[Kryptid]

Well, if it is too difficult to offer the dark matter density formula for the milky way then let's move on.

What would you want such a formula to say? How the density of dark matter correlates with distance from the galactic center?

Do you confirm that the dark matter can ONLY explain at its best case the orbital velocity at the galactic disc and no more than that?

I don't know why you would come to that conclusion.

If you can't do so, then how can we believe in the dark matter invention/imagination?

I'm not an astrophysicist. I haven't researched much into why the galaxy has the structure that it does. Just because I don't know the answer doesn't mean that no one does. If you want to know the answers to these questions, perhaps you should address them to an actual astrophysicist.

[Dave Lev (OP)]

What would you want such a formula to say?

Well, I hope that you agree that such formula would say - what is needed from the dark matter in order to keep the orbital velocity of star at a fixed velocity while it is in the galactic disc (3KPC to 15KPC). That's all.
Our astrophysicists can invent any sort of formula for that task as they wish. They might need different formulas for different galaxies, but that is still ok, as they don't have to prove anything. They are the master of knowledge and they have the privilege that other people don't have.
Just think for one moment on the following scenario –
Let's assume that we don't know how the gravity really works. If I will tell you that there is dark glue that holds the stars together, would you believe in this imagination?
Won't you demand to get real data for this dark glue imagination?
So, luckily for our astrophysicists, they don't have to prove anything as they control the science.

How the density of dark matter correlates with distance from the galactic center?

When it comes to distance from the galactic center (at the Bar section- below 3KPC), then there is severe problem.
Without being astrophysicist it is very clear that orbital velocity in the Bar (Below 3KPC) is totally different from that in the galactic disc as in this section the velocity is increasing dramatically and linearly as we move further away from the center (up to 3KPC).
Therefore, the invented formula for the dark matter in the galactic disc totally fail in the bar section.
I hope that by now you see the severe contradiction in the dark matter imagination..

I'm not an astrophysicist. I haven't researched much into why the galaxy has the structure that it does. Just because I don't know the answer doesn't mean that no one does. If you want to know the answers to these questions, perhaps you should address them to an actual astrophysicist.

The same formula for the imagination dark matter that can solve the fixed orbital velocity at the galactic disc can't solve the dramatically increasing in the same orbital velocity at the Bar.
Therefore, the dark matter can't offer even one answer to all my questions as it isn't the correct solution
You won't find even one astrophysicist in the entire planet (or if you wish - in the entire universe) that can help you to answer my questions based on the imagination that is called dark matter!

[Kryptid]

Well, I hope that you agree that such formula would say - what is needed from the dark matter in order to keep the orbital velocity of star at a fixed velocity while it is in the galactic disc (3KPC to 15KPC). That's all.
Our astrophysicists can invent any sort of formula for that task as they wish.

Ideally, they wouldn't "invent" a formula so much as derive one. They would need to take a look at how the rotation curve correlates with the mass of visible matter in the galaxy, then deduce from that what the needed distribution of dark matter would have to be in order to explain the rotation curve. Once you get that predicted distribution, you'd look for an equation that best matches it.

Let's assume that we don't know how the gravity really works. If I will tell you that there is dark glue that holds the stars together, would you believe in this imagination?

That would depend on what your definition for "dark glue" is. If your definition is "whatever it is that's holding the stars together", then I would agree with you.

Without being astrophysicist it is very clear that orbital velocity in the Bar (Below 3KPC) is totally different from that in the galactic disc as in this section the velocity is increasing dramatically and linearly as we move further away from the center (up to 3KPC).

That's not surprising, honestly. Orbital velocity is dependent upon how much mass you are orbiting. When a star is orbiting very close to the center of the galaxy, then most of the galactic mass is outside of its orbit, not inside of it. So the pull of gravity on that star is weaker than on a star further out. It's the same principle that makes an object deep inside the Earth weigh less than that same object on the surface. Why this relationship seems to be linear in the galactic core is something I don't know the answer to. It's no doubt due to the way that mass is distributed in the galaxy. So this is not a problem for dark matter.

Therefore, the invented formula for the dark matter in the galactic disc totally fail in the bar section.

Please demonstrate this.

I hope that by now you see the severe contradiction in the dark matter imagination..

No, I don't.

The same formula for the imagination dark matter that can solve the fixed orbital velocity at the galactic disc can't solve the dramatically increasing in the same orbital velocity at the Bar.
Therefore, the dark matter can't offer even one answer to all my questions as it isn't the correct solution

How do you know? Have you done the math?

You won't find even one astrophysicist in the entire planet (or if you wish - in the entire universe) that can help you to solve my questions.

Feel free to support that claim. Have you even asked an astrophysicist yet?

[Dave Lev (OP)]

Ideally, they wouldn't "invent" a formula so much as derive one. They would need to take a look at how the rotation curve correlates with the mass of visible matter in the galaxy, then deduce from that what the needed distribution of dark matter would have to be in order to explain the rotation curve. Once you get that predicted distribution, you'd look for an equation that best matches it.

That is very clear
However, on which section in the galactic disc they invent the formula?
Please look again in the following diagram:
https://www.astronomy.ohio-state.edu/thompson.1847/1101/RotCurve2.gif
Is it for the section of the spiral arms where the velocity is more or less fixed at radius above 3KPC?
Or is it for the section of the Bar where the velocity is increasing linearly and dramatically at radius below 3KPC?

Quote from: Dave Lev on Today at 04:42:56
Therefore, the invented formula for the dark matter in the galactic disc totally fail in the bar section.

Please demonstrate this.

How can I demonstrate it while you refuse to offer the dark matter density formula for the milky way?

Have you done the math?

Please offer the formula and I will prove by math that this formula is a pure nonsense.

Have you even asked an astrophysicist yet?

How can I find that astrophysicist that had not been born yet.
Sorry - if you ask all the astrophysicists in the planet, no one would be able to answer my following questions:

1. please specify the dark matter density formula that is invented for the Milky way.

2. Galactic Disc -
A. How this dark matter formula can set the disc only at the spiral arms (3KPC to 15KPC)?
B. Why in the Bulge there is no Disc at all?
C. Why the disc does not continue after 15KPC? Actually, do you confirm that when arm is ended, the stars after that point are ejected from the disc?
D. Why the thickeners of the arm at the base is 3000LY while at the end it is 400LY? How Kepler law can explain this phenomenon

3. Bar -
Can you please explain how the same dark matter that aim to keep the orbital velocity of the stars in the galactic disc at a fixed velocity can suddenly increase so dramatically the orbital velocity of stars in this section? How the dark matter formula can justify that dramatic increase

4. Ring
A. How the dark matter formula can justify the creation of the Ring?
B. Why the ring is always created between the end of the bar to the base of the spiral arms?
C. Why do you think that Kepler law works better with dark matter for this section?

If you think that they can do so, then would you kindly direct my questions to one of them?

[Bored chemist]

How can I find that astrophysicist that had not been born yet.

Nobody asked you to.
Why do you ask stupid questions like that?
Are you trolling, or are you unable to understand that it's a stupid question?

take all the astrophysicists in the planet, and no one would be able to answer my following questions:

How would you know?
Did you ask , even one astrophysicist?

[Kryptid]

Is it for the section of the spiral arms where the velocity is more or less fixed at radius above 3KPC?
Or is it for the section of the Bar where the velocity is increasing linearly and dramatically at radius below 3KPC?

Who said a single formula can't apply to both?

How can I demonstrate it while you refuse to offer the dark matter density formula for the milky way?

Okay, so you admit that you can't demonstrate your claim. You shouldn't make claims that you can't back up.

Who said that such a formula had actually been derived yet anyway?

Please offer the formula and I will prove by math that this formula is a pure nonsense.

Interesting how you assume in advance that a formula is wrong without ever having seen it.

How can I find that astrophysicist that had not been born yet.

Please demonstrate that astrophysicist hasn't yet been born.

Sorry - if you ask all the astrophysicists in the planet, no one would be able to answer my following questions:

Please demonstrate that no astrophysicist can answer those questions.

If you think that they can do so, then would you kindly direct my questions to one of them?

I don't know why you think I am any more capable of finding an astrophysicist than you are. Perhaps you can find one in the science sections of Reddit to ask.

[Dave Lev (OP)]

Quote from: Dave Lev on Today at 13:25:00
Sorry - if you ask all the astrophysicists in the planet, no one would be able to answer my following questions:

Please demonstrate that no astrophysicist can answer those questions.

Easy
Let's assume that somehow our astrophysicists have invented a perfect formula for the following rotation velocity in the milky way:
https://www.astronomy.ohio-state.edu/thompson.1847/1101/RotCurve2.gif
We can take this formula and run it on a computer and get back exactly the same identical orbital velocity as we have in the diagram.
So, far so good.
However, what about the shape?
How that formula that is all about different densities at different radius can set the unique structure of spiral galaxy?
Why the Bulge has a spherical shape from 0 to 1K PC?
How the Bar gets its two propeller arms from 1KPC to 3KPC
How the ring with all its stars is there exactly at 3KPC and why it has a ring shape and not a spherical shape as the Bulge?
How the spiral arms (above 3KPC) had been formed and why it is on a disc?

Sorry, no one (including all the astrophysicists in the Universe) can answer those questions as the shape of the galaxy isn't part of the dark matter density formula and can't be.
Therefore, as this invented formula can't be used to reproduced the full structure shape of the spiral galaxy, then we all need to understand that it is just imagination.

[Kryptid]

Sorry, no one (including all the astrophysicists in the Universe) can answer those questions as the shape of the galaxy isn't part of the dark matter density formula and can't be.

Then don't ask it to explain something that it was never meant to explain in the first place. That's like saying that the formula for Kepler's third law is wrong because it doesn't explain why the planets in the Solar System have the distances from the Sun that they have. It's a non-sequitur.

[paul cotter]

I am not an astrophysicist, not even a physicist. I am not impressed by dark matter, dark energy or dark flow. However, until someone has a better theory it is the best explanation for observations at the present moment. That is how science works and it is futile "throwing stones" at a theory unless you have better concept complete with full mathematical description.

[Dave Lev (OP)]

Sorry, no one (including all the astrophysicists in the Universe) can answer those questions as the shape of the galaxy isn't part of the dark matter density formula and can't be.

Then don't ask it to explain something that it was never meant to explain in the first place.

Thanks
So you fully confirm that the dark matter can't give any sort of indication about the shape of the spiral galaxy.

That's like saying that the formula for Kepler's third law is wrong because it doesn't explain why the planets in the Solar System have the distances from the Sun that they have. It's a non-sequitur.

No it is not
If you run the kepler law on the computer you would get a perfect match to the observation with regards to the velocity and shape.
However, if you run the dark matter on the computer you only get the velocity.
As it doesn't cover the shape, then it can't be used as a theory for the spiral galaxy.
This is my opinion.

until someone has a better theory it is the best explanation for observations at the present moment.

No.
If you are using wrong theory then you stuck with that theory.

That is how science works and it is futile "throwing stones" at a theory unless you have better concept complete with full mathematical description.

Actually I have a theory that meets the observation by 100%.
However, if you believe in the dark matter imagination, it might be too difficult for you to accept the real theory.

The real theory is all about gravity between ordinary matter.

We have clear observation that proves the gravity forces in the arms
It is stated:
” As the bar and spiral arm approach each other, their mutual attraction due to gravity makes the bar slow down and the spiral speed up Once connected"

I have just found an excellent article about the Bar:
https://scitechdaily.com/galactic-bar-paradox-a-mysterious-and-long-standing-cosmic-conundrum-resolved-in-cosmic-dance/
It is stated:
"The bar pulsations result from its regular encounters with the Galactic spiral arms, in what can be described as a “cosmic dance”. As the bar and spiral arm approach each other, their mutual attraction due to gravity makes the bar slow down and the spiral speed up.Once connected, the two structures move as one and the bar appears much longer and slower than it actually is. As the dancers split apart, the bar speeds up while the spiral slows back down."
It is specifically stated: "their mutual attraction due to gravity makes the bar slow down and the spiral speed up."
It is also stated: "Once connected, the two structures move as one"

So it is all about gravity that connects the stars in the Bar to those in the spiral arm so they all become one.
Wow!!!
What a great information!!!
I was looking for that information for years.
This is the smoking gun of the spiral galaxy!

Not gravity between dark matter to ordinary matter but gravity between two key elements (Bar and spiral arms) in the spiral galaxy that are all based on ordinary matter as stars.
If our scientists would understand the real meaning of this explanation, they would verify that there is no need for dark matter. The stars (ordinary matter) in each element in the galaxy are good enough to maintain its full structure (Bulge, Bar, Ring, Spiral arms...) without any need for even one particle of dark matter!
Take out one element from that complex and you break down the galaxy.
Nothing would help - not even dark matter.

Please also see the following reply:

The Bar and the spiral arms are connected (or their motions are associated with each other) by mutual attraction due to gravity as one temporarily object?

That does seem to be the case.

Other group of scientists gave us the explanation how it works:

I have found a breakthrough literature that fully supports my understanding:
http://pubs.sciepub.com/ijp/7/3/2/index.html#Figure4
"New Formulas and Mechanism for the Spiral Arm Formation of Galaxies"
It is stated:
"This model is the first attempt to think the spiral arm formation with the hydrogen originated from inside of the galactic center to outside. The proposed mechanism of the hydrogen production seems highly speculative, but the result of the simulations is very satisfactory, this indicates that the idea for the hydrogens originated from inside the bar is a promising approach, may lead us to re-think about the property of the black holes and hope to serve as a trigger to promote the future research in this direction."

It is stated clearly:
"This model is the first attempt to think the spiral arm formation with the hydrogen originated from inside of the galactic center to outside"
"this indicates that the idea for the hydrogens originated from inside the bar is a promising approach"
Wow
What a great literature!!!
Remember please - "from inside of the galactic center to outside"
I don't need to add even one more word.

Based on all of that, I have offered a simple explanation how it really works:

There is no need for dark matter to explain the anomalous galactic rotation curve.
Please look again at the rotation curve:
https://www.astronomy.ohio-state.edu/thompson.1847/1101/RotCurve2.gif
1. Bar - Below 3KPC
I have already explained how this segment works.
There is no need for dark matter as gravity that funnels the stars from the Bulge into the inwards side of the spiral arms is good enough:
Quote from: Dave Lev on 23/06/2022 19:50:59
http://pubs.sciepub.com/ijp/7/3/2/figure/4
The yellow line represents stars as they migrate outwards from the Bulge directly into the spiral arms.
We see that the Bar looks as a propeller of an airplane.
Let's assume that a star in a radius of 1KPC (R1) orbits at velocity V1 and try to verify the velocity of a star at different radius at this Bar (propeller)
It is clear that:
V = V1 (R / R1).
If R = R2 = 2KPC
V2 (at 2KPC) = 2 V1 (at 1KPC)
V3 (at 3KPC) = 3 V1
That linear increase in the calculated orbital velocity is fully correlated with the orbital velocity observations at the Bar section (Below 3KPC):
https://www.astronomy.ohio-state.edu/thompson.1847/1101/RotCurve2.gif
If you agree with that we can move on to the spiral arms.

2. Spiral arm segment 3KPC to 15 KPC
We already know that as the bar spines faster than the spiral arm, it adds new stars to the most inwards side of the arm and therefore it increases the spiral arm size (from inside).
In order to keep the spiral shape of the arm while new stars are added from inside, the stars that are already there must drift backwards and keep on with their current fixed velocity.
So, please look at the following image and focus on the connection point between the Bar and the spiral arm.
http://pubs.sciepub.com/ijp/7/3/2/figure/4
Let's assume that in this point there is a star (Let's call it Star A) which had just been delivered by the bar and is connected now to the spiral arm.
So, technically, star A is currently the most inwards star in the spiral arm and its orbital velocity might represent the maximal velocity of the spiral arm.
However, as the spin velocity of the bar is faster than the spin velocity of the spiral arm, than let's assume that after a given time frame (T) the Bar would move upwards and new star (let's call it star B) would be delivered from the bar to the arm.
Now star B is located at the most inwards side of the arm, while star A is second one in the yellow line.
As the Bar keeps its motion, new stars are coming and are connected to the most inwards side of the spiral arm.
After 100 new stars, Star A is already located 100 stars away from the most inwards point of the spiral arm.
Therefore, star A could keep its orbital velocity while new stars are added from inwards by the bar.
The key idea is that the spiral arm isn't a solid object where a star in the top would stay there forever.
It is a temporary structure of stars that constantly drift backwards while maintaining their fixed orbital velocity.
However, as new stars are constantly added from inside, the spiral arm shape is maintained over time.
So, if a star moves backwards at distance of D at a given time T then after 100T star A had already drifted backwards is the arm by a distance of 100D.
Hence, while new stars are added constantly at the most inwards side of the arm, all the millions or billions stars in this arm can maintain a fixed orbital velocity of about 220 Km/s without breaking the spiral arm shape.
However, that means that stars can't hold themselves in the arm for indefinitely.
Sooner or later a star which had been delivered by the bar at the most inwards side of the arm would be eventually ejected from the most outwards side of the arm.
In this way the orbital velocity of all the stars in the arm would be fixed and the temporary structure of the spiral arm would be stable.
Is it clear?

And the answer was:

Is it clear?

Clearly wrong. Orbital velocity is determined by gravity.

Quote from: Dave Lev on 25/06/2022 09:09:17
There is no violation of any physical law by the Bar (including the Kepler's third law).

If it's orbiting faster than Kepler's third law allows, then it is.

My answer to that is as follow:
In the galaxy we discuss about stars that are bounded together by gravity.
Please remember:
” As the bar and spiral arm approach each other, their mutual attraction due to gravity makes the bar slow down and the spiral speed up Once connected"

Therefore, we can't just discuss about a single star as it orbits around the center of the galaxy.
The star is not there by itself as it is connected to the arm by gravity. So, its gravity only connects it to the arm while its movement around the galaxy is dictated by the arm.

As an example, let me use the idea of a person that is crossing the air in an airplane.
So, by simple calculation, there is no way for a person by itself to fly at so high velocity in the air.
However, once you understand that this person holds itself in the airplane,  then you can understand how it gets its high velocity.
In the same token, once you understand that the star holds itself in the arm, then you can understand how it gets its high velocity.
Why is it so complicate to understand so simple observation?
 
All the billions stars in the disc are connected by gravity to the spiral arms.
Therefore, they all orbit in one direction around the galaxy center without any collision between them.
That also explains the thickness of the arms. It is 3000 LY in the base (3KPC) and 400LY at the end of the arm (15KPC).If you would consider the spiral arm as some sort of elastic cable then this is exactly the phenomenon that you get once you start to spin that cable.

Hence, from now on we must set the calculation on the arm that holds the stars and not on individual star.

The Sun for example holds itself to the Orion arm.
We have a solid evidence for that - The density of stars in the Orion arm near our sun.
I have already introduce that the measured G stars density in a radius of 100 LY is 512 therefore, the calculated densities per 50 LY is 64 G stars. Surprisingly, our scientists found that the measured stars in a radius of 50 LY is exactly 64 Stars.
So, there is a perfect match between the calculated densities to the measured density.
Therefore, the sun holds itself to the Orion arm and not to the center of the galaxy.
I can tell you that by 100% you won't find even one star that orbits at the disc while it is there by itself.
Actually, if a star would move away from the arm it would be ejected from the disc as a rocket. We see those stars and we call them hypervelocity stars.
Hence, as long as the Sun holds itself to the Orion Arm – we are save and we get the protection of the galaxy. However, we are quite close to the edge of the arm (about 200LY). If we cross that edge we would also be ejected from the disc.
The dark matter imagination can't help to any star that is moving away from the arm.
Therefore, if you want a real theory – then you must consider the arm (the bar arms and the spiral arms) as a temporary connected stars structures by gravity, and you already have full understanding on how spiral galaxy really works without a need for one particle of dark matter.

So which theory is more realistic?
Is it the one that can explain the full structure of spiral galaxy including velocities and shape at each segment of the galaxy (Bulge, Bar, Ring, spiral arms...) without any need for extra gravity, or is it a theory that is based on imagination dark matter while it can't give us any indication about the galaxy shape/structure?

I am not an astrophysicist, not even a physicist.

You don't need to be a scientist
Just read the following:
” As the bar and spiral arm approach each other, their mutual attraction due to gravity makes the bar slow down and the spiral speed up Once connected"
Do you agree that this arm structure is real?
Therefore, if our scientists would drop the dark matter imagination and focus on all the observations that are there infront of their eyes, they would get to the simple understanding that the arm is real.
As long as they ignore the impact of that real arm, they would never understand how the spiral galaxy really works!

[Kryptid]

So you fully confirm that the dark matter can't give any sort of indication about the shape of the spiral galaxy.

Then let's not pretend that it was ever supposed to in the first place.

No it is not
If you run the kepler law on the computer you would get a perfect match to the observation with regards to the velocity and shape.

It does? Where does Kepler's third law say anything about a galaxy's shape?

As it doesn't cover the shape, then it can't be used as a theory for the spiral galaxy.

It can be used for what it was originally proposed to explain: the anomalous rotation curve. It doesn't have to explain literally everything about a galaxy (in large part because it's not the only thing that galaxies contain). That's like saying that the fat in my body has to explain why the rest of my body that isn't fat behaves the way it does.

Actually I have a theory that meets the observation by 100%.

No, it doesn't. Your model doesn't explain the anomalous galactic rotation curve. Stars are orbiting faster than they are supposed to be able to in the outer parts of the galaxy if you only include normal matter in the measurement of gravity. Without dark matter (or perhaps MOND) there isn't enough gravity to keep those stars orbiting at such a high speed.

The real theory is all about gravity between ordinary matter.

It's not enough. That's why I brought up Kepler's third law. If you only include the mass of normal matter, the results don't match what Kepler's third law predicts. That's how we know that the known gravity produced by normal matter is insufficient to explain the data.

We have clear observation that proves the gravity forces in the arms
It is stated:
” As the bar and spiral arm approach each other, their mutual attraction due to gravity makes the bar slow down and the spiral speed up Once connected"

You see that part I underlined? That's the part you are ignoring.

As an example, let me use the idea of a person that is crossing the air in an airplane.
So, by simple calculation, there is no way for a person by itself to fly at so high velocity in the air.
However, once you understand that this person holds itself in the airplane,  then you can understand how it gets its high velocity.
In the same token, once you understand that the star holds itself in the arm, then you can understand how it gets its high velocity.
Why is it so complicate to understand so simple observation?

Because it's a false analogy. In the case of the airplane, you have a propulsion system that can accelerate both the plane and the person against gravity. The bar doesn't have a propulsion system. It can't gain net acceleration like a plane can. Remember, the bar slows down as its gravity makes the spiral speed up. You don't get an overall increase in average speed with the galactic objects like you do with an airplane using a jet engine.

Hence, from now on we must set the calculation on the arm that holds the stars and not on individual star.

Kepler's third law still applies, as all of the matter in those arms that are in orbit demands. Assuming you maintain orbital distance, you can only speed up part of the arm by causing another part of it to slow down. So you don't get to cheat Kepler's third law this way.

Therefore, the sun holds itself to the Orion arm and not to the center of the galaxy.

It holds on to both. Gravity has an unlimited range.

The dark matter imagination can't help to any star that is moving away from the arm.

It can if the dark matter is exerting so much gravity that the star doesn't reach escape velocity.

Therefore, if you want a real theory – then you must consider the arm (the bar arms and the spiral arms) as a temporary connected stars structures by gravity, and you already have full understanding on how spiral galaxy really works without a need for one particle of dark matter.

And then throw Kepler's third law away while you're at it, because this idea does not mesh with it.

So which theory is more realistic?
Is it the one that can explain the full structure of spiral galaxy including velocities and shape at each segment of the galaxy (Bulge, Bar, Ring, spiral arms...) without any need for extra gravity, or is it a theory that is based on imagination dark matter while it can't give us any indication about the galaxy shape/structure?

The one that doesn't break the laws of physics: dark matter.

[Dave Lev (OP)]

Dear Kryptid
Lets move step by step:
To my following question:
"The Bar and the spiral arms are connected (or their motions are associated with each other) by mutual attraction due to gravity as one temporarily object?"
You have replied:

That does seem to be the case.

Actually you have already confirmed that the bar and the spiral arm creates a temporary structure that is there due to gravity force
So as the gravity force holds the two arms in one structure, why do you refuse to accept that the same gravity force helps the arm to holds its stars together?

[Origin]

Actually I have a theory that meets the observation by 100%.

There are 2 options here:
1.  You are lying.
2.  You don't know what a theory is.

[Kryptid]

So as the gravity force holds the two arms in one structure, why do you refuse to accept that the same gravity force helps the arm to holds its stars together?

I don't. What I don't accept is your claim that it somehow results in an overall speed increase that violates Kepler's third law.

[Dave Lev (OP)]

Quote from: Dave Lev on Today at 15:25:01
So as the gravity force holds the two arms in one structure, why do you refuse to accept that the same gravity force helps the arm to holds its stars together?

I don't.

Just to be sure about it.
You fully accept that the bar arm (and spiral arm) are made out of stars that are bonded by gravity force.

What I don't accept is your claim that it somehow results in an overall speed increase that violates Kepler's third law.

However, you claim that this Bar arm that is all about stars that are bonded by gravity can't increase its orbital velocity as it violates Kepler's third law.
Did I understand you correctly?

[Bored chemist]

Actually I have a theory that meets the observation by 100%.

There are 2 options here:
1.  You are lying.
2.  You don't know what a theory is.

The two options are not mutually exclusive.

[Origin]

The two options are not mutually exclusive.

You're correct, 3 options.

[Kryptid]

You fully accept that the bar arm (and spiral arm) are made out of stars that are bonded by gravity force.

And dark matter too.

However, you claim that this Bar arm that is all about stars that are bonded by gravity can't increase its orbital velocity as it violates Kepler's third law.

They orbit faster than Kepler's third law allows only if you solely count visible matter as the source of gravity. Add dark matter and the problem goes away.

[Dave Lev (OP)]

You fully accept that the bar arm (and spiral arm) are made out of stars that are bonded by gravity force.

And dark matter too.

Wow, What great news!!!
At last, after so many years you finally confirm that the stars are bonded to the arm.

I really don't care at this phase if it is due to the gravity of ordinary matter, dark matter or even supper glue.
As long as you confirm that the stars are bonded to the arms it is perfectly OK with me.
We will discuss later on how that glue really works
So, many thanks for this confirmation

[Kryptid]

As long as you confirm that the stars are bonded to the arms it is perfectly OK with me.

So long as you don't get the impression that they behave like some kind of single, solid object.