accounts for missing matter in our galactic rotation calculations and is invisible and transparent to EM radiation. That's at least part of what "dark" means. 

I suppose the name may change when we can explain it more accurately, but maybe not. Yet some folks place a lot of importance in the name only being a "placeholder label".

[Mordred]

2 hours ago, julius2 said:

The aim of my posts is to "stitch together" the "right theory". It is a difficult topic however. So the model so to speak would be the overall combination of my posts.

Hopefully small breakthroughs occur along the way which satisfy the rules of the forum?

Piece of advise it would be impossible to stitch together some model for DM without having a sufficient mainstream understanding in the related mainstream physics theories and models.

For example how does one determine the measurable effects via indirect evidence unless one knows how calculate galaxy rotation curves or what influence DM would have on expansion.

If you cannot perform those calculations then you have zero ability to test any theory with regards to DM.

 There is also mainstream formulas that describe and define the most likely distributions of DM in terms of their early universe large scale structure formation contributions.

(Trust me it's not an easy formula to use).

The formula will return a Gaussian distribution (it's also one I've never mentioned before on this forum)

Edited July 30 by Mordred

[joigus]

3 hours ago, julius2 said:

The aim of my posts is to "stitch together" the "right theory". It is a difficult topic however. So the model so to speak would be the overall combination of my posts.

A good place to start is trying to understand the virial theorem.

Also, having a good understanding of physics beyond the standard model. The standard model is a pre-requisite for the latter.

For starters, are you familiar with the fact that for gravitational systems the average kinetic energy is minus a half the average potential energy?

If this thread goes well you could be on track to a Nobel Prize, who knows.  

[MigL]

10 hours ago, exchemist said:

I can summarise what I have learned as follows:

pretty well bang on for someone who claims to not be an astronomer either, and the "little ... learned about Dark Matter also comes from magazine articles and the internet".
I guess you just stick to the evidence, and don't jump to unsupported conclusions, like a good scientist.

[julius2]

4 hours ago, joigus said:

A good place to start is trying to understand the virial theorem.

Also, having a good understanding of physics beyond the standard model. The standard model is a pre-requisite for the latter.

For starters, are you familiar with the fact that for gravitational systems the average kinetic energy is minus a half the average potential energy?

If this thread goes well you could be on track to a Nobel Prize, who knows.  

I am not interested in a Nobel Prize, truly.

I just want Earth to have a future.

We all watched Star Wars as kids. Why can't we have a future like this?

2 hours ago, MigL said:

pretty well bang on for someone who claims to not be an astronomer either, and the "little ... learned about Dark Matter also comes from magazine articles and the internet".
I guess you just stick to the evidence, and don't jump to unsupported conclusions, like a good scientist.

It is not possible to stick to "conventional" scientific methods in this case (trust me)!

But these scientific methods have served us well in the past.

5 hours ago, Mordred said:

Piece of advise it would be impossible to stitch together some model for DM without having a sufficient mainstream understanding in the related mainstream physics theories and models.

For example how does one determine the measurable effects via indirect evidence unless one knows how calculate galaxy rotation curves or what influence DM would have on expansion.

If you cannot perform those calculations then you have zero ability to test any theory with regards to DM.

 There is also mainstream formulas that describe and define the most likely distributions of DM in terms of their early universe large scale structure formation contributions.

(Trust me it's not an easy formula to use).

The formula will return a Gaussian distribution (it's also one I've never mentioned before on this forum)

Gaussian distribution.

I haven't heard this in a long time. (Basically a curve symmetric around the mean.)

I looked it up. Thank you.

[Mordred]

Yeah but when you factor in the speed of information exchange c (this includes baryonic matter as well as DM)  and the scale of the universe it gets rather complicated.

The equations I mentioned is below

https://en.m.wikipedia.org/wiki/Press–Schechter_formalism

For galaxy rotation curves the methodology including DM is the NFW profile..

 

https://en.m.wikipedia.org/wiki/Navarro–Frenk–White_profile

Essentially this profile is a power law in point of detail one can derive a log function for the above profile that shows that by enveloping a galaxy with DM so the mass is uniformly distributed with mass greater than the mass of the galaxy itself you get the observed galaxy rotation curves. Without this distribution and no DM the mass terms of strictly baryonic matter would give what's called a Kepler decline.

 As to the first set of equations they ger applied primarily in predictions involving early universe large structure formation due to DM halos in the early universe.

 Which is another factor in cosmology where DM is needful.

Edited July 31 by Mordred

[exchemist]

25 minutes ago, Mordred said:

Yeah but when you factor in the speed of information exchange c (this includes baryonic matter as well as DM)  and the scale of the universe it gets rather complicated.

The equations I mentioned is below

https://en.m.wikipedia.org/wiki/Press–Schechter_formalism

For galaxy rotation curves the methodology including DM is the NFW profile..

 

https://en.m.wikipedia.org/wiki/Navarro–Frenk–White_profile

Essentially this profile is a power law (an example of a power law is logarithmic functions) in point of detail one can derive a log function for the above profile that shows that by enveloping a galaxy with DM so the mass is uniformly distributed with mass greater than the mass of the galaxy itself you get the observed galaxy rotation curves. Without this distribution and no DM the mass terms of strictly baryonic matter would give what's called a Kepler decline.

 As to the first set of equations they ger applied primarily in predictions involving early universe large structure formation due to DM halos in the early universe.

 Which is another factor in cosmology where DM is needful.

This raises a point that has only just struck me after reading the Wiki article on rotation curves: DM has to be uniformly distributed across the galaxy to produce the observed rotation curve. But surely, if DM responds to gravitation, surely one would expect its distribution to mirror that of the normal matter, viz. more concentrated in the centre and becoming progressively attenuated towards the periphery? How, then, would one account for its distribution being so different? 

[Eise]

1 hour ago, julius2 said:

(trust me)!

Nope. Because:

15 hours ago, julius2 said:

I obtained my information about dark matter from reading some books and also a magazine.

So you think that is more or less equivalent to studying astrophysics at a university? 

And to add to exchemist's points, there are more empirical points that hint at the existence of DM:

• movement of galaxies in galaxy clusters: they move faster then can be expected if we only take visible mass in account
• there is some evidence that when galaxies collide, DM and Normal Matter separate, due to the difference in how eager DM on one side, and NM on theother interact
• the CMB (Cosmic Microwave Background radiation) also hints at the existence of DM

But as long as there is no direct observation of DM, it stays, as exchemist said, a placeholder for a set of phenomena we do not yet understand.

[Mordred]

A good way to understand the difference is that DM doesn't interact with the EM field nor the strong force. So lets use a simplified analogy.

Two DM particles approach one another. Without EM interactions or strong force interactions they will simply drift by each other.

Whereas two baryonic particles will have a higher likelyhood ie form into atoms etc.

 

5 minutes ago, exchemist said:

This raises a point that has only just struck me after reading the Wiki article on rotation curves: DM has to be uniformly distributed across the galaxy to produce the observed rotation curve. But surely, if DM responds to gravitation, surely one would expect its distribution to mirror that of the normal matter, viz. more concentrated in the centre and becoming progressively attenuated towards the periphery? How, then, would one account for its distribution being so different? 

 

It is the lack of strong force and EM interaction that keep DM from clumping though they can form halos due to gravity.

Edited July 31 by Mordred

[Eise]

7 minutes ago, exchemist said:

How, then, would one account for its distribution being so different? 

Because, if DM really is composed of WIMPS, it does not interact with itself either. That means it does not contract to a galactic disk, because this is due to collisions of normal matter particles. For collisions you need some interaction. In the case of normal matter that would be EM mostly.

X-posted with Mordred. Didn't realise he was still logged in.

Edited July 31 by Eise

[Mordred]

We both x posted There but our answer is the same lol

[exchemist]

6 minutes ago, Eise said:

Because, if DM really is composed of WIMPS, it does not interact with itself either. That means it does not contract to a galactic disk, because this is due to collisions of normal matter particles. For collisions you need some interaction. In the case of normal matter that would be EM mostly.

Ah yes, unless there is some means of losing kinetic energy or rather changing their trajectories to heat motion, the particles cannot clump together under gravitation. They whizz past each other and out the other side, and go on doing so indefinitely, like an electron in an s orbital. Neat! 
 

But then, how come DM is clumped in galaxies at all? Shouldn’t it be spread even.y throughout the universe?

Edited July 31 by exchemist

[Mordred]

That detail gets into expansion rates vs jeans instability.  (Which includes the speed of information exchange (often described as accoudtic oscillations ) example BAO of the CMB. This of course also includes baryonic matter to generate localized anistropies lending itself to localized gravity terms hence the halo formations 

 Essentially early universe expansion rates will generate anistropies in mass distribution because baryonic matter and DM are limited by c.  While expansion rates due to inflation are not limited by c. This lends itself to halo formation as well as galaxy and LSS formation.

The first equation above applies jeans instability and expansion rates.

Should add this also directly applies the virialization mentioned above by @joigus