| Black holes...help! Posted: 3/7/2007 12:35:51 AM | Okay I have nearly given up with this question, however you guys seem quite informative on here and maybe you can help me:
First of all, I want you to know I am familiar with the concept of a 'black' (HOLE.) However I cannot get my head around the concept of a black hole in space..bear with me here...
I am led to believe when picturing a black hole..as a hole..a hole in space..sureley it should be a black sphere! Not hole!?
I shall try to explain:
If I am on earth...anywhere on earth, the gravitational pull would be the same.whether in China, Australia or the Americas.
And the same would be true if I was on a neutron star..?
when a neutron star collapses...it collapses on itself...yes? and the gravitational pull would be equal..Yes?
So when a black hole is produced regardless at which angle I or an object approached the black hole...the gravitational pull would be the same? thus it would be a black shpere not hole...?
Would be grateful for your thoughts on this | |
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| Black holes...help! Posted: 3/7/2007 4:10:41 AM | Black holes - should be called Black Spheres
By calling them Black Holes, individuals consider that they are a place where one goes after entering it - likened to the black hole that Bugs Bunny jumps into when he's trying to escape Elmer Fudd.
The reality is that these are Black Spheres that have no top or a bottom. They draw matter into them without bias, from all directions. Once a piece of matter or a spaceship is drawn onto the surface of a Black Sphere, it is consumed as matterless particles with minimal energy being released to signify the immediate destruction.
These are not Black Holes, but rather Black Spheres that consume everything around them.??????
Black holes are the densest, most massive singular objects in the universe. Formed in one of three main processes, they exert so much gravitational force that nothing - not even light - can escape their pull. Since nothing can ever come out, it is called a HOLE. Since not even light nor other electromagnetic radiation can escape, it is called a BLACK HOLE
The event horizon is depicted as a black sphere and within is the black hole
And of course that totally cleared it up for you honey ......... Not ...... teehee | |
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| Black holes...help! Posted: 3/7/2007 4:45:19 AM | By calling them Black Holes, individuals consider that they are a place where one goes after entering it - likened to the black hole that Bugs Bunny jumps into when he's trying to escape Elmer Fudd.
The reality is that these are Black Spheres that have no top or a bottom. They draw matter into them without bias, from all directions. Once a piece of matter or a spaceship is drawn onto the surface of a Black Sphere, it is consumed as matterless particles with minimal energy being released to signify the immediate destruction.
You never cease to amaze me! Wow...clever as well as beautiful......I am so gonna marry you! | |
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| Black holes...help! Posted: 3/7/2007 4:55:59 AM | ROFLMAO!!!!!!! Woooooooooooohoooooooooooooooooooooooooo | |
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| Black holes...help! Posted: 3/7/2007 9:32:25 AM | The gravitational pull from the center of a black hole is so great that light, which is subject to gravity, will be pulled back in. That's why they're black - light does not escape them. We've been watching black holes for a little more than a decade I believe.
Incidentally, if you want space/time travel you can check out wormholes. http://en.wikipedia.org/wiki/Wormhole | |
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| Black holes...help! Posted: 3/7/2007 10:20:06 AM | ^^ Good follow-up page that describes wormhole evaporation:
http://en.wikipedia.org/wiki/Hawking_radiation
The article calculates the time for evaporation and mention small blackhole masses have a theoretical 'expiration date' of about 3 or more billion years - so it should be plausible to find evidence of expiring blackholes (explosions?).
Pretty cool stuff. | |
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| Black holes...help! Posted: 3/7/2007 11:32:54 AM | | I don;t get the collapsing in on itself. Once it collapses in on itself, what is on the other side of all that sucking, where is the matter that is getting sucked going after it gets sucked? | |
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| Black holes...help! Posted: 3/7/2007 12:19:31 PM | Basically the mass is so strong that it wraps its self in the "fabric of space" untill there's only a little hole left.
Think of the "fabric of space" as a bag and put a glowing ball inside.
The hole of the bag is your "black hole".
The mass does not go away when you wrap it in a "fabric of space" bag so if you want to fly into a wormhole you're just going to slam right into it.
As for collapsing When the "fabric of space" reaches the objects mid point (equator) it is said to start collaping in on it's self. The fact is that it starts moving into the next dimension giving the illustion that it's shrinking. This is when the hole starts to form. | |
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| Black holes...help! Posted: 3/7/2007 12:34:47 PM | They don't exist, least no one has visited one, or has any physical proof.
Black holes are a theory, subject to be reinvented at any time.
Even Stephen Hawking changed his theory on black holes recently.
Black holes, like many other hollywood creations ie: warp speed, hyper space.. etc
All fictional at the moment... | |
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| Black holes...help! Posted: 3/7/2007 12:41:53 PM |
I don;t get the collapsing in on itself. Once it collapses in on itself, what is on the other side of all that sucking, where is the matter that is getting sucked going after it gets sucked? There is no other side (as far as anyone knows.) It's just all getting squished together.
If you took a sheet of aluminum foil you could ball it up loosely so that it's about the size of a baseball. You could then further squish it so it's the size of a golf ball, and then some more so it's the size of a marble. With a black hole, everything that has fallen into it is squished so small you can't see any of it anymore.
Kind of.  | |
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| Black holes...help! Posted: 3/7/2007 12:55:52 PM | Not exactly, Hawking - the basis of almost all of black hole theory used to feel thet nothing escaped from a black hole. (which all of the world accepted as canon, praised and held aloft for all to see a fact)
Recently he changed his theory that black holes convert matter to enegry to allow it to escape out the other side...
So is he right? or is he wrong?
We can't even figure what came first a chicken or an egg and we can physically interact and alter these things.. how can we even begin to prove an idea that we cannot even see, let alone pysically witness in any way...
Specially when the guy who invented it keeps changing the rules to keep himself employed... | |
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| Black holes...help! Posted: 3/7/2007 1:05:54 PM | In My opinion: Hawking is an egotistical nut and does not deserve being referred to as a father of anything but writing a book non physists could read.
There's a hundred other scientists out there worth more praise. | |
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| Black holes...help! Posted: 3/7/2007 3:28:49 PM | | The Black Hole is what is beyond the Event Horizon. That is the distance from the singularity where the escape velocity exceeds the speed of light. That is what makes the hole "Black". The singularity is a mathematical point that takes up no space where all the mass collapsed into infinite density. For example if the Sun collapsed (yes, I know it doesn't have enough mass for a gravitational collapse) into a singularity its event horizon say may be equal to the Earth's diameter. But the Earth and all the other planets would still remain in orbit because the gravitational interaction has not changed. It is only when you get too close to the Event Horizon where gravity gets incredibly strong and tidal forces will rip you apart before you get sucked into the Event Horizon. I hop that explains some of it for you. | |
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| Black holes...help! Posted: 3/7/2007 5:36:48 PM |
They don't exist, least no one has visited one, or has any physical proof.
Black holes are a theory, subject to be reinvented at any time.
Even Stephen Hawking changed his theory on black holes recently. Regardless of whatever it is that Stephen Hawking does in his spare time, the existence of black holes is a virtual certainty. You are correct that no one has visited one, and even if they did they wouldn't be here to testify, but there is a considerable amount of proof of their existence. One of the black holes in the milky way is in Sagittarius A. Here's some (not very good) pictures of a few more. http://csep10.phys.utk.edu/guidry/violence/active.html
Pictures never do a black hole justice since they don't emit light and are usually too far to see well anyway. Generally we 'see' a black hole by observing the effects of its gravitational pull on its surroundings.
Incidentally, a "theory" takes on a difference of meaning depending on the context in which it is used. In casual conversation, one could make up something ridiculous and call it a theory. In a scientific context a theory is defined as "a coherent group of general propositions used as principles of explanation for a class of phenomena" (or in layman's terms, it is something that explains facts). For example, gravity is a fact, and the explanation for how it works is a theory. A scientific theory in no way implies uncertainty - quite the opposite; a scientific theory has withstood enormous scrutiny from countless others trying desperately to prove it wrong. | |
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| Black holes...help! Posted: 3/7/2007 8:13:42 PM | | Don't think of Black Holes as holes. They're more like vaccuum cleaners. | |
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| Black holes...help! Posted: 3/8/2007 4:58:03 PM |
They don't exist, least no one has visited one, or has any physical proof.
"No one has visited one" That's a good one. The furthest we've been able to send humans has been the moon. Mars will be next. Black holes are many light years away. Even if we could send a probe it would take centuries to get there and centuries and as many years to get a signal back as it is in light years of distance away. And we would never hear back from it because it would be a one way trip. There is plenty of scientific evidence for the existance of black holes. And Einstein thought of it, not Hawking. Hawking has done further research on it. | |
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| Black holes...help! Posted: 3/8/2007 10:23:09 PM | That is the distance from the singularity where the escape velocity exceeds the speed of light.
Actually is it not at the Event Horizon where nothing including light can escape. The singularity is that point right in the center where the most density where ALL the matter and other things end up. The Event Horizon represents the point of no return for anything including light. | |
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| Black holes...help! Posted: 3/9/2007 1:35:35 AM | Black holes were 'discovered' as a theoretical object in the late 1700's or early 1800's as an exercise to find out if the Newtonian Theory would be able to calculate at what mass and volume would not allow light to escape. I don't remember who it was but I do remember reading a number of years ago of a physicist who was playing with Newton's equations as a exercise only. As Black Holes being theoretical and never been observed directly, that is true. You cannot see a black hole by definition. You can measure its effect on the surrounding space. What happens to material that enters the black hole, no one knows either. The known mathematics for calculating what happens totally breaks down. | |
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| Black holes...help! Posted: 3/9/2007 8:59:03 AM |
Black holes are many light years away.
Hopefully this is true on the macro scale, however our current understanding of cosmology leads us to believe that countless micro-black holes were produced during the Big Bang.
Black holes, like many other hollywood creations ie: warp speed, hyper space.. etc
All fictional at the moment...
Warp Speed's creator is Gene Rodenberry Hyperspace seems to have its modern origins in Asimov's foundation series. Black Holes were first theorized by Einstein.....
Hey, one out of three isn't bad eh?
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| Black holes...help! Posted: 3/9/2007 9:51:03 AM | Uhh, not so fast.
First, see this page: http://casswww.ucsd.edu/public/tutorial/GR.html
Under Black Holes:
The French mathematician LaPlace first speculated about the existence of an object so compact that the escape speed would be greater than the speed of light. The first relativistic calculation was performed by Karl Schwarzschild (1916) shortly after Einstein published his theory. Curiously, Schwarzschild's result is the same as that of LaPlace.
So, we look up Laplace at Wikipedia: http://en.wikipedia.org/wiki/Pierre-Simon_Laplace
And we find that indeed, he was publishing this theory in the early 1800s.
This is neither common knowledge nor would be naturally expect a hypothesis of blackhole behavior to precede Relativity Theory of the Twentieth century by nearly a hundred years.
I am impressed with Auggies mention of LaPlace.  | |
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| Black holes...help! Posted: 3/9/2007 12:12:02 PM | Uhh, not so fast sombient.
Theorizing about an 'object', and mathematically proving the mechanics of black holes are two seperate things. Are we to credit Democritus with the discovery of atoms because he dreamed of their possibility in 5th century BC? Of course not. | |
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| Black holes...help! Posted: 3/9/2007 12:31:40 PM | | It's kind of like in string theory where they are trying to prove the absense of the graviton which explains why gravity is way less powerful than strong force/EM. THey can only postulate that because there is this great absence of light with all this high energy stuyff whirlin g arond it that they conclude it's a black hole in the middle. it could just be an optical illusion what with our primitive instruments and all. until someone gets close enough to see a black hole but not be sucked into it I won't believe it. It is a nice theory though. | |
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| Black holes...help! Posted: 3/9/2007 12:47:31 PM | Here is something interesting that you may want to read.
Try to jump so high that you fly right off of the Earth into outer space. What happens? Why don't you get very far? You are essentially trapped on Earth, unless you can find a rocket that can travel at escape velocity away from the Earth. The escape velocity can be calculated in Newtonian gravity by using energy conservation of an object of mass m in the gravitational field of a planet of mass M in D space dimensions: The escape velocity for the surface of the Earth is about 11 km/sec. Notice that's only 37 millionths of the speed of light. Under what conditions would the escape velocity from the surface of some planet or star be equal to the speed of light? For a planet the mass of the Earth, this distance is only about a centimeter. So if the Earth were less than a centimeter in diameter, the escape velocity at the surface would be greater than the speed of light. But thanks to Einstein we learned that when any velocity in a gravitating system approaches the speed of light, the Newtonian theory of gravity has to be put aside for the relativistically invariance theory of Einstein. The relativistic formulation of gravity in General Relativity starts with the Einstein equation relating the curvature of the spacetime geometry to the energy of the matter and radiation in the spacetime The solution to the Einstein equations for the spacetime around a planet or star of mass M is called the Schwarzschild metric (This is for d=4 spacetime dimensions. Can you guess from the Newtonian limit for D space dimensions what the Schwarzschild metric looks like for d spacetime dimensions?) In units where Newton's constant and the speed of light are both set to unity, the gravitational radius RG can be written Note that an assumption has been made that we are outside the gravitating body in question. If we're outside the body, and the radial size R of the body satisfies R>RG, then we don't need to know about what happens at coordinate r=RG because this metric doesn't apply to r RG to r RG. In this case, this gravitating body is called a black hole, and at the coordinate value r=RG, there exists something called a black hole event horizon. The event horizon is the relativistic geometric expression of the escape velocity becoming equal to the speed of light. Once anything, even light, crosses the event horizon, it can never escape back out to r>RG again. Black holes can be created by the gravitational collapse of large stars that are at least twice as massive as our Sun. Normally, stars balance the gravitational force with the pressure from the nuclear fusion reactions inside. When a star gets old and burns up all of its hydrogen into helium and then turns the helium into heavier elements like iron and nickel, it can have three fates. The first two fates occur for stars less than about twice the mass of our Sun (and one of them will be our Sun's eventual fate). These two fates both depend on the fermionic repulsion pressure described by quantum mechanics -- two fermions cannot be in the same quantum state at the same time. This means that the two stable destinies for a collapsing star will be: 1. a white dwarf supported by the fermionic repulsion pressure of the electrons in the heavy atoms in the core 2. a neutron star supported by the fermionic repulsion pressure of the neutrons in the nuclei of the heavy atoms in the core If the mass of the collapsing star is too large, bigger than twice the mass of our Sun, the fermionic repulsion pressure of either the electrons or the neutrons is not strong enough to prevent the ultimate gravitational collapse into a black hole. The estimated age of the Universe is several times the lifespan of an average star. This means there must have been a lot of stars bigger than twice the mass of our Sun that have burned their hydrogen and collapsed since the Universe began. Our Universe ought to contain many black holes, if the model that astrophysicists use to describe their formation is correct. Black holes created by the collapse of individual stars should only be about 2 to 100 times as massive as our Sun. Another way that black holes can be created is the gravitational collapse of the center of a large cluster of stars. These types of black holes can be very much more massive than our Sun. There may be one of them in the center of every galaxy, including our galaxy, the Milky Way. The black hole shown above sits in the middle of the galaxy called NGC 7052, surrounded by a bright cloud of dust 3,700 light-years in diameter. The mass of this black hole is about 300 million times the mass of our Sun. | |
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| Black holes...help! Posted: 3/9/2007 4:11:50 PM |
That is the distance from the singularity where the escape velocity exceeds the speed of light.
Actually is it not at the Event Horizon where nothing including light can escape. The singularity is that point right in the center where the most density where ALL the matter and other things end up. The Event Horizon represents the point of no return for anything including light.
Thanks, that's what I meant to say. | |
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