A rudementary question on dark matter

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    Dark matter Matter
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Discussion Overview

The discussion revolves around the classification and visibility of dark matter, particularly whether it should be considered "visible" or "invisible" mass. Participants explore the nature of dark matter, its interaction with electromagnetic radiation, and its gravitational effects on visible matter in galaxies.

Discussion Character

  • Exploratory
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant suggests that dark matter has mass that is significantly greater than the total mass of stars in a galaxy and questions how to classify this mass into visible and invisible categories.
  • Another participant asks whether dark matter is visible to the eye and if it emits electromagnetic radiation in the visible spectrum.
  • A later reply asserts that dark matter does not emit radiation in any region of the electromagnetic spectrum, which is why it cannot be directly detected, and emphasizes that its existence is inferred from its gravitational effects on visible matter.
  • Another participant mentions gravitational lensing as a method to infer the existence and location of dark matter, reiterating that dark matter is classified as invisible matter, while visible matter includes planets, stars, and galaxies.

Areas of Agreement / Disagreement

Participants generally agree that dark matter is classified as invisible and does not emit electromagnetic radiation, but there are varying interpretations regarding its classification in relation to visible and invisible mass. The discussion remains unresolved regarding the implications of these classifications.

Contextual Notes

Participants express uncertainty about the definitions of visible and invisible mass and the implications of dark matter's invisibility on its classification. There are also references to indirect detection methods, which may depend on specific assumptions about gravitational effects.

hms.tech
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I think that there is mass associated with all dark matter in the universe and this mass is much greater than the total mass of the stars in a particular galaxy.

Now, if I were to classify the mass into two categories :
1. visible
2. invisible

How would I carry that out ?

Is dark matter invisible mass or would it be counted as visible mass ?
 
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let me rephrase that, is dark matter visible to the eye ?

Does it emit e.m radiation in the visible region of the spectrum ?
 
hms.tech said:
let me rephrase that, is dark matter visible to the eye ?

Does it emit e.m radiation in the visible region of the spectrum ?

"dark matter" does not emit radiation in the visible region or any other region of the EM spectrum...otherwise we would be able to detect it, and not just theorize its existence. the best evidence of the existence of dark matter is indirect - that is, we can't detect dark matter directly, but we can see its effects on ordinary matter. take spiral galaxies for instance - surely their inner regions orbit their respective galactic centers faster than their outer regions...and yet the outer regions still appear to orbit their respective galactic centers much faster than their detectable masses suggest. and so some scientists theorize that there is a substantial amount of "dark matter" in those outer regions (that cannot be seen by any ordinary means of detection) that provide the additional gravity necessary to account for the faster-than-predicted orbits of the outer regions of spiral galaxies about their respective galactic centers.

so your hypothesis that there is mass associated w/ dark matter is in line w/ dark matter theory, b/c even though it does not radiate anywhere in the EM spectrum, its gravitational effects can be detected.
 
The existence and location of dark matter can be inferred by gravitational lensing. It is one of the best ways we have to locate it but even then it's not easy. I do remember a team of astronomers created a map of the dark matter, if I find it ill link it. However dark matter is still classified as invisible matter in your question. Visible matter are things like planets, stars, galaxies, etc. Dark matter is its own form of matter and does have mass and it is predicted to be much larger than the mass of what we can see.
 

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