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Author Topic: What doesnt science understand about a galaxy?  (Read 2084 times)

Offline acecharly

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What doesnt science understand about a galaxy?
« on: 04/04/2012 09:40:45 »
I have an idea surounding what a black hole is and im looking for things with regards to galaxies that dont add up such as the percieved need for dark matter to account for the galaxy not flying apart and galactical rotation being at odds with how the planets orbit our sun or the relationship between the size of a black hole and the mass within its galaxy....what other things cannot currently be explained?

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Ace


 

Offline Soul Surfer

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Re: What doesnt science understand about a galaxy?
« Reply #1 on: 04/04/2012 11:36:38 »
That question is unanswerable because it is totally open ended.  There is however one area that may produce interesting results.  Stars are very much electromagnetic structures and a lot of their effects, like sunspots and coronal mass ejections, are produced by collective electromagnetic turbulence.  We are just starting to understand about the existence of galactic electromagnetic fields.  They are very weak and are very difficult to detect but like gravity could have a significant effect on galactic structure shaping and controlling the shock waves that create visible structures like spiral arms.
 

Offline acecharly

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Re: What doesnt science understand about a galaxy?
« Reply #2 on: 04/04/2012 12:06:46 »
Thats interesting stuff I shall have to have a look into that. I see what you mean about it being an openended question it should have read more along the lines of what areas science currently find unexplainable.

Im asking the question because I was thinking about black holes when I woke this morning and i was wondering weather there is a possibility that were actually inside one or that what we think is around us is maybe like a projection as the space is warped almost inside out ...i find it odd that the mass in a galaxy is fairly proportional to the size of its black hole and so the projection would obviously be bigger aswell there would be no need for dark matter... any thoughts on this idea or does it make total nonsense?

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Ace
 

Offline acecharly

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Re: What doesnt science understand about a galaxy?
« Reply #3 on: 04/04/2012 12:31:56 »
just adding to this if dark matter accounts for 80-90% of the universe is there a similar relationship between the mass of the black hole in the center to the mass of the rest of the galaxy it is in?
 

Offline Ęthelwulf

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Re: What doesnt science understand about a galaxy?
« Reply #4 on: 04/04/2012 12:47:32 »
just adding to this if dark matter accounts for 80-90% of the universe is there a similar relationship between the mass of the black hole in the center to the mass of the rest of the galaxy it is in?

Actually, Dark matter makes up something like 27% of all matter. We make up a small percentage of this... I forget the exact percentage, but it surely is no more than 3% or something like that. Then a very smaller percentage of this makes up free hydrogen, then dark energy makes up the rest.
 

Offline CliffordK

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Re: What doesnt science understand about a galaxy?
« Reply #5 on: 05/04/2012 02:07:46 »
One of the problems with Galaxies that isn't fully understood is how do spiral galaxies exist?

The problem is summarized here with the Density wave theory, with stars slipping into and out of the spiral arms. 

The problem is that the further one progresses from the center of rotation, the slower the object orbits. 

So, from our own solar system,
Mercury orbits the sun in 88 days.
Venus in 225 days.
Earth in 365 days.
Mars in just under 2 years.
Jupiter in 12 years.
Saturn in 29 years
Uranus in 84 years.
Neptune in 164 years
Pluto in 248 years.

If the planets were connected in a spiral, there would be a big problem with the different orbital speeds.

The current theory is that stars spend some time within the arm, then slip between arms.  But, perhaps other theories will come.
 

Offline MikeS

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Re: What doesnt science understand about a galaxy?
« Reply #6 on: 05/04/2012 07:29:39 »
CliffordK

Personally, I believe what holds galaxies together in a way that stops them from winding up is the differential gravitational gradient from center to outside.
This gravitational gradient is accompanied by a matching time dilation gradient.  In other words time passes much faster (locally) at the periphery.  This allows the periphery to rotate at a slower speed.

When viewed from a distance we are not aware that in its local time frame the periphery of the galaxy is rotating at a slower speed.  It appears to us that the galaxy should wind itself up and obliterate the spiral arms but it does not for the afore mentioned reason.

modify added.
One galaxy revolution per unit time is meaningless as the passage of time is not linear across the radius of the Galaxy.

Why then are the arms not straight but spiral?  This maybe probably is an effect of 'frame dragging'.

Going back to the original question it also shows that dark matter is not required to explain the above.
« Last Edit: 07/04/2012 08:39:19 by MikeS »
 

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Re: What doesnt science understand about a galaxy?
« Reply #6 on: 05/04/2012 07:29:39 »

 

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