What color is the dark matter

Discussion in 'Astronomy, Exobiology, & Cosmology' started by timojin, Oct 17, 2016.

  1. The God Valued Senior Member

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    This graviton travelling at c has a problem with BH concept.

    And the fact of matter is that a hypothetical DM should not be explained by a hypothetical graviton.
     
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  3. The God Valued Senior Member

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    No, they are not the frequencies, they are THE EMRs just like visible radiation. Read about wavelengths of EMR too for better understanding.

    And, no, black does not mean absence of color. Please read about scattering, absorption of radiation and emission.
     
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  5. Boris2 Valued Senior Member

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    Last edited: Oct 23, 2016
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  7. paddoboy Valued Senior Member

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    The graviton [if it exists] is applicable in QFT.....
    The gravity from a BH as asked in the OP does not have to get out of the BH, for the previous reasons stated..ie a fossil field and the property of nonlinearity.
    DM is an accepted part of standard cosmology today, despite your refusal to recognise that fact, and is not needed to be explained by a graviton.
    Not sure where you dragged that from, although I could guess?

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  8. Boris2 Valued Senior Member

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    radiation doesn't have a ''colour". We give certain frequency a colour name because our eyes have receptors sensitive to those frequencies which we interpret as "colour".
     
  9. paddoboy Valued Senior Member

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    "They are frequencies of the EMR outside our the viewable range of the human eye, and have no connection with DM".
    The frequency of the wave most certainly determines what we interpret as its color.
    Or are you just attempting to be contrary?
    Black is most certainly the absence of colour in relation to what we are debating, ie DM.
    Your use of the word "means" is your use of the word....I simply said black is the absence of colour.
    http://education.seattlepi.com/not-list-black-white-colors-physics-3426.html
    Visible light, radio waves, x-rays and other types of radiation are all part of the electromagnetic spectrum. Visible light is electromagnetic radiation with wavelengths ranging from roughly 400 and 700 nanometers. In physics, a color is visible light with a specific wavelength. Black and white are not colors because they do not have specific wavelengths. Instead, white light contains all wavelengths of visible light. Black, on the other hand, is the absence of visible light.
     
  10. The God Valued Senior Member

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    This concept of fossil field with respect to BH is quite funny. Rather some kind of makeshift arrangement to keep BH alive.

    A very simple aspect: Fossil field, if any, should be non transferrable from point to point in space-time (same coordinates in BH reference but spatially different due to motion of BH), but field moves along with BH? Since we do not know the mechanism of manifestation of gravity by Mass in general, the problem gets further compounded for gravity of an object inside its Event Horizon, this weird fossil field concept was brought in.
     
  11. The God Valued Senior Member

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    Non linearity as property? Non linearity in the context is related with mathematical solution for effect of multiple object on a space-time point. It simply means that equations are complex and non linear, it is not that you find the curvature at some point due to Mass one and curvature at that point due to Mass two, and add them up for resultant curvature. The effect just does not add up. I see no reason why you should bring in this non linearity business here?
     
  12. paddoboy Valued Senior Member

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    Not at all, rather common sense.

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    What you need to consider is that any BH is simply critical curved spacetime, with a compressed mass/singularity at its core.
    Gravity/spacetime is also nonlinear; In other words, gravity makes gravity.
     
  13. paddoboy Valued Senior Member

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    The same reason that I bring "fossil field"business here...it's relevant and terminates your fabricated alternative.
    http://archive.ncsa.illinois.edu/Cyberia/NumRel/glossary.html
    But near a black hole, Einstein's Equations predict that the curvature of spacetime is highly non-linear. At the center of the black hole, distance and time become infinitely stretched! Furthermore, the nonlinearity of the equations can lead to strange effects such as the formation of black holes where none exist initially. Nonlinearity complicates life, but makes it more interesting!
     
    Last edited: Oct 23, 2016
  14. The God Valued Senior Member

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    The point which I was hammering across
    To Paddoboy was that if a radiation is beyond the visible range, we will not be able to see the object which is emitting that radiation only. So technically that should also be dark.

    But DM, simply radiates no EM. It has nothing to do with absence of color, it is complete absence of EMR.
     
  15. The God Valued Senior Member

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    1. How is it common sense?

    2. What do you mean space-time as nonlinear?

    Writing some nonsense for the sake of it?
     
  16. paddoboy Valued Senior Member

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    Not neccessarilly...simply beyond the viewing sensitivities of our eyes.
    Complete absence of EMR, or the fact that it reflects nor absorbs EMR, means its black or dark.
     
  17. paddoboy Valued Senior Member

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    Do you believe the gravity/spacetime curvature of the star from whence the BH formed just magically disappeared?

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    Just as I simplistically explained....in essence, gravity makes gravity.
    http://www.einstein-online.info/spotlights/gravity_of_gravity
    "One reason why the physics of general relativity is much more difficult than that of Newton's theory of gravity or the theory of electrodynamicsis a property called non-linearity. In short, gravity can beget further gravity - where gravitational systems are concerned, the whole is not the sum of its parts".
    No, no nonsense at all, other then from yourself as usual.
    But all you need to do is offer a citation and or reputable link supporting your cause.

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  18. The God Valued Senior Member

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    So you mean charcoal, which appears black or your fancy suit which appears black, does not reflect nor absorb EMR? Yeah?
     
  19. The God Valued Senior Member

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    But the mass has magically disappeared?!
    I urge you to be consistent. Do not bring in sense when you are talking nonsense. You are right the total gravitational effect, the total curvature at a given point, is not the sum of multiple mass effect. Thats noninearity. It is not that you solve the maths individually for m1, m2 etc and add up the roots.
     
  20. paddoboy Valued Senior Member

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    Charcoal would near absorb all light that falls on it.
    As you well know, we are speaking of DM, so I really suggest you stop asking your foolish little questions by taking a contrary position.
    Black is seen as the absence of colour.
    But all you need to do is offer a citation and or reputable link supporting your cause.

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    [whatever that cause may be]
     
  21. paddoboy Valued Senior Member

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    No it hasn't.

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    The fossil field is evidence of that.
    I'm always consistent, despite your attempts to be contrary...contrary as well as wrong on most occasions. I urge you to reform before you run into any more difficulties.
     
  22. The God Valued Senior Member

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    But in earlier post, you only defined black as something which neither reflects nor absorbs radiation. Did you not?

    My point is Paddoboy, cool down, learn, understand and then post. You are an enthusiast, and your comprehension of what you read is not up to the mark.
     
  23. Q-reeus Banned Valued Senior Member

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    Simplistic and wrong. In GR gravity does NOT 'make gravity'. You have never understood the significance of zero Ricci curvature in ALL vacuum solutions of EFE's. I won't bother pointing to previous threads where that issue was argued about over many pages.
     

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