Galaxy orbital velocities explained without 'dark matter' halos.

Discussion in 'Pseudoscience' started by nebel, Dec 19, 2014.

  1. nebel Valued Senior Member

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    How about galaxy NGC 7331 (apo dec.18 2014) rotating ~like a solid because of: no central bulge, diffuse matter through out?
     
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  3. origin In a democracy you deserve the leaders you elect. Valued Senior Member

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    No one is disputing that if the mass of the galaxy was distributed evenly then the outer limits of the galaxy would have a rotational period very close to the rotational period of the inner parts of the galaxy. That is precisely why the idea that the majority of the matter in the galaxy is unseen was developed.
     
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  5. origin In a democracy you deserve the leaders you elect. Valued Senior Member

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    Yes the calculations have been done. The visible amount of material and it's distribution indicate that the outer parts of the galaxies should be spinning much faster than the inner sections of the galaxy. That does not occur so calculating out how much mass would be required to be evenly distributed through the galaxy to get the outer arms to move close to the speed of the inner areas of the galaxy show that the amount of unseen matter is more than the matter that can be seen. There is either dark matter or the theory of gravity is wrong. Dark matter seems more likely.
     
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  7. nebel Valued Senior Member

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    origin, as to post 22: in an entity where the mass is distributed evenly , like NGC 7331 apod Dec 18 2014., The velocities in the inner orbits would fall to zero, and do so gradually commensurate with the mass remaining toward the center, but fall to zero nevertheless, whereas it would be at the maximum at the perimeter, with no halo needed at all. It would be a stunning zero at the center rising to the extreme at the fringes. It is this low inner velocity that I believe has been downplayed too much.
    on #23. I like to see those calculation or a vulgarisation of them, and as I mentioned in my previous post #20, The dark areas between the star-rich arms are just as massive, only not glowing. The basic theory of gravity is not wrong, but most people are stunned when you prove to them that the center of gravity has no gravity at all, and areas adjacent very little to boot.
    can you reference, link us these calculations you mentioned? thank you.
    On dark matter= dark energy. Is it not now thought, that dark energy is a property of the void, space itself? if that were the case, there would not be more of it near toward the outside, adding to the nature of things, that mandate high gravity/velocities=energy there ?
     
    Last edited: Dec 25, 2014
  8. nebel Valued Senior Member

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    origin, re: galaxy with even matter distribution; post #22: in such a body, the graphics presenting the velocities would be showing a Linear decline, a straight line from the top right corner, through the center and toward the left bottom end to negative max again.
    ( to show the reversal in the direction) .
    This would be opposite of what we see in the Solar System - type situations, where the resultant falls from the maximum at sun's "surface" to near zero at the infinity distance.
    The results of more or less flat velocity distributions we see in various galaxies are the are the result of the various uneven matter distributions, but in neither case should dark matter be needed to account for the data, in my POV.
    --?
     
    Last edited: Dec 25, 2014
  9. origin In a democracy you deserve the leaders you elect. Valued Senior Member

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    The visible mass is not distributed evenly in that galaxy.
    The velocities do not fall to zero, if they did then the stars would fall into the black hole in the center of the galaxy. The stars near the center of our galaxy are moving incredibly fast compared to the stars in the rest of the galaxy.
    A first year physics book will have all you need to understand this.
    First of all I find it hilarious that you state there is no need for dark matter in the galaxy because there is dark matter in the galaxy.

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    Secondly that idea fails because there would be evidence of that amount of mass.
    The only people stunned by this are people that have never taken physics.
     
  10. origin In a democracy you deserve the leaders you elect. Valued Senior Member

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    That is because your point of view is from a position of ignorance. The observable mass in all galaxies is not evenly distributed, ergo there must be unseen matter that results in the velocity profiles seen.
     
  11. river

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    Which means that the current cosmic theory , mainstream theory , is incomplete
     
  12. origin In a democracy you deserve the leaders you elect. Valued Senior Member

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    Wow, you figured out that we do not know everything? Impressive.
     
  13. river

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    Your admittance of the fact is even more impressive !!!!!
     
  14. nebel Valued Senior Member

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    origin, I was referring to your 'theoretical galaxy' with even matter distribution, post 22. Clearly, a black hole in the center is not such. Look at a situation in globular clusters, mini galaxies, with no central mass, no common rotation, the stars in the central portion of their orbits are doing just fine with low velocities.
    Rubin et al observed flat velocity distributions, until the black hole screamers were discovered.
    Re: center of gravity without gravity: even academics swallow hard when confronted (in front of an audience) with that proposition/ essential fact.
    I take exception to the use of the word "---ignorance" even if it describes reality. This idea was not put into pseudo science for nothing. Please offer some real refuting figures please, not platitudes.
     
  15. origin In a democracy you deserve the leaders you elect. Valued Senior Member

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    What do those have to do with what we were discussing? We were discussing how the rotational curve of galaxies does not match the visible matter distribution.
    Don't be absurd. This is something that is covered in a first or second semester physics course.
    You are the one who has the alternative hypothesis so don't just wave your arms lets see some calculations that support you conjectures.
     
  16. nebel Valued Senior Member

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    What do those have to do with what we are discussing? such a "ideal" galaxy would be a starting point of calculations, discussion, and in an 'evenly distributed matter' normal matter situation, Peripheral orbit velocities are the highest.
    Not all galaxies look like the Sombrero, that is why i posted APOD Dec 18, mentioned the smooth elipticals, the non-rotating star clusters.
    You can pack a lot of more matter into the center, on top of the already evenly distributed matter, to lift that curve there to the level that naturally exists in the perimeter.
    There seems to exist a circular reasoning too: we establish the amount of mass by looking at the velocities, not necessarily looking at what the gravity gradient should indicate there.
    attempting to calculate any one of the myriads of galaxy configurations would by beyond my expertise. That is why I like your 'smooth matter' model as a starting point.
     
  17. nebel Valued Senior Member

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    new research*: dark matter is not reacting with itself, as if it did not exist? in the shell theory, gravity does not exist in the center, interior of shells. perhaps this is overlooked,?
    * "dark matter even darker than once thought" Science news daily
     
  18. nebel Valued Senior Member

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    They just found a galaxy without dark matter:
    NASA/Goddard Space Flight Center. "Dark matter goes missing in oddball galaxy." ScienceDaily. ScienceDaily, 28 March 2018. <www.sciencedaily.com/releases/2018/03/180328130724.htm>.
    One swallow does not make a summer, but needed adjustments in theories are discovered where the models fail.
     
  19. nebel Valued Senior Member

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    View attachment 1940

    Case of a disk, spiral galaxy: with equal distribution of matter, (which will not be the case, what with thousands of black holes holed up near the center), a gravity detector flying at 2 R, in the outer halo, would detect 8 times more "total gravity "* than when at 1/4 R.
    * strength of the field x distance (circumference) through which it acts. Partially copied from main cosmology site.
    think about that, in the halo, twice as far out then then " the perimeter", gravity is still as strong as it is only a quarter out from the center. in total 8 times more. (not corrected for density variation). and
    we have not begun to figure in dark energ yet.
     
    Last edited: Apr 21, 2018
  20. nebel Valued Senior Member

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    In a globular cluster, or elliptical, the surrounding imaginary sphere at 2R would constitute 64 times the gravity pulling compared in total to an even density 1/4 R inner sphere.
    An unrelenting pull for an orbiting object to overcome with velocity.
    If you upped the ante by having more stars present at any time near the center, does that change the strength at distance?
     
  21. nebel Valued Senior Member

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    I here transferred origin's diagram of the strength of gravity from the " where is more gravity in or out" thread.
    When applying the formula for surface of a sphere to origin's "2R, 1/4 g" dotted line, you can see that in the space surrounding a sphere, at 2 R there is 64 times the total gravity* of the inside, although at any given individual point on the outside at 2R there is the same g as at .25 R , and from there it is downhill endlessly to infinity. Thinking of an elliptical galaxy or globular star clusters here.
    This is for a perfect sphere, situations for a perfect disk, pancake or Ravioli shaped body would vary
     
  22. nebel Valued Senior Member

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    In the above graph, at ~ 8/10 of gravity and R, ( approximately as much down from the surface apex, than the 1/9 g line is up rom the r axis), there would be equal amount of total gravitational force in the inside than here is in the outside space.
    Arrived at by having the volume of the inside ~ .8 R globe deducted from the volume of a ~1.04R outside globe, assuming that the strength of gravity is ~ equal in both spaces as the graph indicates, but that the parity, unity value is reached at half the distance outside than the distance down from the surface)
    That equal at ,04 R ratio has risen to 1/64 inside /outside at 2R above the surface, and going to infinity should close the case.
    Density gradient inside the globe would alter the ratios, but not in the general picture.
    Let it be resolved then, that there is more gravity on the outside than the inside.
     
    Last edited: Jun 14, 2018
  23. nebel Valued Senior Member

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    In the above graph, parity between the inside total force of gravity, and the one present in the outside space, is reached at .04 r above the "surface" of the entity, possibly an elliptical galaxy. Stars have been discovered at 2R , 3R from our galactic centre.
     

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