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What are black holes? Dont call me stupid for not knowing this but what are they?

google?

Ahhh. . . large things in space.

Something to do with when a star explodes, or something.

Basically, I don't know.

Think of Rosanne or Oprah, and you'll have a good idea of what they do-- Consume everything

Yeah, black holes are fat and stupid.

Wait, what?

A black hole is any region of space so dense that nothing can escape, not even light.

Originally posted by DrDoom101
What are black holes? Dont call me stupid for not knowing this but what are they? Extreme gravitational points wich were caused by dying stars or something.. Instead of imploding it just keeps pulling everything together with extreme proportions..
Matter can't escape (only through radiation I think) and not even light can escape wich makes it black (nothing).

Well.. Something like that.. I hope it gives you an idea.

Okay, there are two forces at work in stars: nuclear fusion, which makes the star burn and pushes outwards, and gravety, which pushes inwards. When a very big star dies, gravety causes the star to collapse. And, since the laws of gravitation involve mass, the bigger the star, the more powerful the force of gravtity. If the star is big enough, than it will collapse into a "black hole," which has such a powerful gravitational pull that not even light can escape it.

Of course, that's just from memory. You could check Wikepedia or something.

I don't get it.

*lays down*

Originally posted by Gregory
If the star is big enough, than it will collapse into a "black hole," which has such a powerful gravitational pull that not even light can escape it.




Most data on black holes is rather weak, but the above is deemed to be accurate.

It is also believed that they may be "holes" to other dimensions etc. Truth is, we don't know much about them.

Originally posted by ToMacco
I don't get it.

*lays down*

Okay, let's say you have a star and a nearby object. The gravitational force between them is (Gm1m1)/(r2) where G is the gravitational constant, m1 is the mass of the star, m2 is the mass of the object, and r (that's r squared in the equation, by the way) is the distance between the center of the star and the center of the object. Now, suppose the star begins to collapse.

Now (I had to ask for clarification from another bulliten board for this, so don't feel bad about not getting it): The mass of the star equals the density of the star times the volume. Mass is a constant, so when the volume of the star decreases (it's collapsing, remember), density has to increase. This results in what's called a singularity, with infinite density, zero volume, and the same mass the star had before it collapsed.

It's misleading to say that a black hole is somehow more gravitationally powerful than the star before it turned into a black hole. If our Sun turned into a black hole, for example, we wouldn't notice any difference (except that we'd have no heat or light). But the black hole is much, much smaller than the original star, and that means you can get a lot closer to the center of it. The force between a black hole and another object is (Gm1m1)/(r2), the same as before, but we can now make r as small as we want. As r decreases, the gravitational force increases, and it will eventually get so strong that even light can't escape from it once it gets close enough.

Well, that was long-winded, but maybe it helped? Credit to the folks at this forum for helping me out.

Thanks, guys

Every galaxy has a super massive black hole at its center. This causes the quaser (The huge light in the center) Black holes are just pits of gravity in space.

A black hole occurs when a fat person bends over.

Actually, thanks to Hawking radiation, black holes are really considered charcoal gray.

Black Holes tend to occur everytime Courtney Love opens her mouth or does the splits.

Originally posted by Itzak
A black hole is any region of space so dense that nothing can escape, not even light.

I can escape it

Originally posted by ToMacco
Ahhh. . . large things in space.


quite the opposite...most of them are tiny...they just have massive amounts of mass and therefor gravity

supermassive black holes on the other hand are an altogether different and still partly theoretical ball game

ever wondered why some galaxies seem to spin around a centre like water down a plug hole?....the answer could be supermassive black holes...and they could be several billion times the mass of our sun

Originally posted by jaden101
quite the opposite...most of them are tiny...they just have massive amounts of mass and therefor gravity

Indeed they are and they do Jade.

if i remember right...black holes form from generally larger mass stars...

stars in there "death" phase go through an expansion phase caused by the running out of nuclear fuel (hydrogen and then helium) which causes its gravitational pull to weaken its hold on the outer layers...thus the star exapands and forms a red supergiant

this pic gives an idea of how big a red supergiant would be in relation to our own solar system

http://zebu.uoregon.edu/~imamura/208/mar1/sg.gif

almost at jupiter...completely enveloping all the inner planets

after this comes the supernova...the explosion stage...one was witnessed by astronomers years ago that outshined the entire galaxy it was located in by over a million times

the pic is of a supernova remenant

http://www.xtec.es/~rmolins1/univers/fotos/estel00.jpg



http://heasarc.gsfc.nasa.gov/Images/animation/supernova.gif

supernovas occur when all the stars fuel is spent...the star collapses in on itself and in doing so creates a massive explosion

most supernova result in the formation of neutron stars...so called because the gravitational force created actually crushes atoms...the outer shell negatively charged electrons are forced into the atoms nucleus and cancel out the positively charged protons...thus leaving neutrons...and thus the name neutron star

the magentic field of a neutron star is about 100 trillion times that of the earth...they are about the size of a large city but in density and mass...every single person alive today could be squashed into the size of a sugar cube....if you weight 150 lbs on earth...on a neutron star you would weigh 21,000,000,000,000 lbs

a black hole is and even more extreme case borne from the same actions

instead of stopping at a neutron star...the mass continues to collapse in on itself to the point where it is extremely small...but that size is dependant on the mass of the size that created it....

Bah, Superman would take a Black Hole. Black Holes don't have any arms, how could it fight back?

Originally posted by Red Superfly
Bah, Superman would take a Black Hole. Black Holes don't have any arms, how could it fight back?

cause it would have sucked in a entire kryptonite planet....eat that superman you *****

Yeah, but Superman would win.

Beat that logic.

Originally posted by Red Superfly
Yeah, but Superman would win.

Beat that logic.

thats just cause he...always...does....GOD DAMNIT...IT'S JUST NOT FAIR

The theory is that a black hole is not a hole at all but a super super dense mass that resulted form a certain type of star dying. This object is relatively small. If it were possible for you to hold a piece the size of a marble it would way 1000s of tons and pull pull in everting in its surroundings. Theoretically

Originally posted by ToMacco
Yeah, black holes are fat and stupid.

Wait, what? hysterical

You don't need a lot of mass!! You need huge energy-density to create black holes.
That is, matter squeezed together to tightly, a mere spoonful would weigh thousands of tons or more.

Galactic center black holes are no mere speculation. Go google it or visit NASA or ESA. They're there all right.

The problems with black holes are not as much that they're "black" since the escape velocity from a black hole exceeds the speed of light. They send out massive amounts of radiation that our telescopes can see.
We don't understand what happens INSIDE a black hole. The center is called a gravitational singularity (just as the moment Big Bang occured), because even EInsteins theory for gravity is not enough to calculate and explain what happens. We still need a socalled quantum-theory for gravity, that is a theory to explain how gravity behaves on VERY small scales.
We have quantum theories for the other three forces of nature (hence teh reason we can use and manipulate these forces), but we need to update gravity.
String-theory, I believe, is NOT the answer. When the LHC opens next year this should be proven, and physicist must go back to the drawing table. About time - I want a floating suitcase

true that you need huge energy density...but given that there isn't a way to produce such density without gravity...and given that the greater the mass of an object the greater its gravitational force...then surely you need mass in order to initiate the sequences that leads to black hole creation

as you state though...once the black hole exists...gravitational physics dont apply as they normally would

You can't have ANY mass without gravity, nor energy-density for that matter, so what's your point? The Milkyway contains a huge amount of MASS! Yes? Is it a black hole? No.
The point that a large amount of mass in ITSELF is not enough to create a black hole is important. It's when you squeeze it into a small space, and the gravitational force becomes so strong you create horizons and the escape velocity exceeds speed-of-light that you get a black hole. Granted, you need to start out with something massive, but the Milkyway itself is rather MASSIVE...

Originally posted by The Omega
You can't have ANY mass without gravity, nor energy-density for that matter, so what's your point? The Milkyway contains a huge amount of MASS! Yes? Is it a black hole? No.
The point that a large amount of mass in ITSELF is not enough to create a black hole is important. It's when you squeeze it into a small space, and the gravitational force becomes so strong you create horizons and the escape velocity exceeds speed-of-light that you get a black hole. Granted, you need to start out with something massive, but the Milkyway itself is rather MASSIVE...

the point is that smaller mass stars dont produce black holes because as they collapse, they gravitional forces generated aren't large enough

hence you do need a large mass...

and while the milky way obviously does have a huge amount of mass and thus gravity...it isn't a single entity who's gravity does't work on itself...all the stars work on each other...

http://antwrp.gsfc.nasa.gov/apod/image/0501/milkyway_garlick_big.jpg

although...given that the milky way is a spiral galaxy...there must obviously be a super massive black hole acting on it

the term "going down the plug hole" would be appropriate...

it would appear we are mere fodder for such a black hole...and that all the mass of the milky way will be enveloped by it...but extremely far off into the future

The Encyclopedia Britannica actually used this as the example question

The presence of the galactic black hole was thought to be indicated by the presence of X-rays presumably from compressed matter... shouldn't the X-rays have been trapped?

Jaden101> You have massive single entities in form of stellar nebulas. It's not enough that something contains a lot of mass, you need it to ALSO be squeezed into a small volume to create a gravitational singularity.

Why do you conclude that because the Milkyway is a spiral galaxy it must contain a supermassive black hole at its center?? The presence of supermassive galaxy-center black holes has nothing to do with the shape of the galaxy. The shape is due to the rotation of the galaxy, and the fact that we can't see all the mass (dark matter) whose gravity act on the galaxy itself.

So there is nothing "going down the plug hole" because of the galactic shape. For all we know everything will be ripped apart in the distance future because of dark energy. To the best of my knowledge we're still to see a "dead" galaxy.

Shaber> When matter falls into a black hole it's accelerated to extremely high velocities and send out radiation. It's not that a black hole can suck up everything that passes it, you need to get "close enough". Check up on event horizons and Schwarschild radius

yes but the point is that without the mass it wouldn't collapse in on itself enough to cause the singularity...hence the fact that smaller stars dont form black holes...because their mass and thus their gravitational power isn't strong enough

normally stellar objects work on each other. hence planets going round the sun, moon going around planets...in a nebulla...although it can be considered a single entity...it still contains many seperate sources of gravity which all act on each other thus preventing it collapsing in on itself

when a star dies, its own gravitational force acts on its own mass and pulls it in on itself...thus creating a higher energy density and a higher gravitational force...thus causing it to collapse in on itself

but the extent to which it can do this is dependant on the initial mass

What was the term for the mass of a supernova's lower limit? Something like 1.4 X Sun mass.

Jaden101> Ehrm... Actually, stellar nebulas occasionally Do collapse to form... stars! If the star formed i a stellar giant its gravity may, after going supernova, form a black hole. We do not disagree on that fact. However, it is still important to have high energy-density.

Shaber> Can't remember. I think it's more than 1,4 x Sun. The Sun is nowhere near massive enough to go supernova. It's go... quietly