Can the rotation of distant galaxies be explained without the use of Dark Matter and Energy?

[exchemist]

8 minutes ago, tar said:

Genady,

We cannot know the position and velocity of a particle such as an electron of an atom with certainty.

what makes you think we can know the position and velocity of a star with certainty?

Do not try to drag quantum theory into a discussion about astronomical objects. It makes you look a fool.  Heisenberg’s uncertainty principle is not relevant at the macroscopic scale, because Planck’s constant is so small it only makes a difference at the atomic scale.

[tar]

I think I will retire from the discussion for a while.   I am trying to offer a required adjustment to our understanding of galactic rotation and you are trying to teach me the standard model, which is find currently in trouble.    Dark Matter to me is much like the epicycles of the planets observed.  The standard model keeps requiring changes in the cosmological constant and the age of the universe and such and requires the place be made up 95% by dark matter and energy and never observed either one.   We infer the presence of such to true the model with observations.   Perhaps we can true the observations with our model by adjusting our model, not by proposing imaginary particles and forces.

[exchemist]

1 minute ago, tar said:

I think I will retire from the discussion for a while.   I am trying to offer a required adjustment to our understanding of galactic rotation and you are trying to teach me the standard model, which is find currently in trouble.    Dark Matter to me is much like the epicycles of the planets observed.  The standard model keeps requiring changes in the cosmological constant and the age of the universe and such and requires the place be made up 95% by dark matter and energy and never observed either one.   We infer the presence of such to true the model with observations.   Perhaps we can true the observations with our model by adjusting our model, not by proposing imaginary particles and forces.

That is what MOND tries to do. But that is based on an actual model with detailed calculations to support it. What you seem to be doing is pulling random ideas out of your arse, with no attempt at quantifying their effect to show how they might explain what we observe. That’s no good.

[tar]

I understand I am lacking in the math department exchemist, but I am not there yet with this idea.  I am trying to set the assumptions and groundwork for expecting the universe to be connected to itself and be composed of ordinary matter and energy that we have been studying for years and know a lot about.

If something only fits the math and has not correlation to reality and ordinary matter and energy, what is the use of it?

 

It is like people finding PI to the quadrillionth digit.   Why?  You cannot measure or fabricate to that precision so what is it for?

I think math is very useful, but it is a symbol system.  You have to know what is standing for what.  You have to be able to say it words to know what you are setting to what and what relationship you wish to illustrate.  

You cannot for instance figure that half a cow will give half as much milk.  Half a cow would give half as much hamburger.

[swansont]

3 hours ago, tar said:

My thought is that the distance and size of distant galaxies is not taken into consideration when applying rotational and gravitational equations.

 

To apply the equation the rotation of the galaxy in question is considered as one thing rotating at once.

This is not what we see.    We see the closer parts of the galaxy 10s of thousands of years before the further parts.   

 

That is we cannot use one equation that takes the whole galaxy at once because we are seeing the galaxy at different times and any motion needs to be thusly "played back" to arrive at a position of the various stars at one moment where they were all in the same moment and then derive their positions in the next moment.

Regards, TAR

like NGC 1068? Notice anything about it?

https://en.m.wikipedia.org/wiki/Spiral_galaxy

45 minutes ago, tar said:

Genady,

We cannot know the position and velocity of a particle such as an electron of an atom with certainty.

what makes you think we can know the position and velocity of a star with certainty?

There’s always uncertainty but we can quantify it.

The thing about spiral galaxies is that the motion is tangential, not radial, so it really doesn’t matter when the time-tag of the measurement is. I don’t see where you've made the case that it matters

[tar]

30 minutes ago, exchemist said:

That is what MOND tries to do. But that is based on an actual model with detailed calculations to support it. What you seem to be doing is pulling random ideas out of your arse, with no attempt at quantifying their effect to show how they might explain what we observe. That’s no good.

yes i like the MOND solution.   I am maybe turning to looking for an explanation of the difference in gravity effects at large distances that would help base the MOND solutionk that involves the delay in gravity's effect on distant objects based on the "speed" of gravity. Thus timing and the consideration of which parts of the model exist "at the same time" becomes pertinent. 

Regards, TAR

22 minutes ago, swansont said:

like NGC 1068? Notice anything about it?

https://en.m.wikipedia.org/wiki/Spiral_galaxy

There’s always uncertainty but we can quantify it.

The thing about spiral galaxies is that the motion is tangential, not radial, so it really doesn’t matter when the time-tag of the measurement is. I don’t see where you've made the case that it matters

I notice that we are seeing it from its axis of rotation.  That is, if we look at a galaxy edge on the closer part of the galaxy is on the edge closest to us but here the fringes of the galaxy are all the same distance, hence happening at the same time as the other portions of the fringe.   Although I would still imagine that the center of the pictured galaxy is closer to us then are its fringes.    Thus implying that we see the rotation near the center before we see the rotation at the fringes that was occurring simultaneously

Regards, TAR

[swansont]

20 minutes ago, tar said:

I notice that we are seeing it from its axis of rotation.  That is, if we look at a galaxy edge on the closer part of the galaxy is on the edge closest to us but here the fringes of the galaxy are all the same distance, hence happening at the same time as the other portions of the fringe.   Although I would still imagine that the center of the pictured galaxy is closer to us then are its fringes.    Thus implying that we see the rotation near the center before we see the rotation at the fringes that was occurring simultaneously

Regards, TAR

The center isn’t rotating, and I addressed the issue of timing, though you didn’t quote that part.

[tar]

Thread.

Lets say mass accretes and tiny pieces of matter gather in one location to make a massive object.   This mass does not instantly affect all the rest of the universe, does it?

Objects close to it I would imagine are effected first and objects further away later.   After a time X after accretion  a close object has been subjected to its gravity for nearly all of time X whereas an object  far away from the accretion is yet to fell its effects.   

[swansont]

1 minute ago, tar said:

Thread.

Lets say mass accretes and tiny pieces of matter gather in one location to make a massive object.   This mass does not instantly affect all the rest of the universe, does it?

The effect of the mass doesn’t “turn on” when it forms a clump with another mass. It’s always on.

 

[exchemist]

18 minutes ago, tar said:

yes i like the MOND solution.   I am maybe turning to looking for an explanation of the difference in gravity effects at large distances that would help base the MOND solutionk that involves the delay in gravity's effect on distant objects based on the "speed" of gravity. Thus timing and the consideration of which parts of the model exist "at the same time" becomes pertinent. 

Regards, TAR

 

 While changes in a gravitational field will propagate at c, a static field, like that exerted by the centre of mass of a galaxy, has no “speed”. And this is just another vague idea, thrown out by you seemingly at random, with no attempt to work it out to show  how it might produce the effect on rotation rate that we observe.

If you want to make a serious scientific suggestion, you have to show how your idea might produce the observed effects. 

[tar]

5 minutes ago, swansont said:

The center isn’t rotating, and I addressed the issue of timing, though you didn’t quote that part.

I am not sure why you know the center is not rotating.  Don't you have to watch a galaxy for a thousand years before you notice a change in position of a unique star?   You can only use red shift and blue shift if the galaxy is edge on.  Looking at it form the axis  you don't know any of it is rotating.

1 minute ago, swansont said:

The effect of the mass doesn’t “turn on” when it forms a clump with another mass. It’s always on.

 

SwansonT, long time no argue with.  Good to see you.

Well Jupiter did not have a strong gravitational pull until it formed out of the accretion disc of the solar system.

You cannot measure Jupiter's gravitational effect on Sirius unless there is a Jupiter.

'

 

[swansont]

4 minutes ago, tar said:

I am not sure why you know the center is not rotating. 

Because that’s how rotation works.

4 minutes ago, tar said:

Don't you have to watch a galaxy for a thousand years before you notice a change in position of a unique star?   You can only use red shift and blue shift if the galaxy is edge on.  Looking at it form the axis  you don't know any of it is rotating.

You are missing information here. You can get doppler shift information even if it’s only a component of the velocity.

If the galaxy was edge-on, you can get the information from the opposite edges, which would in fact be the same distance away, but wouldn’t get the information from the interior part, since you can’t see it.

 

4 minutes ago, tar said:

SwansonT, long time no argue with.  Good to see you.

Well Jupiter did not have a strong gravitational pull until it formed out of the accretion disc of the solar system.

The individual parts still had gravitational pull. And at distances far enough away, it won’t matter if the mass is concentrated or not (it’s why a black hole has the same gravitational attraction as a normal star of equal mass, as long as you’re further away than the radius of the star. (i.e. the earth wouldn’t notice a gravity difference if the sun were a 1 solar mass BH)

[tar]

9 minutes ago, exchemist said:

 While changes in a gravitational field will propagate at c, a static field, like that exerted by the centre of mass of a galaxy, has no “speed”. And this is just another vague idea, thrown out by you seemingly at random, with no attempt to work it out to show  how it might produce the effect on rotation rate that we observe.

If you want to make a serious scientific suggestion, you have to show how your idea might produce the observed effects. 

If the spiral arm of a galaxy contains a lot of stars and mass and you pick a point on the fringes of the galaxy the gravitational pull of the arm will speed up a mass that is "behind" it, rotationally and retard the rotational movement if it is"ahead" of the arm and the arm would add to the gravitation mass of the center of the galaxy if center of mass of the arm was between the fringe point and the center of mass of the galaxy.    Thus "when" the arm is in the various positions relative to the fringe point matters in terms of the acceleration  the arm's mass will impart on the fringe point.

swansont, the galaxy pictured was seen from its axis of rotation.  All the fringe was equal distant more or less.   An edge on galaxy the far side would be further away and hence what you saw of it was its position a long time before what you see on the closer edge.

 

Regards, TAR

9 minutes ago, swansont said:

Because that’s how rotation works.

You are missing information here. You can get doppler shift information even if it’s only a component of the velocity.

If the galaxy was edge-on, you can get the information from the opposite edges, which would in fact be the same distance away, but wouldn’t get the information from the interior part, since you can’t see it.

 

The individual parts still had gravitational pull. And at distances far enough away, it won’t matter if the mass is concentrated or not (it’s why a black hole has the same gravitational attraction as a normal star of equal mass, as long as you’re further away than the radius of the star. (i.e. the earth wouldn’t notice a gravity difference if the sun were a 1 solar mass BH)

edge on the close edge is more recent than the far edge.   Looking from the axis of rotation the edges are all approximately equal in age.

If my theory is correct the rotational speeds of galaxies viewed from the axis of rotation would be more consistent with Kepler's law than galaxies viewed edge on.

I do not know if there are  observations categorized in this manner.  Edge on or from the axis of rotation.

not theory, not even hypothesis.  If my speculation is correct the edge on galaxy would be figured to require more dark matter to explain its rotation than the axis viewed galaxy because the time component is not throwing off the observation as much in the axis view

[swansont]

33 minutes ago, tar said:

edge on the close edge is more recent than the far edge.   Looking from the axis of rotation the edges are all approximately equal in age.

But not left or right. If it’s edge-on, you can’t see the far edge anyway, so that’s moot.

Quote

 

If my theory is correct the rotational speeds of galaxies viewed from the axis of rotation would be more consistent with Kepler's law than galaxies viewed edge on.

I do not know if there are  observations categorized in this manner.  Edge on or from the axis of rotation.

not theory, not even hypothesis.  If my speculation is correct the edge on galaxy would be figured to require more dark matter to explain its rotation than the axis viewed galaxy because the time component is not throwing off the observation as much in the axis view

 

You’ve provided no reason why this timing matters. The stars would have to speed up or slow down, which requires the distance from the center change, which requires a radial velocity component. Is there evidence of this?

[exchemist]

2 hours ago, tar said:

If the spiral arm of a galaxy contains a lot of stars and mass and you pick a point on the fringes of the galaxy the gravitational pull of the arm will speed up a mass that is "behind" it, rotationally and retard the rotational movement if it is"ahead" of the arm and the arm would add to the gravitation mass of the center of the galaxy if center of mass of the arm was between the fringe point and the center of mass of the galaxy.    Thus "when" the arm is in the various positions relative to the fringe point matters in terms of the acceleration  the arm's mass will impart on the fringe point.

 

So what? How does this do away with the need for extra, invisible mass to account for the observed rotation rates? 

[Markus Hanke]

10 hours ago, tar said:

what you saw of it was its position a long time before what you see on the closer edge.

But this is entirely irrelevant to Dark Matter. The mathematical relationship we are talking about here (Tully-Fisher relation and Faber-Jackson relation) are statistical statements; they relate the average rotational velocity of a large collection of stars in a galaxy to their total combined mass. Notions of simultaneity for an arbitrary observer as to the position of a single star at any given time never come into this at all, so this entire discussion is pretty much mood.

The other thing of course is that DM is needed for a lot more than just galaxies’ rotation curves; you cannot just ignore all the other evidence we have for its existence when discussing this subject.