Black Holes: Questions from a Non-Scientist

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Discussion Overview

This discussion revolves around various questions and concepts related to black holes, particularly focusing on their magnetic fields, interactions with dark matter and dark energy, and the growth of black holes. The scope includes theoretical inquiries and conceptual clarifications, with a participant expressing a desire to understand these complex topics better.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant inquires about the size of the magnetic field around a supermassive black hole, questioning whether it extends beyond the Earth's orbit or even beyond the galaxy.
  • Another participant explains that magnetic fields weaken with distance and suggests that the magnetic field of the Milky Way's central black hole is negligible at the distance of the solar system.
  • There is a discussion about the interaction of black holes with dark matter and dark energy, with some participants asserting that these forms of matter do not interact with magnetic fields in a relevant way.
  • Questions arise regarding the measurement of a black hole's size, with one participant noting that the Schwarzschild radius grows linearly with mass, while others discuss the implications of this on volume measurements.
  • Participants express uncertainty about the existence of gases entering the galaxy from unknown sources, with one participant seeking clarification on this point.
  • There is a debate about the characteristics of dark matter and dark energy, with some participants asserting that dark matter does not interact with normal matter except through gravity, while others suggest it could interact via weak forces.

Areas of Agreement / Disagreement

Participants express differing views on the nature of dark matter and dark energy, particularly regarding their interactions with magnetic fields and their effects on black holes. The discussion remains unresolved, with no consensus on several key points.

Contextual Notes

Participants highlight limitations in understanding dark matter and dark energy, noting that while their effects are well understood, their fundamental nature remains largely unknown. There are also unresolved questions about the measurement of black holes and the sources of gases entering the galaxy.

Who May Find This Useful

This discussion may be of interest to individuals curious about astrophysics, particularly those exploring the nature of black holes, magnetic fields, and the roles of dark matter and dark energy in the universe.

orionis
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Hello, my name is Bjørnar Bergetun I am somewhat new here, I've created a few posts during my stay but i tend to get warned off for not being able to scientifically formulate my questions.
im no scientist, i lack math in school and have a job where i work with my hands but I've been thinking a lot about black holes these last few months and have made a list i hope i can place here for someone to take a look at.
help me get a better understanding about the nature of the black hole so to speak.

here are my questions:

1: What is the size of the magnetic field around a black hole the mass of the one in the center of the Milky Way galaxy? is it big enough to go outside the orbit the Earth is in? bigger then the galaxy?

2: If you put 2 magnets with opposing fields against each other the smaller magnet will be pushed away by the magnetic fields interacting. could in theory the black hole's magnetic field be moving the black hole by outside forces like for instance black energy/matter pushing on the magnetic field? could this cause direction change or accelleration of a galaxy?

*3 I've read that the size of a black hole grows 8 times more then the size of the input inserted into it. is this true?

*4: I've also read that there are gasses coming into the galaxy from outside from the north and south position of the center from sources unknown. is this also true?

* Sources for question 3 and 4 cannot be found, i have been searching the internet but in hindsight i think it is from a science magazine called "illustrated science" sold in norway.

i have more questions but would like to see some kind of response to these before asking more.
like i said, I am no scientist but would apreciate it a lot if you guys and gals could help me figure this out because its starting to take up a lot of the idle time in my brain.
 
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Magnetic fields do not have a fixed size. With increasing distance, they just become weaker and weaker. For the black hole at the center of our galaxy, the magnetic field at the distance of (earth<->sun) is still quite strong. At the distance of our sun to the galactic center it is completely negligible.

orionis said:
2: If you put 2 magnets with opposing fields against each other the smaller magnet will be pushed away by the magnetic fields interacting.
That depends on the positions and orientations of all magnets relative to each other.

There is no "black energy/matter". I guess you mean dark matter and dark energy. Both do not interact with magnetic fields (or at least not in a relevant way). And even if they would, this would not move galaxies around.

orionis said:
*3 I've read that the size of a black hole grows 8 times more then the size of the input inserted into it. is this true?
How do you measure size? Black holes distort spacetime so much the classical concept of a volume does not make sense inside. Their Schwarzschild radius (which is a measure of their size) grows linearly with mass, so anything volume-like would grow with the third power of mass, yes.
orionis said:
*4: I've also read that there are gasses coming into the galaxy from outside from the north and south position of the center from sources unknown. is this also true?
Hard to tell without a source.
 
mfb said:
Magnetic fields do not have a fixed size. With increasing distance, they just become weaker and weaker. For the black hole at the center of our galaxy, the magnetic field at the distance of (earth<->sun) is still quite strong. At the distance of our sun to the galactic center it is completely negligible.
Does that mean it indeed stretches as far as the position of our solar system?
mfb said:
There is no "black energy/matter". I guess you mean dark matter and dark energy. Both do not interact with magnetic fields (or at least not in a relevant way). And even if they would, this would not move galaxies around.

i do mean dark matter and energy. not black. I am sorry.
how can you know this though? i was under the impression we knew almost nothing about dark energy and matter besides the fact that there is a lot more of it in the universe then normal matter. dark energy in particular has a bigger presence in the universe then dark matter and normal matter combined.
how do you know that magnet fields do not interact with it? in this way or any other way?
 
orionis said:
Does that mean it indeed stretches as far as the position of our solar system?

i do mean dark matter and energy. not black. I am sorry.
how can you know this though? i was under the impression we knew almost nothing about dark energy and matter besides the fact that there is a lot more of it in the universe then normal matter. dark energy in particular has a bigger presence in the universe then dark matter and normal matter combined.
how do you know that magnet fields do not interact with it? in this way or any other way?
Dark energy and dark matter have unknown sources / reasons for existence, BUT ... they have very well understood effects. That is, we don't know what they are or how they came to be but we know a lot about their characteristics.

Dark energy has NOTHING to do with magnetism. That would be like saying that the energy you exert by lifting a grapefruit is effected by magnetism. It is not.

Dark matter is, as the name suggests, believed to be a form of matter BUT ... it does not interact with normal matter except due to gravity. Magnetism is not gravity.
 
orionis said:
Does that mean it indeed stretches as far as the position of our solar system?
In the same way the gravitational field of a stone next to me stretches throughout the whole galaxy: completely negligible.
orionis said:
how can you know this though?
If dark matter would interact with magnetic fields, it would have a charge, and then it would not be dark. The fact that it is "dark" tells us a lot about it.
Dark energy is something completely different anyway.

phinds said:
Dark matter is, as the name suggests, believed to be a form of matter BUT ... it does not interact with normal matter except due to gravity. Magnetism is not gravity.
It could interact via the weak interaction. Nearly all searches for dark matter look for processes of the weak interaction.
 

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