How Can We Be Sure About Black Holes and Galaxies?

[dj1972]

Couple of questions here;
I know they may sound dumb but here they go. I'm "new" with some questions, so be gentle.

1.) So, if a black hole has enough gravitational pull to pull in stars and what nots, and nothing can pull away from this force once it is to close, its consumed by the black hole. Why can't anything orbit this black hole? I know stars, matter, gas and such orbit while its being consumed, but what prevents it from being in a orbit around the black hole?

2.) If the center of our galaxy is a super massive black hole, then why are we staying in orbit around it and not being consumed into the black hole? I would assume that stars and matter and gas are being pulled in when they are close enough towards the center, but as an effect would that not be pulling in the rest of the galaxy into itself? I'm assuming galaxies can and do expand over time, how can one not effect the other? (If the black hole is consuming, how can we be expanding?)

 

[DaveC426913]

Stuff does orbit a black hole. But, just like a collapsing protostellar disc, there is an amount of accretion where friction and pressure cause the orbits of much of the inner matter to decay.

 

[v2kkim]

I agree to Dave. If an object moves to the black hole exact head-on then it will collide matters around orbiting. If the object does not go head-on then it will move in an orbit like ellipic which could be stable until there is disturbance. Actually some stars orbit a black hole very fast, and astronomers can observe the oscillation of the red shift (forward and backword),-- which is interesting to me considering the massive black hole mass and the extremely fast speed of the orbiting star.

 

[DaleSwanson]

Black holes have the same gravitational pull as any other object of the same mass. If the Sun was collapsed into a black hole Earth's orbit wouldn't change. The weird stuff only happens when you start to get closer to the center of gravity than you would have been able to before (since you'd hit the surface, and then part of the mass would be behind you).

 

[dj1972]

That's interesting. I always believed that a black hole had more gravitational effect then that. So its really no more then obviously the collapsed layers and core of a sun that is exposed, then I'm assuming it slowly turns into a singularity. I thought that a black hole was more powerful then that, I always imagined it would say like eat up our solar system if our sun collapsed and became one. So is it likely to think that this is how galaxies are formed if they have a black hole in the center? This is some pretty neat stuff. I kinda like it.

 

[DaveC426913]

That's interesting. I always believed that a black hole had more gravitational effect then that.

Oh. You hadn't mentioned you thought this or I would have corrected you. It's probably the single most common misconception about BHs.

Yes, there's nothing special about a BH in terms of its mass or its gravity. The only thing special about a BH is that you can get very close to it. If our sun collapsed into a BH, Earth would not change its orbit.

However, BHs do not from from stars smaller than 1.5 solar masses, and they do tend to accumulate mass, so that's why there's so much talk about massive BHs gobbling up stars.

 

[Chalnoth]

Couple of questions here;
I know they may sound dumb but here they go. I'm "new" with some questions, so be gentle.

1.) So, if a black hole has enough gravitational pull to pull in stars and what nots, and nothing can pull away from this force once it is to close, its consumed by the black hole. Why can't anything orbit this black hole? I know stars, matter, gas and such orbit while its being consumed, but what prevents it from being in a orbit around the black hole?

Far away from a black hole, its gravitational field is like that of any other object with the same mass. If, for example, our Sun were replaced by a black hole of equal mass, there would be no difference as far as the orbits of solar system objects are concerned.

However, if you get very close to a black hole, it turns out that there are no stable orbits, and anything in orbit inside that distance will rather quickly fall into the black hole.

2.) If the center of our galaxy is a super massive black hole, then why are we staying in orbit around it and not being consumed into the black hole? I would assume that stars and matter and gas are being pulled in when they are close enough towards the center, but as an effect would that not be pulling in the rest of the galaxy into itself? I'm assuming galaxies can and do expand over time, how can one not effect the other? (If the black hole is consuming, how can we be expanding?)

The supermassive black hole at the center of our galaxy is only a tiny fraction of a percent of the mass of the stars in our galaxy. The mass of this black hole is a few million solar masses, while there are around 400 billion stars in our galaxy. And yet from the movements of these stars we know that the stars themselves are not orbiting one another, but are instead mostly orbiting the unseen dark matter that exists within our galaxy.

And galaxies don't expand over time. They're quite stable.

 

[v2kkim]

In our galaxy case, the size of black hole is several light hours, so anything approaching closer than that will be sucked in completely including photons. This size looks quite small in star-to-star distance scale. This size is called event horizon, and a little bit outside of it there can be photon(light)s orbiting -- kind of captured.

 

[dj1972]

I'm sorry DaveC426913, mostly what I know is from what I read. And I fill in the gaps to make sense to myself. So this is mostly from my speculations because mostly what I read they leave gaps all over the place with no real explanation. Sorry, I should have said that. That's why some of my questions sound stupid. These are my thoughts from what I read, I am just trying to clarify what I don't know. LOL

And to Chalnoth, our galaxies don't expand? We stay the same size constantly? So if we don't expand, how did we become this size? I would "Assume" were expanding because if we started from a orbit from around a black hole per say, with stars and gases and debris orbiting we had to expand to become the size we are. So if another galaxy merges with ours (Hopefully much smaller) we wouldn't expand to accommodate the extra mass or volume?

To v2kkim, Photons (Light) are orbiting the black holes in such cases like our galaxy, which is why when you view the center of galaxies it is bright. So bright it actually lights up the center which is the black hole but can't see it because of the dust and gases and debris in the way right, you just see a big blob of brightness? In some cases I have actually seen in pictures a bar shape in the center of galaxies. In another thread I was talking in, I said something to the effect that if two black holes came together, (My assumption) they would possibly orbit each other and not consume one another. I thought in my mind that they would have a tight knit orbit, (And by orbit I don't mean in a circular fashion, more of an elliptical) which in my mind I can see the bar shape appearing in the center of the galaxy. Maybe not from one or two of these but from several orbiting tightly. Again my speculation. See what happens when you read articles but have no clue. LOL

 

[Chalnoth]

And to Chalnoth, our galaxies don't expand? We stay the same size constantly? So if we don't expand, how did we become this size?

What happens is that galaxies collide with one another to make bigger galaxies. Our own Milky Way galaxy is currently undergoing collisions with two dwarf galaxies, the large and small Magellanic clouds. In a few billion years, it will undergo a collision with Andromeda, which is approximately the same size as our galaxy, a collision which will disrupt our spiral and produce a new, larger galaxy from the merger.

I would "Assume" were expanding because if we started from a orbit from around a black hole per say, with stars and gases and debris orbiting we had to expand to become the size we are. So if another galaxy merges with ours (Hopefully much smaller) we wouldn't expand to accommodate the extra mass or volume?

This isn't an expansion.

 

[DaveC426913]

I'm sorry DaveC426913, mostly what I know is from what I read. And I fill in the gaps to make sense to myself. So this is mostly from my speculations because mostly what I read they leave gaps all over the place with no real explanation. Sorry, I should have said that. That's why some of my questions sound stupid. These are my thoughts from what I read, I am just trying to clarify what I don't know. LOL

I hope I didn't sound like I thought your questions were stupid!

And to Chalnoth, our galaxies don't expand? We stay the same size constantly? So if we don't expand, how did we become this size? I would "Assume" were expanding because if we started from a orbit from around a black hole per say, with stars and gases and debris orbiting we had to expand to become the size we are. So if another galaxy merges with ours (Hopefully much smaller) we wouldn't expand to accommodate the extra mass or volume?

Galaxies don't expand, they contract. They start as a giant collection of dust and gas that come together under gravity, concentrating in the centre, in the same way our solar system was formed. THe BH came after (or at least as) the galaxy was formed, or so is the prevailing opinion. THe BH is not the cause of the galaxy formation, it is the consequence of galaxy formation.

To v2kkim, Photons (Light) are orbiting the black holes in such cases like our galaxy, which is why when you view the center of galaxies it is bright. So bright it actually lights up the center which is the black hole but can't see it because of the dust and gases and debris in the way right, you just see a big blob of brightness?

Photons don't orbit BHs. (BTW, note the logic here: if photons were orbiting a BH, we would never see them, would we? They'd have to reach us.)

The brightness at the centre of our galaxy is, in fact, due to the high density of stars in the core of the galaxy; it is so packed with stars that it appears just one giant blob of light.

Nearer the BH, it's bit different. Infalling gas and dust (and even stars) form a disk of very hot, dense matter, which radiates its energy across the EM spectrum. Very close to the BH, the in-falling matter actually emits X-radiation as it falls. It's this X-radiation that is characteristic of BHs and that's what we detect to determine that we think we've spotted one.

In some cases I have actually seen in pictures a bar shape in the center of galaxies. In another thread I was talking in, I said something to the effect that if two black holes came together, (My assumption) they would possibly orbit each other and not consume one another. I thought in my mind that they would have a tight knit orbit, (And by orbit I don't mean in a circular fashion, more of an elliptical) which in my mind I can see the bar shape appearing in the center of the galaxy. Maybe not from one or two of these but from several orbiting ticghtly. Again my speculation. See what happens when ou read articles but have no clue. LOL

The bar is simply another effect of the pressure waves that cause the galactic arms, which are just like the radial waves you see in water spiraling down the drain.

 

[Chalnoth]

Galaxies don't expand, they contract. They start as a giant collection of dust and gas that come together under gravity, concentrating in the centre, in the same way our solar system was formed. THe BH came after (or at least as) the galaxy was formed, or so is the prevailing opinion. THe BH is not the cause of the galaxy formation, it is the consequence of galaxy formation.

Well, except that gravitational orbits are stable. The only way for galaxies to contract is for the stuff that makes them up to lose their orbital energy, which comes about through friction (for large objects) and through radiative cooling (for gas).

 

[Nabeshin]

The only way for galaxies to contract is for the stuff that makes them up to lose their orbital energy, which comes about through friction (for large objects) and through radiative cooling (for gas).

Which happens. So galaxies over time contract (ignoring galactic collisions).

 

[Chalnoth]

Which happens. So galaxies over time contract (ignoring galactic collisions).

True. But I like to point out that it isn't gravity that makes them do so: gravitational orbits are quite stable unless perturbed by external objects. It's the loss of energy through other means that causes this contraction.

 

[dj1972]

No DaveC426913, that's not what I think, Its just my ignorance in this field against your experience. This is how I learn and I have learned a lot thanks to all of you. And as far as photons rotating around the black hole that makes sense. Gees why don't I think that far ahead before I write something? LOL
OK, I think I get it now? So let's create a mess. Clouds of gas and debris and what nots starts to billow in the middle of nowhere. (Isnt this a nebula? And isn't a nebula an exploding star?) Well, in the center of this mess starts a so called galaxy we'll call dj020709 (LOL I made it so I can name it whatever) Stars are forming towards the center from these clouds of gas and debri and what nots from collapses of gas and gravity and friction packing itself into a ball of huge gas. (I know its more technical then this but hey) Well they start to orbit each other or whatever and over a few billion years one explodes. A massive one. Let's say over 10 SM. And wah lah a large BH is formed, starts to eat up stuff and at the same time more stars are being formed just packing the center because its the best place to get stars because of all the gases and debri and such, they want to be where the action is. Now that is a pretty far out there. I know its more technical then that. But that is the best my brain can come up with.

 

[v2kkim]

I hope I didn't sound like I thought your questions were stupid!


Galaxies don't expand, they contract. They start as a giant collection of dust and gas that come together under gravity, concentrating in the centre, in the same way our solar system was formed. THe BH came after (or at least as) the galaxy was formed, or so is the prevailing opinion. THe BH is not the cause of the galaxy formation, it is the consequence of galaxy formation.


Photons don't orbit BHs. (BTW, note the logic here: if photons were orbiting a BH, we would never see them, would we? They'd have to reach us.)

The brightness at the centre of our galaxy is, in fact, due to the high density of stars in the core of the galaxy; it is so packed with stars that it appears just one giant blob of light.

The bar is simply another effect of the pressure waves that cause the galactic arms, which are just like the radial waves you see in water spiraling down the drain.

Regarding the bright bar in our Galaxy Dave is right. we are looking at our galaxy from side not top view. But some photons can orbit BH though unstable. Remember that the space time is so greatly bent near BH that the light can make a circular orbit, which also can be considered as an extreme case of gravitational lensing, but these photons does not have strong density and maybe theoretical calculation so far.
By the way, I do not understand what causes our galaxy contract ? due to gas and material collision etc ?

 

[Nabeshin]

Regarding the bright bar in our Galaxy Dave is right. we are looking at our galaxy from side not top view. But some photons can orbit BH though unstable. Remember that the space time is so greatly bent near BH that the light can make a circular orbit, which also can be considered as an extreme case of gravitational lensing, but these photons does not have strong density and maybe theoretical calculation so far.
By the way, I do not understand what causes our galaxy contract ? due to gas and material collision etc ?

Yes, energy loss due to heating of gasses and collisions. Also, because of the simply massive amount of stars orbiting, the perturbations introduced by random close encounters tends to destabilize the orbits over time.

So let's create a mess. Clouds of gas and debris and what nots starts to billow in the middle of nowhere. (Isnt this a nebula? And isn't a nebula an exploding star?) Well, in the center of this mess starts a so called galaxy we'll call dj020709 (LOL I made it so I can name it whatever) Stars are forming towards the center from these clouds of gas and debri and what nots from collapses of gas and gravity and friction packing itself into a ball of huge gas. (I know its more technical then this but hey) Well they start to orbit each other or whatever and over a few billion years one explodes. A massive one. Let's say over 10 SM. And wah lah a large BH is formed, starts to eat up stuff and at the same time more stars are being formed just packing the center because its the best place to get stars because of all the gases and debri and such, they want to be where the action is.

There are a few things that would work to make this model not as simple as you've stated. Yes, stars would form towards the center of this dense cloud of gas and dust, but solar wind usually clears out the surrounding disk of material relatively soon. So, for all intents and purposes, the stellar systems (be they lone, binary, etc.) are essentially alone in their local neighborhoods, even in areas of relatively "high" density. The most that happens when one turns into a black hole is it begins to accrete matter from its companion star. It will not gobble up everything in the nucleus, for as we have said, it behaves (gravitationally, and non-locally) exactly the same as a star on the grand scale of things. And stars almost never collide or interact on more than light year scales.

 

[dj1972]

Well, like I said. I know its more technical then what I stated. (on the other hand I don't need to know how many solar masses something has to be before it can do something else or a bunch of crazy math to have a simple understanding of it.) But I put it into terms I can understand. Remember, I'm not a cosmologist, so I need to make it easy. I'm trying to imagine how this is all coming together as I go. But you were definitely helpful with a clear explanation. Thank you.

So another question, you stated "And stars almost never collide or interact on more than light year scales". I am also assuming your saying it happens, just not very often. So is there someplace I can go and see a picture if there is one cause I think that would be neat to see. So what would happen to these stars if that were to happen? Would they merge, explode? If they merge, what happens to the cores, do they merge as well? I can't even imagine what that would be like.

 

[v2kkim]

http://www.haydenplanetarium.org/resources/ava/stars/S0606neutcoll"
http://www.universetoday.com/2004/04/22/wallpaper-galaxy-with-a-ring-of-star-formation/"
I found 2 web sites. The first is a simulation of the star collision. I know to see is to believe but stars are too far away so I am not sure we can see collision details at all.
The second one is the actual photo but of galaxy collision, where we see the attacked galaxy forms a ring and and generating many young stars.

 

[DaveC426913]

The second one is the actual photo but of galaxy collision, where we see the attacked galaxy forms a ring and and generating many young stars.

Yes, although even in collisions of galaxies, there is little collision of stars. They gravitationally interact, forming huge shockwaves and walls of gas and dust, and star-forming regions - but the stars don't so much physically interact.

 

[Nabeshin]

http://www.haydenplanetarium.org/resources/ava/stars/S0606neutcoll"
http://www.universetoday.com/2004/04/22/wallpaper-galaxy-with-a-ring-of-star-formation/"
I found 2 web sites. The first is a simulation of the star collision. I know to see is to believe but stars are too far away so I am not sure we can see collision details at all.
The second one is the actual photo but of galaxy collision, where we see the attacked galaxy forms a ring and and generating many young stars.

That simulation is pretty cool, v2kkim, thanks for that!

Also, I only say almost never because it is technically possible for them to collide (of course) but has never been observed and likely never will be. The nature of star formation and galactic motion, not to mention the vastness of space between stars. Here's an example to illustrate how rare the event would be:

A typical star such as our sun has a radius of about 10^9 meters. The distance to the nearest stars is on the order of 5 light years, or about 10^16 meters. Imagine the sun to be a pea (radius of roughly .01m), then the nearest star is 100,000m (100km) away. This gives you an idea of the absolute improbability of two peas 100km away from each other colliding.

 

[dj1972]

WOW thanks for sharing that v2kkim, that is so cool.

And one would think that if two galaxies collide, stars would collide. But they don't or almost never do no matter how catastrophic. That is really interesting. So if one is to think that if let's say Andromeda collides with our galaxy in a few billion years, our sun and or solar system would still be here. Not necessarily us cause of shock waves and debris and such would more then likely wipe out life form and the solar system would probably be pushed in further or pushed out further in the spirals from the merger or passing of the two? That would be cool to see that, your whole life waking up like nothing from the norm to look in the sky and see another galaxy approach. OK that's a little far fetched but I am going with it. LOL

And Nabeshin, that puts a lot into perspective when you state it like that.

 

[scupydog]

Do you think that the human race will still be around in a few billion years?

 

[Chalnoth]

Do you think that the human race will still be around in a few billion years?

It's certainly a possibility. Of course, I don't think we'd be human any longer, but it is entirely possible that some of our descendants will survive that long.

 

[dj1972]

I did say that is far fetched. And who knows, why couldn't we be here.

OK DaveC426913, you got me curious again! LOL You stated that "They gravitationally interact," can you explain that a little more. I'm guessing your trying to say because of the massive gravitation between all of these, instead of them physically interacting they react this way because of immense gravitation between them? Which in turn is keeping them separated through shockwaves and debris and such? Doesn't that kind of go against what gravitation does or is this phenomenon (Massive shockwaves and such) reacting against gravitation to make it do something totally different? Or am I thinking of gravitation wrongly?

Wow, I learned a lot about BH and galaxies and space itself. Thanks guys.

 

[Chalnoth]

I did say that is far fetched. And who knows, why couldn't we be here.

OK DaveC426913, you got me curious again! LOL You stated that "They gravitationally interact," can you explain that a little more. I'm guessing your trying to say because of the massive gravitation between all of these, instead of them physically interacting they react this way because of immense gravitation between them? Which in turn is keeping them separated through shockwaves and debris and such? Doesn't that kind of go against what gravitation does or is this phenomenon (Massive shockwaves and such) reacting against gravitation to make it do something totally different? Or am I thinking of gravitation wrongly?

Wow, I learned a lot about BH and galaxies and space itself. Thanks guys.

"Gravitational interaction" just means that the primary means of interaction is through the gravitational force, as opposed to, say, through the electromagnetic force through direct collisions.

 

[DaveC426913]

"Gravitational interaction" just means that the primary means of interaction is through the gravitational force, as opposed to, say, through the electromagnetic force through direct collisions.

Yes, that's what I'm saying. When galaxies "collide", the stars don't physically collide. Though the dust and gas does.

 

[dj1972]

Hmmm, that makes sense. So like what "v2kkim" posted up above, when the galaxies do "collide", it will and does make new stars, I am assuming this would be from the gas and dust "colliding" (friction and gravity and more) as the two galaxies are merging or passing through one another? Which in my mind makes sense because it is friction and gravity and what nots creating more stars from the excess gas and dust disruption.

So to clarify "colliding" its not like per say two dust particles bumping into one another and gas mingling, this is grand scale such as dust or debris is hitting dust or debris with such force its actually merging with one another forming bigger dust particles and gas is getting compressed with the dust or debris to form even bigger particles and eventually stars. (I know, more then that) Am I at least on the right trail here or no?
The reason why I am trying to get this straight is this, if one is to think about this, if there is to much force, then why don't it just burn up or vaporize. To much friction and other things, that's a lot of heat and force for something to collide and not obliterate itself or vaporize upon impact no matter how small. I really couldn't tell you how fast galaxies are moving when they collide. So I guess I am kind lost there.

 

[v2kkim]

dj... let me try to explain in conjunction with the black hole case. I do not want to deviate from our main topic.
In black hole, a lot of materials can orbit at closer distance from the BH center, called horizon of event, and they are quite violent because they move extremely fast colliding each other emitting light, where if the material got momentum toward the center then it got sucked in (no return). These orbiting materials are very hot but they still stay there because there is a binding force which is the strong BH gravitation. Similarly when gases got heated by friction etc in star formation beginning, they can not escape well because of the gravity pool. The gases feel the total sum of the big gravity of the gas collection which could be as large as our sun. So if the gas density and amount involved is not high enough, then the high temp gases will escape so no star formation.

 

[dj1972]

Thanks v2kkim. Your not deviating as far as I am concerned, it is the subject of both galaxies and BH. You guys are like walking encyclopaedias on this stuff and it just fascinates me beyond belief. I would like to thank everyone for trying to help me understand more of this and you have. I know its probably easier for you guys just to through up a math equation in most cases, but I am trying to keep it simple. I deviated many years ago away from this subject cause of the complicated math behind it. But as long as it remains simple or fairly simple, I am interested. You guys have actually painted a fairly clear picture for me.

So another one for you guys regarding a BH. I think I seen some where's, may have been in here, that when a star collapses, the core collapses down to about 12 - 15 Km. So, when it collapses further down, I think its a "singularity", about the size of the head of a needle, is the gravitational pull the same as before the collapse or does it decrease as well. I'd say it decreases to, but nothing seems to be apparent out there? Any insight on that?

 

[DaveC426913]

So, when it collapses further down, I think its a "singularity", about the size of the head of a needle, is the gravitational pull the same as before the collapse or does it decrease as well. I'd say it decreases to, but nothing seems to be apparent out there? Any insight on that?

Simply put, if the mass hasn't changed (which it hasn't), the gravity won't change.

 

[dj1972]

WOW, that would definitely part your hair! So when they say a teaspoon full of matter would weigh something like 40 billion tons, there serious. That is almost incomprehensible! But seriously cool.

 

[DaveC426913]

WOW, that would definitely part your hair! So when they say a teaspoon full of matter would weigh something like 40 billion tons, there serious. That is almost incomprehensible! But seriously cool.

Yep.

In theory of course...

It's that dense because it's under huge pressure. If you literally extracted a teaspoon of it, it would explode like a bomb because of the release in pressure.

 

[dj1972]

Yeah, have to think theoretically. But still, that's some pretty wicked stuff.
So if it starts out roughly around 12 - 15 km, how does it get to the size of a head of a needle? Its already compressed beyond belief, but to compress more... I know its massive pressure, and its getting broken down smaller and smaller, but if your not losing mass, how does it get to a little point like that? I know they release radiation and such, but wouldn't that be from the BH releasing trapped energy and not mass? Or is the energy coming from the mass breaking down creating the energy? But then it would be losing mass. So how do you get one without the other??

 

[Chalnoth]

Yeah, have to think theoretically. But still, that's some pretty wicked stuff.
So if it starts out roughly around 12 - 15 km, how does it get to the size of a head of a needle? Its already compressed beyond belief, but to compress more... I know its massive pressure, and its getting broken down smaller and smaller, but if your not losing mass, how does it get to a little point like that? I know they release radiation and such, but wouldn't that be from the BH releasing trapped energy and not mass? Or is the energy coming from the mass breaking down creating the energy? But then it would be losing mass. So how do you get one without the other??

Are we talking about neutron stars now? Well, under the gravity of the neutron star, the matter gets compressed to such extreme levels that the electrons and the protons combine to produce neutrons (neutrons are slightly higher energy states, but under high pressure scenarios, the energy balance shifts so that neutrons are preferred). And neutrons are much, much smaller than atoms, so the density becomes much higher. Bear in mind that atoms are mostly empty space, so without the electrostatic repulsion of the electron shell, they can be vastly more compact.

If instead you are talking about the degenerate matter that makes up white dwarfs, what's basically going on there is that the atoms are squeezed together so tightly that the quantum mechanical limit that prevents two electrons from being in the same state at the same time prevents them from being squeezed further.

 

[dj1972]

AHHHHHHHHH, that makes sense. Got ya. I knew there was an answer some where's.

OK, so let's back up a bit in time right as the sun starts to do all this. The sun goes through these phases where it loses it outer layers as in collapsing or exploding or what ever it does and the core is left. Right? (Trying to keep it simple, so if you need to be technical OK, let it fly) So why isn't the core being vaporized. Is this from the gravitational effect on itself? "I" would think from the initial explosion it would literally pull the core apart. Let's face it, that is very catastrophic. Or is it because the core expanded rapidly from the explosion then the core pulls itself back with so much force it is causing the initial collapse of the core to be so small then continues to get smaller from pressure? And if all of this is from gravitational effect, then I really don't want nothing to do with it! LOL I know these question might seem to be off the wall or not as technical as you may ask them, but I am not that advanced in the technical side of this. Sorry.

 

[Chalnoth]

Well, I'm not quite sure what you're talking about here, but when a star undergoes an explosive event, it does tend to throw out lots and lots of matter. However, it isn't able to throw out too much matter, as the self gravity is just so strong that there remains a significant portion that is unable to escape.

 

[Nabeshin]

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

This page should give you an idea of the mechanisms involved in the supernova process and why it is not always enough to prevent collapse into neutron stars or black holes.

 

[dj1972]

Sorry to confuse, had baby girl at same time. Totally thanks for the info Nabeshin, I'm reading it right now.

 

[ElectroBurger]

If instead you are talking about the degenerate matter that makes up white dwarfs, what's basically going on there is that the atoms are squeezed together so tightly that the quantum mechanical limit that prevents two electrons from being in the same state at the same time prevents them from being squeezed further.

It was in my understanding though that all matter, even neutrons obey the rules of degereracy and try to stay apart. Would this come to play in the big bang? Since all of the matter started out as the size of a single proton, was degeneracy what forced the matter ot of its starting position?

 

[DaveC426913]

It was in my understanding though that all matter, even neutrons obey the rules of degereracy and try to stay apart. Would this come to play in the big bang? Since all of the matter started out as the size of a single proton, was degeneracy what forced the matter ot of its starting position?

There were no atoms, or even protons at or even much later* than the BB. It was far, far too hot and energy-dense for any kind of matter. There was only energy.

* about 1 millisecond - an epoch in a BB timeline

 

[v2kkim]

Black hole has no volume but it affects other objects through gravitation, meaning that the gravitation field is so magical that it escapes through horizon of event and announces its existence to all other stars. My question is about electrostatic force. If the BH has some charge, say positively charged, then can we feel that from outside ? Can the electrostatic force can escape BH to reach outside ?

 

[Chalnoth]

It was in my understanding though that all matter, even neutrons obey the rules of degereracy and try to stay apart. Would this come to play in the big bang? Since all of the matter started out as the size of a single proton, was degeneracy what forced the matter ot of its starting position?

Not all matter. Only fermions. But yes, Neutron stars are supported by neutron degeneracy pressure in the same way that white dwarfs are supported by electron degeneracy pressure. It's just that the physics works out such that Neutron degeneracy pressure allows for denser matter (by a very significant amount).

Caveat: this is a rather simplistic view, and is understood not to be completely accurate. Apparently some regions within the neutron star are actually composed of a proton-electron superfluid that is at about the same density, and there may be other complexities. But the basic idea of why a neutron star is so dense can be understood just from neutron degeneracy pressure.

 

[dj1972]

OK I'm back, went did some reading. Everything I'm reading I'm assuming is mostly theory. Understood. So if this is all theory, how can we be certain this is right? I'm not trying to make anyone mad by stating this, I'm just being curious. (I meen come on, once upon a time we thought the Earth was flat, look where that got us) So what if its something totally different? Let's take for example, the sun. We haven't been there, not walk on it (Which would be totally cool) let alone touched any of it. We can only assume we know what is going on from the things that happen here on earth. So what if our data is wrong from what is really going on? I just read an article that they just realized that our galaxy is bigger then once believed. So again, if we haven't been outside of it looking back how can we really know? I know they plotted out where some stars are at. But wouldn't that be a small portion of what were looking at? I understand the deal with the red shift and all, but that isn't answering anything that is physically going on with galaxies and BH and super novas. I know this is probably where its going to get heavy in the math area. So if you have to let it fly. Again, I'M really intrigued by all this don't get me wrong and if I offend someone I'M sorry, I did not mean too.

 

[DaveC426913]

OK I'm back, went did some reading. Everything I'm reading I'm assuming is mostly theory. Understood. So if this is all theory, how can we be certain this is right? I'm not trying to make anyone mad by stating this, I'm just being curious. (I meen come on, once upon a time we thought the Earth was flat, look where that got us) So what if its something totally different? Let's take for example, the sun. We haven't been there, not walk on it (Which would be totally cool) let alone touched any of it. We can only assume we know what is going on from the things that happen here on earth. So what if our data is wrong from what is really going on? I just read an article that they just realized that our galaxy is bigger then once believed. So again, if we haven't been outside of it looking back how can we really know? I know they plotted out where some stars are at. But wouldn't that be a small portion of what were looking at? I understand the deal with the red shift and all, but that isn't answering anything that is physically going on with galaxies and BH and super novas. I know this is probably where its going to get heavy in the math area. So if you have to let it fly. Again, I'M really intrigued by all this don't get me wrong and if I offend someone I'M sorry, I did not mean too.

Science is based on building models that fit our observations. The model we've created does so.

Anyone, anywhere is free to create a different model based on a different theory to challenge it. But their model has to explain our observations at least as good as if not better than the generally-accepted model.

It is as easy as that.

And as hard as that.

Our current models explain what we see exquisitely well. So well in fact, that we can be pretty confident enough to extraploate into areas we're less sure about.

 

[Nabeshin]

OK I'm back, went did some reading. Everything I'm reading I'm assuming is mostly theory. Understood. So if this is all theory, how can we be certain this is right? I'm not trying to make anyone mad by stating this, I'm just being curious. (I meen come on, once upon a time we thought the Earth was flat, look where that got us) So what if its something totally different? Let's take for example, the sun. We haven't been there, not walk on it (Which would be totally cool) let alone touched any of it. We can only assume we know what is going on from the things that happen here on earth. So what if our data is wrong from what is really going on? I just read an article that they just realized that our galaxy is bigger then once believed. So again, if we haven't been outside of it looking back how can we really know? I know they plotted out where some stars are at. But wouldn't that be a small portion of what were looking at? I understand the deal with the red shift and all, but that isn't answering anything that is physically going on with galaxies and BH and super novas. I know this is probably where its going to get heavy in the math area. So if you have to let it fly. Again, I'M really intrigued by all this don't get me wrong and if I offend someone I'M sorry, I did not mean too.

You're putting far too much speculation into a lot of things. If you want to go this route, we don't know anything. Yet your cell phone continues to work, your computer boots up, we communicate with satellites, etc. Our understanding of a lot of physics is, at the very least, a very good approximation of reality. Our knowledge of our own sun is quite extensive in most areas, although lacking in a few. Fundamental things such as the composition of the sun and its mechanism for energy production are so well established that I would call them fact.

As far as BH's are concerned, which is really what this thread is about, they seem to be purely theoretical constructs to most people. However, there is a lot of evidence for their existence in the universe. For one, the observed high-intensity x-ray radiation spectra from certain objects conforms almost exactly to what is predicted in the situation of a BH accretion matter. More direct evidence (I would consider) comes from observations of gravitational interactions where we deduce there are x solar masses of material in a space of y, so the density must be z, where z corresponds to densities that result in a black hole.

As far as galactic modelling is concerned it is notoriously difficult to study our own galaxy because of the massive amount of dust which interferes with measurements. We did discover that our galaxy was bigger than previously thought, but not so much so that it drastically changed our concept of the Milky Way. We also recently discovered that the milky way is probably a barred spiral galaxy instead of a normal spiral galaxy. The refinement of measurements leads to more and more accurate data which allow us to refine our models, but in general they are not terribly far off.

Like I said at the beginning of this post, I think you are introducing far more uncertainty than actually exists into a realm of study where (although we cannot directly manipulate objects), many things are quite well understood.