Where is most "gravity", inside or out?

Discussion in 'Astronomy, Exobiology, & Cosmology' started by nebel, Feb 29, 2016.

  1. RainbowSingularity Valued Senior Member

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    if i gather an impresion there is more than "no" Trolls inhabiting the science threads then maybe i will.
    i have posted threads on the subject before using adjacent definitions which any physacist should be able to join the dots easily, however, they probably do not have the time to read soo much or post.
     
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  3. nebel Valued Senior Member

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    Yes this a great place top[lace your ideas, but do not expect kudos. Ideas are always in competition, conflict, and to be challenged. support is not what to expect. Be happy that your ideas is out and here; like
    gravity, it is not an interior thing, it is on the outside.
     
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  5. RainbowSingularity Valued Senior Member

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    watching city starve to death for the sake of giving a child a free meal.
    capitalism is not my master.
     
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  7. nebel Valued Senior Member

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    ?
     
  8. RainbowSingularity Valued Senior Member

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    my little poem means
    somewhere inbetween(pure capitalism & communism) we should try and meet as humans caring for other humans
     
  9. nebel Valued Senior Member

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    I think this happens on these sciforums. free exchange of ideas. if they fly, fine, a place for naysayers too.
    To stay on topic:
    Even if you consider gravity overlapping between the surfaces of an entity, not coming to zero, cancelling at the centre, because it is reaching to infinity on the "outside" makes it huge there, and means that it, and it's other source, energy, must be reaching to the infinite too.
     
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  10. RainbowSingularity Valued Senior Member

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    "event horizon"
    does it have a start and finish point ?

    can a hole go through a hole ?
     
  11. nebel Valued Senior Member

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    This so aptly called horizon is really a sphere, a certain distance from the central singularity, and spheres have a way of being without start and finish points. You might try the bible, it speaks of the four corners of the Earth.

    I do not know whether they can go through each other, they merged, and we got the message in the form of gravitational waves seen by LIGO.
    Take a black hole, the singularity, all the gravity is outside, the event horizon is just one feature, line of demarcation outside of it.
     
  12. nebel Valued Senior Member

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    In the proven shell theorem, the effective zero gravitational field at the centre is not due to overlapping fields cancelling each other, or waves interfering, but the simple fact, as in origin's graph in post #2 shows, --- only the enclosed mass generates gravity, and it is getting ever smaller toward the centre, the outer shell never contributes to the inner gravity, no outer halo would effect the inner orbital velocities of stars in galaxies.
     
  13. nebel Valued Senior Member

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  14. NotEinstein Valued Senior Member

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  15. nebel Valued Senior Member

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    sorry, posted that and could not get rid of it, but
    the connection is that energy is said to be increasing to feed the accelerated expansion, greater velocities becoming evident, and dark matter halos , the "more gravity" outside, is driving the higher velocities at the fringes of Galaxies, cluster too, so, dark energy and dark matter have similar effects, perhaps you cant have one without the other, and
    " dark matter free" galaxies have been discovered too.
    perhaps the universe is more enlightened, lightened period.
    perhaps the dark ages are over.
     
  16. Write4U Valued Senior Member

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    Questions: How is a black hole measured? At the point of the singularity or in the cone reaching out to the event horizon? Does matter in the well cone exert gravity? Can we even measure that?

    The gravity inside the well cone prevents light from escaping, The whole thing is a black hole, no .......

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    Is it possible that Dark matter is the matter contained in BH cones?
     
    Last edited: Sep 7, 2018
  17. Q-reeus Valued Senior Member

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    No. That interesting article linked to in #210 relies on our neighborhood being in an unexpectedly large inhomogeneous region of total matter (dark plus normal) having an accelerated 'flow' presumably towards some other such inhomogeneous region. Which flow they find perversely skewed earlier SN1a surveys that assumed homogeneity applied at the scales considered.
    Dark matter gravitates, whereas what I still think will be found to be real 'DE' anti-gravitates. So they are opposites in that fundamental respect.
     
  18. origin In a democracy you deserve the leaders you elect. Valued Senior Member

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    One of the ways is to measure the mass of a black hole is to look at the orbit of a star orbiting around the black hole. If you can measure the speed of the star and the diameter of the orbit you can calculate the mass of the black hole.

    There is no cone. I think you are talking about the graphical representation of the gravity well in 2 dimension, there isn't really any sort of cone, it is just a device to help visualize the black hole. The mass of the black hole can be calculated as I stated above and based on the mass, the event horizon diameter can be calculated.

    Again there is no cone, forget the cone, it does not exist and just seems to be confusing you. There is no light coming from a black hole so it would not so much be black as it would be invisible. Typically there would be an accretion disc around a black hole which we can 'see' in the form of energetic x-rays, such as Cygnus x-1.

    Any dark matter that gets too close to the black hole will be swept into it but the major percent of the mass will be 'normal' matter. Black holes are formed from the compression of matter that has 'clumped' together, such as stars. Dark matter does not appear to clump together - it is rather diffuse so probably cannot form a black hole (just like there does not appear to be any dark matter stars).
     
  19. NotEinstein Valued Senior Member

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    So it was off-topic; if you want to discuss the misunderstandings in your post just now, feel free to open another thread.
     
  20. nebel Valued Senior Member

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    well, it should have gone onto our past battlefield, the "ALMA" thread, because that lead me down the path to infinite time, infinitely old energy, energy waiting for us in the future we are moving into. . Waiting for a good one like Einstein "Block time" article on BBC again. thanks,
     
  21. Write4U Valued Senior Member

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    Thanks for responding. Of course a black hole is also not a black hole. It just appears that way. But I was not so much talking about the size and mass of the singularity as the greater area below the event horizon. The warped space fabric.
    I used "cone" to describe the area (volume of spacetime) as I would when identifying volume of a whirlpool. Ok, but is that space between the singularity and the event horizon empty? If not, and there is mass present even as it may be falling toward the singularity, we would not be able to observe that mass.
    Why do we assume that dark matter is dark and not just invisible except by secondary effects (radiation)?
    Diffused matter is still matter and if we consider that a black hole has an "unobservable" area of enormous proportions, plus the recent proposition that there are many, many black holes of various size.

    I am just trying to visualize what lies between the event horizon and the singularity.

    It occurred to me that if a massive singularity distorts spacetime, spacetime itself must be composed of some form of massive substance, a medium, even if it is widely dispersed. Why else would space time be affected at all by a singularity? You cannot warp nothing. Does space itself consist of dark matter, a particle so small as to be currently unmeasurable, unless you measure it in its universal entirety and call it universal "dark matter"....

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    A type of boson?
     
    Last edited: Sep 8, 2018
  22. nebel Valued Senior Member

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    Applying the interesting, enlightening points made on Black Holes to this illustration,(thank you origin), the Zero position would remain, but the inside slope become steeper and the outside blue portion remain, but continue up to the new higher max at the limit of the BH, with an obviously smaller R. That peak of the force of gravity or spacetime warp would be the "size" the R of the BH, and there would remain to be more gravity outside then inside, giving us those measured large orbital velocities.
     
  23. DaveC426913 Valued Senior Member

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    Technically not always. However, any mass is infalling at relativistic speeds, so is between EH and singularity for a vanishingly short duration.

    Dark matter does not interact electromagnetically; it does not emit, absorb or otherwise interact with light. It is invisible across the EM spectrum.


    Vast numbers of small black holes is a hypothesis that has been tested and ruled out.


    Nothing that stays there for any length of time.

    To be clear though
    : while any infalling matter does not remain above the singularity for any appreciable time, that's not relevant - its massive effect is still felt. A black hole's mass IS the mass of its infallen matter, and that mass remains there, exerting gravitational influence forever - at least, until the BH evaporates.


    No.
     
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