Black Holes .

Discussion in 'Astronomy, Exobiology, & Cosmology' started by river, Aug 11, 2019.

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  1. Write4U Valued Senior Member

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    It's interesting to follow the history of the term "planet".
    Of course it all started some way back;
    https://en.wikipedia.org/wiki/Definition_of_planet

    Which of course is much broader in scope than it is now.
     
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  3. davewhite04 Valued Senior Member

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    You'd get sacked if you were a high school science teacher. A good thing.
     
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  5. DaveC426913 Valued Senior Member

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    I said nothing of the sort, 'in effect' or otherwise.
    You have misread something, which explains why your responses are non sequitur.


    We agree on this. No one has said otherwise. Please review the thread.
    If you're uncertain, feel free to quote something, we I can see where you went awry.
     
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  7. DaveC426913 Valued Senior Member

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    Yes, and this has its place. But sometimes it does not have its place, and simply leads to confusion.

    A implies B.
    It does not follow that B implies A.

    'Planet' implies 'orbit'. (except for rogues, this is pretty much true)

    'Orbit' implies 'planet'. (False. Orbit implies a large list of things not planet-like: asteroid, moon, spaceship, star, galaxy, supercluster etc.)

    That is the trap you fell into in post 172.
     
  8. davewhite04 Valued Senior Member

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    It's just scientific schematics, who cares?
     
  9. DaveC426913 Valued Senior Member

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    'Scientific schematics'? You mean like blueprints?

    Write4U seems to care.
     
  10. davewhite04 Valued Senior Member

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    Well if you want to join the science blueprint you'll never be right, over time.
     
  11. DaveC426913 Valued Senior Member

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    You follow a cryptic comment with another cryptic comment.

    I retain some faint hope that some on-topic content may yet rise from the ashes of this thread on black holes.
     
  12. Write4U Valued Senior Member

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    Yes, and it seems I am not alone. Geologists particularly are not happy with the current definition.
    ..................
    https://phys.org/news/2017-02-geophysical-planet-definition.html
     
  13. river

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    So you can't define the essence of a BH , in the physical ; it is purely a mathematical concept .
     
  14. Write4U Valued Senior Member

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    If you're looking for gravity;
    https://en.wikipedia.org/wiki/Schwarzschild_radius

    i.e. the Schwarzschild radius is a geometric potential and therefore an essence of a BH.
     
    Last edited: Aug 27, 2019
  15. river

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    Yet gravity waves emanate; not turn inwards upon themselves . If they did , turn inwards , the gravity wave would never exist .
     
    Last edited: Aug 27, 2019
  16. DaveC426913 Valued Senior Member

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    Well, since we can point to it, and say 'that there doohickey's a black hole'
    and since stars in our galactic core are orbiting it,
    and, since if we get too close to it we get our asses kicked
    I'd say it's about as physical as you can get.

    Look, just because you don't understand it doesn't mean it doesn't exist.
     
  17. river

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    What of the galactic core in the first place ? Since ALL Galactic cores have a BH at their core.

    Yet you can't tell me what this BH is physically based on .
     
  18. DaveC426913 Valued Senior Member

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    You have been told already that this is false.

    Can and have.
    The fact that you don't understand it - that's on you, not me.
     
  19. river

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    Then the BH theory is false .
     
  20. DaveC426913 Valued Senior Member

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    Don't be silly.
     
  21. Janus58 Valued Senior Member

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    Nonsense. You are confusing gravitational waves which carry information about changes in gravity, and the gravitational field. Gravitational waves cannot escape the event horizon of a black hole, But the gravitational field, which exists outside the BH was there before the BH formed and remains after the BH forms. The gravitational waves detected an were the result of BHs colliding were generated outside of the event horizons.
     
  22. river

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    What is silly about my last post ?
     
  23. river

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    To your last statement ; how so ?

    Why would BHs collide ?
     
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