[Dave Lev (OP)]

If it was solid, you couldn't fly a ship through it,could you?

Why do you keep calling it "solid"?
We don't use this word any more.
Kryptid called it Metastable and I really like it

Metastable is probably the better word.

Please look at the following diagram:
https://www.differencebetween.com/difference-between-stable-and-metastable/
A represents the metastable stage, while C represents the stable stage.
Therefore, M80 is currently at its stable stage.
However, if you set that M80 at the arm (Bar or spiral) it would get the arm stracture and it would be at its Metastable stage.
So, the arm shape is not a stable shape but Metastable shape.
Many thanks to Kryptid for this word!!!

[Kryptid]

Hence, each star in this local solar neighborhood orbits around its Com at about that velocity, while they all are bonded by the mutual gravitational attraction with all the other stars in the arm and they orbit around the galaxy at about 220Km/s.

I've already told you why that doesn't work.

[Dave Lev (OP)]

Hence, each star in this local solar neighborhood orbits around its Com at about that velocity, while they all are bonded by the mutual gravitational attraction with all the other stars in the arm and they orbit around the galaxy at about 220Km/s.

I've already told you why that doesn't work.

Yes it works
We will discuss it as we get to the spiral arms
However, currently we are at the bar stage and we already know that there is no need for dark matter for the bar operation. We also know that the arms (Bar or spiral) are just metastable stage of globular cluster.

[Kryptid]

Yes it works

The stars can't stay in the arm for even a single orbit around the galaxy:

So what happens when you look at two such stars in the same spiral arm? In order to complete one orbit around the galaxy, the one that is twice as far out has to travel twice as far to complete one orbit. But both stars are orbiting at the same speed. So if we wait long enough for the innermost star to complete one orbit, the outermost star has only completed half an orbit. In other words, they are now on opposite sides of the galaxy. So they are no longer in the same spiral arm and thus we can safely conclude that the spiral arm does not just drag stars around as a single, rigid unit. The only way that would work would be if the outermost star orbited at twice the speed of the innermost star (which it quite clearly does not).

[Dave Lev (OP)]

The stars can't stay in the arm for even a single orbit around the galaxy:

Ok
As you insist to discuss about the spiral arms:
We already know that the Bar funnels stars from the Bulge to the spiral arms and the ring.
Therefore, the spiral arms get fresh delivery of stars from the Bar.
Due to this delivery the stars in the arms are drifted outwards without disconnecting from the ring and beark the spiral shape.
please be aware that at the base (ring) the  thickness is 3000 LY while at the edge of the arm it is just 400LY.
The inwards radius is 3KPC (about 9000LY) while outwards radius is 15KPC (50,000LY).
However, due to the spiral shape of the arm its length could is much longer than that (about 50,000LY to 100,000LY?)
We already know that the spiral arm is all about a metastable stage of a globular cluster.
However, to set this kind of 100,000 Ly arm you need at least 1,000 or even 10,000 globular clusters as M80.
Now think about long lines of globular clusters that are connected to each other by gravity and form that metastable shape of the spiral arm.
The glubular cluster that is located at the outermost side of the arm is under the stronget forces due to its furthest location and therefore the thickness of the arm at the edge is just 400LY.
At some point it would be disconnected from the arm and would be ejected from the galactic disc.
The section that is disconnected from the arm would form a globular cluster shape
However, in the same time new stars stream would be added to the spiral arm from the Bar.
Therefore, when we look at the arm we won't see any difference as it keeps its very long spiral shape.
However, due to the migration of stars from the bar to the edge, the fixed orbital velocity would be maintained.
The idea is that for any given time frame each star in the spiral arm would cross the same distance regardless from its location in the spiral arm.
Based on the spiral shape we can easily extract the drifting outwards velocity of stars that is requested to maintain the shape of the spiral arm.
I agree that stars in the spiral arms can stay in the arm for very few galactic orbital cycles before they would be ejected from the arm.

[Bored chemist]

Why do you keep calling it "solid"?

I don't.

[Kryptid]

The glubular cluster that is located at the outermost side of the arm is under the stronget forces due to its furthest location

How does that put it under the strongest forces?

At some point it would be disconnected from the arm and would be ejected from the galactic disc.

Not at a mere 220 km/s, it won't be. The escape velocity of the Milky Way is over 500 km/s.

However, due to the migration of stars from the bar to the edge, the fixed orbital velocity would be maintained.

That's not how that works. As they get further away from the central source of gravity, they should slow down (if normal matter was all there was in the galaxy). So your proposal is (still) wrong.

I agree that stars in the spiral arms can stay in the arm for very few galactic orbital cycles before they would be ejected from the arm.

Much less than one.

[Origin]

We already know that the spiral arm is all about a metastable stage of a globular cluster.

Nope.

The glubular cluster that is located at the outermost side of the arm is under the stronget forces due to its furthest location and therefore the thickness of the arm at the edge is just 400LY.

Most globular clusters are not located in arms of the galaxy.

[Dave Lev (OP)]

Quote from: Dave Lev on Yesterday at 19:50:08
At some point it would be disconnected from the arm and would be ejected from the galactic disc.

Not at a mere 220 km/s, it won't be. The escape velocity of the Milky Way is over 500 km/s.

How did you get the 500 Km/sec
Is it based on the dark matter imagination?
If so, please eliminate the dark matter and reset the calculation.

That's not how that works. As they get further away from the central source of gravity, they should slow down (if normal matter was all there was in the galaxy). So your proposal is (still) wrong.

You still miss the main activity of the arm.
The stars in the arm don't care about the central source of gravity as they only care about the arm.
They hold themselves to the arm and goes wherever the arm goes.
This is identical to the Erath/moon motion.
They really don't care about their motion in the galaxy.
They just hold sun by gravity and they go wherever the sun goes.
In the same token, the sun just holds itself in the Orion arm and goes wherever the arm goes.

Quote from: Dave Lev on Yesterday at 19:50:08
I agree that stars in the spiral arms can stay in the arm for very few galactic orbital cycles before they would be ejected from the arm.

Much less than one.

Well, if the diameter of the arm was fixed then this answer was correct.
However, we know that the diameter of the arm at the base is 3000LY while at the edge it is 400LY.
This is similar to a pipe that goes narrow at the edge.
If the water comes in at a radius of R1 and goes out at smaller radius of R2 then the water flow should be increased by:
(R1 / R2) ^2
Hence the drifting flow of the stars is increasing as we move further away from the base.
The diameter of the arm at our location is 1000LY
So the radius of the arm had been already decreased by 3
Therefore, the drifting flow of the stars would be increased by 3^2 = 9
At the edge, the diameter is only 400LY. Therefore, the drifting flow would be increased by:
(3000/400)^2 = 56.4
That increase in the drifting flow of stars in the arm, would give the arm the possibility to keep the stars for longer orbital cycle around the galactic center.
However, when the arm gets so narrow its gravity bonding force is decreasing dramatically.
As its diameter gets to 400LY it actually gets to its maximal ability to hold the star in the arm.
It can't be narrower than that as the gravity force of the arm is too low and it can't hold the stars any more.
Therefore, the stars would be ejected from the arm and set the globular cluster shape that we see around the galaxy.

.

Quote from: Dave Lev on Yesterday at 19:50:08
The globular cluster that is located at the outermost side of the arm is under the strongest forces due to its furthest location and therefore the thickness of the arm at the edge is just 400LY.

Most globular clusters are not located in arms of the galaxy.

That is correct
Theoretically, a global cluster in the arm would be considered in its metastable phase and it would form the arm shape.
Once it would be disconnected from the arm, it would get its stable spherical shape

[Kryptid]

How did you get the 500 Km/sec

I looked it up.

Is it based on the dark matter imagination?
If so, please eliminate the dark matter and reset the calculation.

You can derive the escape velocity based on the orbital velocity of the outermost stars in the galaxy (and therefore Kepler's third law).

The stars in the arm don't care about the central source of gravity as they only care about the arm.

Absolutely wrong. If that was true, then all the stars in the spiral arm would drift away from the galaxy. Gravity is a force with unlimited range.

They hold themselves to the arm and goes wherever the arm goes.

That's not possible because of this:

So what happens when you look at two such stars in the same spiral arm? In order to complete one orbit around the galaxy, the one that is twice as far out has to travel twice as far to complete one orbit. But both stars are orbiting at the same speed. So if we wait long enough for the innermost star to complete one orbit, the outermost star has only completed half an orbit. In other words, they are now on opposite sides of the galaxy. So they are no longer in the same spiral arm and thus we can safely conclude that the spiral arm does not just drag stars around as a single, rigid unit. The only way that would work would be if the outermost star orbited at twice the speed of the innermost star (which it quite clearly does not).

Because the innermost stars and the outermost stars are travelling at about the same orbital speed, but the innermost stars have much less distance travel around the Milky Way than the outermost stars, the stars that are closer to the center of the galaxy are constantly getting further and further away from those stars further out. So those stars absolutely do not "go wherever the arm goes".

This is identical to the Erath/moon motion.

That's not even remotely close. Both the Earth and the Moon are the same average distance from the center of the galaxy and take the same amount of time to complete one trip around the galaxy. The stars in the spiral arm are spread over many thousands of light-years away from the galactic center. Unlike the Earth-Moon system, they take a widely varying amount of time to go around the galaxy.

They really don't care about their motion in the galaxy.
They just hold sun by gravity and they go wherever the sun goes.

Because their average distance to the galactic center is the same as that of the Sun. They all three take the same amount of time to complete one orbit around the galaxy. As pointed out before, this is not true of the stars in the spiral arm. Your proposal simply does not work.

In the same token, the sun just holds itself in the Orion arm and goes wherever the arm goes.

The Earth and Moon stay with the Sun because there are in orbit around the Sun. The whole of the stars in the spiral arms are not in orbit around each other.

Well, if the diameter of the arm was fixed then this answer was correct.

It's correct. Period:

So what happens when you look at two such stars in the same spiral arm? In order to complete one orbit around the galaxy, the one that is twice as far out has to travel twice as far to complete one orbit. But both stars are orbiting at the same speed. So if we wait long enough for the innermost star to complete one orbit, the outermost star has only completed half an orbit. In other words, they are now on opposite sides of the galaxy. So they are no longer in the same spiral arm and thus we can safely conclude that the spiral arm does not just drag stars around as a single, rigid unit. The only way that would work would be if the outermost star orbited at twice the speed of the innermost star (which it quite clearly does not).

This is similar to a pipe that goes narrow at the edge.
If the water comes in at a radius of R1 and goes out at smaller radius of R2 then the water flow should be increased by:
(R1 / R2) ^2

Very poor analogy. The stars in a galactic arm don't behave even remotely like water flowing through a narrowing pipe. There are no giant pipes constraining the movement of stars. They are in a near-vacuum.

[Dave Lev (OP)]

Quote from: Dave Lev on Today at 03:19:18
This is similar to a pipe that goes narrow at the edge.
If the water comes in at a radius of R1 and goes out at smaller radius of R2 then the water flow should be increased by:
(R1 / R2) ^2

Very poor analogy. The stars in a galactic arm don't behave even remotely like water flowing through a narrowing pipe. There are no giant pipes constraining the movement of stars. They are in a near-vacuum.

Why do you insist to ignore the structure of the spiral arm?
Why?
Do you confirm that the thickness of the arm at the base (3KPC) is 3000 LY, at our location (8KPC) it is 1000LY and at the edge (15KPC) it is 400LY?
YES or NO please
If yes, how can you explain that structure of the arm? Why it gets narrower?  Or you just don't care?

The Earth and Moon stay with the Sun because there are in orbit around the Sun. The whole of the stars in the spiral arms are not in orbit around each other.

Sorry, you totally misunderstand how the gravity works at a glubular cluster that is located in its Metastable phase while it is in the arm.
So, please look again at M80:

Please look at the following image of M80:
https://en.wikipedia.org/wiki/Globular_cluster#/media/File:A_Swarm_of_Ancient_Stars_-_GPN-2000-000930.jpg
"M80 contains hundreds of thousands of stars, all held together by their mutual gravitational attraction."

Do you confirm that each one of those hundreds of thousands of stars must orbit around its Common center of mass in order to hold itself in that Globular cluster?
Yes or no please?

[Kryptid]

Why do you insist to ignore the structure of the spiral arm?
Why?

I'm not. I'm pointing out that your analogy isn't remotely sensible. Spiral arms aren't contained inside of pipes.

Do you confirm that the thickness of the arm at the base (3KPC) is 3000 LY, at our location (8KPC) it is 1000LY and at the edge (15KPC) it is 400LY?
YES or NO please

I haven't looked it up, but it sounds reasonable so I'll say "yes" for now.

If yes, how can you explain that structure of the arm? Why it gets narrower?  Or you just don't care?

I don't know, but it sure isn't because it's flowing like water through a narrowing pipe.

Sorry, you totally misunderstand how the gravity works at a glubular cluster

Globular clusters aren't galactic arms.

Do you confirm that each one of those hundreds of thousands of stars must orbit around its Common center of mass in order to hold itself in that Globular cluster?
Yes or no please?

Yes, but like I said, globular clusters aren't galactic arms. A spiral arm might contain a globular cluster, but that's not all a spiral arm is.

[Dave Lev (OP)]

Quote from: Dave Lev on Today at 05:05:08
Do you confirm that the thickness of the arm at the base (3KPC) is 3000 LY, at our location (8KPC) it is 1000LY and at the edge (15KPC) it is 400LY?
YES or NO please

I haven't looked it up, but it sounds reasonable so I'll say "yes" for now.

Thanks

Spiral arms aren't contained inside of pipes.

Spiral arms are made out of Gas and Stars.
Our scientists tell us the diameter of that arm and it goes thinner as we go further away from the base.
Therefore, don't you agree that technically it has a pipe shape?

Quote from: Dave Lev on Today at 05:05:08
If yes, how can you explain that structure of the arm? Why it gets narrower?  Or you just don't care?

I don't know, but it sure isn't because it's flowing like water through a narrowing pipe.

As you don't know, how do you know that what you don't know is correct or incorrect?
You don't know:
Why there is a ring
Why the bar is always in the inner side of the ring,
Yhy the Bar has a propeller shape
Why there is no need for dark matter to explain the orbital velocity at the bar.
Why the spiral arms are always at the outwards side of the ring,
Why it gets thinner at we move further away from the base
Why it has always spiral shape (why not bar shape)?
But you know that what I say is just incorrect.

I have a simple question for you:
Do you reconfirm that there is no need for the Dark matter in the Bar?
If so, do you confirm that it was a fatal error from our scientists to offer dark matter also for the Bar?

How can you agree with the logic that for one key section - the bar section (up to 3KPC) there is no need for dark matter while as our scientists can't explain the spiral arm based on ordinary matter - then suddenly the dark matter pop up?

Sorry - the bar by itself proves that there is no need for dark matter. Not in the bar and not in the spiral arm
If you don't agree with my explanation - then please look for better explanation that is based on ordinary matter and not on the imagination dark matter.

I offer you a solution for how the spiral can work without dark matter and you reject this explanation without knowing how it really works.

Is there any possibility for you to evaluate my explanation based on the same level that you evaluate the message from our scientists?
Or is it just impossible request as whatever our scientists say is always correct (even if we prove that their message is just incorrect (as there is no need for dark matter for the bar and no solution for all the questions) while whatever I say is always incorrect (even if it meets the observation by 100%)?

[Origin]

Or is it just impossible request as whatever our scientists say is always correct (even if we prove that their message is just incorrect (as there is no need for dark matter for the bar and no solution for all the questions) while whatever I say is always incorrect (even if it meets the observation by 100%)?

What is your explanation that meets the observation by 100%?

[Kryptid]

Therefore, don't you agree that technically it has a pipe shape?

Only vaguely. I have never looked at the spiral arm of a galaxy and thought, "that's shaped like a pipe". "Pipe-shaped" does not imply "behaves like a pipe". A carrot is shaped like a narrowing pipe, but it sure doesn't act like one. Besides, pipes have a well-defined edge, whereas the spiral arms do not.

As you don't know, how do you know that what you don't know is correct or incorrect?

Non-sequitur. Not knowing the entire explanation for something doesn't mean that just anything is possible. For example, I don't know if there is life native to Mars, but I know that if there is, it doesn't take the form of little green men. The reason is that there isn't enough oxygen in Mars' atmosphere to support that kind of complex life. Likewise, I know your pipe explanation is incorrect because an increase in pressure is what causes water flowing through a narrowing pipe to speed up. Since the pressure in interstellar space is practically zero, that explanation cannot possibly apply to stars in the spiral arm.

But you know that what I say is just incorrect.

Right.

Do you reconfirm that there is no need for the Dark matter in the Bar?
If so, do you confirm that it was a fatal error from our scientists to offer dark matter also for the Bar?

There is no need for it to be there in the sense that normal matter has enough gravity to explain it, but that doesn't mean that it isn't there. It's not a fatal error.

How can you agree with the logic that for one key section - the bar section (up to 3KPC) there is no need for dark matter while as our scientists can't explain the spiral arm based on ordinary matter - then suddenly the dark matter pop up?

I never said that dark matter was only in the spiral arms: just that dark matter can solve the rotation curve anomaly in the spiral arms.

Sorry - the bar by itself proves that there is no need for dark matter.

That's like saying that the fact that an electric vehicle doesn't need gasoline, then no other cars should need gasoline either.

I offer you a solution for how the spiral can work without dark matter

Your explanation breaks the laws of physics (Kepler's third law, in particular) and makes no sense (stars and gases in the vacuum of space do not behave like water under pressure moving through a narrowing pipe).

Is there any possibility for you to evaluate my explanation based on the same level that you evaluate the message from our scientists?

I am: yours breaks the laws of physics, their's doesn't.

Or is it just impossible request as whatever our scientists say is always correct

It isn't always correct and I'm not pretending that it is. That doesn't mean dark matter is wrong.

even if we prove that their message is just incorrect

Let me know when you've done that.

while whatever I say is always incorrect (even if it meets the observation by 100%)?

What you say doesn't come close to meeting observation by 100%. There are no giant pipes in space that the spiral arms are moving through.

[Dave Lev (OP)]

There is no need for it to be there in the sense that normal matter has enough gravity to explain it, but that doesn't mean that it isn't there. It's not a fatal error.

So we all agree that there s no need for dark matter in the Bar.
However, you claim that the dark matter is there without any need to be there won't effect the bar.
You offer the following explanation:

That's like saying that the fact that an electric vehicle doesn't need gasoline, then no other cars should need gasoline either.

I claim that your example is just incorrect.
Dark matter isn't gasoline - it is an engine or jet engine by itself.
How can you tell the dark matter to work at the spiral while based on your explanation it covers the whole galaxy?
So how can you tell it to work at the spiral and ignore the bar?
Sorry - If you belive that the dark matter has an impact on stars in the spiral arms then it also must have an impact on stars in the Bar.

I never said that dark matter was only in the spiral arms: just that dark matter can solve the rotation curve anomaly in the spiral arms.

Let's make it clear - the rotation curve anomaly exists ONLY in the spiral arms
Therefore I hope that you fully agree, that this dark matter is ONLY needed to solve the rotation curve anomaly in the spiral arms.
So, how could it be that you are using a something that is called dark matter that has a sever impact on any star in the galaxy and force it to work on the stars at the spiral arms but not on the stars in the Bar.
Do you have some sort of a switch that you can set it on and of?
On for the spiral, off for the bar.
Would you kindly explain how that switch really works?

Don't you agree that the dark matter works as sort of a jet engin as it must speed up any star at the spiral from 3KPC to 15KPC.
However, the bar also gets to 3KPC.
Our scientists OBSERVE that the spiral arms is fully connected to the Bar exactly at 3KPC - I have PROVED IT.
So how can you tell the dark matter to work on a star that is located at 3KPC in the spiral arm and not work on a nearby star that is still located at 3KPC in the bar.

Therefore, your example about the an electric vehicle that doesn't need gasoline is just irrelevant.
You have to explain how an electric vehicle could still work while we connect a Jet engine to that vehicle that works constantly.

Actually, while I write this message I have a brilliant idea for our scientists.
I hope that we all agree that our scientists don't have a basic clue what is the dark matter, how it had been formed and why it came to save the spiral galaxies in the entire universe.
They just hope that this dark matter exists as a sphere around the center of the galaxy at different densities which is based on a very specific formula that they have invented.
For each spiral galaxy there is a need for different density of dark matter and therefore, different formula is needed for all the millions of a billions spiral galaxies.
Please also be aware that the dark matter should move with the MW galaxy while it cross the space at 600 Km/s.
It can't move from the center of the galaxy.
Any movement of the dark matter from the center, would break the spiral arms and our scientists would be very upset.
So, at least so far we fully agree that the dark matter fully obey to the wish of our scientists

I wonder, why there are still 30% galaxies which are not spiral.
How could it be that the dark matter has neglected those poor galaxies?
I also wonder what would happen to the dark matter after the collision between two spiral galaxies?

In any case, as we discuss about imagination dark matter that we can't see, I have a brilliant advice to our scientists.
Instead of asking the dark matter cover the whole galaxy and distinguish between a star at 3KPC that is located at the bar to the other one at 3KPC that is located in the spiral arm, why can't we just invent a formula that works only at the spiral arm?
So, this dark matter would be able to bond the stars in the spiral arm and stretch it as we wish.
Therefore, wherever you claim that my explanation is incorrect:

Quote from: Dave Lev on Yesterday at 21:41:37
But you know that what I say is just incorrect.

Right.

I would use the magic dark matter to do the job.
I can invent the formula for the dark matter that can do whatever I wish it to do.
As it works only at the spiral arm, it won't have any negative impact on the bar.

So please, why our scientists can't use my idea of dark matter that is only focus in the spiral arms in order to solve the rotation curve anomaly in those arms without any negative impact on the bar?

What you say doesn't come close to meeting observation by 100%. There are no giant pipes in space that the spiral arms are moving through.

That replay shows that you refuse to understand my message for how the spiral arms work.

Therefore, are you ready to accept my explanation about the spiral arms while I'm using the dark matter imagination to support my wish?

Or it is forbidden for me to use the dark matter as only our key scientists have the permission to use it whenever is needed,and at any formula that they wish/invent as my name is Dave and not Einstein?.

PS
I 'm living today outside the country for few days and may not have time to respond

[Kryptid]

How can you tell the dark matter to work at the spiral while based on your explanation it covers the whole galaxy?
So how can you tell it to work at the spiral and ignore the bar?

My suspicion is this: close to the galactic center, it could be that the density of normal matter is higher than that of dark matter. If that's the case, then the gravitational influence of normal matter would dominate the orbital speeds of stars. In the outer regions of the galaxy, where normal matter is less dense, dark matter would dominate the contribution to the orbital speeds.

that this dark matter is ONLY needed to solve the rotation curve anomaly in the spiral arms.

Are you acknowledging the need for dark matter to explain the rotation curve anomaly now?

Would you kindly explain how that switch really works?

See above.

I hope that we all agree that our scientists don't have a basic clue what is the dark matter

I've already corrected this claim before.

They just hope that this dark matter exists as a sphere around the center of the galaxy at different densities which is based on a very specific formula that they have invented.

You've got it backwards: they infer the density of dark matter from the data, not the other way around.

Please also be aware that the dark matter should move with the MW galaxy while it cross the space at 600 Km/s.
It can't move from the center of the galaxy.

It isn't just in the center of the galaxy.

So, at least so far we fully agree that the dark matter fully obey to the wish of our scientists

What it obeys is the laws of physics, not scientists.

I would use the magic dark matter to do the job.
I can invent the formula for the dark matter that can do whatever I wish it to do.
As it works only at the spiral arm, it won't have any negative impact on the bar.

So please, why our scientists can't use my idea of dark matter that is only focus in the spiral arms in order to solve the rotation curve anomaly in those arms without any negative impact on the bar?

Therefore, are you ready from now on to accept my explanation about the spiral arms while I'm using the dark matter imagination to support my wish?

Or it is forbidden for me to use the dark matter as only our key scientists have the permission to use it whenever is needed and at any formula that they wish and invent as my name is Dave and not Einstein?.

You could do that if you wanted to, but you'd need to show why your version of dark matter is better than what scientists have already come up with.

[Dave Lev (OP)]

My suspicion is this: close to the galactic center, it could be that the density of normal matter is higher than that of dark matter. If that's the case, then the gravitational influence of normal matter would dominate the orbital speeds of stars. In the outer regions of the galaxy, where normal matter is less dense, dark matter would dominate the contribution to the orbital speeds.

The outwards section of the bar is located at the same radius as the most inwards side of the spiral arms.
Therefore, this answer is clearly incorrect.

Are you acknowledging the need for dark matter to explain the rotation curve anomaly now?

There is no need for dark matter.
However, you refuse to understand how the ordinary matter can fully explain the rotation curve anomaly.

What it obeys is the laws of physics, not scientists.

The dark matter by itself doesn't obey to any law of physics.
As there is no person that can see without been seen, there is no matter that can set a gravity impact without detecting its existence by any sort of detectors.
However I really wish to thank you for giving me permission to use this dark magic,

You could do that if you wanted to, but you'd need to show why your version of dark matter is better than what scientists have already come up with.

Yes, I would show you why my personal imagination about the dark matter works perfectly OK at the spiral galaxy and how this magic answers all the open questions and meet the observation by 100%.
From now on there will be no puzzled scientist.
You would know how everything really works.

However, I would do so upon my return from the Business trip.
Thanks and have a good day

[Bored chemist]

Yes, I would show you why my personal imagination about the dark matter works perfectly OK at the spiral galaxy and how this magic answers all the open questions and meet the observation by 100%.

Don't forget to include the mathematics, or nobody will pay you any attention.

[Kryptid]

The outwards section of the bar is located at the same radius as the most inwards side of the spiral arms.
Therefore, this answer is clearly incorrect.

That would be the location at which gravitational dominance switches from that of normal matter to that of dark matter. Take a look at figure 22 on this page: https://ned.ipac.caltech.edu/level5/Sept16/Sofue/Sofue4.html

The mass contribution of the dark halo begins to dominate the other forms of mass between 1 and 10 kiloparsecs. Inside of that, the other, normal parts of the galaxy make up greater mass contributions. At about 100 parsecs, the bulge appears to have over 10 times the mass contribution of the dark halo.

There is no need for dark matter.

To explain the anomalous rotation curve, there is (either that or some form of MOND).

However, you refuse to understand how the ordinary matter can fully explain the rotation curve anomaly.

I'm not refusing to understand it, it's just that it doesn't work. It violates Kepler's third law. There is a limit on how fast the gravity from normal matter can make the stars orbit. That limit is represented by Kepler's third law. By proposing that you can go faster than that, you are violating Kepler's third law. Where do you propose all of that extra kinetic energy is coming from that is needed to make those stars go faster than gravity allows?

If you're proposing that stars closer in are dragging around the stars that are further out with gravity, then that would slow down the stars closer in. What you end up with isn't the outer stars moving just as fast as the inner stars would normally be moving due to Kepler's third law: you end up having those inner stars slow down at the expense of the outer stars speeding up because some of the kinetic energy of those inner stars is being transferred to the outer stars. That wouldn't fit the galactic rotation curve. All of those stars would be moving slower than 220 km/s, not at 220 km/s.

The dark matter by itself doesn't obey to any law of physics.

It would have to.

As there is no person that can see without been seen, there is no matter that can set a gravity impact without detecting its existence by any sort of detectors.

People are made out of normal matter, which interacts with light and therefore can be seen. Dark matter doesn't interact with light. And we can detect dark matter using telescopes (by using them to measure the speed of stars).

However I really wish to thank you for giving me permission to use this dark magic,

I gave you permission to use dark matter, not "magic". If your proposal does not lend itself to the scientific method, then it isn't science.

Yes, I would show you why my personal imagination about the dark matter works perfectly OK at the spiral galaxy and how this magic answers all the open questions and meet the observation by 100%.
From now on there will be no puzzled scientist.
You would know how everything really works.

Color me skeptical.