Dark Matter & Black Holes

[thedarkshade]

However, it is just as valid to ask "Why is the unit of mass so small compared to the unit of charge?"

Well I think that would be because there is no elementary mass, just like there is elementary charge ([math]1.60217646 \times 10^{-19} C[/math]), which is the charge of an electron. If we took the mass of the electron ([math]9.10938188 \times 10^{-31} kg[/math]) as the elementary mass, perhaps we could reach a sort of balance between the two.

[Riogho]

Except the charge of an electron is not an elementary charge.

[thedarkshade]

Except the charge of an electron is not an elementary charge.

Care to share a link?

[ydoaPs]

shade, do you know the charges of quarks?

[thedarkshade]

shade, do you know the charges of quarks?

Yes, I do, and I understand what your point is. But in many many textbooks I have come across the term elementary charge and it's value is the charge carried by an electron (a proton too), so I see no reason of ignoring it.

[Severian]

shade, do you know the charges of quarks?

 

I don't see what that has to do with his point, unless you are trying to claim that electrons are made of quarks.

 

It is an interesting mystery why the neutron is actually neutral. Why are quark charges in units of e/3? No-one knows..

[Mr Skeptic]

Going back to the dark matter/black hole issue, even if dark matter is unable to condense to form a black hole, it should still be able to be sucked into an already existing black hole.

[Klaynos]

Going back to the dark matter/black hole issue, even if dark matter is unable to condense to form a black hole, it should still be able to be sucked into an already existing black hole.

 

About as much as being sucked into a star, yep....

[swansont]

Going back to the dark matter/black hole issue, even if dark matter is unable to condense to form a black hole, it should still be able to be sucked into an already existing black hole.

 

If it isn't already gravitationally bound, how would it become so?

[Mr Skeptic]

If it isn't already gravitationally bound, how would it become so?

 

Gravitational interactions with nearby stars or planets might change their orbits. Also, how likely is dark matter to bump into itself? I'm thinking of the dark matter as behaving kind of like permanently hot gas, that can't cool and is very unlikely to bump into anything. Or like orbiting dust that again can't bump into much of anything. I was thinking that if it tends to spread out too easily to form a large body or black hole, then a significant portion would tend to spread out enough to reach a black hole. Though it would probably have to go almost straight at the event horizon for it to go in.

 

Or maybe I have no clue what I'm talking about.

[ydoaPs]

I don't see what that has to do with his point, unless you are trying to claim that electrons are made of quarks.

I was merely giving an example of something with a charge which is not a multiple of e. I thought you said you had me on ignore, anyway!

[Riogho]

Yes, I do, and I understand what your point is. But in many many textbooks I have come across the term elementary charge and it's value is the charge carried by an electron (a proton too), so I see no reason of ignoring it.

 

We don't feel like rewriting the text books and giving the quark a charge of 1, and -1, and making an electron three. It's that simple. But it isn't the quanta of charge.

[timo]

I'm not convinced that it's that simple (e.g. as soon as you go to electroweak theory the electric charge is just a composite of two other "more fundamental" charges, the weak isospin and the weak hypercharge). The elementary (electric) charge is currently defined as the charge of the electron (or position? not exactly sure). If a textbook sais so, then it's not because it was outdated - it's still the working definition of the term.

[Riogho]

So you're saying that charge itself is a property that is composed of two other properties?

 

Like density being a property of mass and volume?

[halogirl]

As YDOAP pointed out, the term "weak" is relative. It is weak enough to be overcome by magnetism and other forces, so it is relative to those that we say it's not as potent (or, weaker).

 

The primary reason that we remain on the surface of Earth and don't just float into space, and why the Earth orbits the sun instead of drifting off into the vacuum is due to the differences in mass involved. Relative to us, the earth is Ginormous, and relative to the earth the sun is HUGE. This is why the gravitational pull of the earth on us, and of the sun on the earth, are so meaningful. Regardless of their size, however, gravitation itself is still no match for the the strong, weak, and electromagnetic forces.

 

 

 

i understand how that works, but it is still all kept in balance by gravity, mass and velocity(I think i'm forgetting one) Its kept in balance by gravity and it still doesn't answer my question,

" does everything give off gravity waves?"

[timo]

So you're saying that charge itself is a property that is composed of two other properties?

Depends on the physics you are doing/using. But as soon as you seriously bother about quarks chances are that you are doing QCD or Standard Model physics. The former case has no electric charge, in the latter the electric charge is indeed modelled via two other charges. Not exactly on-topic, though.

Like density being a property of mass and volume?

No, I don't think that's going to serve as an analogy. It's more like a coordinate transformation.

[Cmac22]

" does everything give off gravity waves?"

 

Im not sure but i believe gravitational waves have to do with acceleration specifically. if an object is changing speeds or direction, hence exceleration, it will give off gravitational waves...for the most part. this is just from my reading from wiki so i could deffinatly be wrong but i suppose it is worth a look... it seemed to be reasonable

http://en.wikipedia.org/wiki/Gravitational_wave

 

But back to the original...or general theme i suppose... so...dark matter doesnt iteract at all with regular matter besides gravitationaly? i mean its hard to say because its unknown what dark matter is i guess. i think that dark matter would fall into black holes more often then it does stars, if its even possible. but for a black hole, or supermasive, that is growing in size, wouldnt it expand to consume the dark matter, rather than the dark matter falling into it? . then again i dont know much about dark matter...

 

but i feel that there is probably a connection between dark matter and black holes.

[halogirl]

in all probability...and beware wikipedia it lies, but thanks anyway. i too am merely a biology nerd doomed to ask questions about physics forever. ;]

[Graviphoton]

Why doesn't dark matter collapse into a black hole? There's supposed to be these huge disks of dark matter in galaxies that only interact gravitationally -- so what prevents them from collapsing since gravity is only attractive?

 

Well, i don't know what you guys are talking about, cuz i haven't read the thread , but i will answer the OP as i normally would

 

Dark matter, has the same gravitational attributes as it would with different and variating magnitudes of gravitational mass, making them fluctuations.

 

Only thing is though, some of these wil have a negative mass. But lets leave that for there.

 

Depending upon the systems density and also based upon its environment, you will find environments that will suit gravitational collapse, and others that don't. This means that any outcome needs to be dual invariant. Therefore, there is a local density and non-local density determining its local state.

 

Therego, there will be some superdense clouds of dark matter that won't collapse due to a certain value of gravity, whilst others do. These are natures of the universe.

[Klaynos]

Only thing is though, some of these wil have a negative mass. But lets leave that for there.

 

Citations please.

 

Oh and also read the above comments about friction.

[Calabi-Yau]

:confused

 

 

 

 

also feel free to correct me. im a biology geek, not physics.:}

 

well done for entering this conversation. physics, along with mathematics is the fundamental science, and extremely enjoyable as it has the capacity to allow one to understand all sciences, and allows one to understand the universe fully, more completely

[halogirl]

thank you. i completely agree, although i doubt any of us shall ever truly understan the ways of the universe, as much as we would love to.

[thedarkshade]

thank you. i completely agree, although i doubt any of us shall ever truly understan the ways of the universe, as much as we would love to.

That is the good part of it. What would there be interesting in life (for physicist and curious people) if we knew how everything worked?! This is perhaps the best gift mankind can offer theirselves.

[halogirl]

indeed, it really is great.